JP6838428B2 - Polyamide resin composition for molded products that come into contact with high-pressure hydrogen and molded products using it - Google Patents

Description

The present invention relates to a polyamide resin composition for a molded product that comes into contact with high-pressure hydrogen, which is obtained by blending a specific amount of an amide-based wax with a polyamide 6 resin, and a molded product obtained by molding the same.

In recent years, in order to respond to the depletion of petroleum fuels and the demand for reduction of harmful gas emissions, fuel cells that generate electricity by electrochemically reacting hydrogen with oxygen in the air are installed in automobiles, and the fuel cells generate electricity. Fuel cell electric vehicles, which supply the generated electricity to a motor and use it as a driving force, are attracting attention. As a tank for high-pressure hydrogen for mounting on automobiles, a resin tank in which the outside of a resin liner is reinforced with carbon fiber reinforced resin is being studied. However, since hydrogen has a small molecular size, it is easier to permeate through the resin than natural gas, which has a relatively large molecular size, and high-pressure hydrogen accumulates in the resin more than normal-pressure hydrogen. In the conventional resin tanks, there is a problem that the tank is deformed or destroyed when the high-pressure hydrogen is repeatedly filled and released. Further, when molding a resin liner, there is a problem that the releasability is insufficient.

As a material for a hydrogen tank liner having excellent gas barrier properties and excellent impact resistance even at a low temperature, for example, a material for a hydrogen tank liner composed of a polyamide resin composition containing polyamide 6, a copolymerized polyamide, and an impact resistant material has been studied. (See, for example, Patent Document 1).

Further, as a liner for a gas storage tank having excellent gas barrier properties, for example, a liner for a gas storage tank containing a polymer composition containing a polyamide, a nucleating agent and an impact resistance improving agent has been studied (for example, Patent Documents). 2).

Japanese Unexamined Patent Publication No. 2009-191871 Special Table 2014-501818

Injection molding is one of the methods for manufacturing a molded product that comes into contact with high-pressure hydrogen. For example, when a resin gas storage tank liner is injection-molded, a large-sized molded product is molded. Therefore, the appearance of the molded product may be poor due to insufficient releasability, and the molded product cannot be obtained. There is. Therefore, high mold releasability is required for injection molding of a large molded product.

However, the hydrogen tank liner described in Patent Document 1 is prone to permeation of hydrogen gas and dissolution of hydrogen in the resin, and repeated filling and releasing of high-pressure hydrogen causes defects in the hydrogen tank liner. There was a challenge. In addition, the releasability of the polyamide resin is low, and there is a problem in releasability.

Further, although the liner for a gas storage tank described in Patent Document 2 is excellent in helium gas permeation resistance, hydrogen gas permeation and hydrogen dissolution in the resin are likely to occur, and high-pressure hydrogen is filled and released. Repeatedly, there was a problem that a defect point was generated in the hydrogen tank liner. In addition, the releasability of the polyamide resin is low, and there is a problem in releasability.

In view of the above problems of the prior art, the present invention provides a polyamide resin composition capable of obtaining a molded product having excellent mold releasability by suppressing the occurrence of defect points even if high-pressure hydrogen is repeatedly filled and released. The task is to do.

In order to achieve the above object, the present invention has the following configuration.

0.1 of the amide wax (B), which is an amide compound obtained by reacting 100 parts by weight of the polyamide 6 resin (A) with a higher aliphatic monocarboxylic acid having 10 or more and 30 or less carbon atoms, a polybasic acid and a diamine. formed by 5 parts by weight blended, Ri polyamide resin composition der for moldings touching high-pressure hydrogen, melting point of the amide-based wax (B) is 215 ° C. to 255 ° C., for moldings to touch the high-pressure hydrogen Polyamide resin composition .

The present invention includes a molded product made of the above-mentioned polyamide resin composition that comes into contact with high-pressure hydrogen.

The present invention includes a tank liner for high-pressure hydrogen made of the above-mentioned polyamide resin composition.

The present invention includes a high-pressure hydrogen tank in which a carbon fiber reinforced resin reinforcing layer is laminated on the surface layer of a tank liner made of the above-mentioned polyamide resin composition.

The polyamide resin composition for a molded product that comes into contact with high-pressure hydrogen of the present invention has a high crystallization temperature and crystallization from a molten state proceeds quickly, so that the crystallization rate becomes high, and high-pressure hydrogen is repeatedly charged and released. However, the occurrence of defective points is suppressed, and a molded product having excellent mold releasability can be provided. The molded product of the present invention is less likely to cause defects even after repeated filling and releasing of high-pressure hydrogen, and is usefully developed as a molded product used for applications in contact with high-pressure hydrogen by taking advantage of its excellent mold releasability. It becomes possible to do.

Hereinafter, the present invention will be described in more detail.

The polyamide resin composition for molded products that comes into contact with high-pressure hydrogen of the present invention (hereinafter, may be referred to as "polyamide resin composition") is an amide-based wax (B) with respect to 100 parts by weight of the polyamide 6 resin (A). ) Is compounded in an amount of 0.01 to 10 parts by weight. By blending a specific amount of the amide wax (B) with the polyamide 6 resin (A), which has an excellent balance of moldability, gas barrier property, rigidity and toughness, the crystallization temperature is high and crystallization from the molten state proceeds quickly. Therefore, the crystallization rate becomes high and dense and uniform crystals are formed, so that the permeation of hydrogen gas and the dissolution of hydrogen in the resin can be suppressed, so that high-pressure hydrogen is repeatedly filled and released. However, defects are unlikely to occur. In addition, the releasability at the time of molding is improved, and a molded product having excellent releasability can be obtained. On the other hand, in the combination of the polyamide 6 resin (A) with a mold release agent other than the amide wax (B), an organic nucleating agent, and an inorganic nucleating agent, when high-pressure hydrogen is repeatedly filled and released, the molded product has defects. Is likely to occur, and the releasability at the time of molding is not improved, and the toughness of the molded product is lowered.

The polyamide 6 resin (A) used in the present invention is a polyamide resin mainly composed of 6-aminocaproic acid and / or ε-caprolactam. Other monomers may be copolymerized as long as the object of the present invention is not impaired. Here, "as the main raw material" means that the unit derived from 6-aminocaproic acid or the unit derived from ε-caprolactam is contained in a total of 50 mol% or more in a total of 100 mol% of the monomer units constituting the polyamide resin. Means. It is more preferable that the unit derived from 6-aminocaproic acid or the unit derived from ε-caprolactam is contained in an amount of 70 mol% or more, and more preferably 90 mol% or more.

Other monomers to be copolymerized include, for example, amino acids such as 11-aminoundecanoic acid, 12-aminododecanoic acid and paraaminomethylbenzoic acid, lactams such as ω-laurolactam; tetramethylenediamine, pentamethylenediamine, etc. An aliphatic diamine such as hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine; Aromatic diamines such as metaxylenediamine and paraxylylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5 -Trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethyl piperazine, etc. Alicyclic diamines; aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid; terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid Aromatic dicarboxylic acids such as acids, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1 , 3-Cyclopentanedicarboxylic acid and other alicyclic dicarboxylic acids. Two or more kinds of these may be copolymerized.

The degree of polymerization of the polyamide 6 resin (A) is not particularly limited, but the relative viscosity measured at 25 ° C. in a 98% concentrated sulfuric acid solution having a resin concentration of 0.01 g / ml is in the range of 1.5 to 7.0. Is preferable. When the relative viscosity is 1.5 or more, the melt viscosity of the polyamide resin composition at the time of molding becomes appropriately high, air entrainment at the time of molding can be suppressed, and the moldability can be further improved. The relative viscosity is more preferably 1.8 or more. On the other hand, when the relative viscosity is 7.0 or less, the melt viscosity of the polyamide resin composition at the time of molding is appropriately lowered, and the moldability can be further improved.

The amount of amino-terminal groups of the polyamide 6 resin (A) is not particularly limited, but is preferably in the range of ^{1.0 × 10-5 to} 10.0 × ^{10-5 mol / g.} When the amount of amino-terminal groups is in ^{the range of 1.0 × 10-5 to} 10.0 × ^10-5 mol / g, a sufficient degree of polymerization can be obtained and the mechanical strength of the molded product can be improved. Here, the amount of amino terminal groups of the polyamide 6 resin (A) is such that the polyamide 6 resin (A) is dissolved in a phenol / ethanol mixed solvent (83.5: 16.5 (volume ratio)) and 0.02N hydrochloric acid is used. It can be obtained by titrating with an aqueous solution.

The amide-based wax (B) used in the present invention includes an amide compound obtained by reacting a monocarboxylic acid with a diamine, an amide compound obtained by reacting a monoamine with a polybasic acid, and a monocarboxylic acid with a polybasic acid and a diamine. Examples thereof include amide compounds that are reacted. These can be obtained by a dehydration reaction of the corresponding amine and carboxylic acid.

As the monoamine, a monoamine having 5 or more carbon atoms is preferable, and specific examples thereof include pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, stearylamine, cyclohexylamine, and benzylamine. , These may be used in combination of two or more. Of these, higher aliphatic monoamines having 10 or more and 20 or less carbon atoms are particularly preferable. When the number of carbon atoms is larger than 20, the compatibility with the polyamide 6 resin (A) is lowered, and there is a risk of precipitation.

The monocarboxylic acid is preferably an aliphatic monocarboxylic acid having 5 or more carbon atoms and a hydroxycarboxylic acid, and specific examples thereof include valeric acid, caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. Examples thereof include acid, linoleic acid, bechenic acid, palmitic acid, 12-hydroxystearic acid, benzoic acid and the like, and two or more of these may be used in combination. Of these, higher aliphatic monocarboxylic acids having 10 or more and 30 or less carbon atoms are particularly preferable. When the number of carbon atoms is larger than 30, the compatibility with the polyamide 6 resin (A) is lowered, and there is a risk of precipitation.

Specific examples of the diamine include ethylenediamine, 1,3-diaminopropane, 1,4-diaminopropane, tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, m-xylylenediamine, and the like. Examples thereof include paraxylylenediamine, tolylenediamine, phenylenediamine, isophoronediamine and the like, and two or more of these may be used in combination. Of these, ethylenediamine is particularly preferable.

The polybasic acid is a carboxylic acid of dibasic acid or more, and specific examples thereof include aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, sebacic acid, pimelic acid, and azelaic acid, phthalic acid, and terephthalic acid. Examples thereof include aromatic dicarboxylic acids such as acid and isophthalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and cyclohexylsuccinic acid, and two or more of these may be used in combination.

Among them, an amide compound obtained by reacting a higher aliphatic monocarboxylic acid, a polybasic acid and a diamine is particularly preferable, and for example, an amide compound obtained by reacting stearic acid, sebacic acid and ethylenediamine is preferable. At that time, the mixing ratio of each component is preferably in the range of 0.18 mol to 1.0 mol of polybasic acid and 1.0 mol to 2.2 mol of diamine with respect to 2 mol of higher aliphatic monocarboxylic acid. The range of 0.5 mol to 1.0 mol of polybasic acid and 1.5 mol to 2.0 mol of diamine is more preferable with respect to 2 mol of higher aliphatic monocarboxylic acid.

The melting point of the amide wax (B) is not particularly limited, but it is preferable that the melting point measured by DSC is equal to or higher than the melting point of the polyamide 6 resin (A). When the melting point of the amide wax (B) is equal to or higher than the melting point of the polyamide 6 resin (A), the releasability during molding is further improved.

Here, the melting points of the polyamide 6 resin (A) and the amide wax (B) in the present invention by DSC measurement can be determined by the following method. First, a differential scanning calorimeter (DSC-7 manufactured by PerkinElmer) is used to perform two-point calibration (indium, lead) and baseline correction. The sample volume is 8 to 10 mg, the temperature is raised at a temperature rising rate of 20 ° C./min, and the temperature is kept at a temperature 15 ° C. higher than the temperature indicating the maximum value of the melting curve for 1 minute, and then the temperature is lowered by 20 ° C./min. Cool to 30 ° C. at a rate. Further, after holding the temperature at 30 ° C. for 1 minute, the second temperature raising step is performed at a rate of 20 ° C./min in the same manner as the first temperature raising step. The melting endothermic peak temperature observed in this second temperature raising step is defined as the melting point.

The blending amount of the amide wax (B) in the polyamide resin composition of the present invention is 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyamide 6 resin (A). If the blending amount of the amide wax (B) is less than 0.01 parts by weight, the effect of improving the releasability is not sufficient, and defects are likely to occur due to repeated filling and releasing of high-pressure hydrogen. Become. The blending amount of the amide wax (B) is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more. On the other hand, when the blending amount of the amide wax (B) exceeds 10 parts by weight, the toughness is lowered, and defects are likely to occur by repeating filling and releasing pressure of high-pressure hydrogen. The blending amount of the amide wax (B) is preferably 7 parts by weight or less, more preferably 5 parts by weight or less.

The polyamide resin composition is preferably further blended with an impact resistant material (C). By blending the impact resistant material (C), the impact resistance of the molded product can be improved. In addition, molded products used for applications that come into contact with high-pressure hydrogen are repeatedly subjected to temperature changes (heat cycles) from -40 ° C or lower to 90 ° C or higher due to the filling and release of high-pressure hydrogen. In the case of a composite product having a portion, cracks are likely to occur at the joint portion between the resin portion and the metal portion. By blending the impact resistant material (C), it is possible to suppress cracking at the joint portion between the resin portion and the metal portion caused by the repetition of such a heat cycle, and it is possible to improve the heat cycle resistance.

Examples of the impact resistant material (C) include olefin resin, acrylic rubber, silicone rubber, fluorine rubber, styrene rubber, nitrile rubber, vinyl rubber, urethane rubber, polyamide elastomer, polyester elastomer, and ionomer. And so on. Two or more of these may be blended.

Among these, an olefin resin is preferably used because it has excellent compatibility with the polyamide 6 resin (A) and the amide wax (B) and has a high effect of improving heat cycle resistance. The olefin resin is a thermoplastic resin obtained by polymerizing an olefin monomer such as ethylene, propylene, butene, isoprene, and pentene. It may be a copolymer of two or more kinds of olefin monomers, or it may be a copolymer of these olefin monomers and other monomers. Specific examples of the olefin resin include polymers such as polyethylene, polypropylene, polystyrene, poly1-butene, poly1-pentene, and polymethylpentene, or polymers thereof; ethylene / α-olefin copolymer, ethylene / At least of α, β-unsaturated carboxylic acid ester copolymer, α-olefin / α, β-unsaturated carboxylic acid ester copolymer, [polymer of (ethylene and / or propylene) and vinyl alcohol ester] Polypolymers obtained by partially hydrolyzing, (ethylene and / or propylene) and (unsaturated carboxylic acid and / or unsaturated carboxylic acid ester), [(ethylene and / or propylene) and (non-saturated carboxylic acid ester). Polymers with saturated carboxylic acids and / or unsaturated carboxylic acid esters)] Polypolymers obtained by metally chloride at least a part of the carboxyl groups, block copolymers of conjugated diene and vinyl aromatic hydrocarbons or blocks thereof. Examples include hydrides. Among these, ethylene / α-olefin copolymers and ethylene / α, β-unsaturated carboxylic acid ester copolymers are more preferable, and ethylene / α-olefin copolymers are even more preferable.

Further, the polyolefin-based resin may be modified with an unsaturated carboxylic acid and / or a derivative thereof. Here, the derivative of the unsaturated carboxylic acid is a compound in which the hydroxy group portion of the carboxyl group of the unsaturated carboxylic acid is replaced with another substituent, and is a metal salt, an acid halide, an ester, or an acid of the unsaturated carboxylic acid. Such as anhydrides, amides and imides. By using such a modified polyolefin-based resin, the compatibility with the polyamide 6 resin (A) and the amide-based wax (B) can be further improved, and the heat cycle resistance can be further improved. Examples of unsaturated carboxylic acids or derivatives thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, methylmaleic acid, methylfumaric acid, mesaconic acid, citraconic acid, glutaconic acid and these carboxylic acids. Metal salts of; methyl hydrogen maleate, methyl hydrogen itaconic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, meta Unsaturated carboxylic acid esters such as hydroxyethyl acrylate, aminoethyl metaacrylate, dimethyl maleate, dimethyl itaconic acid; maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo- (2,2,1) -5 Acid anhydrides such as −hepten-2,3-dicarboxylic acid, endobicyclo- (2,2,1) -5-heptene-2,3-dicarboxylic acid anhydride; maleimide, N-ethylmaleimide, N-butylmaleimide , N-Phenylmaleimide, glycidyl acrylate, glycidyl methacrylate, glycidyl etaclilate, glycidyl itaconic acid, glycidyl citraconic acid, 5-norbornene-2,3-dicarboxylic acid and the like. Among these, unsaturated dicarboxylic acids and their acid anhydrides are preferable, and maleic acid or maleic anhydride is particularly preferable.

As a method for introducing these unsaturated carboxylic acids or derivatives thereof into a polyolefin-based resin, for example, a method for copolymerizing an olefin monomer with an unsaturated carboxylic acid and / or a derivative thereof, or a radical initiator is used. Examples thereof include a method of graft-introducing an unsaturated carboxylic acid and / or a derivative thereof into an unmodified polyolefin resin.

As the ethylene / α-olefin copolymer, a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms is preferable. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-hexene, 1-octene, 1-nonene, 1-decene, and 1-undecene. , 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-hexene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1 -Pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl Examples thereof include -1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. Two or more of these may be used. Among these α-olefins, α-olefins having 3 to 12 carbon atoms are preferable from the viewpoint of improving mechanical strength. In addition, non-conjugated diene such as 1,4-hexadiene, dicyclopentadiene, 2,5-norbornadiene, 5-ethylidene norbornene, 5-ethyl-2,5-norbornadiene, 5- (1'-propenyl) -2-norbornene. At least one of the above may be copolymerized. A copolymer of ethylene modified with an unsaturated carboxylic acid and / or a derivative thereof and an α-olefin having 3 to 12 carbon atoms further enhances compatibility with the polyamide 6 resin (A) and the amide wax (B). It is more preferable because it can be improved and the heat cycle resistance can be further improved. Further, even if filling and releasing pressure are repeated with higher pressure hydrogen, the occurrence of defective points can be suppressed. The α-olefin content in the ethylene / α-olefin copolymer is preferably 1 to 30 mol%, more preferably 2 to 25 mol%, still more preferably 3 to 20 mol%.

The structure of the impact resistant material (C) is not particularly limited, and is, for example, a so-called core-shell type multilayer structure composed of at least one layer made of rubber and one or more layers made of polymers different from the same. It may be. The number of layers constituting the multilayer structure may be two or more, and may be three or more or four or more, but it is preferable to have one or more rubber layers (core layers) inside. .. The type of rubber constituting the rubber layer of the multilayer structure is not particularly limited, and for example, an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component, an ethylene component, a propylene component, and isobutylene. Examples thereof include rubber obtained by polymerizing components and the like. The type of the heterogeneous polymer constituting the layer other than the rubber layer of the multilayer structure is not particularly limited as long as it is a polymer having thermoplasticity, but a polymer having a glass transition temperature higher than that of the rubber layer is used. preferable. Examples of the polymer having thermoplasticity include unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, unsaturated dicarboxylic acid anhydride units, aliphatic vinyl units, and aromatic vinyl units. Polymers containing vinyl cyanide units, maleimide units, unsaturated dicarboxylic acid units and other vinyl units can be mentioned.

The amount of the impact-resistant material (C) blended in the polyamide resin composition is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the polyamide 6 resin (A). The heat cycle resistance can be further improved by setting the blending amount of the impact resistant material (C) to 1 part by weight or more. The blending amount of the impact resistant material (C) is more preferably 5 parts by weight or more, further preferably 10 parts by weight or more. On the other hand, by setting the blending amount of the impact resistant material (C) to 50 parts by weight or less, it is possible to suppress the occurrence of defective points even if the filling and releasing pressure are repeated with high-pressure hydrogen. The blending amount of the impact resistant material (C) is more preferably 45 parts by weight or less, further preferably 40 parts by weight or less, and further preferably 35 parts by weight or less.

If necessary, other components other than the above components (A), (B) and (C) may be added to the polyamide resin composition as long as the characteristics are not impaired. Examples of other components include fillers, thermoplastic resins other than the components (A) to (C), and various additives.

For example, by blending a filler as another component in the polyamide resin composition, the strength and dimensional stability of the obtained molded product can be improved. The shape of the filler may be fibrous or non-fibrous, and the fibrous filler and the non-fibrous filler may be used in combination. Examples of the fibrous filler include glass fiber, glass milled fiber, carbon fiber, potassium titanate whisker, zinc oxide whisker, aluminum borate whisker, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, and stone wool. Examples include fibers and metal fibers. Non-fibrous fillers include, for example, silicates such as warastenite, zeolite, sericite, kaolin, mica, clay, pyrophyllite, bentonite, asbestos, talc, alumina silicate; alumina, silicon oxide, magnesium oxide, oxidation. Metal oxides such as zirconium, titanium oxide and iron oxide; metal carbonates such as calcium carbonate, magnesium carbonate and dolomite; metal sulfates such as calcium sulfate and barium sulfate; Metal hydroxides; glass beads, ceramic beads, boron nitride, silicon carbide and the like. These may be hollow. Further, it is preferable to use these fibrous and / or non-fibrous fillers after pretreatment with a coupling agent in the sense of obtaining better mechanical properties. Examples of the coupling agent include isocyanate compounds, organic silane compounds, organic titanate compounds, organic borane compounds, epoxy compounds and the like.

Examples of thermoplastic resins include polyester resin, polyphenylene sulfide resin, polyphenylene oxide resin, polycarbonate resin, polylactic acid resin, polyacetal resin, polysulfone resin, tetrafluoride polyethylene resin, polyetherimide resin, polyamideimide resin, and polyimide resin. , Polyether sulfone resin, polyether ketone resin, polythioether ketone resin, polyether ether ketone resin, styrene resin such as polystyrene resin and ABS resin, polyalkylene oxide resin and the like. It is also possible to blend two or more kinds of such thermoplastic resins.

Examples of various additives include antioxidants, antioxidants such as hindered phenol and hindered amine, mold release agents, plasticizers, heat stabilizers, lubricants, UV inhibitors, colorants, flame retardants, foaming agents and the like. Can be mentioned.

It is preferable to add a copper compound to the polyamide resin composition because long-term heat resistance can be improved. Examples of copper compounds include cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, cupric sulfate, and cupric nitrate. , Copper phosphate, cuprous acetate, cupric acetate, cupric salicylate, cupric stearate, cupric benzoate and the inorganic copper halides and xylylene diamine, 2-mercaptobenzimidazole, benzimidazole. Examples include complex compounds such as. Two or more of these may be blended. Among them, a monovalent copper compound, particularly a monovalent copper halide compound is preferable, and cuprous acetate, cuprous iodide and the like are preferable. The blending amount of the copper compound is preferably 0.01 part by weight or more, and more preferably 0.015 part by weight or more with respect to 100 parts by weight of the polyamide 6 resin (A). On the other hand, from the viewpoint of suppressing coloring due to the release of metallic copper during molding, the blending amount of the copper compound is preferably 2 parts by weight or less, and more preferably 1 part by weight or less.

Further, an alkali halide may be blended together with the copper compound. Examples of the alkali halide compound include lithium chloride, lithium bromide, lithium iodide, potassium chloride, potassium bromide, potassium iodide, sodium bromide and sodium iodide. Two or more of these may be blended. Potassium iodide or sodium iodide is particularly preferred.

The temperature-lowering crystallization temperature of the polyamide resin composition measured by DSC is preferably 180 ° C. or higher, more preferably 183 ° C. or higher. When the temperature-lowering crystallization temperature of the polyamide resin composition is 180 ° C. or higher, dense and uniform crystals are easily formed in the cooling process from the molten state of the polyamide resin composition, so that the hydrogen permeability is lowered. The temperature-lowering crystallization temperature of the polyamide resin composition capable of suppressing the occurrence of defect points even when the high-pressure hydrogen is repeatedly filled and released is preferably 180 ° C. or higher, more preferably 183 ° C. or higher.

In the present invention, the temperature-decreasing crystallization temperature of the polyamide resin composition measured by DSC can be determined by the following method. First, a differential scanning calorimeter (DSC-7 manufactured by PerkinElmer) is used to perform two-point calibration (indium, lead) and baseline correction. The sample volume is 8 to 10 mg, the temperature is raised at a temperature rising rate of 20 ° C./min, and the temperature is kept at a temperature 15 ° C. higher than the temperature indicating the maximum value of the melting curve obtained for 1 minute, and then the temperature is lowered by 20 ° C. The crystallization exothermic peak temperature observed when cooled to 30 ° C. at a rate is defined as the temperature-decreasing crystallization temperature. However, when two or more peaks are observed, the temperature corresponding to the largest exothermic crystallization peak is defined as the temperature-decreasing crystallization temperature of the polyamide resin composition.

As a means for setting the temperature lowering crystallization temperature of the polyamide resin composition in the above range, for example, a method using the above-mentioned preferable polyamide resin composition can be mentioned.

Next, a method for producing the polyamide resin composition of the present invention will be described. The method for producing the thermoplastic polyamide resin composition of the present invention is not particularly limited, and for example, a polyamide 6 resin (A), an amide-based wax (B), an impact-resistant material (C) and other components as necessary are used. A method of batch kneading, a method of kneading the amide wax (B) and, if necessary, an impact resistant material (C) and other components after melting the polyamide 6 resin (A), a method of kneading the polyamide 6 resin (A) and the amide wax. Examples thereof include a method of melting the (B) and then kneading the impact resistant material (C) and other components as needed. As the kneading device, for example, a known kneading device such as a Banbury mixer, a roll, or an extruder can be adopted. When the polyamide resin composition of the present invention is blended with other components such as the impact resistant material (C) and various additives, these can be blended at any stage. For example, when the polyamide resin composition of the present invention is produced by a twin-screw extruder, the impact-resistant material (C) and other components are simultaneously blended when the polyamide 6 resin (A) and the amide wax (B) are blended. A method of blending the impact-resistant material (C) and other components by a method such as side feeding during melt-kneading of the polyamide 6 resin (A) and the amide wax (B), or a method of blending the polyamide 6 resin (A) and the amide wax (B) in advance. ) And the amide wax (B) are melt-kneaded and then the impact-resistant material (C) and other components are blended, or the polyamide 6 resin (A) is mixed with the impact-resistant material (C) and other components in advance. Then, after melt-kneading, a method of blending the amide wax (B) and the like can be mentioned.

The polyamide resin composition of the present invention can be molded by any method to obtain a molded product. Examples of the molding method include extrusion molding, injection molding, hollow molding, calender molding, compression molding, vacuum molding, foam molding, blow molding, rotary molding and the like. Examples of the molding shape include a pellet shape, a plate shape, a fibrous shape, a strand shape, a film or sheet shape, a pipe shape, a hollow shape, a box shape, and the like.

The molded product of the present invention is used for a molded product that comes into contact with high-pressure hydrogen, taking advantage of its excellent feature that the generation of defective points is suppressed even when the high-pressure hydrogen is repeatedly filled and released. The molded product that comes into contact with high-pressure hydrogen here is a molded product that comes into contact with hydrogen at a pressure higher than normal pressure. Since it has the effect of suppressing the occurrence of defective points when high-pressure hydrogen is repeatedly filled and released, it is preferably used for molded products that come into contact with hydrogen at a pressure of 20 MPa or more, and depending on the use of molded products that come into contact with hydrogen of 30 MPa or more. It is preferably used. On the other hand, it is preferably used for articles that come into contact with hydrogen at a pressure of 200 MPa or less, preferably for articles that come into contact with hydrogen of 150 MPa or less, and more preferably for articles that come into contact with hydrogen of 100 MPa or less. Molded products that come into contact with high-pressure hydrogen include, for example, an on-off valve for high-pressure hydrogen, a check valve for high-pressure hydrogen, a pressure reducing valve for high-pressure hydrogen, a pressure regulating valve for high-pressure hydrogen, a seal for high-pressure hydrogen, a hose for high-pressure hydrogen, and a hose for high-pressure hydrogen. Tank, tank liner for high pressure hydrogen, pipe for high pressure hydrogen, packing for high pressure hydrogen, pressure sensor for high pressure hydrogen, pump for high pressure hydrogen, tube for high pressure hydrogen, regulator for high pressure hydrogen, film for high pressure hydrogen, sheet for high pressure hydrogen, high pressure Examples include hydrogen fibers and high-pressure hydrogen joints. Among them, on-off valve for high-pressure hydrogen, check valve for high-pressure hydrogen, pressure reducing valve for high-pressure hydrogen, pressure regulating valve for high-pressure hydrogen, tank for high-pressure hydrogen, tank liner for high-pressure hydrogen, packing for high-pressure hydrogen, pressure sensor for high-pressure hydrogen, It can be preferably used for high-pressure hydrogen containers such as high-pressure hydrogen pumps, high-pressure hydrogen regulators, and high-pressure hydrogen joints, and their peripheral parts. Among these, it can be particularly preferably used for a high-pressure hydrogen tank.

The tank liner for high-pressure hydrogen can be obtained by molding by any method. Examples of the molding method include extrusion molding, injection molding, hollow molding, calender molding, compression molding, vacuum molding, foam molding, blow molding, rotary molding and the like.

Further, as a method of forming the tank liner for high-pressure hydrogen, a method of forming two or more divided bodies constituting the tank liner for high-pressure hydrogen by molding and joining them by welding can be mentioned. For example, a method of forming a high-pressure hydrogen tank liner by joining two molded bodies having a shape in which a high-pressure hydrogen tank liner is vertically divided in half by welding, and a method in which a high-pressure hydrogen tank liner is horizontally divided in half. A method of forming a tank liner for high-pressure hydrogen by joining two molded bodies of the above, two end plates having a semicircular or elliptical shape that close both ends of the high-pressure hydrogen tank liner, and a body. Examples thereof include, but are not limited to, a method of forming a tank liner for high-pressure hydrogen by joining the portions by welding.

Examples of the welding include hot plate welding, ultrasonic welding, vibration welding, laser welding, infrared welding, infrared / vibration welding in which the welded portion is warmed by infrared rays and then vibration welding is performed. Of these, infrared welding and infrared / vibration welding are preferable.

A particularly preferable embodiment is an embodiment in which the tank liner made of the polyamide resin composition of the present invention is used as the resin liner for a high-pressure hydrogen tank in which the outside of the resin liner is reinforced with a carbon fiber reinforced resin. That is, the high-pressure hydrogen tank of the present invention is a high-pressure hydrogen tank in which a carbon fiber reinforced resin (CFRP) reinforcing layer is laminated on the surface layer of a tank liner made of the polyamide resin composition of the present invention.

By laminating a CFRP reinforcing layer on the surface layer of the tank liner, it is possible to develop strength and elastic modulus that can withstand high pressure, which is preferable. The CFRP reinforcing layer is composed of carbon fibers and a matrix resin. As the carbon fiber, one having a tensile elastic modulus of 50 to 700 GPa is preferable from the viewpoint of bending characteristics and strength, and one having a tensile elastic modulus of 200 to 700 GPa is more preferable from the viewpoint of specific rigidity, and the cost performance is higher. From the viewpoint, the one with 200 to 450 GPa is most preferable. The tensile strength of the carbon fiber alone is preferably 1500 to 7000 MPa, and preferably 3000 to 7000 MPa from the viewpoint of specific strength. The density of carbon fibers is preferably 1.60 to 3.00, more preferably 1.70 to 2.00 from the viewpoint of weight reduction, and most preferably 1.70 to 1.90 from the viewpoint of cost performance. Further, the fiber diameter of each carbon fiber is preferably 5 to 30 μm, more preferably 5 to 20 μm from the viewpoint of handleability, and most preferably 5 to 10 μm from the viewpoint of weight reduction. The carbon fiber may be used alone, or may be used in combination with reinforcing fibers other than the carbon fiber. Examples of reinforcing fibers other than carbon fibers include glass fibers and aramid fibers. Further, when the ratio of the carbon fiber and the matrix resin is defined by the body integral ratio Vf of the carbon fiber in the carbon fiber reinforced resin reinforcing layer material, the Vf is preferably 20 to 90% from the viewpoint of rigidity, and from the viewpoint of productivity and required rigidity. Therefore, it is preferable that Vf is 40 to 80%.

The matrix resin constituting the CFRP reinforcing layer may be a thermosetting resin or a thermoplastic resin. When the matrix resin is a thermosetting resin, examples of the main material thereof include epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, polyurethane resin, and silicone resin. Only one of these types may be used, or two or more types may be mixed and used. Epoxy resins are particularly preferred. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and isocyanate-modified bisphenol A type epoxy resin. When a thermosetting resin is used as the matrix resin, it is possible to add an appropriate curing agent or reaction accelerator to the thermosetting resin component.

When the matrix resin is a thermoplastic resin, the main materials thereof are polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin, polystyrene resin, AS resin, polyamide resin, polyacetal resin, polycarbonate resin, thermoplastic polyester resin, and PPS resin. , Fluororesin, polyetherimide resin, polyetherketone resin, polyimide resin and the like can be exemplified. These thermoplastic resins may be used alone, as a mixture of two or more kinds, or as a copolymer. In the case of a mixture, a compatibilizer may be used in combination. Further, as the flame retardant, a brominated flame retardant, a silicon flame retardant, red phosphorus or the like may be added.

Known methods for laminating the CFRP reinforcing layer on the surface layer of the tank liner for high-pressure hydrogen include a known filament winding (hereinafter FW) method, tape winding (hereinafter TW) method, sheet winding (hereinafter SW) method, hand layup method, and RTM. (Resin Transfer Molding) method and the like can be exemplified. Of these molding methods, only a single method may be used for molding, or two or more types of molding methods may be combined for molding. From the viewpoint of property expression, productivity and moldability, a method selected from the FW method, the TW method and the SW method is preferable. These FW method, SW method and TW method are basically the same molding method from the viewpoint of applying a matrix resin to strand-shaped carbon fibers and laminating them on a liner, and the carbon fibers are applied to the liner. , The name differs depending on whether it is wound in a filament (thread) form, a tape (tape-like form in which threads are bundled to some extent), or a sheet (sheet-like form in which tapes are bundled to some extent). Here, the most basic FW method will be described in detail, but the contents can also be applied to the TW method and the SW method.

In the FW method, when the matrix resin is a thermosetting resin, it is possible to directly wind the carbon fiber in a pre-coated state (uncured) around the liner, or to apply the resin to the carbon fiber immediately before winding it around the liner. It is also possible to do. In these cases, after wrapping carbon fiber and uncured matrix resin around the liner, it is necessary to perform resin curing treatment under conditions suitable for the resin used in a batch furnace (oven) or continuous curing furnace in order to cure the resin. There is.

In the FW method, when the matrix resin is a thermoplastic resin, it is possible to directly wind the carbon fiber coated (impregnated) with the resin around the liner to form a tank shape for high-pressure hydrogen. In this case, it is necessary to raise the temperature of the carbon fiber coated with the resin to a temperature higher than the melting point of the thermoplastic resin immediately before winding it around the liner. It is also possible to apply the melted thermoplastic resin to the carbon fiber immediately before winding it around the liner. In this case, the resin curing step as applied to the thermosetting resin is unnecessary.

When the high-pressure hydrogen tank of the present invention is obtained by the FW method, the TW method, the SW method, or the like, the most important thing is the fiber orientation design of the carbon fibers. In the FW method, the TW method and the SW method, a carbon fiber strand (continuous fiber) or a prepreg in which a carbon fiber strand is impregnated with a resin in advance is wound around a liner to form a liner. At the time of design, it is preferable to design so as to satisfy the rigidity and strength that satisfy the required characteristics, with the continuous fiber direction and the laminated thickness in the liner body as design factors.

Further, as the high-pressure hydrogen tank, it is preferable that the valve is inserted into the tank liner by insert molding. By integrating the valve with the tank liner by insert molding, the airtightness of high-pressure hydrogen is enhanced, which is preferable. Here, the valve acts as a filling port and a discharge port for high-pressure hydrogen. Examples of the material of the metal part used as the valve include carbon steel, manganese steel, chrome molybdenum steel, stainless steel, and aluminum alloy. Examples of carbon steel include carbon steel pipes for pressure piping, carbon steel pipes for high pressure piping, steel pipes for low temperature piping, and carbon steel materials for machine structure. Examples of manganese steel include seamless steel pipes for high-pressure gas containers, manganese steel materials for machine structures, and manganese chrome steel materials. Examples of chrome molybdenum steel and low alloy steel include seamless steel pipes for high-pressure gas containers, alloy steel pipes for machine structures, nickel chrome molybdenum steel materials, and chrome molybdenum steel materials. Examples of stainless steel include stainless steel forged steel products for pressure, stainless steel pipes for piping, stainless steel rods, hot-rolled stainless steel plates and steel strips, and cold-rolled stainless steel plates and steel strips. Examples of aluminum alloys include aluminum and aluminum alloy plates, strips, rods, wires, seamless pipes, and forged products. For carbon steel, quenching and tempering, for manganese steel, quenching and quenching and tempering, and for chromium molybdenum steel and low alloy steel, quenching and tempering, stainless steel. For solidification treatment, for aluminum alloys, a material that has been quenched and tempered may be applied. Further, for the aluminum alloy, those subjected to solution treatment and T6 aging treatment may be applied.

The most preferable aspect of the high-pressure hydrogen tank of the present invention is a high-pressure structure in which a CFRP reinforcing layer is laminated on the surface layer of a tank liner made of the polyamide resin composition of the present invention, and a valve is inserted into the tank liner. It is a tank for hydrogen.

Hereinafter, the effects of the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples. The evaluation in each Example and Comparative Example was performed by the following method.

(1) High-pressure hydrogen filling and discharge repeated characteristics (defect points)
From the pellets obtained in each Example and Comparative Example, a cylinder temperature: 240 ° C., a mold temperature: 80 ° C., and an injection speed of 10 mm / using an injection molding machine "SU75DUZ-C250" manufactured by Sumitomo Heavy Industries, Ltd. A columnar test piece having a diameter of 29 mm and a height of 12.6 mm was injection-molded under molding conditions of seconds, holding pressure of 15 MPa, holding time of 15 seconds, and cooling time of 15 seconds.

The obtained test piece was subjected to X-ray CT analysis using "TDM1000-IS" manufactured by Yamato Scientific Co., Ltd., and the presence or absence of defective points was observed. After putting the test piece without defects into the autoclave, hydrogen gas was injected into the autoclave to a pressure of 30 MPa over 3 minutes, held for 2 hours, and then depressurized over 1 minute until the pressure became normal. This was set as one cycle and repeated 700 cycles. The test piece after repeating 700 cycles was subjected to X-ray CT analysis using "TDM1000-IS" manufactured by Yamato Scientific Co., Ltd., and the presence or absence of defects of 10 μm or more was observed.

(2) Temperature-lowering crystallization temperature of the polyamide resin composition For the pellets obtained in each Example and Comparative Example, a two-point calibration (indium, lead) was performed using a differential scanning calorimeter (DSC-7 manufactured by PerkinElmer). After the baseline correction, the sample volume was set to 8 to 10 mg, and the temperature was maintained at a temperature 15 ° C. higher than the temperature indicating the maximum value of the melting curve obtained by raising the temperature at a heating rate of 20 ° C./min for 1 minute. After that, it was cooled to 30 ° C. under the condition of a temperature lowering rate of 20 ° C./min. The peak temperature of exothermic crystallization observed in this cooling step was defined as the temperature-decreasing crystallization temperature.

(3) Releasability From the pellets obtained in each Example and Comparative Example, a cylinder temperature: 240 ° C. and a mold temperature: 80 were used using an injection molding machine "SE75DUZ-C250" manufactured by Sumitomo Heavy Industries, Ltd. A square plate molded product of 80 mm × 80 mm × thickness 3 mm was injection-molded under molding conditions of ° C., injection speed: 40 mm / sec, holding pressure: 20 MPa, and cooling time: 20 seconds. It was confirmed whether or not it was stuck to the mold during injection molding.

(4) Heat cycle resistance The pellets obtained in each Example and Comparative Example were subjected to cylinder temperature: 240 ° C., mold temperature: 80 ° C., using an injection molding machine "NEX1000" manufactured by Nissei Jushi Kogyo Co., Ltd. Under the molding conditions of an injection speed of 100 mm / sec and a cooling time of 20 seconds, the metal core of 47 mm × 47 mm × 27 mm was overmolded with a thickness of 1.5 mm.

The three obtained metal / resin composite molded products were allowed to stand at a temperature of −60 ° C. for 1 hour and then allowed to stand at 90 ° C. for 1 hour, and the composite molded products were visually observed to determine the presence or absence of cracks. This operation was repeated, and the number of cycles in which all three composite molded products were broken was designated as A, 200 to 499 times as B, and 199 or less as C.

(5) Impact resistance From the pellets obtained in each Example and Comparative Example, a cylinder temperature: 240 ° C. and a mold temperature: 80 were used using an injection molding machine "SE75DUZ-C250" manufactured by Sumitomo Heavy Industries, Ltd. An ASTM D256 compliant notched Izod impact molded piece was injection molded under the molding conditions of ° C., injection speed: 40 mm / sec, holding pressure: 20 MPa, and cooling time: 20 seconds.

The impact resistance (notched Izod impact strength) of the obtained seven notched Izod impact molded pieces was evaluated at 23 ° C. according to ASTM D256. The average value of 7 measurements was taken as the impact resistance.

The raw materials and abbreviations used in each Example and Comparative Example are shown below.
PA6: Polyamide 6 resin (relative viscosity 2.70 at 25 ° C in a 98% concentrated sulfuric acid solution with a melting point of 223 ° C and a resin concentration of 0.01 g / ml)
PA66: Polyamide 66 resin (relative viscosity 2.70 at 25 ° C. in a 98% concentrated sulfuric acid solution having a melting point of 263 ° C. and a resin concentration of 0.01 g / ml)
PA6 / PA66 copolymer: Polyamide 6 / Polyamide 66 copolymer (relative viscosity 4.20 at 25 ° C. in a 98% concentrated sulfuric acid solution having a melting point of 190 ° C. and a resin concentration of 0.01 g / ml).
Amide wax 1: Ethylenediamine / stearic acid / sebacic acid polycondensate "" Light Amide "WH-215" (manufactured by Kyoeisha Chemical Co., Ltd., melting point 215 ° C)
Amide wax 2: Ethylenediamine / stearic acid / sebacic acid polycondensate "" Light Amide "WH-255" (manufactured by Kyoeisha Chemical Co., Ltd., melting point 255 ° C)
Fatty acid ester: Ethylene glycol dimontanate "" Licowax "E" (manufactured by Clariant Japan Co., Ltd.)
Organic nucleating agent: N, N', N "-tris (2-methylcyclohexane-1-yl) Propane-1-2-3 triylcarboxamide""Ricaclear" (registered trademark) PC-1 "(New Japan Chemical Co., Ltd.) Made by Co., Ltd.)
Inorganic nucleating agent: Talc "" MicroAce "(registered trademark) P-6" (manufactured by Japan Talc Co., Ltd., median diameter (D50) 4.0 μm)
Impact-resistant material 1: Maleic anhydride-modified ethylene / 1-butene copolymer "" Toughmer "(registered trademark) MH7020" (manufactured by Mitsui Chemicals, Inc.)
Impact-resistant material 2: Glycidyl methacrylate-modified polyethylene copolymer "" Bond First "(registered trademark) 7L" (manufactured by Sumitomo Chemical Co., Ltd.)
Impact-resistant material 3: Ionomer "" Hymilan "(registered trademark) 1706" (manufactured by DuPont Co., Ltd.).
Impact-resistant material 4: Maleic anhydride-modified ethylene / 1-butene copolymer "" Toughmer "(registered trademark) MH5040" (manufactured by Mitsui Chemicals, Inc.)

[Examples 1 to 9, Comparative Examples 1 to 7]
A twin-screw extruder (JSW TEX30α-) in which the cylinder temperature of each of the raw materials shown in Tables 1 and 2 is set to 240 ° C., a screw arrangement with one kneading zone is provided, and the screw rotation speed is 150 rpm. It was supplied to 35BW-7V) (L / D = 45 (where L is the length from the raw material supply port to the discharge port)) and melt-kneaded. The gut discharged from the die at a speed of 20 kg / h was rapidly cooled by passing it through a cooling bath filled with water whose temperature was adjusted to 10 ° C. for 10 seconds, and then pelletized with a strand cutter to obtain pellets. .. The obtained pellets were vacuum-dried at a temperature of 80 ° C. for 12 hours in a vacuum dryer, and after drying, the pellets were used to evaluate by the above-mentioned method, and the results are shown in Tables 1 and 2.

From the above results, the polyamide resin composition obtained by blending the polyamide 6 resin (A) and the amide wax (B) has a high crystallization temperature and crystallization from the molten state proceeds quickly, so that the crystallization rate is high. It was found that the molded product obtained by molding the polyamide resin composition became faster, and the occurrence of defect points was suppressed even when the high-pressure hydrogen was repeatedly filled and released, and the mold releasability was excellent.

Further, it was found that the molded product obtained by molding the polyamide resin composition obtained by blending the impact resistant material (C) has excellent heat cycle resistance.

The polyamide resin composition of the present invention has a high crystallization temperature and crystallization from a molten state proceeds quickly, so that the crystallization rate is high, and the occurrence of defect points is suppressed even if high-pressure hydrogen is repeatedly filled and released. Furthermore, it has excellent releasability, which is important in injection molding. The molded product obtained by molding the polyamide resin composition of the present invention can be widely used for a molded product that comes into contact with high-pressure hydrogen by taking advantage of these characteristics.

Claims (9)

0.1 of the amide wax (B), which is an amide compound obtained by reacting 100 parts by weight of the polyamide 6 resin (A) with a higher aliphatic monocarboxylic acid having 10 or more and 30 or less carbon atoms, a polybasic acid and a diamine. formed by 5 parts by weight blended, Ri polyamide resin composition der for moldings touching high-pressure hydrogen, melting point of the amide-based wax (B) is 215 ° C. to 255 ° C., for moldings to touch the high-pressure hydrogen Polyamide resin composition . The polyamide resin composition according to claim 1, wherein the melting point of the amide wax (B) measured by DSC is equal to or higher than the melting point of the polyamide 6 resin (A). The polyamide resin composition according to claim 1 or 2, further comprising 1 to 50 parts by weight of the impact resistant material (C) blended with 100 parts by weight of the polyamide 6 resin (A). The polyamide resin composition according to claim 3, wherein the impact-resistant material (C) contains an ethylene / α-olefin copolymer modified with an unsaturated carboxylic acid and / or a derivative thereof. The polyamide resin composition according to any one of claims 1 to 4, wherein the temperature-decreasing crystallization temperature measured by DSC is 180 ° C. or higher. A molded product that comes into contact with high-pressure hydrogen and comprises the polyamide resin composition according to any one of claims 1 to 5. A tank liner for high-pressure hydrogen comprising the polyamide resin composition according to any one of claims 1 to 5. A high-pressure hydrogen tank in which a carbon fiber reinforced resin reinforcing layer is laminated on the surface layer of a tank liner made of the polyamide resin composition according to any one of claims 1 to 5. The high-pressure hydrogen tank according to claim 8, wherein a valve is inserted into the tank liner.