WO2023249051A1

WO2023249051A1 - Polyamide resin composition for molded product contacting high pressure gas

Info

Publication number: WO2023249051A1
Application number: PCT/JP2023/022930
Authority: WO
Inventors: 和代若杉; 望重光; 龍仁神藤; 康治福井; 英之蔵田; 勇馬堀池
Original assignee: トヨタ自動車株式会社; Ｕｂｅ株式会社
Priority date: 2022-06-22
Filing date: 2023-06-21
Publication date: 2023-12-28

Abstract

Provided is a polyamide resin composition having high fluidity and an excellent hydrogen gas barrier property when made into molded products, and does not compromise flexibility in low-temperature environments.　This polyamide resin composition for a molded product that contacts high-pressure hydrogen gas includes an aliphatic homopolyamide resin (A) and an aliphatic copolyamide resin (B), and as an optional component, at least one compound (C) selected from the group consisting of fatty acids having 18-32 carbon atoms and derivatives thereof, and does not substantially include a polyolefin resin. The relative viscosity of (A) is 1.80-2.70, the relative viscosity of (B) is 2.90-4.20, the relative viscosity of a mixture of (A) and (B) is 2.30-3.60, and in 100 mass% of the polyamide resin composition, the total of (A) and (B) is 93.0-100 mass%, (C) accounts for 0-2.0 mass%, and other components account for 0-5.0 mass%, with the ratio of (A) and (B) being 50:50 to 90:10 on a mass basis.

Description

Polyamide resin composition for molded products that come into contact with high-pressure hydrogen gas

The present invention relates to a polyamide resin composition for molded articles that come into contact with high-pressure hydrogen gas.

Polyamide resins have excellent mechanical properties, heat resistance, and chemical resistance, so they are used in a variety of applications as engineering plastics and are used in a variety of molding methods. For example, for the purpose of improving heat resistance, mechanical strength, etc., a polyamide resin composition in which an aliphatic copolymer polyamide resin and an aliphatic homopolyamide resin, each having a specific relative viscosity, are used in combination, and a fibrous reinforcing agent is used. are known (for example, see Patent Documents 1 and 2). Further, flame-retardant polyamide resin compositions are known in which an aliphatic copolymerized polyamide resin and an aliphatic homopolyamide resin are used together, and a triazine-based compound or the like is combined (for example, see Patent Document 3).

On the other hand, hydrogen tanks used in hydrogen vehicles, for example, are known as molded products that come into contact with high-pressure hydrogen gas, and polyamide resin compositions are also used in such fields. The hydrogen tank used in hydrogen vehicles is a high-pressure hydrogen storage container with a barrel-like exterior, and consists of a long inner layer (long liner) made of metal or resin that comes into direct contact with hydrogen gas, and a layer laminated on the outer circumference of the long inner layer (long liner). It consists of a fiber-reinforced resin layer.
The hydrogen in the hydrogen tank is under high pressure and at an extremely low temperature of -40°C or less. Therefore, long liners that come into direct contact with hydrogen gas are required to have gas barrier properties, as well as flexibility that can withstand high pressure and maintain flexibility even at extremely low temperatures.

Conventionally, in applications where molded products come into contact with high-pressure hydrogen gas, molded products made of polyamide resin compositions whose impact resistance has been improved by adding modified polyolefin resins to polyamide resins have been used. As such a polyamide resin composition, a polyamide resin composition containing polyamide and acid-modified polyolefin in a predetermined ratio is disclosed (for example, see Patent Document 4). In addition, materials for hydrogen tank liners have been proposed that are made of polyamide resin compositions containing impact-resistant materials such as polyamide 6, copolyamides, and acid-modified ethylene/α-olefin copolymers, which have excellent gas barrier properties and low temperature However, it has been shown to have excellent impact resistance (for example, see Patent Document 5). Furthermore, it contains a polyamide resin and an impact-resistant material, the relative viscosity of the polyamide resin is 2.7 or more, the terminal amino group concentration of the polyamide resin, the content of acid anhydride groups of the impact-resistant agent, and the content of the impact-resistant material. A polyamide resin composition having a predetermined range has been proposed, and it has been shown that the composition has excellent blow moldability while maintaining a good surface appearance of a molded article (for example, see Patent Document 6). reference).

It is also known to improve abrasion resistance, mold releasability, etc. by blending an unmodified olefin resin into a polyamide resin composition. Examples of such a polyamide resin composition include a polyamide resin composition containing a polyamide resin and an olefin elastomer resin having a predetermined weight average particle diameter in a predetermined ratio (see, for example, Patent Document 7), a polyamide resin, a modified polyamide resin A polyamide resin composition (see, for example, Patent Document 8) containing polypropylene wax and unmodified polypropylene resin in a predetermined ratio is known.

Japanese Patent Application Publication No. 4-63863 Japanese Patent Application Publication No. 6-299068 International Publication No. 2013/099522 Japanese Patent Application Publication No. 2020-122157 Japanese Patent Application Publication No. 2009-191871 Japanese Patent Application Publication No. 2017-206639 Japanese Patent Application Publication No. 2007-119581 JP 2019-1934 Publication

From the perspective of energy saving, molded products are required to be lighter and thinner. Particularly in molded products that come into contact with high-pressure hydrogen gas, thinning the walls reduces gas barrier properties and flexibility in low-temperature environments. Therefore, polyamide resin compositions used for molded products that come into contact with high-pressure hydrogen gas are required to maintain gas barrier properties without impairing flexibility in low-temperature environments even when the walls are thinned. Moreover, since it is a molded article, the polyamide resin composition is also required to have good moldability due to improved fluidity.

The polyamide resin compositions described in Patent Documents 1 to 3 do not take into account the use of molded products that come into contact with high-pressure hydrogen gas, and have insufficient gas barrier properties and flexibility. Although the polyamide resin compositions described in Patent Documents 4 to 6 have high flexibility and impact resistance in a low-temperature environment, the resulting molded products are required to further improve fluidity and moldability. Although the polyamide resin compositions described in Patent Documents 7 and 8 have high abrasion resistance and mold releasability of the molded articles obtained, no attention is paid to flexibility and impact resistance in a low-temperature environment.

An object of the present invention is to provide a polyamide resin composition that has high fluidity, excellent hydrogen gas barrier properties when molded, and does not impair flexibility in a low-temperature environment.

The present invention relates to the following [1] to [12].
[1] Aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B), and as an optional component, at least one member selected from the group consisting of fatty acids having 18 to 32 carbon atoms and derivatives thereof. A polyamide resin composition for a molded article that comes into contact with high-pressure hydrogen gas, which contains compound (C) and does not substantially contain a polyolefin resin,
According to JIS K 6920, 1 g of polyamide resin is dissolved in 100 ml of 96% sulfuric acid, and the relative viscosity of the aliphatic homopolyamide resin (A) is 1.80 to 2.70 when measured at 25°C. The aliphatic copolyamide resin (B) has a relative viscosity of 2.90 to 4.20, and the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) has a relative viscosity of 2.90 to 4.20. 30 to 3.60,
In 100% by mass of the polyamide resin composition, the total amount of aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B) is 93.0 to 100% by mass, and the above compound (C) is 0 to 2.0% by mass. % by mass, and 0 to 5.0% by mass of other components, and the ratio of aliphatic homopolyamide resin (A) to aliphatic copolyamide resin (B) is 50:50 to 90:10 on a mass basis. A polyamide resin composition.
[2] The polyamide resin composition according to [1], wherein the ratio of the aliphatic homopolyamide resin (A) to the aliphatic copolyamide resin (B) is 65:35 to 90:10 on a mass basis.
[3] The polyamide resin composition according to [1] or [2], wherein the aliphatic homopolyamide resin (A) has a relative viscosity of 1.80 to 2.60.
[4] Any one of [1] to [3], wherein the relative viscosity of the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) is 2.40 to 2.80. The polyamide resin composition described.
[5] The aliphatic copolymer polyamide resin (B) contains 75 mol% or more and less than 95 mol% of ε-caprolactam-derived structural units and 6-aminocaproic acid-derived structural units in 100 mol% of the total structural units, [1] The polyamide resin composition according to any one of [4].
[6] Any one of [1] to [5], wherein the compound (C) is at least one selected from the group consisting of fatty acids having 18 to 32 carbon atoms, and metal salts, esters and amides thereof. The polyamide resin composition described in .
[7] Aliphatic homopolyamide resin (measured according to ISO 1183-3 using a Type-A1 test piece molded in an injection molding machine with a resin temperature of 250°C and a mold temperature of 80°C according to ISO 294-1) A), the density of the aliphatic copolymerized polyamide resin (B) and the polyamide resin composition is 1.120 g/cm ³ to 1.150 g/cm ³ , 1.100 g/cm ³ to 1.130 g/cm ³ and The polyamide resin composition according to any one of [1] to [6], which has a weight of 1.120 g/cm ³ to 1.140 g/cm ³ .
[8] Density of polyamide resin composition measured according to ISO 1183-3 using a Type-A1 test piece molded in an injection molding machine with a resin temperature of 250°C and a mold temperature of 80°C according to ISO 294-1 is 1.126 to 1.129 g/cm ³ , the polyamide resin composition according to [7].
[9] According to JIS K 7126-1, the polyamide resin composition was molded using an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C, with a thickness of 2.0 mm and a diameter of Φ60 mm. Regarding the circular molded product, the hydrogen gas permeability coefficient at 55°C and 1 atm measured using the differential pressure method is 0.1 x 10 ^-10 cm ³ cm/(cm ² s cm Hg) or more than 1.8 x The polyamide resin composition according to any one of [1] to [8], which has a surface resistance of less than 10 ^-10 cm ³ ·cm/(cm ² ·s·cmHg).
[10] A molded article that is exposed to high-pressure hydrogen gas and includes the polyamide resin composition according to any one of [1] to [9].
[11] The molded article that comes into contact with high-pressure hydrogen gas according to [10], which is one selected from the group consisting of a high-pressure hydrogen tank liner, a high-pressure hydrogen hose, a high-pressure hydrogen tube, and a high-pressure hydrogen joint.
[12] A high-pressure hydrogen tank comprising a high-pressure hydrogen tank liner comprising the polyamide resin composition according to any one of [1] to [9] and a continuous fiber-reinforced resin layer.

According to the present invention, it is possible to provide a polyamide resin composition that has high fluidity, excellent hydrogen gas barrier properties when molded, and does not impair flexibility in a low-temperature environment.

In this specification, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, the content of each component in the composition refers to the total amount of the multiple substances present in the composition. means. Further, the relative viscosity defined for polyamide resin means a value measured at 25° C. in accordance with JIS K 6920 by dissolving 1 g of polyamide resin in 100 ml of 96% sulfuric acid.

The polyamide resin composition of the present invention is selected from the group consisting of an aliphatic homopolyamide resin (A), an aliphatic copolyamide resin (B), and, as an optional component, a fatty acid having 18 to 32 carbon atoms and a derivative thereof. A polyamide resin composition for molded articles that comes into contact with high-pressure hydrogen gas, containing at least one compound (C) containing at least one compound (C) containing substantially no polyolefin resin, according to JIS K 6920, containing 1 g of polyamide resin. The relative viscosity of the aliphatic homopolyamide resin (A) is 1.80 to 2.70 when measured at 25° C. by dissolving it in 100 ml of 96% sulfuric acid, and the aliphatic copolyamide resin (B) The relative viscosity of the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) is 2.30 to 3.60, and the polyamide resin In 100% by mass of the composition, the total of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) is 93.0 to 100% by mass, and the compound (C) is 0 to 2.0% by mass. , and other components in an amount of 0 to 5.0% by mass, and the ratio of the aliphatic homopolyamide resin (A) to the aliphatic copolyamide resin (B) is 50:50 to 90:10 on a mass basis. .
By not blending substantially any polyolefin resin, keeping the relative viscosities of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) within the above range, and setting the ratio of each component within the above range, fluidity can be improved. It is possible to obtain a polyamide resin composition that has high properties, excellent hydrogen gas barrier properties when formed into a molded product, and does not impair flexibility in a low-temperature environment.
The present invention also relates to the use and method of use of polyamide resin compositions for producing molded articles that are exposed to high pressure hydrogen gas. Furthermore, the present invention provides the use and method of using a polyamide resin composition for producing one selected from the group consisting of a high-pressure hydrogen tank liner, a high-pressure hydrogen hose, a high-pressure hydrogen tube, and a high-pressure hydrogen joint. be. Further, the present invention is the use and method of use of a polyamide resin composition to manufacture one selected from the group consisting of hydrogen storage tank liners, hydrogen transfer hoses, hydrogen transfer tubes, and hydrogen transfer fittings.

Here, "substantially not contained" means that it is not contained to the extent that it impairs the function or characteristics of the polyamide resin composition of the present invention and its molded product, or it is not contained to the extent that it changes, This does not preclude inclusion to the extent that the function or characteristics are not impaired.

<Aliphatic homopolyamide resin (A)>
The polyamide resin composition contains an aliphatic homopolyamide resin (A).
The aliphatic homopolyamide resin (A) means a polyamide resin in which only one type of monomer component constitutes the aliphatic polyamide resin. The aliphatic homopolyamide resin (A) may consist of at least one of one type of lactam and an aminocarboxylic acid that is a hydrolyzate of the lactam, and one type of aliphatic diamine and one type of aliphatic diamine. It may also consist of a combination with a dicarboxylic acid. Here, when the monomer component constituting the aliphatic polyamide resin is a combination of an aliphatic diamine and an aliphatic dicarboxylic acid, the combination of one type of aliphatic diamine and one type of aliphatic dicarboxylic acid produces one type of monomer. shall be considered as an ingredient.

The aliphatic homopolyamide resin (A) is prepared by dissolving 1 g of the aliphatic homopolyamide resin (A) in 100 ml of 96% sulfuric acid according to JIS K 6920, and the relative viscosity measured at 25°C is 1.80-2. It is 70. By setting the relative viscosity of the aliphatic homopolyamide resin (A) within the above range, the fluidity of the polyamide resin composition can be increased, and the moldability of large molded products such as hydrogen tank liners can be improved. Does not impair the flexibility of molded products in low-temperature environments. In particular, from the viewpoint of increasing the fluidity of the polyamide resin composition and improving the moldability of large molded products such as hydrogen tank liners, the relative viscosity of the aliphatic homopolyamide resin (A) is preferably 1.80 to 2. 60, more preferably 2.20 to 2.60, particularly preferably 2.40 to 2.60.

When the aliphatic homopolyamide resin (A) contains two or more types of polyamide resins having different relative viscosities, the relative viscosity of the aliphatic homopolyamide resin (A) is preferably measured as described above.

From the perspective of obtaining better molding processability without impairing the hydrogen gas barrier properties of the molded product, Type-A1 is molded using an injection molding machine with a resin temperature of 250°C and a mold temperature of 80°C in accordance with ISO 294-1. The density of the aliphatic homopolyamide resin (A) measured according to ISO 1183-3 using a test piece is preferably 1.120 g/cm ³ to 1.150 g/cm ³ , and 1.120 g/cm ³ It is more preferably from 1.140 g/cm ³ to 1.125 g/cm 3 , and even more preferably from 1.125 g/cm ³ to 1.135 g/cm ³ .

Examples of the aliphatic homopolyamide resin (A) include aliphatic homopolyamide resins made of aliphatic diamines and aliphatic dicarboxylic acids, aliphatic homopolyamide resins made of lactams or aminocarboxylic acids, and the like.

The monomer components constituting the aliphatic homopolyamide resin (A) include an aliphatic diamine having 2 to 20 carbon atoms, preferably 4 to 12 carbon atoms, and a fatty acid having 2 to 20 carbon atoms, preferably 6 to 12 carbon atoms. Examples include combinations of group dicarboxylic acids, lactams having 6 to 12 carbon atoms, or aminocarboxylic acids.

Examples of aliphatic diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, peptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, Tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,8-octanediamine, 2,2,4/2,4,4-trimethylhexamethylene Examples include diamine. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedione. Examples include acids such as pentadecanedioic acid, hexadecanedionic acid, octadecanedioic acid, eicosandioic acid, and derivatives thereof.

Examples of the combination of aliphatic diamine and aliphatic dicarboxylic acid include a combination of hexamethylene diamine and adipic acid, a combination of hexamethylene diamine and sebacic acid, a combination of hexamethylene diamine and dodecanedioic acid, etc. Salt is preferably used.

Examples of the lactam include α-pyrrolidone, δ-valerolactam, ε-caprolactam, ω-enantholactam, ω-octalactam, ω-undecanelactam, and ω-laurolactam. From the viewpoint of productivity, the lactam is preferably ε-caprolactam, ω-undecanelactam or ω-laurolactam. Further, examples of the aminocarboxylic acid include γ-aminobutyric acid, 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

Specifically, the aliphatic homopolyamide resin (A) includes polyamide 4, polyamide 6, polyamide 7, polyamide 8, polyamide 9, polyamide 11, polyamide 12, polyamide 66, polyamide 412, polyamide 59, polyamide 510, polyamide 512, Polyamide 69, polyamide 610, polyamide 612, polyamide 96, polyamide 99, polyamide 910, polyamide 912, polyamide 106, polyamide 109, polyamide 1010, polyamide 1012, polyamide 126, polyamide 129, polyamide 1210, polyamide 1212, polyamide 122, etc. It will be done.

From the viewpoint of productivity, the aliphatic homopolyamide resin (A) is preferably one or more selected from the group consisting of polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11, and polyamide 12; 6 and/or polyamide 66 are particularly preferred.

The aliphatic homopolyamide resin (A) may be used alone or in combination of two or more.

<Aliphatic copolymer polyamide resin (B)>
The polyamide resin composition includes an aliphatic copolymerized polyamide resin (B).
The aliphatic copolymerized polyamide resin (B) means a polyamide resin in which the monomer components constituting the aliphatic polyamide resin are a combination of two or more types. The aliphatic copolymerized polyamide resin (B) is a copolymer of two or more selected from the group consisting of a combination of an aliphatic diamine and an aliphatic dicarboxylic acid, a lactam, and an aminocarboxylic acid. Here, the combination of aliphatic diamine and aliphatic dicarboxylic acid is considered to be one type of monomer component.

The aliphatic copolyamide resin (B) is prepared by dissolving 1 g of the aliphatic copolyamide resin (B) in 100 ml of 96% sulfuric acid and having a relative viscosity of 2.90 to 2.90 at 25°C, according to JIS K 6920. It is 4.20. By setting the relative viscosity of the aliphatic copolymer polyamide resin (B) within the above range, the flexibility of the resulting molded product in a low-temperature environment can be improved without impairing the moldability of the polyamide resin composition. The relative viscosity of the aliphatic copolyamide resin (B) is preferably 2.90 to 3.50, more preferably 2.90 to 3.20.

When the aliphatic copolyamide resin (B) contains two or more types of polyamide resins having different relative viscosities, the relative viscosity of the aliphatic copolyamide resin (B) is preferably measured as described above.

From the viewpoint of obtaining good hydrogen gas barrier properties without impairing moldability, using a Type-A1 test piece molded in an injection molding machine with a resin temperature of 250 ° C. and a mold temperature of 80 ° C. according to ISO 294-1, The density of the aliphatic copolyamide resin (B) measured according to ISO 1183-3 is preferably 1.100 g/cm ³ to 1.130 g/cm ³ , and preferably 1.100 g/cm ³ to 1.125 g. /cm ³ is more preferable, and even more preferably 1.110 g/cm ³ to 1.120 g/cm ³ .

Examples of the aliphatic diamine include the same ones as those exemplified as raw materials for the aliphatic homopolyamide resin (A).

Examples of the aliphatic dicarboxylic acids include those exemplified as raw materials for the aliphatic homopolyamide resin (A).

Examples of the lactam include those exemplified as raw materials for the aliphatic homopolyamide resin (A). Moreover, as the aminocarboxylic acid, the same ones as those exemplified as the raw material for the aliphatic homopolyamide resin (A) can be mentioned.

These aliphatic diamines, aliphatic dicarboxylic acids, lactams, and aminocarboxylic acids may be used alone or in combination of two or more.

Specifically, the aliphatic copolymerized polyamide resin (B) includes polyamide 6/66, polyamide 6/69, polyamide 6/610, polyamide 6/611, polyamide 6/612, polyamide 6/11, polyamide 6/12, Examples include polyamide 6/66/12, polyamide 6/66/610, polyamide 6/66/612, and the like.

Among these, at least one selected from the group consisting of polyamide 6/66, polyamide 6/12 and polyamide 6/66/12 is preferred, and at least one selected from the group consisting of polyamide 6/66 and polyamide 6/66/12 is preferred. At least one kind is more preferred.

From the viewpoint of flexibility in a low-temperature environment, the aliphatic copolymer polyamide resin (B) contains 30 mol% or more of ε-caprolactam-derived structural units and 6-aminocaproic acid-derived structural units in 100 mol% of all structural units. The content is preferably less than 75 mol%, more preferably 75 mol% or more and less than 95 mol%, and particularly preferably 85 mol% or more and 93 mol% or less.

The aliphatic copolymer polyamide resin (B) may be used alone or in combination of two or more.

(Mixture of aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B))
The relative viscosity of the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) is 2.30 to 3.60. Here, the above-mentioned mixture means a mixture consisting only of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B), which are mixed in the same proportion as in the polyamide resin composition.
The aliphatic homopolyamide resin (A) has a relative viscosity of 1.80 to 2.70, the aliphatic copolyamide resin (B) has a relative viscosity of 2.90 to 4.20, and the aliphatic homopolyamide resin By setting the relative viscosity of the mixture of (A) and aliphatic copolymerized polyamide resin (B) to 2.30 to 3.60, the fluidity of the polyamide resin composition is increased, and it can be used in a low-temperature environment when molded. Hydrogen gas barrier properties can be improved without impairing the flexibility underneath. The relative viscosity of the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) is preferably 2.30 to 3.00, more preferably 2.40 to 2.80, Particularly preferably 2.50 to 2.80.

The relative viscosity of the mixture of aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B) is measured at 25 ° C. by dissolving 1 g of the mixture in 100 ml of 96% sulfuric acid according to JIS K 6920. is preferable.

From the viewpoint of the fluidity of the composition, the hydrogen gas barrier property of the molded article, and the flexibility in a low-temperature environment, the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) in 100% by mass of the polyamide resin composition. The total content of is 93.0 to 100% by mass, more preferably 98.0 to 100% by mass. It is particularly preferable that the polyamide resin contained in the polyamide resin composition consists only of an aliphatic homopolyamide resin (A) and an aliphatic copolyamide resin (B). Among these, from the viewpoint of crystallinity of the polyamide resin, a mixture of polyamide 6 and polyamide 6/66 or a mixture of polyamide 6 and polyamide 6/66/12 is particularly preferred.

From the viewpoint of the fluidity of the composition, the hydrogen gas barrier properties of the molded product, and the flexibility in a low-temperature environment, the ratio of the aliphatic homopolyamide resin (A) to the aliphatic copolyamide resin (B) is 50% by mass. :50 to 90:10, preferably 65:35 to 90:10.

(Other polyamide resins)
The polyamide resin composition can contain other polyamide resins than the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B), as long as the object of the present invention is not hindered. Examples of other polyamide resins include polyamide resins that are copolymers having an alicyclic, aromatic, etc. structure in the main chain or side chain. The other polyamide resin is preferably a copolyamide resin containing at least two aromatic monomer components, for example.

Other aliphatic diamines and aliphatic dicarboxylic acids that are raw materials for the polyamide resin include those exemplified for the aliphatic homopolyamide resin (A). As the lactam and aminocarboxylic acid that are raw materials for other polyamide resins, those exemplified for the aliphatic homopolyamide resin (A) can be mentioned.

Examples of other alicyclic diamines constituting the polyamide resin include cyclohexane diamine, methylcyclohexane diamine, isophorone diamine, and bis(3-methyl-4-aminocyclohexyl)methane. Examples of aromatic diamines constituting other polyamide resins include p-phenylenediamine, m-phenylenediamine, p-xylenediamine, m-xylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl Examples include sulfone, 4,4'-diaminodiphenyl ether, and the like.

Examples of other alicyclic dicarboxylic acids constituting the polyamide resin include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Examples of aromatic dicarboxylic acids constituting other polyamide resins include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4- phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, dibenzoic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, Examples include 4,4'-biphenyldicarboxylic acid.

Specifically, other polyamide resins include isophthalic acid/terephthalic acid/hexamethylene diamine/bis(3-methyl-4-aminocyclohexyl)methane polycondensate, terephthalic acid/2,2,4-trimethylhexamethylene diamine /2,4,4-trimethylhexamethylene diamine polycondensate, isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-laurolactam polycondensate, isophthalic acid/terephthalic acid/hexamethylene diamine (polyamide 6T/6I), isophthalic acid/2,2,4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine polycondensate, isophthalic acid/terephthalic acid/2,2, Examples include polycondensates of 4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine, and polycondensates of isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-laurolactam. .

Specifically, other polyamide resins are preferably those consisting of 40 to 95 mol% of terephthalic acid component units, 5 to 60 mol% of isophthalic acid component units, and an aliphatic diamine. Preferred combinations of monomer components constituting other polyamide resins include equimolar salts of hexamethylene diamine and terephthalic acid, and equimolar salts of hexamethylene diamine and isophthalic acid.

Other polyamide resins contain units derived from a monomer component consisting of aliphatic diamine, isophthalic acid, and terephthalic acid in an amount of 60% by mass or more and 99% by mass or less, and 1% by mass or more and 40% by mass of units from the aliphatic polyamide component. A copolymer containing the following is preferable.

(Production of polyamide resin)
Polyamide resin manufacturing equipment includes batch reaction vessels, single-vessel or multi-vessel continuous reaction apparatuses, tubular continuous reaction apparatuses, kneading reaction extruders such as single-screw kneading extruders, twin-screw kneading extruders, etc. Known polyamide manufacturing equipment can be mentioned. As the polymerization method, known methods such as melt polymerization, solution polymerization, solid phase polymerization, etc. can be used, and polymerization can be carried out by repeating normal pressure, reduced pressure, and pressurization operations. These polymerization methods can be used alone or in combination as appropriate.

<At least one compound (C) selected from the group consisting of fatty acids having 18 to 32 carbon atoms and derivatives thereof>
It is preferable that the polyamide resin composition further contains at least one compound (C) selected from the group consisting of fatty acids having 18 to 32 carbon atoms and derivatives thereof (hereinafter also referred to as compound (C)). . Compound (C) is more preferably at least one selected from the group consisting of fatty acids having 18 to 32 carbon atoms, metal salts, esters, and amides thereof. By containing the compound (C) in the polyamide resin composition, it is possible to improve the mold releasability during the production of molded products by injection molding etc. without impairing the flexibility in low-temperature environments when molded products are made. can. The compound (C) may be used alone or in combination of two or more types, and from the viewpoint of mold releasability, a mixture of two or more types is preferable.

Fatty acids having 18 to 32 carbon atoms include saturated fatty acids such as stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melisic acid, and dotriacontanoic acid; oleic acid, vaccenic acid, and linoleic acid. , linolenic acid, eleostearic acid, eicosenoic acid, erucic acid, nervonic acid, and other unsaturated fatty acids; compounds in which some of the hydrogen atoms of the alkyl or alkenyl groups of the above fatty acids such as ricinoleic acid are substituted with hydroxyl groups, etc. can be mentioned.

Derivatives of fatty acids having 18 to 32 carbon atoms include metal salts of the fatty acids, ester compounds formed from the fatty acids or halides of the fatty acids, and compounds having hydroxyl groups, and compounds formed from the fatty acids and compounds having amino groups. Examples include amide compounds. Examples of the metal of the metal salt of fatty acid include lithium, magnesium, calcium, aluminum, cadmium, barium, zinc, and lead.

The ester compounds include butyl stearate, stearyl stearate, arachidyl arachidate, behenyl behenate, lignoceryl lignocerate, hexacosyl cerotate, octacosyl montanate, melisyl melisinate, dotriacontanoate, oleyl oleate, and monostearin. Monoester compounds such as ethylene glycol acid, glyceryl monostearate, pentaerythrityl monostearate; ethylene glycol distearate, ethylene glycol dimontanate, (di- or tri-)glyceryl stearate, (di- or tri-)montane Polyvalent ester compounds of fatty acids and polyhydric alcohols such as acid glyceryl, (di-, tri- or tetra-)pentaerythrityl stearate, (di-, tri- or tetra-)pentaerythrityl montanate, etc. It will be done.
From the viewpoint of availability and moldability, stearyl stearate, behenyl behenate, ethylene glycol monostearate, ethylene glycol dimontanate, or (di- or tri-)glyceryl montanate are preferred.

Examples of the metal salts of fatty acids include calcium stearate, magnesium stearate, zinc stearate, barium stearate, aluminum stearate, calcium 12-hydroxystearate, zinc 12-hydroxystearate, magnesium 12-hydroxystearate, and 12-hydroxystearate. Aluminum stearate, barium 12-hydroxystearate, lithium 12-hydroxystearate, sodium 12-hydroxystearate, lithium behenate, calcium behenate, zinc behenate, magnesium behenate, sodium behenate, potassium behenate, montan Examples include calcium acid, zinc montanate, magnesium montanate, aluminum montanate, sodium montanate, potassium montanate, and the like.
From the viewpoint of moldability, calcium stearate, zinc stearate, lithium behenate, calcium 12-hydroxystearate or calcium montanate are preferred.

The amide compounds include stearic acid amide, arachidic acid amide, behenic acid amide, lignoceric acid amide, cerotic acid amide, montanic acid amide, melisic acid amide, dotriacontanoic acid amide, oleic acid amide, erucic acid amide, and ricinoleic acid. Aliphatic monocarboxylic acid amides such as amide, 12-hydroxystearic acid amide; methylenebisstearic acid amide, methylenebis-12-hydroxystearic acid amide, methylenebisarachidic acid amide, methylenebisbehenic acid amide, methylenebislignoceric acid amide, methylenebiscerotinamide, methylenebismontanamide, methylenebismericinamide, methylenebisdotricontanoic acidamide, ethylenebisstearamide, ethylenebis-12-hydroxystearamide, ethylenebisarachidine Acid amide, ethylene bisbehenic acid amide, ethylene bislignoceric acid amide, ethylene biscerotic acid amide, ethylene bismontanic acid amide, ethylene bismericic acid amide, ethylene bisdotriacontanoic acid amide, butylene bisstearic acid amide, Hexamethylene bis-oleic acid amide, hexamethylene bis-stearic acid amide, hexamethylene bis-12-hydroxystearic acid amide, hexamethylene bis-arachidic acid amide, hexamethylene bis-behenic acid amide, hexamethylene bis lignoceric acid Aliphatic carboxylic acid bisamides such as amide, hexamethylene biscerotinamide, hexamethylene bismontanic acid amide, hexamethylene bismeric acid amide, hexamethylene bisdotriacontanoic acid amide; N-stearyl stearic acid N-substituted compounds of the above-mentioned amide compounds, such as amide, N-hydroxymethylstearamide, and N-octacosylmontanamide, can be mentioned.
From the viewpoint of moldability, stearamide, behenic acid amide, montanic acid amide, oleic acid amide, erucic acid amide or ethylene bisstearic acid amide is preferable, and ethylene bis stearic acid amide is more preferable.

From the viewpoint of the hydrogen gas barrier property of the molded product, the flexibility in a low-temperature environment, and the balance of mold releasability, the content of compound (C) in 100% by mass of the polyamide resin composition is 0 to 2.0% by mass. , preferably from 0.01 to 2.0% by weight, more preferably from 0.1 to 1.5% by weight, even more preferably from 0.2 to 1.0% by weight.

<Other ingredients>
The polyamide resin composition can contain other components as long as the effects of the present invention are not impaired. Other functional ingredients include antioxidants, crystal nucleating agents, crystallization accelerators, heat resistant agents, plasticizers, foaming agents, weathering agents, antistatic agents, flame retardants, flame retardant aids, pigments, and dyes. Imparting agents; resins other than the aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B), lubricants other than the compound (C), and the like.
The content of other components is 0 to 5.0% by mass, preferably 0.01 to 2.0% by mass, more preferably 0.05 to 1.5% by mass based on 100% by mass of the polyamide resin composition. It is.

The polyamide resin composition is substantially free of polyolefin resin. By substantially not containing a polyolefin resin, the fluidity of the composition can be increased and the moldability can be improved. Furthermore, the hydrogen gas barrier properties of the molded article can be improved, and the coefficient of linear expansion can also be reduced. Here, "substantially not contained" means that it is not contained to the extent that it impairs the function or characteristics of the polyamide resin composition of the present invention and its molded product, or it is not contained to the extent that it changes, This does not preclude inclusion to the extent that the function or characteristics are not impaired. Specifically, "substantially free" means that the content of polyolefin resin in 100% by mass of the polyamide resin composition is less than 0.1% by mass, preferably 0.05% by mass. %, more preferably less than 0.01% by mass.
Such polyolefin resins include unmodified polyolefin resins and modified polyolefin resins. Examples of unmodified polyolefin resins include homopolymers of α-olefins such as ethylene and propylene; (ethylene and/or propylene)/α-olefin copolymers, and the like. Modified polyolefin resins include polyethylene, polypropylene, (ethylene and/or or propylene)/α-olefin copolymer; (ethylene and/or propylene)/(α,β-unsaturated carboxylic acid and/or α,β-unsaturated carboxylic acid ester) copolymer Copolymerized polyolefin resins such as polymers; Olefin ionomers such as salts of (ethylene and/or propylene)/(α,β-unsaturated carboxylic acid and/or α,β-unsaturated carboxylic acid ester) copolymers etc.

It is preferable that the polyamide resin composition contains an antioxidant as another component. Examples of the antioxidant include organic antioxidants and inorganic antioxidants.

(Organic antioxidant)
Examples of organic antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. From the viewpoint of improving the antioxidant performance of the molded article, the organic antioxidant is preferably at least one selected from the group consisting of phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants. Preferably, it is more preferable to contain both a phenolic antioxidant and a phosphorus antioxidant.

Specifically, as a phenolic antioxidant, N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide (Irganox (registered trademark) 1098; BASF Japan Ltd. ), pentaerythrityl-tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate] (Irganox® 1010; manufactured by BASF Japan Ltd.), ethylene bis(oxyethylene ) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate] (Irganox (registered trademark) 245; manufactured by BASF Japan Ltd.), 3,9-bis[2-[3-(3 -tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane (Sumilyzer (registered trademark) GA -80; manufactured by Sumitomo Chemical Co., Ltd.), and at least one kind selected from the group consisting of these is preferred.The phenolic antioxidant may be used alone or in combination of two or more kinds. .

Specifically, the phosphorus antioxidants include tris(2,4-di-t-butylphenyl) phosphite (Irgafos (registered trademark) 168; manufactured by BASF Japan Ltd.), bis(2,6-di-t- -butyl-4-methylphenyl) pentaerthritol diphosphite (ADEKA STAB (registered trademark) PEP-36; manufactured by ADEKA Co., Ltd.), tetrakis (2,4-di-tert-butylphenoxy)-4,4-biphenyl Examples include a reaction product of biphenyl containing diphosphine as a main component, phosphorus trichloride, and 2,4-di-tert-butylphenol (Hostanox (registered trademark) P-EPQ (registered trademark) P; manufactured by Clariant Japan Co., Ltd.). At least one selected from the group consisting of these is preferred. The phosphorus antioxidants may be used alone or in combination of two or more.

Examples of sulfur-based antioxidants include thioether-based antioxidants, specifically distearyl-3,3-thiodipropionate (Irganox (registered trademark) PS802; manufactured by BASF Japan Ltd.), pentaeryth Lythyltetrakis (3-laurylthiopropionate) (Sumilyzer (registered trademark) TP-D; manufactured by Sumitomo Chemical Co., Ltd.), didodecyl (3,3'-thiodipropionate) (Irganox (registered trademark) PS800; BASF Japan) Co., Ltd.), and at least one selected from the group consisting of these is preferred. The sulfur-based antioxidants may be used alone or in combination of two or more.

The content of the organic antioxidant is preferably 0.01 to 5.0% by mass, more preferably 0.01 to 2.0% by mass in 100% by mass of the polyamide resin composition. , 0.05 to 1.5% by mass is particularly preferred.

(Inorganic antioxidant)
Examples of inorganic antioxidants include metal halide antioxidants. The metal halide antioxidant is a component that mainly provides long-term heat resistance. A metal halide antioxidant is a compound of a halogen and a metal. Examples of the halogen include fluorine, chlorine, bromine, and iodine. Examples of metals include Group 1 elements (alkali metals), Group 2 elements (alkaline earth metals), Group 3 elements to Group 12 elements (eg, transition metals), and the like. The metal in the metal halide is preferably a Group 1 element (alkali metal) or a Group 11 element (copper group).

Examples of the metal halide when the metal is a Group 1 element (alkali metal) include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. In addition, when the metal is a Group 11 element (copper group), metal halides include cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, Examples include cupric iodide. The metal halide antioxidant is more preferably a mixture of cuprous iodide and potassium halide, or a mixture of cuprous bromide and potassium halide; Particularly preferred are mixtures or mixtures of cuprous bromide and potassium bromide. A mixture of cuprous iodide and potassium iodide, or a mixture of cuprous bromide and potassium bromide has a lower amount of potassium iodide than the amount (mass%) of cuprous iodide or cuprous bromide. Alternatively, it is preferable that the amount (mass %) of potassium bromide is large.
Furthermore, it is more effective to use a nitrogen-containing compound such as melamine, benzoguanamine, dimethylol urea, or cyanuric acid in combination.

The inorganic antioxidants may be used alone or in combination of two or more.

The content of the inorganic antioxidant is preferably 0.01 to 5.0% by mass, more preferably 0.01 to 2.0% by mass in 100% by mass of the polyamide resin composition. , 0.05 to 1.0% by mass is particularly preferred.

[Method for manufacturing polyamide resin composition]
The method for producing the polyamide resin composition is not particularly limited, and for example, the following method can be applied.
When mixing the aliphatic homopolyamide resin (A), the aliphatic copolyamide resin (B), and the arbitrary compound (C) and/or other components, a single screw or twin screw extruder, Commonly known melt-kneading machines such as Banbury mixers, kneaders, and mixing rolls can be used, and blenders that do not perform melt-kneading may also be used. When melt-kneading, for example, using a twin-screw extruder, all the raw materials are blended and then melt-kneaded, or some of the raw materials are blended, then melt-kneaded, and the remaining raw materials are blended and melt-kneaded. Any method may be used, such as a method of blending some of the raw materials, or a method of mixing the remaining raw materials using a side feeder during melt-kneading. The polyamide resin composition may be in the form of pellets or powder, for example.

[Density of polyamide resin composition]
From the viewpoint of the rigidity and low-temperature properties of the molded product, measurements were made in accordance with ISO 1183-3 using Type-A1 test pieces molded in an injection molding machine with a resin temperature of 250°C and a mold temperature of 80°C in accordance with ISO 294-1. The density of the polyamide resin composition is preferably 1.120 g/cm ³ to 1.140 g/cm ³ , more preferably 1.121 g/cm ³ to 1.135 g/cm ³ , It is more preferably .125 g/cm ³ to 1.135 g/cm ³ , particularly preferably 1.126 to 1.129 g/cm ³ . The density of the polyamide resin composition may be determined from the density of each raw material of the polyamide resin composition and the composition ratio thereof.

[Applications of polyamide resin composition]
Polyamide resin compositions have high fluidity and excellent hydrogen gas barrier properties and flexibility in low-temperature environments when made into molded products, and can be used for molded products that come into contact with high-pressure hydrogen gas. The polyamide resin composition is not particularly limited, and can be used to manufacture molded articles using known methods.

A molded product that comes into contact with high-pressure hydrogen gas is a molded product that comes into contact with hydrogen gas at a pressure higher than normal pressure. Since the molded product according to the present invention has excellent hydrogen gas barrier properties, it is expected to have the effect of suppressing the occurrence of defective points when repeatedly filling and releasing high-pressure hydrogen gas. It is preferably used for molded products that come into contact with the above hydrogen gas, and more preferably used for molded products that come into contact with hydrogen gas of 30 MPa or more. On the other hand, it is preferably used for molded products that come into contact with hydrogen gas at a pressure of 200 MPa or less, more preferably used for molded products that come into contact with hydrogen gas at a pressure of 150 MPa or less, and even more preferably used for molded products that come into contact with hydrogen gas at a pressure of 100 MPa or less.

Examples of molded products that come into contact with high-pressure hydrogen gas include high-pressure hydrogen containers and their parts, which are selected from the group consisting of high-pressure hydrogen tank liners, high-pressure hydrogen hoses, high-pressure hydrogen tubes, and high-pressure hydrogen joints. It is preferable that there is one.
Another aspect of the invention is one selected from the group consisting of a hydrogen storage tank liner, a hydrogen transfer hose, a hydrogen transfer tube, and a hydrogen transfer fitting, comprising a polyamide resin composition. The hydrogen can be high pressure hydrogen.

A high-pressure hydrogen tank liner containing a polyamide resin composition can be suitably used as a high-pressure hydrogen tank in combination with a continuous fiber-reinforced resin layer. That is, another aspect of the present invention is a high-pressure hydrogen tank liner including a polyamide resin composition and a high-pressure hydrogen tank including a continuous fiber-reinforced resin layer. In a high-pressure hydrogen tank, it is preferable that a continuous fiber-reinforced resin layer is laminated on the outside of a high-pressure hydrogen tank liner containing a polyamide resin composition. In the present invention, continuous fibers refer to fibers with a fiber length of 100 mm or more.
Yet another aspect of the invention is a hydrogen storage tank that includes a hydrogen storage tank liner that includes a polyamide resin composition and a continuous fiber reinforced resin layer.

Examples of the continuous fibers constituting the continuous fiber reinforced resin layer include carbon fibers, glass fibers, aramid fibers, etc. Among them, carbon fibers are preferred from the viewpoint of specific strength and weight reduction. The continuous fibers may be used alone or in combination of two or more.
From the viewpoint of ease of handling and weight reduction, the fiber diameter of the continuous fibers is preferably 5 to 30 μm, more preferably 5 to 20 μm, and even more preferably 5 to 10 μm.

The resin constituting the continuous fiber reinforced resin layer may be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, polyurethane resins, and silicone resins, among which epoxy resins are particularly preferred from the viewpoint of processability. Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, isocyanate-modified bisphenol A epoxy resin, and the like. These thermosetting resins may be used alone or in combination of two or more. When using a thermosetting resin, a curing agent, a reaction accelerator, etc. may be used in combination.

Examples of thermoplastic resins include polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin, polystyrene resin, AS resin, polyamide resin, polyacetal resin, polycarbonate resin, thermoplastic polyester resin, PPS resin, fluororesin, and polyetherimide resin. , polyetherketone resin, polyimide resin, and copolymers of these resins. These thermoplastic resins may be used alone or in combination of two or more. When using a thermoplastic resin, a compatibilizer, a flame retardant, etc. may be used in combination.

Another aspect of the present invention is a method of manufacturing a high-pressure hydrogen tank, which includes forming a high-pressure hydrogen tank liner from a polyamide resin composition.
The method for manufacturing a high-pressure hydrogen tank is not particularly limited, and for example, continuous fibers are wrapped around a high-pressure hydrogen tank liner formed into a tank shape, and then a thermosetting resin is applied to the continuous fibers and then thermoset. Method: After wrapping continuous fibers around the high-pressure hydrogen tank liner, the continuous fibers are coated with a hot-melted thermoplastic resin; The continuous fibers are coated with or impregnated with an uncured thermosetting resin. , a method in which the continuous fiber coated or impregnated with a thermoplastic resin is wrapped around the high-pressure hydrogen tank liner and then thermally cured; a method in which the continuous fiber is wrapped around the high-pressure hydrogen tank liner and then thermally melted. ; A method of molding a high-pressure hydrogen tank liner inside a continuous fiber-reinforced resin layer formed into a tank shape in advance; After molding a continuous fiber-reinforced resin layer and a high-pressure hydrogen tank liner separately, A method such as inserting a liner molded product into the container can be adopted.
Yet another aspect of the invention is a method of making a hydrogen storage tank that includes forming a hydrogen storage tank liner from a polyamide resin composition.

[Method for manufacturing molded products that come into contact with high-pressure hydrogen gas]
Examples of methods for manufacturing molded products that come into contact with high-pressure hydrogen gas include blow molding, extrusion molding, injection molding, and rotational molding, and injection molding and rotational molding can be used more preferably.

There is no particular restriction on the method of producing an injection molded article from a polyamide resin composition by injection molding, and any known method can be used. For example, a method based on ISO 294-1 may be considered. The molding conditions during injection molding are not particularly limited, but for example, the resin temperature of the polyamide resin composition can be 250 to 270°C, and the mold temperature can be 60 to 80°C.

There is no particular restriction on the method for manufacturing a rotationally molded article from a polyamide resin composition by rotationally molding, and any known method can be used. For example, the method described in International Publication No. 2019/054109 may be considered.

(Density of molded product)
The density of molded articles exposed to high pressure hydrogen gas can be measured according to ISO 1183-3. Alternatively, the density of the molded article may be determined from the density and composition of each raw material of the molded article. For example, the density of the molded article may be calculated using the following formula (1).
Density of molded product = Σ(ρ _i ×W _i ) ----- Formula (1)
In the formula, ρ _i is the density (g/cm ³ ) of each raw material, and W _i is the composition ratio of each raw material.
From the viewpoint of the rigidity and low-temperature properties of the molded article, the density of the molded article that comes into contact with high-pressure hydrogen gas is preferably 1.120 g/cm ³ to 1.140 g/cm ³ , and 1.121 g/cm ³ to 1.1 g/cm 3 . It is more preferably 135 g/cm ³ , even more preferably 1.125 g/cm ³ to 1.135 g/cm ³ , and particularly preferably 1.126 to 1.129 g/cm ³ .

(Hydrogen gas permeability coefficient of molded product)
The molded product that comes into contact with high-pressure hydrogen gas is made using the polyamide resin composition according to JIS K 7126-1, and is molded in an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C to a size of 80 mm x 80 mm and a thickness of 2.5 mm. The hydrogen gas permeability coefficient at 55°C and 1 atm measured using the differential pressure method for a circular molded product with a diameter of 60 mm cut from a 0 mm plate-shaped test piece was 0.1 × 10 ^- It is preferably ^{more than 1.8×10 −10 cm 3} ^・ ^cm ^/ (cm ² ^・s・cmHg), and less than 0.1×10 ⁻¹⁰ cm More preferably ^, it is more than 3.cm/(cm 2.s.cmHg) and less than ^1.7 ×10 ⁻¹⁰ cm ^3.cm/(cm 2.s.cmHg), and less ^than 0.1×10 ⁻¹⁰ cm ³ -More preferably cm/(cm ² s·cmHg) and less than 1.5×10 ⁻¹⁰ cm ³ ·cm/(cm ² s·cmHg). When the hydrogen gas permeability coefficient is within the above range, it has excellent hydrogen gas barrier properties and can be suitably used for molded products that come into contact with high-pressure hydrogen gas.

(Low temperature flexibility of molded product)
The molded product that comes into contact with high-pressure hydrogen gas is Type-A1, which is obtained by molding the polyamide resin composition in an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C in accordance with ISO 294-1. Regarding the test piece, after storing the test piece at -60°C for 1 hour, the tensile elastic modulus between 0.3% and 0.5% of the nominal tensile strain measured at a test speed of 50 mm/min according to ISO 527-2 is , preferably more than 1,600 MPa and less than 2,800 MPa, more preferably more than 1,600 MPa and less than 2,750 MPa, even more preferably more than 1,600 MPa and less than 2,700 MPa. When the tensile modulus at −60° C. is within the above range, the molded product has an excellent balance between flexibility and mechanical strength in a low-temperature environment, and can be suitably used for molded products exposed to high-pressure hydrogen gas. If the tensile modulus is 1,600 MPa or less, the molded product is likely to be deformed. If the tensile modulus is 2,800 MPa or more, the molded product will easily break.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these Examples.

[Evaluation method]
1. Relative Viscosity For aliphatic homopolyamide resins, aliphatic copolyamide resins, and mixtures thereof, 1 g of polyamide resin was dissolved in 100 ml of 96% sulfuric acid and the relative viscosity at 25° C. was measured according to JIS K 6920.

2. Density Type-A1 test piece molded with an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C according to ISO 294-1 for aliphatic homopolyamide resin, aliphatic copolyamide resin, and polyamide resin composition. The density was measured according to ISO 1183-3.

3. Injection flow length An injection molding machine (manufactured by Nissei Jushi Kogyo Co., Ltd., product name: PS40E) equipped with a bar flow mold with a cavity thickness of 1 mm, width of 15 mm, and length of 360 mm was used, the injection pressure was 50 MPa, the cylinder temperature was 265°C, The pellets of Examples and Comparative Examples were each injection molded under the molding conditions of a mold temperature of 65° C., an injection speed of 38 mm/sec, an injection time of 4 seconds, and a cooling time of 15 seconds. The total length of the molded product obtained by injection molding from the gate exit was measured as the L/T flow length. The fluidity of the polyamide resin composition was evaluated based on the following criteria.
◎: L/T flow length is 120 mm or more ○: L/T flow length is 105 mm or more and less than 120 mm ×: L/T flow length is less than 105 mm

4. Hydrogen gas permeability coefficient According to JIS K7126-1, pellets of Examples and Comparative Examples were molded into plates of 80 mm x 80 mm and 2.0 mm thickness using an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C. A test piece was molded, and a hydrogen gas permeation test was conducted on a circular molded product with a diameter of 60 mm cut from the test piece at 55° C., 0% RH, and 1 atm using a differential pressure method. As the measuring device, a differential pressure type gas/vapor permeability measuring device (GTR-30XAD, serial number G2700T/F (manufactured by GTR Tech)) was used. Hydrogen gas barrier properties were evaluated based on the following criteria.
◎: Hydrogen gas permeability coefficient is more than 0.1×10 ^-10 cm ³・cm/(cm ²・s・cmHg) and less than 1.5×10 ⁻¹⁰ cm ³・cm/(cm ²・s・cmHg) ○ :Hydrogen gas permeability coefficient is 1.5×10 ^-10 cm ³・cm/(cm ²・s・cmHg) or more and less than 1.8×10 ⁻¹⁰ cm ³・cm/(cm ²・s・cmHg) ×: Hydrogen gas permeability coefficient is 1.8×10 ^-10 cm ³・cm/(cm ²・s・cmHg) or more

5. Tensile modulus at -60°C According to ISO 294-1, the pellets of Examples and Comparative Examples were molded using an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C to obtain a Type-A1 test piece. Created. After storing the test piece at −60° C. for 1 hour, the tensile modulus was measured at a nominal tensile strain of 0.3% to 0.5% at a test speed of 50 mm/min according to ISO 527-2. In addition, the presence or absence of brittle fracture during the tensile test was evaluated. The testing machine used was a tensile testing machine model 5567 manufactured by Instron. The flexibility was evaluated based on the tensile modulus value using the following criteria.
◎: Tensile modulus at -60°C is more than 1,600 MPa and less than 2,700 MPa ○: Tensile modulus at -60°C is 2,700 MPa or more and less than 2,800 MPa ×: Tensile modulus at -60°C is 2,800 MPa or more

[Materials used]
1. Polyamide resin (1) Aliphatic homopolyamide resin PA6-1: Polyamide 6 (manufactured by UBE Corporation: relative viscosity = 1.93, density = 1.129 g/cm ³ )
PA6-2: Polyamide 6 (manufactured by UBE Corporation: relative viscosity = 2.24, density = 1.129 g/cm ³ )
PA6-3: Polyamide 6 (manufactured by UBE Corporation: relative viscosity = 2.45, density = 1.129 g/cm ³ )
PA6-4: Polyamide 6 (manufactured by UBE Corporation: relative viscosity = 2.64, density = 1.129 g/cm ³ )
PA6-5: Polyamide 6 (manufactured by UBE Corporation: relative viscosity = 2.78, density = 1.129 g/cm ³ )
(2) Aliphatic copolymer polyamide resin PA6/66-1: Polyamide 6/66 (manufactured by UBE Corporation: relative viscosity = 3.04; copolymer of polyamide 6 component = 92 mol% and polyamide 66 component = 8 mol%) , density = 1.117g/cm ³ )
PA6/66-2: Polyamide 6/66 (manufactured by UBE Corporation: relative viscosity = 4.05; copolymer of polyamide 6 component = 90 mol% and polyamide 66 component = 10 mol%, density = 1.117 g/cm ³ )
PA6/66/12-1: Polyamide 6/66/12 (manufactured by UBE Corporation: relative viscosity = 4.05; polyamide 6 component = 88 mol%, polyamide 66 component = 5 mol%, polyamide 12 component = 7 mol%) Polymer, density = 1.117g/cm ³ )

2. Polyolefin resin Maleic anhydride-modified ethylene-butene copolymer (manufactured by Mitsui Chemicals, Inc., Tafmer (registered trademark) MH5020, density = 0.866 g/cm ³ (catalog data))

3. Compound (C)
Mixture of long chain fatty acid ester and long chain fatty acid calcium having 18 to 32 carbon atoms

4. Antioxidant Metal halide antioxidant: mixture of cuprous iodide and potassium iodide, mass ratio 1:6

Examples 1 to 9 and Comparative Examples 1 to 7
The components listed in Tables 1 and 2 were mixed using a ZSK32mc twin-screw extruder (manufactured by Coperion, cylinder diameter 32 mm, L/D 48), which is a twin-screw kneading machine, at a cylinder temperature of 250°C, a screw rotation speed of 200 rpm, and a discharge rate. The mixture was melt-kneaded at 50 kg/hrs to produce pellets of the desired polyamide resin composition. Note that the unit of composition in the table is mass %, and the entire resin composition is 100 mass %.

The pellets thus obtained were evaluated as described above. The evaluation results of the polyamide resin compositions of Examples 1 to 9 and Comparative Examples 1 to 7 are shown in Tables 1 and 2, respectively.

From Table 1, the aliphatic homopolyamide resin (A) having a relative viscosity of 1.80 to 2.70 and the aliphatic copolyamide resin (B) having a relative viscosity of 2.90 to 4.20, The polyamide resin compositions of Examples 1 to 9, in which the mixture of component A) and component (B) have a relative viscosity of 2.30 to 3.60 and do not contain a polyolefin resin, have high fluidity; It can be seen that the molded article has excellent hydrogen gas barrier properties, no brittle fracture during a tensile test at -60°C, and excellent flexibility in a low-temperature environment. The relative viscosity of the aliphatic homopolyamide resin (A) is 2.20 to 2.60, the relative viscosity of the aliphatic copolyamide resin (B) is 2.90 to 4.20, the (A) component and the (B) component. The polyamide resin compositions of Examples 3, 4, and 7, in which the relative viscosity of the mixture is 2.40 to 2.80, have excellent fluidity, hydrogen gas barrier properties of molded products, and flexibility in low-temperature environments. Yes, it is preferable.

Comparative Example 1 using only an aliphatic homopolyamide resin whose relative viscosity is outside the range of the present invention as a polyamide resin has poor fluidity. Comparative Examples 2 to 4, which use an aliphatic homopolyamide resin whose relative viscosity is within the range of the present invention, but do not contain an aliphatic copolyamide resin (B), have poor flexibility in a low-temperature environment. A comparative example in which an aliphatic homopolyamide resin (A) and an aliphatic copolyamide resin (B) whose relative viscosities are within the range of the present invention are used, but the relative viscosity of a mixture of these is outside the range of the present invention. In No. 5, brittle fracture occurred during the tensile test at -60°C.
Comparative Example 6 using only the aliphatic copolymerized polyamide resin (B) had poor fluidity. Comparative Example 7, in which an aliphatic homopolyamide resin and a modified polyolefin resin were used in combination, was inferior in fluidity and hydrogen gas barrier properties of the molded article.

The polyamide resin composition of the present invention can be suitably used for producing various molded products by injection molding, rotational molding, etc.

Claims

Aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B), and as an optional component, at least one compound selected from the group consisting of fatty acids having 18 to 32 carbon atoms and derivatives thereof (C ) and substantially free of polyolefin resin, the polyamide resin composition is for molded products exposed to high-pressure hydrogen gas,
According to JIS K 6920, 1 g of polyamide resin is dissolved in 100 ml of 96% sulfuric acid, and the relative viscosity is measured at 25°C.
The relative viscosity of the aliphatic homopolyamide resin (A) is 1.80 to 2.70,
The aliphatic copolymer polyamide resin (B) has a relative viscosity of 2.90 to 4.20,
The relative viscosity of the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) is 2.30 to 3.60,
In 100% by mass of the polyamide resin composition, the total amount of aliphatic homopolyamide resin (A) and aliphatic copolyamide resin (B) is 93.0 to 100% by mass, and the above compound (C) is 0 to 2.0% by mass. % by mass, and 0 to 5.0% by mass of other components,
A polyamide resin composition in which the ratio of aliphatic homopolyamide resin (A) to aliphatic copolyamide resin (B) is 50:50 to 90:10 on a mass basis.
The polyamide resin composition according to claim 1, wherein the ratio of the aliphatic homopolyamide resin (A) to the aliphatic copolyamide resin (B) is 65:35 to 90:10 on a mass basis.
The polyamide resin composition according to claim 1 or 2, wherein the aliphatic homopolyamide resin (A) has a relative viscosity of 1.80 to 2.60.
The polyamide resin composition according to claim 1 or 2, wherein the mixture of the aliphatic homopolyamide resin (A) and the aliphatic copolyamide resin (B) has a relative viscosity of 2.40 to 2.80.
According to claim 1 or 2, the aliphatic copolymerized polyamide resin (B) contains 75 mol% or more and less than 95 mol% of ε-caprolactam-derived structural units and 6-aminocaproic acid-derived structural units in 100 mol% of the total structural units. polyamide resin composition.
The polyamide resin composition according to claim 1 or 2, wherein the compound (C) is at least one selected from the group consisting of fatty acids having 18 to 32 carbon atoms, metal salts thereof, esters, and amides thereof.
Aliphatic homopolyamide resin (A) measured according to ISO 1183-3 using a Type-A1 test piece molded in an injection molding machine with a resin temperature of 250 ° C. and a mold temperature of 80 ° C. according to ISO 294-1, The densities of the aliphatic copolymerized polyamide resin (B) and the polyamide resin composition are 1.120 g/cm 3 to 1.150 g/cm 3 , 1.100 g/cm 3 to 1.130 g/cm 3 and 1.120 g, respectively. The polyamide resin composition according to claim 1 or 2, wherein the polyamide resin composition has a weight/cm 3 to 1.140 g/cm 3 .
The density of the polyamide resin composition measured according to ISO 1183-3 using a Type-A1 test piece molded in an injection molding machine with a resin temperature of 250°C and a mold temperature of 80°C according to ISO 294-1 is 1. The polyamide resin composition according to claim 7, which has a weight of 126 to 1.129 g/cm 3 .
A circle with a thickness of 2.0 mm and a diameter of 60 mm was obtained by molding the polyamide resin composition using an injection molding machine at a resin temperature of 250°C and a mold temperature of 80°C in accordance with JIS K 7126-1. The hydrogen gas permeability coefficient at 55°C and 1 atm measured using the differential pressure method is 0.1 x 10 -10 cm 3 cm / (cm 2 - s cmHg) or more than 1.8 x 10 -10 The polyamide resin composition according to claim 1 or 2, wherein the polyamide resin composition is less than cm 3 ·cm/(cm 2 ·s·cmHg).
A molded article that comes into contact with high-pressure hydrogen gas and includes the polyamide resin composition according to claim 1 or 2.
The molded article that comes into contact with high-pressure hydrogen gas according to claim 10, which is one selected from the group consisting of a high-pressure hydrogen tank liner, a high-pressure hydrogen hose, a high-pressure hydrogen tube, and a high-pressure hydrogen joint.
A high-pressure hydrogen tank comprising a high-pressure hydrogen tank liner comprising the polyamide resin composition according to claim 1 or 2 and a continuous fiber-reinforced resin layer.