JP2020117637A - Polyamide resin composition for molded product that comes into contact with high pressure hydrogen and molded product therewith - Google Patents

Abstract

To provide a polyamide resin composition that can suppress occurrence of defects even when filling and releasing of high pressure hydrogen are repeated and can obtain molded products having excellent rigidity and releasing property.SOLUTION: A polyamide resin composition for molded products that come into contact with high pressure hydrogen, is obtained by blending, relative to 100 pts.mass of a polyamide 6 resin (A), 0.01 to 5 pts.mass of a polyamide resin (B) that has a melting point due to a DSC measurement of a melting point of the polyamide 6 resin (A) +20°C or lower, and has a falling crystallization temperature due to DSC measurement higher than the falling crystallization temperature of the polyamide 6 resin (A), and 0.01 to 10 pts.mass of an amide-based wax (C).SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polyamide resin composition for a molded article that is exposed to high-pressure hydrogen, which is obtained by mixing a specific polyamide resin and an amide wax in a specific amount with a polyamide 6 resin, and a molded article obtained by molding the same.

In recent years, to meet the demand for exhaustion of petroleum fuel and reduction of harmful gas emissions, automobiles have been equipped with fuel cells that generate hydrogen by electrochemically reacting hydrogen with oxygen in the air. Fuel cell electric vehicles, which use the generated electricity as a driving force by supplying the electricity to a motor, have been attracting attention. As a high-pressure hydrogen tank for automobiles, a resin tank in which the outside of a resin liner is reinforced with a carbon fiber reinforced resin is under study. However, since hydrogen has a small molecular size, it is more likely to permeate through the resin than natural gas, which has a relatively large molecular size, and that high-pressure hydrogen accumulates in the resin more than atmospheric pressure hydrogen. Since the number of tanks has increased, the conventional resin tank has a problem that the tank is deformed or destroyed when the high-pressure hydrogen is repeatedly filled and released. Further, there is a problem that the releasability is insufficient when molding a resin liner.

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

Further, as a gas storage tank liner having excellent gas barrier properties, for example, a gas storage tank liner containing a polymer composition containing a polyamide, a nucleating agent and an impact resistance improver has been studied (for example, Patent Document 1). 2).

Further, as a polyamide resin composition capable of suppressing the generation of defect points even when charging and releasing pressure of high-pressure hydrogen are repeated and obtaining a molded article excellent in weld characteristics, for example, a melting point of polyamide 6 resin and polyamide 6 resin is used. A polyamide resin composition for a molded product which is exposed to high-pressure hydrogen and which is prepared by blending a polyamide resin having a temperature of +20° C. or lower and a temperature lowering crystallization temperature higher than that of a polyamide 6 resin has been studied (for example, see Patent Document 3).

Further, as a polyamide resin composition capable of obtaining a molded article excellent in releasability, in which generation of defect points is suppressed even when high-pressure hydrogen is repeatedly filled and released, for example, polyamide 6 resin and amide wax are used. A polyamide resin composition for a molded product that is exposed to high-pressure hydrogen has been studied (see, for example, Patent Document 4).

JP, 2009-191871, A Special table 2014-501818 gazette International Publication No. 2016/136025 JP, 2017-226817, A

Injection molding is one of the methods for producing a molded product that is exposed to high-pressure hydrogen. For example, when a resin-made gas storage tank liner is injection-molded, a large-sized molded product is molded, so that the molded product has a poor appearance due to insufficient releasability, and a molded product cannot be obtained. There is. Therefore, in order to injection-mold a large-sized molded product, high mold releasability is required. Further, due to lack of toughness, cracks may occur when used as a hydrogen tank liner. Therefore, high toughness is also required.

However, the hydrogen tank liner described in Patent Document 1 is apt to cause permeation of hydrogen gas and dissolution of hydrogen in the resin, and when the high-pressure hydrogen is repeatedly filled and released, defects occur in the hydrogen tank liner. There were challenges. In addition, the releasability of the polyamide resin is low, and there is a problem in releasability.

Further, the liner for a gas storage tank described in Patent Document 2 is excellent in helium gas permeation resistance, but is apt to cause permeation of hydrogen gas and dissolution of hydrogen in a resin, and thus filling and releasing pressure of high-pressure hydrogen. Repeatedly, there were problems that the hydrogen tank liner had defect points and cracks due to insufficient toughness. In addition, the releasability of the polyamide resin is low, and there is a problem in releasability.

On the other hand, although the polyamide resin composition described in Patent Document 3 suppresses the generation of defect points even when the high-pressure hydrogen is repeatedly filled and released, it may cause cracks due to insufficient toughness, and is injection-molded. There was a problem with the releasability of time.

Further, although the polyamide resin composition described in Patent Document 4 suppresses the generation of defect points even when charging and releasing pressure of high-pressure hydrogen are repeated and the mold releasability at the time of injection molding is improved, the toughness is insufficient. There was a concern that cracking would occur.

In view of the above-mentioned problems of the prior art, the present invention is to obtain a molded product which is suppressed in the occurrence of defect points even after repeating high-pressure hydrogen filling and pressure release, and which has excellent toughness and releasability during injection molding. An object of the present invention is to provide a polyamide resin composition that can be used.

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

With respect to 100 parts by weight of polyamide 6 resin (A), the melting point measured by DSC is not more than the melting point of polyamide 6 resin (A) +20° C., and the temperature falling crystallization temperature measured by DSC is the temperature falling crystal of polyamide 6 resin (A). A polyamide resin composition for a molded product exposed to high-pressure hydrogen, which comprises 0.01 to 5 parts by weight of a polyamide resin (B) having a temperature higher than the curing temperature and 0.01 to 10 parts by weight of an amide wax (C). ..

The present invention includes a molded product made of the above polyamide resin composition and exposed to high-pressure hydrogen.

The present invention includes a tank liner for high pressure hydrogen comprising the above 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 polyamide resin composition.

The polyamide resin composition for a molded article that is exposed to high-pressure hydrogen of the present invention has a high crystallization temperature, and the crystallization rate from the molten state progresses rapidly, so that the crystallization rate becomes fast, and the high-pressure hydrogen is repeatedly charged and released. Also, it is possible to provide a molded product in which the occurrence of defect points is suppressed and which has excellent toughness and releasability during injection molding. The molded product of the present invention is useful as a molded product used in applications where it is exposed to high-pressure hydrogen by taking advantage of its excellent toughness and releasability, even if repeated filling and releasing of high-pressure hydrogen are not likely to occur. It is possible to deploy it.

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

The polyamide resin composition of the present invention for a molded article exposed to high-pressure hydrogen (hereinafter sometimes referred to as “polyamide resin composition”) has a melting point measured by DSC with respect to 100 parts by weight of polyamide 6 resin (A). Is the melting point of the polyamide 6 resin (A) +20° C. or less, and 0.01 to 5 parts by weight of the polyamide resin (B) whose temperature-lowering crystallization temperature measured by DSC is higher than the temperature-lowering crystallization temperature of the polyamide 6 resin (A). , And amide wax (C) in an amount of 0.01 to 10 parts by weight. By mixing the polyamide resin (B) and the amide wax (C) in a specific amount with the polyamide 6 resin (A) having an excellent balance of moldability, gas barrier property, rigidity and toughness, the crystallization temperature is high and The crystallization speed of the high speed increases the crystallization speed, and a dense and uniform crystal is formed, so that the permeation of hydrogen gas and the dissolution of hydrogen in the resin can be suppressed. Defect points are less likely to occur even after repeated filling and pressure release, and it has excellent toughness. Further, the releasability at the time of injection 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) and the polyamide resin (B) or the combination of the polyamide 6 resin (A) and the amide wax (C), the polyamide 6 resin (A), the polyamide resin (B) and The toughness is inferior to the combination of the amide wax (C). Further, a technique of adding a nucleating agent for the purpose of accelerating crystallization of a resin composition is known, but with an organic nucleating agent or an inorganic nucleating agent other than polyamide (B), the crystallization rate is known. However, since denser and more uniform crystals are not formed as compared with the polyamide resin (B), defect points are likely to occur when the high-pressure hydrogen is repeatedly filled and released. Further, a technique of adding a release agent to improve the release property at the time of injection molding is known, but with a release agent other than the amide wax (C), when high-pressure hydrogen is repeatedly filled and released. However, defects are likely to occur in the molded product, and the releasability during molding is not improved.

The polyamide 6 resin (A) used in the present invention is a polyamide resin containing 6-aminocaproic acid and/or ε-caprolactam as a main raw material. Other monomers may be copolymerized as long as the object of the present invention is not impaired. Here, "to be a main raw material" means that a total of 50 mol% or more of a unit derived from 6-aminocaproic acid or a unit derived from ε-caprolactam in 100 mol% of the total of 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 70 mol% or more, further preferably 90 mol% or more.

Examples of other monomers to be copolymerized include amino acids such as 11-aminoundecanoic acid, 12-aminododecanoic acid and para-aminomethylbenzoic acid, lactams such as ω-laurolactam; tetramethylenediamine, pentamethylenediamine, Aliphatic diamines such as hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-/2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine; Aromatic diamines such as meta-xylylenediamine and para-xylylenediamine; 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, aminoethylpiperazine, etc. Aliphatic dicarboxylic acids; adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and other aliphatic dicarboxylic acids; terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalate 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 And alicyclic dicarboxylic acids such as 3-cyclopentanedicarboxylic acid. You may copolymerize 2 or more types of these.

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 with a resin concentration of 0.01 g/ml is in the range of 1.5 to 7.0. Is preferred. When the relative viscosity is 1.5 or more, the melt viscosity of the polyamide resin composition at the time of molding becomes moderately high, air entrapment at the time of molding can be suppressed, and 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.

Although the amount of amino terminal groups of the polyamide 6 resin (A) is not particularly limited, it is preferably in the range of 1.0×10 ^{−5 to} 10.0×10 ⁻⁵ mol/g. When the amount of the amino terminal group 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 amino terminal group amount of the polyamide 6 resin (A) is 0.02N hydrochloric acid obtained by dissolving the polyamide 6 resin (A) in a phenol/ethanol mixed solvent (83.5:16.5 (volume ratio)). It can be determined by titrating with an aqueous solution.

The polyamide resin (B) used in the present invention has a melting point measured by DSC of not more than the melting point of the polyamide 6 resin (A)+20° C., and a temperature falling crystallization temperature measured by DSC is falling temperature crystallization of the polyamide 6 resin (A). It is a polyamide resin that is higher than the temperature.

Here, the melting point and the falling crystallization temperature by DSC measurement of the polyamide 6 resin (A) and the polyamide resin (B) in the present invention can be determined by the following methods. First, using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.), two-point calibration (indium, lead) and baseline correction are performed. The sample amount is set to 8 to 10 mg, and the temperature is raised by 15° C. higher than the temperature showing the maximum value of the melting curve obtained by raising the temperature at a heating rate of 20° C./min. The crystallization exothermic peak temperature observed when cooled to 30° C. at a speed is set as the temperature-falling crystallization temperature. Further, after holding at 30° C. for 1 minute, the second heating step is performed at a rate of 20° C./minute in the same manner as the first heating step. The melting endothermic peak temperature observed in the second heating step is taken as the melting point.

When the melting point of the polyamide resin (B) exceeds the melting point of the polyamide 6 resin (A)+20° C., the dispersed state of the polyamide resin (B) in the polyamide resin composition of the present invention is lowered, so that the crystallization rate is improved. The effect becomes small, and defect points are likely to occur by repeating high-pressure hydrogen filling and pressure release. The melting point of the polyamide resin (B) is preferably the melting point of the polyamide 6 resin (A) +15°C or less, more preferably the melting point of the polyamide 6 resin (A) +12°C or less, and the melting point of the polyamide 6 resin (A) +10°C or less. More preferable. If the melting point of the polyamide resin (B) is equal to or lower than the melting point of the polyamide 6 resin (A)+10° C., the temperature range of the solid-liquid phase separation state between the polyamide 6 resin (A) and the polyamide resin (B) becomes narrow. Thereby, the crystallization speed is improved. On the other hand, the lower limit of the melting point of the polyamide resin (B) is not particularly limited, but the melting point of the polyamide 6 resin (A) + 1° C. or more is preferable as the lowering crystallization temperature of the polyamide resin (B) is within the preferable range described later. It is preferable because it tends to be easily formed.

In addition, when the cooling crystallization temperature of the polyamide resin (B) is not more than the cooling crystallization temperature of the polyamide 6 resin (A), crystals of the polyamide 6 resin (A) are crystallized in the cooling process from the molten state of the polyamide resin composition. Since the rate of crystallization is higher than the rate of crystallization of polyamide resin (B), dense and uniform crystals are not formed, and when high-pressure hydrogen is repeatedly filled and released, defects are likely to occur and weld characteristics are deteriorated. To do. The cooling crystallization temperature of the polyamide resin (B) is preferably 1° C. or higher, more preferably 3° C. or higher, even more preferably 5° C. or higher, than the cooling crystallization temperature of the polyamide 6 resin (A). .. If the cooling crystallization temperature of the polyamide resin (B) is higher than the cooling crystallization temperature of the polyamide 6 resin (A) by 5° C. or more, the cooling process from the molten state of the polyamide 6 resin (A) and the polyamide resin (B) In the above, since the crystallization of the polyamide resin (B) occurs remarkably faster than the crystallization of the polyamide 6 resin (A), the effect of the polyamide resin (B) as a crystallization accelerator is remarkably exhibited and the densification is improved. As a result, a uniform crystal is likely to be formed, and even if the high-pressure hydrogen is repeatedly filled and released, defect points are unlikely to occur and the weld characteristics are improved. On the other hand, the cooling crystallization temperature of the polyamide resin (B) is preferably the melting point of the polyamide 6 resin (A) + 20°C or less, more preferably the melting point of the polyamide 6 resin (A) + 15°C or less, and more preferably the melting point of the polyamide 6 resin (A). The melting point +10°C or lower is more preferable. If the cooling crystallization temperature of the polyamide resin (B) is not higher than the melting point of the polyamide 6 resin (A)+20° C., the melt retention stability of the polyamide 6 resin (A) during production of the polyamide resin composition is maintained. However, the effect of the present invention can be exhibited.

Examples of means for adjusting the melting point and the cooling crystallization temperature of the polyamide resin (B) to the above ranges include, for example, a method of selecting a polyamide resin having a desired melting point or cooling crystallization temperature from polyamide resins having different melting points or cooling crystallization temperatures. , A method of adjusting the degree of polymerization, the copolymerization ratio, and the like.

The polyamide resin (B) is not particularly limited as long as it is a polyamide resin whose melting point and cooling crystallization temperature satisfy the above-mentioned conditions. Generally, amino acids, lactams or diamines and dicarboxylic acids can be obtained as main raw materials. it can. Typical examples of the raw material include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and para-aminomethylbenzoic acid; lactams such as ε-caprolactam and ω-laurolactam; tetramethylenediamine. , Pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-/2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, etc. Aromatic diamines such as meta-xylylenediamine and para-xylylenediamine; 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 Alicyclic diamines such as aminoethylpiperazine; 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 Aromatic dicarboxylic acids such as 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2- Examples thereof include alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and 1,3-cyclopentanedicarboxylic acid. In the present invention, polyamide homopolymers or copolymers derived from these raw materials can be used. You may mix|blend 2 or more types of such polyamide resins.

Specific examples of the polyamide resin (B) preferably used in the present invention include polyhexamethylene sebacamide (polyamide 610), polyhexamethylene adipamide (polyamide 66), polypentamethylene adipamide ( One or more selected from polyamide 56), polytetramethylene adipamide (polyamide 46) and polytetramethylene sebacamide (polyamide 410), and polycaproamide (polyamide 6), polyundecane amide (polyamide 11), poly Examples include copolymers with one or more selected from dodecane amide (polyamide 12), polyhexamethylene sebacamide (polyamide 610), polypentamethylene sebacamide (polyamide 510) and polyhexamethylene dodecamide (polyamide 612). To be Among these, the polyamide 610 resin is more preferable because the weld characteristics are further improved.

The degree of polymerization of the polyamide resin (B) 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. It is preferable to have. When the relative viscosity is 1.5 or more, the melt viscosity of the polyamide resin composition at the time of molding becomes moderately high, air entrapment at the time of molding can be suppressed, and 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 becomes appropriately low, and the moldability can be further improved.

The amount of amino terminal groups of the polyamide resin (B) is not particularly limited, but it is preferably in the range of 1.0×10 ^{−5 to} 10.0×10 ⁻⁵ mol/g. When the amount of the amino terminal group 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, as the amino terminal group amount of the polyamide resin (B), the polyamide resin (B) is dissolved in a phenol/ethanol mixed solvent (83.5:16.5 (volume ratio)), and a 0.02N hydrochloric acid aqueous solution is used. It can be determined by titration with.

The content of the polyamide resin (B) in the polyamide resin composition of the present invention is 0.01 to 5 parts by weight with respect to 100 parts by weight of the polyamide 6 resin (A). When the blending amount of the polyamide resin (B) is less than 0.01 part by weight, the effect of improving the crystallization rate is not sufficient, and defects are likely to occur due to repeated high-pressure hydrogen filling and pressure release. In addition, since it is difficult to form a dense and uniform crystal, the weld characteristics deteriorate. The blending amount of the polyamide resin (B) is preferably 0.05 part by weight or more, more preferably 0.1 part by weight or more. On the other hand, when the blending amount of the polyamide resin (B) exceeds 5 parts by weight, phase separation between the polyamide 6 resin (A) and the polyamide resin (B) easily proceeds in the cooling process from the molten state of the resin composition. However, the effect of improving the crystallization rate is not sufficient, and defect points are likely to occur due to repeated high-pressure hydrogen filling and pressure release. In addition, since it is difficult to form a dense and uniform crystal, the weld characteristics deteriorate. The content of the polyamide resin (B) is preferably 4.5 parts by weight or less, more preferably 4 parts by weight or less.

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

The monoamine is preferably a monoamine having 5 or more carbon atoms, 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 to 20 carbon atoms are particularly preferable. When the carbon number 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, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and olein. Acid, linoleic acid, behenic acid, montanic acid, 12-hydroxystearic acid, benzoic acid and the like can be mentioned, and these may be used in combination of two or more kinds. Of these, higher aliphatic monocarboxylic acids having 10 to 30 carbon atoms are particularly preferable. When the carbon number is more than 30, the compatibility with the polyamide 6 resin (A) decreases 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, metaxylylenediamine, Paraxylylenediamine, tolylenediamine, phenylenediamine, isophoronediamine, etc. are mentioned, and these may use 2 or more types together. Of these, ethylenediamine is particularly suitable.

The polybasic acid is a carboxylic acid of a 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 acids, aromatic dicarboxylic acids such as isophthalic acid, cyclohexanedicarboxylic acids, and alicyclic dicarboxylic acids such as cyclohexylsuccinic acid, and these may be used in combination of two or more kinds.

Among them, an amide compound obtained by reacting a higher aliphatic monocarboxylic acid, a polybasic acid and a diamine is particularly preferable. For example, an amide compound obtained by reacting stearic acid, sebacic acid and ethylenediamine is preferable. In that case, 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. Further, 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 (C) is not particularly limited, but the melting point measured by DSC is preferably the melting point of the polyamide 6 resin (A) or higher. When the melting point of the amide wax (C) is equal to or higher than the melting point of the polyamide 6 resin (A), releasability at the time of molding is further improved.

Here, the melting point of the amide wax (C) in the present invention measured by DSC can be determined by the following method. First, using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.), two-point calibration (indium, lead) and baseline correction are performed. The sample amount is set to 8 to 10 mg, and the temperature is raised by 15° C. higher than the temperature showing the maximum value of the melting curve obtained by raising the temperature at a heating rate of 20° C./min. Cool at a rate of 30°C. Further, after the temperature is maintained at 30° C. for 1 minute, the second temperature raising step is performed at a rate of 20° C./minute in the same manner as the first temperature raising step. The melting endothermic peak temperature observed in the second heating step is taken as the melting point.

The blending amount of the amide wax (C) 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). When the blending amount of the amide wax (C) is less than 0.01 part by weight, the effect of improving the releasability is not sufficient, and defects are likely to occur due to repeated filling of high pressure hydrogen and pressure release. Become. The blending amount of the amide wax (C) is preferably 0.05 part by weight or more, more preferably 0.1 part by weight or more. On the other hand, if the blending amount of the amide wax (C) exceeds 10 parts by weight, the toughness decreases, and defects are likely to occur due to repeated filling of high pressure hydrogen and pressure release. The compounding amount of the amide wax (C) is preferably 7 parts by weight or less, more preferably 5 parts by weight or less.

The polyamide resin composition preferably further comprises an impact resistant material (D). By blending the impact resistant material (D), the impact resistance of the molded product can be improved. In addition, a molded article used for the purpose of being exposed to high-pressure hydrogen is repeatedly subjected to a temperature change (heat cycle) from −40° C. or lower to 90° C. or higher due to filling and pressure 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 (D), it is possible to suppress cracks in the joint portion between the resin portion and the metal portion caused by such repeated heat cycles, and improve the heat cycle resistance.

As the impact resistant material (D), for example, olefin resin, acrylic rubber, silicone rubber, fluorine rubber, styrene rubber, nitrile rubber, vinyl rubber, urethane rubber, polyamide elastomer, polyester elastomer, ionomer. And so on. You may mix these 2 or more types.

Among these, the olefin resin is preferably used because it has excellent compatibility with the polyamide 6 resin (A), the polyamide resin (B), and the amide wax (C) and has a high heat cycle resistance improving effect. The olefin resin is a thermoplastic resin obtained by polymerizing olefin monomers such as ethylene, propylene, butene, isoprene and pentene. It may be a copolymer of two or more kinds of olefin monomers, or a copolymer of these olefin monomers and other monomers. Specific examples of the olefin-based resin include polymers such as polyethylene, polypropylene, polystyrene, poly 1-butene, poly 1-pentene, and polymethylpentene or copolymers thereof; ethylene/α-olefin copolymers, ethylene/ at least α,β-unsaturated carboxylic acid ester copolymer, α-olefin/α,β-unsaturated carboxylic acid ester copolymer, [copolymer of (ethylene and/or propylene) and vinyl alcohol ester] A polyolefin obtained by partially hydrolyzing, a copolymer of (ethylene and/or propylene) and (unsaturated carboxylic acid and/or unsaturated carboxylic acid ester), [(ethylene and/or propylene) and (unsaturated [Copolymer with Saturated Carboxylic Acid and/or Unsaturated Carboxylic Acid Ester]] and a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon obtained by metallizing at least a part of the carboxyl group of 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 further preferable.

Moreover, the olefin resin may be modified with an unsaturated carboxylic acid and/or a derivative thereof. Here, the unsaturated carboxylic acid derivative is a compound in which the hydroxy group portion of the carboxyl group of the unsaturated carboxylic acid is substituted with another substituent, and is a metal salt of unsaturated carboxylic acid, an acid halide, an ester, an acid. Such as anhydrides, amides and imides. By using such a modified olefin resin, the compatibility with the polyamide 6 resin (A), the polyamide resin (B), and the amide wax (C) is further improved, and the heat cycle resistance is further improved. You can Examples of unsaturated carboxylic acids or their derivatives 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 itaconate, 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 methacrylate, dimethyl maleate, dimethyl itaconate; maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo-(2,2,1)-5 Acid anhydrides such as -heptene-2,3-dicarboxylic acid and endobicyclo-(2,2,1)-5-heptene-2,3-dicarboxylic acid anhydride; maleimide, N-ethylmaleimide, N-butylmaleimide , N-phenylmaleimide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, glycidyl citracone, 5-norbornene-2,3-dicarboxylic acid and the like. Among these, unsaturated dicarboxylic acids and acid anhydrides thereof are preferable, and maleic acid or maleic anhydride is particularly preferable.

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

The ethylene/α-olefin copolymer is preferably a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene. , 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 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 -1-Hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene and the like can be mentioned. You may use 2 or more types of these. Among these α-olefins, α-olefins having 3 to 12 carbon atoms are preferable from the viewpoint of improving mechanical strength. Further, non-conjugated dienes 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 is a polyamide 6 resin (A), a polyamide resin (B), and an amide wax (C. ) And the heat cycle resistance can be further improved, which is more preferable. Further, even if the filling of hydrogen at a higher pressure and the release of pressure are repeated, the generation of defect 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%, and further preferably 3 to 20 mol%.

The structure of the impact resistant material (D) is not particularly limited, and is, for example, a so-called core-shell type multilayer structure including at least one layer made of rubber and one or more layers made of a polymer different from the rubber. 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 examples thereof include acrylic component, silicone component, styrene component, nitrile component, conjugated diene component, urethane component, ethylene component, propylene component, isobutene component. A rubber obtained by polymerizing The type of different polymers constituting the layers 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 may be used. preferable. As the polymer having thermoplasticity, for example, unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, unsaturated dicarboxylic acid anhydride units, aliphatic vinyl units, aromatic vinyl units, Examples of the polymer include vinyl cyanide units, maleimide units, unsaturated dicarboxylic acid units, and other vinyl units.

The content of the impact resistant material (D) 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). By setting the content of the impact resistant material (D) to be 1 part by weight or more, the heat cycle resistance can be further improved. The content of the impact resistant material (D) is more preferably 5 parts by weight or more, further preferably 10 parts by weight or more. On the other hand, by setting the amount of the impact resistant material (D) to be 50 parts by weight or less, it is possible to suppress the generation of defect points even when the high pressure hydrogen is repeatedly filled and released. The content of the impact resistant material (D) 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, the polyamide resin composition may contain other components than the components (A), (B), (C) and (D) as long as the characteristics are not impaired. Examples of the other components include fillers, thermoplastic resins other than the components (A) to (D), and various additives.

For example, the strength and dimensional stability of the resulting molded article can be improved by blending a polyamide resin composition with a filler as another component. 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 fiber. Examples include fibers and metal fibers. Examples of the non-fibrous filler include silicates such as wollastonite, zeolite, sericite, kaolin, mica, clay, pyrophyllite, bentonite, asbestos, talc, and alumina silicate; alumina, silicon oxide, magnesium oxide, and 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; magnesium hydroxide, calcium hydroxide, aluminum hydroxide and the like. Metal hydroxides; glass beads, ceramic beads, boron nitride, silicon carbide and the like can be mentioned. These may be hollow. Further, it is preferable to pretreat these fibrous and/or non-fibrous fillers with a coupling agent before use in order to obtain better mechanical properties. Examples of the coupling agent include isocyanate compounds, organic silane compounds, organic titanate compounds, organic borane compounds, and epoxy compounds.

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

Examples of various additives include anti-coloring agents, antioxidants such as hindered phenols and hindered amines, mold release agents, plasticizers, heat stabilizers, lubricants, anti-UV agents, coloring agents, flame retardants, foaming agents, etc. Are listed.

It is preferable to add a copper compound to the polyamide resin composition because the long-term heat resistance can be improved. Examples of the copper compound include cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, cupric sulfate, cupric nitrate. , Copper phosphate, cuprous acetate, cupric acetate, cupric salicylate, cupric stearate, cupric benzoate and the aforementioned inorganic copper halides and xylylenediamine, 2-mercaptobenzimidazole, benzimidazole Complex compounds such as. You may mix these 2 or more types. Of these, monovalent copper compounds, particularly monovalent copper halide compounds, are preferable, and cuprous acetate, cuprous iodide, and the like are preferable. The compounding amount of the copper compound is preferably 0.01 parts by weight or more, and more preferably 0.015 parts 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 coloration due to liberation of metallic copper during molding, the compounding amount of the copper compound is preferably 2 parts by weight or less, and more preferably 1 part by weight or less.

Moreover, you may mix|blend an alkali halide compound with a 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. You may mix these 2 or more types. Particularly preferred is potassium iodide or sodium iodide.

The temperature falling crystallization temperature of the polyamide resin composition measured by DSC is preferably 180° C. or higher, and more preferably 183° C. or higher. When the cooling crystallization temperature of the polyamide resin composition is 180° C. or higher, in the cooling process from the molten state of the polyamide resin composition, dense and uniform crystals are likely to be formed, resulting in low hydrogen permeability, The occurrence of defect points can be suppressed even when the high-pressure hydrogen is repeatedly filled and released. The temperature falling crystallization temperature of the polyamide resin composition is preferably 180°C or higher, more preferably 183°C or higher.

In the present invention, the temperature falling crystallization temperature of the polyamide resin composition by DSC measurement can be determined by the following method. First, using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.), two-point calibration (indium, lead) and baseline correction are performed. The sample amount is set to 8 to 10 mg, and the temperature is raised by 15° C. higher than the temperature showing the maximum value of the melting curve obtained by raising the temperature at a heating rate of 20° C./min. The crystallization exothermic peak temperature observed when cooled to 30° C. at a speed is set as the temperature-falling crystallization temperature. However, when two or more peaks are observed, the temperature corresponding to the largest crystallization exothermic peak is set as the lowered crystallization temperature of the polyamide resin composition.

Examples of means for adjusting the temperature falling crystallization temperature of the polyamide resin composition to the above range include a method using the above-mentioned preferred polyamide resin composition.

Next, a method for producing the polyamide resin composition of the present invention will be described. The method for producing the polyamide resin composition of the present invention is not particularly limited and includes, for example, polyamide 6 resin (A) and polyamide resin (B), amide wax (C), and, if necessary, impact resistant material (D). ) And other components are kneaded together, or the polyamide 6 resin (A) is melted and then the polyamide resin (B), the amide wax (C) and, if necessary, the impact resistant material (D) and other components are kneaded. A method of melting the polyamide 6 resin (A) and the polyamide resin (B) and then kneading the amide wax (C) and, if necessary, the impact resistant material (D) and other components, and the polyamide 6 resin (A) Method of kneading polyamide resin (B) and, if necessary, impact-resistant material (D) and other components after melting amide wax (C), polyamide 6 resin (A), polyamide resin (B), and amide Examples include a method of melting the system wax (C) and then kneading the impact resistant material (D) and other components as necessary. 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 (D) and various additives, these can be blended at any stage. For example, in the case of producing the polyamide resin composition of the present invention with a twin-screw extruder, when the polyamide 6 resin (A), the polyamide resin (B), and the amide wax (C) are blended, the impact resistant material (D ) And other components at the same time, or during the melt-kneading of the polyamide 6 resin (A), the polyamide resin (B), and the amide wax (C), the impact resistant material (D) by a method such as side feed. And a method of blending other components, or a method of blending the polyamide 6 resin (A) and the polyamide resin (B) and the amide wax (C) in advance and then blending the impact resistant material (D) and other components. Alternatively, there may be mentioned a method in which the impact resistant material (D) and other components are blended in advance with the polyamide 6 resin (A), melt-kneaded, and then the polyamide resin (B) and the amide wax (C) are blended.

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, calendar molding, compression molding, vacuum molding, foam molding, blow molding, and rotation molding. Examples of the molding shape include pellet shape, plate shape, fiber shape, strand shape, film or sheet shape, pipe shape, hollow shape, box shape and the like. In particular, the polyamide resin composition of the present invention is suitable for injection molding because of its excellent moldability.

INDUSTRIAL APPLICABILITY The molded product of the present invention is used for a molded product exposed to high-pressure hydrogen by taking advantage of the excellent feature that the generation of defect points is suppressed even if the high-pressure hydrogen is repeatedly charged and released. The molded product that is exposed to high-pressure hydrogen as used herein is a molded product that is exposed to hydrogen at a pressure higher than normal pressure. Since it has the effect of suppressing the generation of defect points when the high-pressure hydrogen is repeatedly filled and released, it is preferably used for molded product applications in which hydrogen at a pressure of 20 MPa or more is exposed, and by molded product applications in which hydrogen at a pressure of 30 MPa or more is exposed. It is preferably used. On the other hand, it is preferably used for molded article applications where hydrogen is exposed to a pressure of 200 MPa or less, more preferably used for molded article applications exposed to hydrogen of 150 MPa or less, and more preferably used for molded article applications exposed to hydrogen of 100 MPa or less. Molded products that come into contact with high-pressure hydrogen include, for example, open/close valves for high-pressure hydrogen, check valves for high-pressure hydrogen, pressure reducing valves for high-pressure hydrogen, pressure adjusting valves for high-pressure hydrogen, high-pressure hydrogen seals, high-pressure hydrogen hoses, high-pressure hydrogen. Tank, tank liner for high pressure hydrogen, high pressure hydrogen pipe, high pressure hydrogen packing, high pressure hydrogen pressure sensor, high pressure hydrogen pump, high pressure hydrogen tube, high pressure hydrogen regulator, high pressure hydrogen film, high pressure hydrogen sheet, high pressure Fibers for hydrogen, joints for high-pressure hydrogen, etc. may be mentioned. Among them, high-pressure hydrogen on-off valve, high-pressure hydrogen check valve, high-pressure hydrogen pressure reducing valve, high-pressure hydrogen pressure adjusting valve, high-pressure hydrogen tank, high-pressure hydrogen tank liner, high-pressure hydrogen packing, high-pressure hydrogen pressure sensor, It can be preferably used for a high-pressure hydrogen container such as a high-pressure hydrogen pump, a high-pressure hydrogen regulator, and a high-pressure hydrogen joint, and its peripheral parts. Among these, the high pressure hydrogen tank can be particularly preferably used.

The high-pressure hydrogen tank liner can be obtained by molding by any method as described above. Examples of the molding method include extrusion molding, injection molding, hollow molding, calendar molding, compression molding, vacuum molding, foam molding, blow molding, and rotation molding.

Further, as a method of forming the tank liner for high-pressure hydrogen, there can be mentioned a method of forming two or more divided bodies forming the tank liner for high-pressure hydrogen by molding and joining these by welding. For example, a method for forming a tank liner for high-pressure hydrogen by welding two molded bodies in the shape of a tank liner for high-pressure hydrogen divided in half, a shape in which the tank liner for high-pressure hydrogen is divided in half. A method of forming a tank liner for high-pressure hydrogen by welding two molded articles of 1 above, closing both ends of the high-pressure hydrogen tank liner, two end plates having a shape such as a semicircle or an ellipse, and a body Examples of the method include forming a tank liner for high-pressure hydrogen by joining the parts by welding, but the method is not limited to this.

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

A particularly preferred embodiment is a mode in which the tank liner made of the polyamide resin composition of the present invention is used as a resin liner for a high-pressure hydrogen tank in which the outside of a 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 the CFRP reinforcing layer on the surface layer of the tank liner, strength and elastic modulus capable of withstanding high pressure can be exhibited, which is preferable. The CFRP reinforcing layer is composed of carbon fiber and matrix resin. From the viewpoint of bending properties and strength, the carbon fiber preferably has a tensile elastic modulus of 50 to 700 GPa in terms of carbon fiber simple substance, and from the viewpoint of specific rigidity, 200 to 700 GPa is more preferable and cost performance is improved. Considering the viewpoints as well, those having 200 to 450 GPa are most preferable. The tensile strength of the carbon fiber itself is preferably 1500 to 7,000 MPa, and from the viewpoint of specific strength, 3,000 to 7,000 MPa is preferable. The density of the carbon fiber 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 further weight reduction. The carbon fibers may be used alone or in combination with reinforcing fibers other than carbon fibers. Examples of the reinforcing fiber other than carbon fiber include glass fiber and aramid fiber. Further, when the ratio of the carbon fiber and the matrix resin is defined by the volume fraction Vf of the carbon fiber in the carbon fiber reinforced resin reinforcing layer material, Vf is preferably 20 to 90% from the viewpoint of rigidity, and the viewpoint of productivity and required rigidity. Therefore, Vf is preferably 40 to 80%.

The matrix resin forming 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, silicone resin and the like. Only one of these may be used, or two or more 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 material is polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin, polystyrene resin, AS resin, polyamide resin, polyacetal resin, polycarbonate resin, thermoplastic polyester resin, PPS resin. Examples thereof include fluororesins, polyetherimide resins, polyetherketone resins, and polyimide resins. 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 together. Moreover, you may add a brominated flame retardant, a silicon flame retardant, red phosphorus, etc. as a flame retardant.

As a method for laminating the CFRP reinforcing layer on the surface layer of the tank liner for high-pressure hydrogen, known filament winding (hereinafter FW) method, tape winding (hereinafter TW) method, sheet winding (hereinafter SW) method, hand layup method, RTM (Resin Transfer Molding) method and the like can be exemplified. Of these molding methods, only a single method may be used, or two or more kinds of molding methods may be used in combination. A method selected from the FW method, the TW method, and the SW method is preferable from the viewpoints of the property developability, the productivity, and the moldability. The FW method, the SW method and the TW method are basically the same molding method from the viewpoint of applying a matrix resin to strand-like carbon fibers and laminating the carbon fibers to the liner. The name is different depending on which of a filament (thread) form, a tape (tape form in which some yarns are bundled) form, and a sheet (sheet form in which tapes are bundled to some extent) form. Here, the most basic FW method will be described in detail, but the contents can 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 resin-coated (uncured) carbon fiber around the liner, or to apply the resin to the carbon fiber immediately before winding around the liner. It is also possible to do so. In these cases, it is necessary to wind the carbon fiber and the uncured matrix resin around the liner, and then perform a resin curing process in a batch oven (oven) or continuous curing oven under the conditions suitable for the resin used 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 onto which the resin has been applied (impregnated) directly on the liner to form a high-pressure hydrogen tank shape. In this case, it is necessary to raise the temperature of the resin-coated carbon fiber to a temperature equal to or higher than the melting point of the thermoplastic resin immediately before being wound on the liner. It is also possible to apply the melted thermoplastic resin to the carbon fibers immediately before winding on the liner. In this case, the resin curing step as applied to the thermosetting resin is unnecessary.

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

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 serves as a filling port and a discharging port for high-pressure hydrogen. Examples of the material of the metal component used as the valve include carbon steel, manganese steel, chrome molybdenum steel, stainless steel, aluminum alloy and the like. 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 structures. Examples of the manganese steel include seamless steel pipes for high-pressure gas containers, manganese steel materials for machine structures, and manganese chromium 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 products, and chrome molybdenum steel products. Examples of the stainless steel include forged stainless steel products for pressure, stainless steel pipes for piping, stainless steel rods, hot rolled stainless steel plates and strips, cold rolled stainless steel plates and strips. Examples of aluminum alloys include aluminum, aluminum alloy plates, strips, rods, wires, seamless tubes, and forged products. For carbon steel, annealing, normalizing, for manganese steel, normalizing, quenching and tempering, for chrome molybdenum steel and low alloy steel, quenching and tempering, stainless steel It is also possible to apply a solution treatment to the above and a material that has been quenched and tempered to the aluminum alloy. Further, the aluminum alloy may be subjected to solution treatment and T6 aging treatment.

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

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

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

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

(2) Temperature-lowering crystallization temperature of polyamide resin composition About the resin composition pellets obtained in each Example and Comparative Example, two-point calibration (indium, indium, using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.) Lead), after performing baseline correction, the sample amount was set to 8 to 10 mg, and the temperature was increased by 15°C at a temperature 15°C higher than the temperature showing the maximum value of the melting curve obtained by raising the temperature at a rate of 20°C/min. After holding for a minute, it was cooled to 30° C. under the condition of the temperature decreasing rate of 20° C./min. The crystallization exothermic peak temperature observed in this cooling step was set as the temperature-falling crystallization temperature.

(3) Releasability From the resin composition pellets obtained in each Example and Comparative Example, using an injection molding machine “SE75DUZ-C250” manufactured by Sumitomo Heavy Industries, Ltd., a cylinder temperature: 240° C., a mold A rectangular plate molded product of 80 mm×80 mm×thickness of 3 mm was injection molded under the molding conditions of temperature: 80° C., injection speed: 40 mm/sec, holding pressure: 20 MPa, cooling time: 20 sec. At the time of injection molding, the presence or absence of sticking to the mold was confirmed.

(4) Heat cycle resistance The resin composition pellets obtained in each Example and Comparative Example were injection-molded by NISSEI PLASTIC INDUSTRIES CO., LTD. "NEX1000" using a cylinder temperature of 240°C and a mold temperature of: Under a molding condition of 80° C., an injection speed of 100 mm/sec and a cooling time of 20 sec, a metal core of 47 mm×47 mm×27 mm was overmolded with a thickness of 1.5 mm.

The three metal/resin composite molded products thus obtained were allowed to stand at a temperature of −60° C. for 1 hour and then at 90° C. for 1 hour, and the composite molded product was visually observed to determine the presence or absence of cracks. Repeating this operation, the number of cycles at which all three composite molded articles were broken was 500 times or more was A, 200 to 499 times was B, and 199 times or less was C.

(5) Toughness (tensile fracture elongation)
From the resin composition pellets obtained in each example and comparative example, using an injection molding machine "SE75DUZ-C250" manufactured by Sumitomo Heavy Industries, Ltd., cylinder temperature: 240°C, mold temperature: 80°C, injection A 1/8 inch ASTM No. 1 dumbbell test piece conforming to ASTM D638 was injection-molded under molding conditions of speed: 40 mm/sec, holding pressure: 20 MPa, cooling time: 20 sec. About 5 of the obtained 1/8 inch ASTM No. 1 dumbbell test pieces, UTA-2.5T manufactured by Orientec was used under an atmosphere of 23° C. and 50% RH, and a sample gauge length was 100 mm and a pulling speed was 100%. The measurement was carried out at 10 mm/min, and the amount of displacement until breaking was taken as the tensile breaking elongation. The average value of the tensile rupture elongations measured on 5 pieces was defined as the toughness.

The raw materials and abbreviations used in each Example and Comparative Example are shown below.
PA6: Polyamide 6 resin (melting point 223° C., crystallization temperature 175° C., resin concentration 0.01 g/ml in 98% concentrated sulfuric acid solution at 25° C., relative viscosity 2.70)
PA610: Polyamide 610 resin (melting point 226° C., crystallization temperature at temperature decrease 187° C., relative viscosity 3.5 at 25° C. in 98% concentrated sulfuric acid solution with resin concentration 0.01 g/ml)
PA66: Polyamide 66 resin (melting point 263° C., crystallization temperature 225° C., resin viscosity 0.01 g/ml in 98% concentrated sulfuric acid solution at 25° C. relative viscosity 2.70)
PA6/PA66 copolymer: Polyamide 6/polyamide 66 copolymer (melting point 190° C., crystallization temperature 122° C., resin viscosity 0.01 g/ml 98% concentrated sulfuric acid solution at 25° C., relative viscosity 4.20)
Amide wax: ethylenediamine/stearic acid/sebacic acid polycondensate ““Light Amide” WH-255” (Kyoeisha Chemical Co., Ltd., melting point 255° C.)
Fatty acid ester: ethylene glycol dimontanate ""Licowax"E" (manufactured by Clariant Japan KK)
Organic Nucleating Agent: N,N',N"-Tris(2-methylcyclohexan-1-yl)propane-1-2-3triylcarboxamide ""Rica Clear" (registered trademark) PC-1" (New Japan Chemical ( Made)
Inorganic nucleating agent: Talc ""MicroAce" (registered trademark) P-6" (manufactured by Nippon Talc Co., Ltd., median diameter (D50) 4.0 µm)
Impact-resistant material 1: Maleic anhydride-modified ethylene/1-butene copolymer ""Tufmer" (registered trademark) MH7020" (manufactured by Mitsui Chemicals, Inc.)
Impact Resistant Material 2: Glycidyl Methacrylate Modified Polyethylene Copolymer ""Bond First" (registered trademark) 7L" (Sumitomo Chemical Co., Ltd.)
Impact-resistant material 3: Ionomer “HIMILAN” (registered trademark) 1706 (manufactured by DuPont).

[Examples 1 to 9 and Comparative Examples 1 to 12]
A twin screw extruder (TEX30α-manufactured by JSW Co., Ltd.) in which each raw material shown in Table 1 and Table 2 was set to a cylinder temperature of 240° C., a screw arrangement provided with one kneading zone and a screw rotation speed of 150 rpm was used. 35 BW-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 a resin composition pellet. Got The obtained resin composition pellets were vacuum-dried at a temperature of 80° C. for 12 hours with a vacuum dryer, and the dried pellets were evaluated by the above-mentioned method. 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), the polyamide resin (B), and the amide wax (C) has a high crystallization temperature, and crystallization from the molten state The crystallization speed became faster because it proceeded faster. Therefore, it was found that the molded product obtained by molding such a polyamide resin composition has suppressed generation of defect points even after repeating high-pressure hydrogen filling and pressure release, and has excellent toughness and releasability. ..

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

The polyamide resin composition of the present invention has a high crystallization temperature, the crystallization rate from the molten state progresses rapidly, so the crystallization rate is high, and the occurrence of defect points is suppressed even when the high-pressure hydrogen is repeatedly charged and released. Further, it is possible to obtain a molded product which is excellent in mold releasability which is important at the time of injection molding and which is excellent in toughness which is an important mechanical property of the molded product obtained by injection molding. Molded products obtained by molding the polyamide resin composition of the present invention can be widely used for molded products exposed to high-pressure hydrogen by utilizing these characteristics.

Claims (9)

With respect to 100 parts by weight of polyamide 6 resin (A), the melting point measured by DSC is not more than the melting point of polyamide 6 resin (A) +20° C., and the temperature falling crystallization temperature measured by DSC is the temperature falling crystal of polyamide 6 resin (A). A polyamide resin composition for a molded product exposed to high-pressure hydrogen, which comprises 0.01 to 5 parts by weight of a polyamide resin (B) having a temperature higher than the curing temperature and 0.01 to 10 parts by weight of an amide wax (C). .. The polyamide resin composition according to claim 1, wherein the polyamide resin (B) is a polyamide 610 resin. The polyamide resin composition according to claim 1 or 2, wherein a melting point of the amide wax (C) measured by DSC is equal to or higher than a melting point of the polyamide 6 resin (A). The polyamide resin composition according to any one of claims 1 to 3, further comprising 1 to 50 parts by weight of the impact resistant material (D) mixed with 100 parts by weight of the polyamide 6 resin (A). The polyamide resin composition according to claim 4, wherein the impact resistant material (D) contains an ethylene/α-olefin copolymer modified with an unsaturated carboxylic acid and/or a derivative thereof. A molded product which is exposed to high-pressure hydrogen and which 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 claim 1. A high-pressure hydrogen tank comprising a tank liner made of the polyamide resin composition according to any one of claims 1 to 5, and a carbon fiber reinforced resin reinforcing layer laminated on a surface layer of the tank liner. The high-pressure hydrogen tank according to claim 8, wherein a valve is inserted into the tank liner.