Composition for fuel cell peripheral components and molded article comprising the composition

Abstract

To provide a composition usable for fuel cell peripheral components that offers low water absorptivity and ion leachability, capable of suppressing increase in conductivity, and a molded article comprising the composition.SOLUTION: A composition for fuel cell peripheral components has water absorptivity of 3.0% or less when subjected to a temperature of 95°C over a period of 500 hours, and is free of copper compounds. There is also provided a molded article comprising the composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composition that can be used for fuel cell peripheral parts and a molded article made of the composition. [Background technology]

[0002] In order to prevent the deterioration of the global environment, various industries are required to reduce carbon dioxide emissions. In particular, in automotive applications, carbon dioxide emissions from the combustion of fuels such as gasoline have become a problem, and the development of cleaner automobiles is being actively pursued.

[0003] One such example is the fuel cell vehicle. Fuel cells are a mechanism for generating electricity from hydrogen and oxygen, and are a clean method of generating electricity that only emits water as a by-product. In addition, compared to electric vehicles, which are also being actively developed, fuel cells have the advantage of being able to travel a longer distance (driving range) on a single refueling, and efforts to put them to practical use are accelerating, especially in commercial vehicles that tend to travel long distances.

[0004] Low ion elution is a required characteristic of materials used in fuel cell vehicles, especially in fuel cell peripheral parts. This is mainly because eluted ions reduce the power generation performance of the fuel cell and increase the electrical conductivity of the coolant, reducing its insulating performance.

[0005] On the other hand, polyamide is widely used in automotive parts due to its excellent mechanical properties and chemical resistance. However, polyamide absorbs water, and there are concerns that ions may easily leach into the water, so its application to peripheral parts of fuel cells is limited.

[0006] Widely known examples include the use of polyphenylene ether or polyether ketone resins, which are less likely to absorb water, and a structure having a protective layer to prevent polyamide from coming into contact with fluids. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2006-009819 [Patent Document 2] Patent Publication No. 2013-064129 [Patent Document 3] Patent Publication No. 2005-090863 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a composition that has low water absorption and ion elution properties and is capable of suppressing an increase in electrical conductivity, and that can be used in peripheral parts for fuel cells, and a molded article using the composition. [Means for solving the problem]

[0009] As a result of intensive research aimed at solving the above problems, the present inventors have conceived the following invention and found that the above problems can be solved.

[0010] That is, the present invention provides the following [1] to [5]. [1] A composition for use in peripheral parts of a fuel cell, comprising a polyamide, having a water absorption rate of 3.0% or less at 95°C for 500 hours, and containing no copper-based compounds. [2] The composition for fuel cell peripheral parts according to [1], wherein the polyamide contains diamine units and dicarboxylic acid units, the diamine units containing aliphatic diamine units having 9 to 12 carbon atoms, and the dicarboxylic acid units containing aromatic dicarboxylic acid units. [3] The polyamide composition for fuel cell peripheral parts according to [2], wherein the diamine unit contains at least one selected from the group consisting of 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine. [4] The composition for fuel cell peripheral parts according to [2] or [3], wherein the dicarboxylic acid unit contains at least one selected from the group consisting of terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. [5] A molded article made of the composition for fuel cell peripheral parts described in any one of [1] to [4]. Effect of the Invention

[0011] According to the present invention, it is possible to provide a composition and a molded article that have low water absorption and ion elution properties, can suppress an increase in electrical conductivity, and can be used for peripheral parts of a fuel cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described based on one example. However, the embodiment shown below is an example for embodying the technical idea of ​​the present invention, and the present invention is not limited to the following description. In addition, in this specification, preferred embodiments are shown, but a combination of two or more of the individual preferred embodiments is also a preferred embodiment. When there are several numerical ranges for matters shown as numerical ranges, the lower limit and upper limit can be selectively combined to form a preferred embodiment. In this specification, when a numerical range is stated as "XX to YY", it means "not less than XX and not more than YY". Furthermore, in this specification, a "unit" (where "" indicates a monomer) means a "structural unit derived from", for example, a "dicarboxylic acid unit" means a "structural unit derived from a dicarboxylic acid", and a "diamine unit" means a "structural unit derived from a diamine".

[0013] (polyamide) The composition for fuel cell peripheral parts of this embodiment (hereinafter also referred to as "composition") contains a polyamide, and the polyamide contains a diamine unit and a dicarboxylic acid unit.

[0014] [Diamine unit] In this embodiment, the diamine unit includes an aliphatic diamine unit having 9 to 12 carbon atoms.

[0015] Examples of the aliphatic diamine unit having 9 to 12 carbon atoms include 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-propyl-1,6-hexanediamine, 2-ethyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 1,3-di Examples of the diamine unit include methyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, and 5-methyl-1,9-nonanediamine. The diamine unit may be one type or a combination of two or more types.

[0016] Among the diamine units, from the viewpoint of more remarkably exhibiting the effects of the present invention, a constitutional unit derived from at least one diamine selected from the group consisting of 1,9-nonanediamine, 1,10-decanediamine, and 2-methyl-1,8-octanediamine is preferred.

[0017] The diamine units preferably account for 80 mol % or more, more preferably 90 mol % or more, and may even account for 100 mol % of the diamine units constituting the polyamide of this embodiment.

[0018] The polyamide may contain, as a diamine unit, a diamine unit other than the above diamine units (hereinafter also referred to as "other diamine units".) Examples of the other diamine units include alicyclic diamine units and aromatic diamine units.

[0019] Examples of the alicyclic diamine unit include cyclohexanediamine, methylcyclohexanediamine, norbornanedimethylamine, tricyclodecanedimethyldiamine, bis(4-amino-3-ethylcyclohexyl)methane, and bis(4-amino-3-ethyl-5-methylcyclohexyl)methane.

[0020] Examples of the aromatic diamine unit include p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylether, and 4,4'-methylenedi-2,6-diethylaniline.

[0021] The content of the other diamine units is preferably 20 mol % or less of the diamine units constituting the polyamide.

[0022] [Dicarboxylic acid unit] In this embodiment, the dicarboxylic acid units include aromatic dicarboxylic acid units.

[0023] Examples of the aromatic dicarboxylic acid unit include terephthalic acid, isophthalic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, and naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. The aromatic dicarboxylic acid unit may be of one type or a combination of two or more types.

[0024] Among the dicarboxylic acid units, from the viewpoint of more remarkably exhibiting the effects of the present invention, a structural unit derived from at least one dicarboxylic acid selected from the group consisting of terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid is preferred.

[0025] The dicarboxylic acid units preferably account for 80 mol % or more, more preferably 90 mol % or more, and may even be 100 mol % of the dicarboxylic acid units constituting the polyamide of this embodiment.

[0026] The polyamide of this embodiment may contain, as a dicarboxylic acid unit, a dicarboxylic acid unit other than the above dicarboxylic acid unit (hereinafter also referred to as "other dicarboxylic acid unit"). Examples of the other dicarboxylic acid unit include an aliphatic dicarboxylic acid unit and an alicyclic dicarboxylic acid unit.

[0027] Examples of the aliphatic dicarboxylic acid unit include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, dimethylmalonic acid, 2,2-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, and trimethyladipic acid.

[0028] Examples of the alicyclic dicarboxylic acid unit include 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid.

[0029] The content of other dicarboxylic acid units is preferably 20 mol % or less of the dicarboxylic acid units constituting the polyamide.

[0030] The molar ratio of diamine units to dicarboxylic acid units in the polyamide [diamine units / dicarboxylic acid units] is preferably 45 / 55 to 55 / 45. When the molar ratio of diamine units to dicarboxylic acid units is within the above range, the polymerization reaction proceeds smoothly, and a composition having desired excellent physical properties is easily obtained. The molar ratio of the diamine unit to the dicarboxylic acid unit can be adjusted according to the compounding ratio (molar ratio) of the raw material diamine to the raw material dicarboxylic acid.

[0031] The total ratio of diamine units and dicarboxylic acid units in the polyamide (the ratio of the total number of moles of diamine units and dicarboxylic acid units to the number of moles of all the structural units constituting the polyamide) is preferably 80 mol% or more, more preferably 90 mol% or more, and may be 100 mol%. By having the total ratio of diamine units and dicarboxylic acid units in the above range, a composition having more excellent desired physical properties can be obtained.

[0032] [Amino carboxylic acid unit] The polyamide may further contain aminocarboxylic acid units in addition to the diamine units and dicarboxylic acid units. Examples of the aminocarboxylic acid unit include structural units derived from lactams such as caprolactam and lauryllactam, and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. The content of the aminocarboxylic acid unit in the polyamide is preferably 20 mol % or less relative to 100 mol % in total of the diamine units and dicarboxylic acid units constituting the polyamide.

[0033] [Polycarboxylic acid unit] The polyamide may also contain structural units derived from trivalent or higher polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid, to the extent that melt molding is possible, so long as the effects of the present invention are not impaired.

[0034] [End capping agent unit] The polyamide may contain structural units derived from an end-capping agent (end-capping agent units). The terminal blocking agent unit is preferably 1.0 mol% or more, more preferably 2.0 mol% or more, and preferably 10 mol% or less, more preferably 5.0 mol% or less, based on 100 mol% of the diamine unit. When the content of the terminal blocking agent unit is within the above range, a polyamide having the desired excellent physical properties is easily obtained. The content of the terminal blocking agent unit can be adjusted to be within the above desired range by appropriately adjusting the amount of the terminal blocking agent when charging the polymerization raw materials. In addition, taking into consideration that the monomer component volatilizes during polymerization, it is desirable to finely adjust the amount of the terminal blocking agent charged so that a desired amount of the terminal blocking agent unit is introduced into the obtained polyamide. As a method for determining the content of the terminal blocking agent unit in the polyamide, for example, as shown in JP-A-7-228690, the inherent viscosity is measured, and the total amount of terminal groups is calculated from the relational equation between the inherent viscosity and the number average molecular weight, and the amount of amino groups and the amount of carboxyl groups determined by titration are subtracted from the total amount of terminal groups, or 1 Examples of the method include a method of determining the amount of the diamine unit and the amount of the end-capping agent unit based on the integral values ​​of the signals corresponding to the diamine unit and the end-capping agent unit using H-NMR, and the latter method is preferred.

[0035] As the terminal blocking agent, a monofunctional compound having reactivity with a terminal amino group or a terminal carboxyl group can be used.Specific examples include monocarboxylic acid, acid anhydride, monoisocyanate, monoacid halide, monoester, monoalcohol, monoamine, etc. From the viewpoint of reactivity and the stability of the blocked end, a monocarboxylic acid is preferable as a terminal blocking agent for a terminal amino group, and a monoamine is preferable as a terminal blocking agent for a terminal carboxyl group.From the viewpoint of ease of handling, etc., a monocarboxylic acid is more preferable as a terminal blocking agent.

[0036] The monocarboxylic acid used as the terminal blocking agent is not particularly limited as long as it is reactive with an amino group, and examples thereof include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclopentane carboxylic acid and cyclohexane carboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalene carboxylic acid, β-naphthalene carboxylic acid, methyl naphthalene carboxylic acid, and phenyl acetic acid; and any mixtures thereof. Among these, at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid is preferred from the standpoints of reactivity, stability of blocked terminals, and price.

[0037] The monoamine used as the terminal blocking agent is not particularly limited as long as it is reactive with a carboxyl group, and examples thereof include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, etc.; alicyclic monoamines such as cyclohexylamine, dicyclohexylamine, etc.; aromatic monoamines such as aniline, toluidine, diphenylamine, naphthylamine, etc.; any mixtures thereof, etc. Among these, at least one selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline is preferred in terms of reactivity, high boiling point, stability of blocked terminals, and cost.

[0038] (Physical properties of polyamide) The polyamide preferably has an inherent viscosity of 0.5 dl / g or more, more preferably 0.7 dl / g or more, and preferably 2.0 dl / g or less, more preferably 1.5 dl / g or less. By having the inherent viscosity in the above range, the polyamide can have more excellent desired physical properties. The inherent viscosity of the polyamide can be determined by measuring the flow time of a solution in concentrated sulfuric acid having a concentration of 0.2 g / dl and a temperature of 30° C., and more specifically, by the method described in the examples.

[0039] The polyamide preferably has a melting point of 250° C. or higher, more preferably 280° C. or higher. The melting point in the above range allows the polyamide to have excellent heat resistance. There is no particular upper limit to the melting point of the polyamide, but in consideration of moldability, it is preferably 330° C. or lower. The melting point of the polyamide can be determined as the peak temperature of an endothermic peak that appears when the temperature is raised at a rate of 10° C. / min using a differential scanning calorimetry (DSC) analyzer.

[0040] The polyamide preferably has a glass transition temperature of not less than 110° C., and more preferably not less than 120° C. When the glass transition temperature is in the above range, the polyamide can have excellent heat resistance. The glass transition temperature of a polyamide can be determined as the temperature of an inflection point that appears when the temperature is raised at a rate of 20° C. / min using a differential scanning calorimetry (DSC) analyzer.

[0041] The amount of terminal amino groups ([NH2]) in the molecular chain of the polyamide is preferably 5 μmol / g or more, more preferably 10 μmol / g or more. Also, it is preferably 100 μmol / g or less, more preferably 90 μmol / g or less. If the amount of terminal amino groups is small, the adhesion to the fibrous filler is insufficient, making it difficult to improve the mechanical properties, and if the amount of terminal amino groups is large, crosslinking reactions between molecules progress, reducing the heat resistance and the stability of the melt viscosity during processing. The amount of terminal amino groups in the polyamide can be determined by titrating a phenol solution in which the polyamide is dissolved, with an aqueous hydrochloric acid solution.

[0042] The amount of terminal carboxyl groups ([COOH]) in the molecular chain of the polyamide is preferably 5 μmol / g or more, more preferably 10 μmol / g or more. Also, it is preferably 100 μmol / g or less, more preferably 90 μmol / g or less. If the amount of terminal carboxyl groups is small, adhesion to the fibrous filler is insufficient, making it difficult to improve mechanical properties, and if the amount of terminal carboxyl groups is large, hydrolysis is likely to occur, reducing chemical resistance. The amount of terminal carboxy groups in the polyamide can be determined by titrating a cresol solution in which the polyamide is dissolved, with a potassium hydroxide solution.

[0043] (Production method of polyamide) The polyamide can be produced by any method known as a method for producing crystalline polyamide. For example, it can be produced by a melt polymerization method, a solid-state polymerization method, a melt extrusion polymerization method, etc., using dicarboxylic acid and diamine as raw materials. Among these, the solid-state polymerization method is preferable from the viewpoint of being able to better suppress thermal degradation during polymerization.

[0044] The polyamide can be produced, for example, by first adding diamine, dicarboxylic acid, and if necessary, a catalyst and an end-capping agent all at once to produce a nylon salt, then heating and polymerizing the prepolymer at a temperature of 200 to 250 ° C., and then further solid-phase polymerizing the prepolymer, or polymerizing the prepolymer using a melt extruder. When the final stage of polymerization is performed by solid-phase polymerization, it is preferable to perform the polymerization under reduced pressure or in an inert gas flow, and if the polymerization temperature is within the range of 200 to 280 ° C., the polymerization rate is high, the productivity is excellent, and coloring and gelation can be effectively suppressed. When the final stage of polymerization is performed using a melt extruder, the polymerization temperature is preferably 370 ° C. or less, and when polymerization is performed under such conditions, a polyamide with almost no decomposition and little deterioration can be obtained.

[0045] Examples of catalysts that can be used in producing the polyamide include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts or esters thereof. Examples of the salts or esters include salts of phosphoric acid, phosphorous acid, or hypophosphorous acid with metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony; ammonium salts of phosphoric acid, phosphorous acid, or hypophosphorous acid; ethyl esters, isopropyl esters, butyl esters, hexyl esters, isodecyl esters, octadecyl esters, decyl esters, stearyl esters, and phenyl esters of phosphoric acid, phosphorous acid, or hypophosphorous acid.

[0046] The amount of the catalyst used is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and preferably 1.0% by mass or less, more preferably 0.5% by mass or less, based on 100% by mass of the total mass of the raw materials. If the amount of the catalyst used is equal to or more than the lower limit, polymerization proceeds well. If the amount is equal to or less than the upper limit, impurities derived from the catalyst are less likely to be generated.

[0047] (Additives) The composition of this embodiment does not contain a copper-based compound. If a copper-based compound is contained, the water absorption rate increases, and ions derived from the copper-based compound are eluted, resulting in an increase in electrical conductivity. Examples of the copper-based compound include a mixture of copper halide and an alkali metal halide, copper oxide, and copper hydroxide. Examples of the mixture of copper halide and an alkali metal halide include a mixture of copper iodide and potassium iodide, and a mixture of copper iodide and potassium bromide.

[0048] It is preferable that the composition of this embodiment contains as few metal components as possible other than the copper-based compound.

[0049] The composition of this embodiment may contain known additives other than the copper-based compound, as long as the effect of this embodiment is not impaired. Examples of known additives include fibrous fillers such as carbon fiber, glass fiber, wollastonite, and aramid fiber; antioxidants such as hindered phenol antioxidants, hindered amine antioxidants, phosphorus antioxidants, and thio antioxidants; colorants; ultraviolet absorbers; light stabilizers; antistatic agents; flame retardants such as brominated polymers, antimony oxide, and phosphinate salts; flame retardant assistants; crystal nucleating agents; plasticizers; lubricants; lubricants; dispersants; oxygen absorbers; hydrogen sulfide adsorbents; crystallization retarders; non-fibrous fillers such as flat or cocoon-shaped; impact modifiers such as α-olefin copolymers and rubbers.

[0050] The properties of the additive are not particularly limited as long as they do not impair the effects of this embodiment, and the additive may be a new product that has just been manufactured, or a product that has been separated and recovered from a product that has been used once in a form other than that of this embodiment, which is called a recycled or reused product.

[0051] The content of the additive is not particularly limited as long as it does not impair the effect of this embodiment, but is preferably 0.02 to 200 parts by mass, and more preferably 0.1 to 100 parts by mass, based on 100 parts by mass of polyamide.

[0052] (Production method of the composition) The method for producing the composition is not particularly limited, and a method capable of uniformly mixing the polyamide and the additives can be preferably adopted. The mixing is usually preferably performed by melt-kneading using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or the like. The melt-kneading conditions are not particularly limited, and examples thereof include a method of melt-kneading for about 1 to 30 minutes at a temperature range about 10 to 50° C. higher than the melting point of the polyamide.

[0053] (Properties of the composition) The water absorption rate of the composition when immersed in water at 95°C for 500 hours is preferably 3.0% or less, more preferably 2.5% or less. When the water absorption rate is within the above range, the composition can have a small amount of ion elution and a resistance to increase in electrical conductivity. The water absorption rate of the composition can be determined by injection molding the composition into a test piece with a thickness of 2 mm and then immersing the test piece in an aqueous solution, and more specifically, can be determined by the method described in the examples.

[0054] The composition has an aqueous solution conductivity of preferably 10 mS / m or less, more preferably 8.5 mS / m or less, when immersed in water at 95°C for 500 hours. When the conductivity is within the above range, the insulating properties of the coolant can be kept high, and the composition can be suitably used as a fuel cell peripheral part. The electrical conductivity can be determined by injection molding the composition into a 2 mm thick test piece, immersing the test piece in the aqueous solution, and measuring the electrical conductivity of the aqueous solution after immersion, and more specifically, by the method described in the examples.

[0055] The composition preferably has an amount of ions other than halogen contained in the aqueous solution when immersed in water at 95°C for 500 hours of 16 ppm or less, more preferably 14 ppm or less. When the amount of ions other than halogen is within the above range, the fuel cell is less likely to deteriorate, and the composition can be suitably used as a fuel cell peripheral part. The amount of ion elution can be determined by injection molding the composition into a 2 mm thick test piece, immersing the test piece in the aqueous solution, and measuring the aqueous solution after immersion, and more specifically, the amount of ion elution can be determined by the method described in the examples.

[0056] The composition preferably has an amount of halogen ions of 30 ppm or less, more preferably 10 ppm or less, and even more preferably 5 ppm or less, contained in the aqueous solution when immersed in water at 95°C for 500 hours. When the amount of halogen ions is within the above range, the fuel cell is less likely to deteriorate, and the composition can be suitably used as a peripheral part of the fuel cell. The amount of ion elution can be determined by injection molding a test piece of the composition having a thickness of 2 mm, immersing the test piece in the aqueous solution, and measuring the aqueous solution after immersion, and more specifically, the amount of ion elution can be determined by the method described in the examples.

[0057] (molded product) As one embodiment of the present invention, the composition may be used as a molded article. The method for producing the molded article is not particularly limited, and any known method may be used. In addition, additives such as a chain extender may be added during molding, and heat treatment or electron beam crosslinking may be performed after molding. Furthermore, during molding, surplus parts other than the molded article, such as runners and sprues, may be collected and crushed, and may be used again as materials for molding.

[0058] The molded article of this embodiment can be suitably used as a fuel cell peripheral part, for example, a stack manifold, an end plate, a cell insulator, a water pump housing, an impeller, a bearing, a humidifier housing, an oxygen inlet and outlet, a hydrogen inlet and outlet, a cooling water inlet and outlet, an oxygen pressure regulator, a purge valve housing, a drain valve housing, a gas-liquid separator, an ion exchanger, a radiator tank, an oxygen hose, a hydrogen hose, a cooling water tube, and a reservoir tank. EXAMPLES

[0059] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0060] In the examples and comparative examples, the following commercially available materials were used as additives. Glass fiber "ECS03T-251H", manufactured by Nippon Electric Glass Co., Ltd. Impact modifier "TAFMER MH7010", manufactured by Mitsui Chemicals, Inc. Antioxidants (1) "SUMILIZER GA-80", manufactured by Sumitomo Chemical Co., Ltd. Antioxidants (2) "KG HS01-P", manufactured by PolyAd Services (Copper compounds: mixture of copper iodide and potassium iodide) Lubricants "LICOWAX OP", manufactured by Clariant Chemicals Co., Ltd. · Nucleating agent "TALC ML112", manufactured by Fuji Talc Co., Ltd. Coloring agents "#980B", manufactured by Mitsubishi Chemical Corporation

[0061] The evaluations in the examples and comparative examples were carried out according to the methods described below.

[0062] Polyamide manufacturing Polyamide(1) 6055g of terephthalic acid, 5897g of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 80 / 20 (molar ratio)], 136g of benzoic acid, 12g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 5L of distilled water were placed in an autoclave with an internal volume of 40L and purged with nitrogen. The mixture was stirred at 100°C for 30 minutes, and the temperature inside the autoclave was raised to 220°C over 2 hours. At this time, the pressure inside the autoclave rose to 2MPa. Heating was continued for 5 hours while maintaining the pressure at 2MPa, and the water vapor was gradually released to cause the reaction. Next, the pressure was reduced to 1.3MPa over 30 minutes, and the mixture was reacted for another hour to obtain a prepolymer. The obtained prepolymer was dried at 100°C under reduced pressure for 12 hours and pulverized to a particle size of 2mm or less. This was subjected to solid-phase polymerization at 230° C. and 13 Pa (0.1 mmHg) to obtain polyamide (1) having a melting point of 300° C. and an inherent viscosity of 1.2 dl / g.

[0063] Polyamide(2) Polyamide (2) having a melting point of 265° C. and an inherent viscosity of 1.3 dl / g was obtained in the same manner as polyamide (1), except that the ratio of 1,9-nonanediamine to 2-methyl-1,8-octanediamine was 50 / 50 (molar ratio).

[0064] Polyamide(3) Polyamide (3) having a melting point of 300° C. and an inherent viscosity of 1.1 dl / g was obtained in the same manner as in polyamide (1), except that 4,330 g of a mixture of 1,6-hexamethylenediamine and 2-methyl-1,5-pentanediamine [former / latter=50 / 50 (molar ratio)] was used instead of 1,9-nonanediamine and 2-methyl-1,8-octanediamine.

[0065] Manufacturing of the composition The components other than the polyamide and glass fiber were mixed in advance in the ratios shown in Table 1 and fed into a twin-screw extruder (Toshiba Machine Co., Ltd., "TEM-26SS") from an upstream hopper, and glass fiber was fed into the side feed port on the downstream side of the extruder in the ratios shown in Table 1. The mixture was melt-kneaded and extruded at a cylinder temperature 20 to 30°C higher than the melting point of the polyamide, and then cooled and cut to produce a pellet-shaped composition.

[0066] - Preparation of test specimens Using an injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd. (clamping force: 80 tons, screw diameter: φ26 mm, injection volume: 49 cm3), the compositions obtained in the examples and comparative examples were used to produce flat plates of 100 x 40 x 2 mm under conditions of a cylinder temperature 20 to 30°C higher than the melting point of the polyamide and a mold temperature of 140°C.

[0067] ·Water absorption rate The three plates and 500 mL of distilled water or a 50 / 50 FCC / distilled water solution (FCC: Toyota FC stack coolant) produced by Yamato Scientific Co., Ltd.'s Autostill "WG730" were placed in a pressure-resistant container and treated for 500 hours at a temperature of 95°C. The weight of the plates before and after immersion was measured, and the water absorption rate was calculated using the following formula. Water absorption rate = (weight after water absorption - weight before water absorption) / (weight before water absorption) x 100 (%)

[0068] ·conductivity The aqueous solution was treated in the same manner as in the case of the water absorption rate, and the electrical conductivity was measured using an electrical conductivity meter "CM-41X" manufactured by DKK-TOA Corporation.

[0069] Ion elution amount (other than halogen) The aqueous solution after the same treatment as for the water absorption rate was used, and in the case of distilled water, it was not diluted, and in the case of containing FCC, it was diluted 10 times with ultrapure water produced by an ultrapure water production apparatus "MilliQ Integral 10" manufactured by Merck Ltd., and filtered through a hydrophilic PTFE filter with a pore size of 0.45 μm. Then, the amount of each ion was quantified by quantitative analysis at each observation wavelength shown below using an ICP optical emission spectrometer "iCAP6500Duo" manufactured by Thermo Fisher Scientific. Al: 167.079 nm B: 249.773nm or 249.678nm Ca: 396.847 nm Cu: 327.396nm or 324.754nm Fe: 259.940 nm K: 766.490 nm P: 177.495 nm S: 182.034 nm Si: 251.611 nm

[0070] Ion elution amount (halogen) The aqueous solution after the same treatment as for the water absorption rate was used, and in the case of distilled water, it was not diluted, and in the case of containing FCC, it was diluted 10 times with ultrapure water produced by an ultrapure water production apparatus "MilliQ Integral 10" manufactured by Merck Ltd., and filtered through a hydrophilic PTFE filter with a pore size of 0.45 μm. Then, halogen ions were quantified using an ion chromatography "ICS-6000" manufactured by Thermo Fisher Scientific under the following measurement conditions. Measurement conditions Column: Thermo Fisher Scientific "IonPAC AS20 (4φ×250mm, electrical conductivity detector)" Eluent: KOH gradient elution method Measurement temperature: 30℃ Eluent flow rate: 1mL / min

[0071] Table 1 shows the compositions of the examples and comparative examples and the measurement results thereof.

[0072] [Table 1]

[0073] From Table 1, it can be seen that Examples 1 to 6, which have a water absorption rate of 3.0% or less and do not contain a copper-based compound, have lower electrical conductivity and ion elution amounts than Comparative Example 1, which contains a copper-based compound. Moreover, Comparative Example 2, which has a smaller number of carbon atoms in the diamine unit in the polyamide, is even inferior to the Examples in terms of water absorption rate, electrical conductivity, and ion elution amount.

[0074] As described above, the composition for fuel cell peripheral parts of the present invention can suppress an increase in electrical conductivity and ion elution, thereby contributing to improving the life of fuel cells and improving safety by ensuring the insulation properties of fuel cell systems, and is therefore extremely useful in combination with molded articles made of the composition.

Claims

1. A composition for fuel cell peripheral parts, which contains polyamide, has a water absorption rate of 3.0% or less at a temperature of 95°C for 500 hours, and does not contain a copper-based compound.

2. 2. The composition for fuel cell peripheral parts according to claim 1, wherein the polyamide comprises diamine units and dicarboxylic acid units, the diamine units comprising aliphatic diamine units having 9 to 12 carbon atoms, and the dicarboxylic acid units comprising aromatic dicarboxylic acid units.

3. 3. The composition for fuel cell peripheral parts according to claim 2, wherein the diamine unit comprises at least one selected from the group consisting of 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine.

4. 3. The composition for fuel cell peripheral parts according to claim 2, wherein the dicarboxylic acid unit comprises at least one selected from the group consisting of terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid.

5. A molded article made of the composition for fuel cell peripheral parts according to any one of claims 1 to 4.