JP2021109905A - Polyamide resin composition for blow molding of jointless long-sized liner for hydrogen tank, and jointless long-sized liner for hydrogen tank - Google Patents

Abstract

To provide a jointless long-sized liner for a hydrogen tank which has good blow moldability of a polyamide resin composition, is excellent in mechanical characteristics under ultralow temperature as a molding, and is excellent in surface smoothness.SOLUTION: A polyamide resin composition for blow molding of a jointless long-sized liner for a hydrogen tank contains 50-80 mass% of a polyamide resin (A), 15-20 mass% of an olefinic ionomer (B), and 5-10 mass% of an impact-resistant material (C) in 100 mass% of the polyamide resin composition. The composition has melt viscosity at a temperature of 250°C and a shear rate of 12 second-1 of 13,000 Pa s or more, and relaxation stress at 0.1 second at the temperature of 250°C of 30 kPa or more.SELECTED DRAWING: None

Description

The present invention relates to a polyamide resin composition for blow molding of a seamless long liner for a hydrogen tank and a seamless long liner for a hydrogen tank.

Conventionally, a hydrogen tank used in a hydrogen vehicle is a high-pressure hydrogen storage container having a barrel-like outer shape, and is a long inner layer (long liner) made of metal or resin that comes into direct contact with hydrogen gas and its outer peripheral surface. It is composed of a fiber-reinforced resin layer laminated on the surface.
The hydrogen in the hydrogen tank has a high pressure and a cryogenic temperature of −40 ° C. or lower. Therefore, a long liner that comes into direct contact with hydrogen gas is required to have strength that can withstand high pressure and that strength can be maintained even at extremely low temperatures.
Further, in order to expand fuel cell vehicles, high cycle is required, and a seamless (seamless) liner using blow molding is required.
Furthermore, the surface smoothness of the long liner is required for the purpose of preventing damage due to stress concentration of the liner when the hydrogen tank is used.
As such a liner material, a polyamide resin having excellent gas barrier properties and excellent mechanical properties even at an extremely low temperature of −40 ° C. or lower has been proposed (see, for example, Patent Document 1).

Further, a polyamide resin composition containing a polyamide resin, a fibrous clay mineral, and a coupling agent in a specific ratio and having a diewell index and a drawdown index of a specific value or less is excellent in blow moldability and surface smoothness. (See, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2009-191871 Japanese Unexamined Patent Publication No. 2013-71994

Patent Document 1 merely discloses a polyamide resin composition suitable for laser welding by injection molding with a mold, and does not describe any application to a seamless liner.
In Patent Document 2, although the polyamide resin composition is blow-molded, there is no description about the mechanical properties of the molded product at a low temperature.
Therefore, the present invention provides a seamless long liner for hydrogen tanks, which has good blow moldability of a polyamide resin composition, excellent mechanical properties at extremely low temperatures as a molded product, and excellent surface smoothness. The purpose is to contribute.

The present invention includes, for example, the following [1] to [6].
[1] A polyamide resin composition for blow molding of a seamless long liner in a hydrogen tank.
100% by mass of the polyamide resin composition contains 50 to 80% by mass of the polyamide resin (A), 15 to 20% by mass of the olefin ionomer (B), and 5 to 10% by mass of the impact resistant material (C).
A polyamide resin composition in which the composition has a melt viscosity of 13000 Pa · s or more at a temperature of 250 ° C. and a shear rate of 12 seconds- ^{1 and a relaxation stress of 30 kPa or more at 0.1 seconds at the same temperature.}
[2] The polyamide resin (A) is a polyamide resin composed of an aliphatic homopolyamide (A-1), an aliphatic copolymerized polyamide (A-2) and an aromatic copolymerized polyamide (A-3) [1]. ] Polyamide resin composition for blow molding of a seamless long liner in a hydrogen tank.
[3] A seamless long liner for a hydrogen tank, which is a blow-molded product of the polyamide resin composition for blow molding of a seamless long liner for a hydrogen tank according to [1] or [2].
[4] The seamless long liner for a hydrogen tank according to [3], wherein the maximum height roughness (measurement length: 20 mm) in the longitudinal direction of the surface is 100 μm or less.
[5] The seamless long liner for a hydrogen tank according to [3] or [4], which has a tensile fracture nominal strain according to ISO527-2 / 1BA / 25 of 18% or more.
[6] The polyamide resin composition for blow molding of the seamless long liner of the hydrogen tank of [1] or [2] is molded using an accumulator type blow molding machine at a cylinder temperature of 220 to 250 ° C. and a molding time of 25 minutes. Hereinafter, a method for manufacturing a seamless long liner for a hydrogen tank, which comprises molding in an accumulator time of 2 to 20 minutes.

According to the present invention, the polyamide resin composition has good blow moldability, has excellent mechanical properties at extremely low temperatures as a molded product, and has excellent surface smoothness, and is a seamless long length for hydrogen tanks. It can contribute to the provision of liners.
In the present specification, the blow moldability is represented by the drawdown amount at the time of parison injection at the time of blow molding, and the blow moldability is better as the drawdown amount is smaller. The mechanical properties are represented by the tensile fracture nominal strain in the tensile test, and the higher the value of the tensile fracture nominal strain, the better the mechanical properties.

It is a figure which shows the measuring method of the drawdown amount in an Example. It is a figure which shows the cut-out position from the liner of the maximum roughness measurement sample in the longitudinal direction of the surface in an Example. It is a flowchart of the manufacturing method of the seamless long liner for a hydrogen tank using an accumulator type blow molding machine. It is a figure which shows an example which extrudes the melted and kneaded resin composition in an accumulator type blow molding machine from an extruder into an accumulator. It is a figure which shows an example of forming a parison using an accumulator type blow molding machine. It is a figure which shows an example at the time of taking out a molded product obtained by using an accumulator type blow molding machine.

[Polyamide resin composition for blow molding of seamless long liner of hydrogen tank]
The polyamide resin composition for blow molding of the seamless long liner of the hydrogen tank of the present invention (hereinafter, also referred to as “polyamide resin composition”) is contained in 100% by mass of the polyamide resin composition, and the polyamide resin (A) 50 to 50 to Containing 80% by mass, 15 to 20% by mass of olefin-based ionomer (B), and 5 to 10% by mass of impact resistant material (C).
The composition is a polyamide resin composition having a melt viscosity of 13000 Pa · s or more at a temperature of 250 ° C. and a shear rate of 12 seconds- ^{1 and a relaxation stress of 30 kPa or more at 0.1 seconds at the same temperature.}

(Polyamide resin (A))
As the polyamide resin (A) of the present invention, a polyamide resin composed of an aliphatic homopolyamide (A-1), an aliphatic copolymerized polyamide (A-2) and an aromatic copolymerized polyamide (A-3) is preferably used. NS.

(Aliphatic homopolyamide (A-1))
The aliphatic homopolyamide (A-1) is a polyamide resin composed of one kind of structural unit derived from an aliphatic monomer. The aliphatic homopolyamide (A-1) may be composed of at least one of one kind of lactam and aminocarboxylic acid which is a hydrolyzate of the lactam, and one kind of diamine and one kind of dicarboxylic acid. It may consist of a combination of. Here, the combination of diamine and dicarboxylic acid is regarded as one kind of monomer by the combination of one kind of diamine and one kind of dicarboxylic acid.

Examples of the lactam include ε-caprolactam, enantractum, undecane lactam, dodecane lactam, α-pyrrolidone, α-piperidone and the like. Among these, one selected from the group consisting of ε-caprolactam, undecane lactam and dodecane lactam is preferable from the viewpoint of polymerization productivity.
Examples of the aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid. Among these, one selected from the group consisting of 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid is preferable from the viewpoint of polymerization productivity.

Examples of diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, peptidemethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, and tetradecanediamine. , Pentadecanediamine, Hexamethylenediamine, Hexamethylenediamine, Octadecandiamine, Nonadecandiamine, Eikosandiamine, 2-Methyl-1,8-octanediamine, 2,2,4 / 2,4,4-trimethylhexamethylenediamine, etc. Hexamethylenediamine; 1,3- / 1,4-cyclohexamethylenediamine, bis (4-aminocyclohexamethylene) methane, bis (4-aminocyclohexamethylene) propane, bis (3-methyl-4-aminocyclohexamethylene) methane, (3 -Methyl-4-aminocyclohexamethylene) propane, 1,3- / 1,4-bisaminomethylcyclohexane, 5-amino-2,2,4-trimethyl-1-cyclopentanemethylamine, 5-amino-1,3 , 3-trimethylcyclohexamethylenediamine, bis (aminopropyl) piperazine, bis (aminoethyl) piperazine, alicyclic diamines such as norbornandimethylenediamine and the like can be mentioned. Among these, an aliphatic diamine is preferable, and a hexamethylenediamine is more preferable, from the viewpoint of polymerization productivity.

Dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, tridecandic acid, tetradecandioic acid, pentadecane. Aliphatic dicarboxylic acids such as dionic acid, hexadecandionic acid, octadecandionic acid, and eicosandionic acid; 1,3- / 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, norbornandicarboxylic acid Such as alicyclic dicarboxylic acid and the like. Among these, an aliphatic dicarboxylic acid is preferable, one selected from the group consisting of adipic acid, sebacic acid and dodecandioic acid is more preferable, and sebacic acid or dodecandioic acid is further preferable.

Specifically, as the aliphatic homopolyamide (A-1), polycaprolactam (polyamide 6), polyenantractum (polyamide 7), polyundecanelactam (polyamide 11), polylauryllactam (polyamide 12), polyhexamethylene azimuth Pamide (polyamide 66), polytetramethylene dodecamide (polyamide 412), polypentamethylene azelamide (polyamide 59), polypentamethylene sebacamide (polyamide 510), polypentamethylene dodecamide (polyamide 512), polyhexa Methylene azelamide (polyamide 69), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polynonamethylene adipamide (polyamide 96), polynonamethylene azelamide (polyamide 99), Polynonamethylene sebacamide (polyamide 910), polynonamethylene dodecamide (polyamide 912), polydecamethylene adipamide (polyamide 106), polydecamethylene azelamide (polyamide 109), polydecamethylene decamide (polyamide 1010) ), Polydecamethylene dodecamide (polyamide 1012), polydodecamethylene adipamide (polyamide 126), polydodecamethylene azelamide (polyamide 129), polydodecamethylene sebacamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1210). Polyamide 1212), polyamide 122 and the like can be mentioned. The aliphatic homopolyamide (A-1) may be used alone or in combination of two or more.

Among them, the aliphatic homopolyamide (A-1) is preferably at least one selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610 and polyamide 612 from the viewpoint of polymerization productivity, and polyamide is preferable. 6. Polyamide 11, polyamide 12, polyamide 610 and polyamide 612 are more preferred, and polyamide 6 is even more preferred.

Examples of the apparatus for producing the aliphatic homopolyamide (A-1) include a batch type reaction kettle, a single-tank or multi-tank continuous reaction device, a tubular continuous reaction device, a uniaxial kneading extruder, a twin-screw kneading extruder, and the like. Examples thereof include known polyamide production equipment such as a kneading reaction extruder of the above. As a polymerization method, a known method such as melt polymerization, solution polymerization or solid phase polymerization 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.

The relative viscosity of the aliphatic homopolyamide (A-1) is measured at 25 ° C. in accordance with JIS K-6920 by dissolving 1 g of the polyamide resin in 100 ml of 96% concentrated sulfuric acid. The relative viscosity of the aliphatic homopolyamide resin is preferably 2.7 or more, and more preferably 2.7 or more and 5.0 or less. Further, from the viewpoint of improving the effect of the present invention, 2.7 or more and less than 4.5 is more preferable. When it is 2.7 or more, the melt viscosity of the polyamide composition is not too low, so that the shape of the molded product during extrusion molding and the parison shape retention during blow molding are particularly good, which is 5.0 or less. And the melt viscosity of the polyamide composition is not too high, and a uniform wall thickness of the molten resin can be obtained during blow molding.

The terminal amino group concentration of the aliphatic homopolyamide (A-1) is determined by neutralization titration after dissolving in a mixed solvent of phenol and methanol. The terminal amino group concentration of the aliphatic homopolyamide (A-1) is preferably 30 μmol / g or more, more preferably 30 μmol / g or more and 50 μmol / g or less.

The content of the aliphatic homopolyamide (A-1) in the polyamide resin (A) is, for example, 35% by mass or more and 75% by mass or less, preferably 40% by mass or more and 70% by mass or less, from the viewpoint of molding processability. , 45% by mass or more and 70% by mass or less is more preferable.

(Aliphatic Copolymerized Polyamide (A-2))
The aliphatic copolymerized polyamide (A-2) is a polyamide resin composed of two or more kinds of constituent units derived from an aliphatic monomer. The aliphatic copolymer polyamide (A-2) is two or more copolymers selected from the group consisting of a combination of a diamine and a dicarboxylic acid and a lactam or an aminocarboxylic acid. Here, the combination of diamine and dicarboxylic acid is regarded as one kind of monomer by the combination of one kind of diamine and one kind of dicarboxylic acid.

Diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, peptidemethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, and tetradecanediamine. , Pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecandiamine, eikosandiamine, 2-methyl-1,8-octanediamine, 2,2,4 / 2,4,4-trimethylhexamethylenediamine, etc. Of the aliphatic diamine; 1,3- / 1,4-cyclohexamethylenediamine, bis (4-aminocyclohexyl) methane, bis (4-aminocyclohexyl) propane, bis (3-methyl-4-aminocyclohexyl) methane, (3) -Methyl-4-aminocyclohexamethylene) propane, 1,3- / 1,4-bisaminomethylcyclohexane, 5-amino-2,2,4-trimethyl-1-cyclopentanemethylamine, 5-amino-1,3 , 3-trimethylcyclohexanemethylamine, bis (aminopropyl) piperazine, bis (aminoethyl) piperazine, alicyclic diamines such as norbornandimethylenediamine and the like can be mentioned. The diamine is preferably at least one selected from the group consisting of these, preferably at least one selected from the group consisting of aliphatic diamines from the viewpoint of polymerization productivity, and is selected from the group consisting of linear aliphatic diamines. At least one of these is more preferred, and hexamethylenediamine is even more preferred.
These diamines may be used alone or in combination of two or more as appropriate.

Dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, tridecandic acid, tetradecandioic acid, pentadecane. Aliphatic dicarboxylic acids such as dionic acid, hexadecandionic acid, octadecandionic acid, and eicosandionic acid; 1,3- / 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, norbornandicarboxylic acid Such as alicyclic dicarboxylic acid and the like. The dicarboxylic acid is preferably at least one selected from the group consisting of these.
These dicarboxylic acids may be used alone or in combination of two or more.

Examples of the lactam include ε-caprolactam, enantractum, undecane lactam, dodecane lactam, α-pyrrolidone, α-piperidone and the like. Among these, at least one selected from the group consisting of ε-caprolactam, undecane lactam and dodecane lactam is preferable from the viewpoint of polymerization productivity.
Examples of the aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid. Among these, at least one selected from the group consisting of 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid is preferable from the viewpoint of polymerization productivity.

Specifically, as the aliphatic copolymerized polyamide (A-2), a caprolactam / hexamethylene diaminoadiponic acid copolymer (polyamide 6/66), a caprolactam / hexamethylene diaminoazeline acid copolymer (polyamide 6/69), Caprolactam / hexamethylene diaminosevacinic acid copolymer (polyamide 6/610), caprolactam / hexamethylene diaminoundecanedicanoic acid copolymer (polyamide 6/611), caprolactam / hexamethylene diaminododecanedic acid copolymer (polyamide 6 / 612), caprolactam / aminoundecanoic acid copolymer (polyamide 6/11), caprolactam / lauryllactam copolymer (polyamide 6/12), caprolactam / hexamethylenediaminoadipic acid / lauryllactam copolymer (polyamide 6/66) / 12), caprolactam / hexamethylene diaminoadiponic acid / hexamethylene diaminosevacinic acid copolymer (polyamide 6/66/610), caprolactam / hexamethylene diaminoadiponic acid / hexamethylene diaminododecandicanoic acid copolymer (polyamide 6 / Examples thereof include aliphatic copolymerized polyamides such as 66/612).
Among these, from the viewpoint of productivity, at least one selected from the group consisting of polyamide 6/66, polyamide 6/12 and polyamide 6/66/12 is preferable, and polyamide 6/66 and polyamide 6/66/12 are preferable. Is more preferable, and polyamide 6/66 is particularly preferable.
These aliphatic copolymerized polyamides (A-2) may be used alone or in combination of two or more.

The equipment for producing the aliphatic copolymerized polyamide (A-2) includes a batch type reaction kettle, a single-tank or multi-tank continuous reaction device, a tubular continuous reaction device, a uniaxial kneading extruder, and a twin-screw kneading extruder. Examples thereof include known polyamide manufacturing apparatus such as a kneading reaction extruder such as. As a polymerization method, a known method such as melt polymerization, solution polymerization or solid phase polymerization 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.

The relative viscosity of the aliphatic copolymerized polyamide (A-2) is not particularly limited, but from the viewpoint of improving the effect of the present invention, 1 g of the polyamide resin is dissolved in 100 ml of 96% concentrated sulfuric acid in accordance with JIS K-6920. The relative viscosity measured at 25 ° C. is preferably 1.8 or more and 5.0 or less.

The terminal amino group concentration of the aliphatic copolymerized polyamide (A-2) is determined by neutralization titration after dissolving in a mixed solvent of phenol and methanol. The terminal amino group concentration of the aliphatic copolymerized polyamide (A-1-2) is preferably 30 μmol / g or more, more preferably 30 μmol / g or more and 50 μmol / g or less.

From the viewpoint of molding processability, the content of the aliphatic copolymerized polyamide (A-2) in the polyamide resin (A) is, for example, 20% by mass or more and 40% by mass or less, and 20% by mass or more and 35% by mass or less. It is preferable, and more preferably 25% by mass or more and 35% by mass or less.

(Aromatic copolymerized polyamide (A-3))
The aromatic copolymerized polyamide resin is a polyamide resin containing at least one structural unit derived from an aromatic monomer component and composed of two or more constituent units. For example, an aliphatic dicarboxylic acid, an aromatic diamine, and an aromatic are used. It is a polyamide resin composed of two or more kinds of constitutional units containing at least one kind of constitutional unit made from dicarboxylic acid and aliphatic diamine or aromatic diamine and aromatic dicarboxylic acid as raw materials. Here, the combination of diamine and dicarboxylic acid is regarded as one kind of monomer by the combination of one kind of diamine and one kind of dicarboxylic acid.
In the present invention, the aromatic copolymerized polyamide (A-3) has an effect of increasing the melt viscosity and an effect of suppressing the crystallization rate.

Examples of the raw material aliphatic diamine and aliphatic dicarboxylic acid include the same as those of the above-mentioned aliphatic polyamide resin, and include those exemplified as alicyclic diamine and alicyclic dicarboxylic acid.
Examples of the aromatic diamine include metaxylylenediamine and paraxylylenediamine, and examples of the aromatic dicarboxylic acid include naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid and phthalic acid.

Specific examples include polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (polyamide 66 / 6T), polyhexamethylene terephthalamide / polycaproamide copolymer (polyamide 6T / 6), and polyhexamethylene adipamide. / Polyhexamethylene isophthalamide copolymer (polyamide 66 / 6I), polyhexamethylene isophthalamide / polycaproamide copolymer (polyamide 6I / 6), polydodecamide / polyhexamethylene terephthalamide copolymer (polyamide 12 / 6T), polyhexamethylene azimuth Pamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (polyamide 66 / 6T / 6I), polyhexamethylene adipamide / polycaproamide / polyhexamethylene isophthalamide copolymer (polyamide 66/6 / 6I), Polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (polyamide 6T / 6I), polyhexamethylene terephthalamide / poly (2-methylpentamethylene terephthalamide) copolymer (polyamide 6T / M5T), polyxylylene adipamide (polyamide 6T / M5T) Polyamide MXD6), a mixture thereof, a copolymer resin, and the like can be mentioned. These aromatic copolymerized polyamides (A-3) may be used alone or in combination of two or more. Among these, polyamide 6T / 6I is preferable.

As the aromatic copolymerized polyamide (A-3) used in the present invention, particularly useful ones include an amorphous partially aromatic copolymerized polyamide resin containing at least two aromatic monomer components. As the amorphous partially aromatic copolymer resin, an amorphous polyamide having a glass transition temperature of 100 ° C. or higher determined by the peak temperature of the loss elastic modulus at the time of absolute drying obtained by measuring the dynamic viscoelasticity is used. preferable.
Here, amorphous means that the amount of heat of crystal melting measured by a differential scanning calorimeter (DSC) is 1 cal / g or less.

The amorphous partially aromatic copolymerized polyamide resin preferably comprises an aromatic dicarboxylic acid composed of 40 to 95 mol% of a terephthalic acid component unit and 5 to 60 mol% of an isophthalic acid component unit, and an aliphatic diamine. Preferred combinations include equimolar salts of hexamethylenediamine and terephthalic acid and equimolar salts of hexamethylenediamine and isophthalic acid.
Further, those containing 99 to 60% by weight of a polyamide-forming component composed of an aliphatic diamine and an aromatic dicarboxylic acid composed of isophthalic acid and terephthalic acid and 1 to 40% by weight of an aliphatic polyamide component are preferable. Examples of the apparatus for producing the aromatic copolymerized polyamide (A-3) include the same as the apparatus for producing the aliphatic homopolyamide (A-1) and the aliphatic copolymerized polyamide (A-2).

The degree of polymerization of the aromatic copolymerized polyamide resin (A-3) in the present invention is not particularly limited, but is relative measured at a concentration of 98% in sulfuric acid of 1% and an aromatic copolymerized polyamide resin temperature of 25 ° C. according to JIS K 6810. The viscosity is preferably 1.5 to 4.0, more preferably 1.8 to 3.0.

The terminal amino group concentration of the aromatic copolymerized polyamide resin (A-3) is determined by neutralization titration after dissolving it in a mixed solvent of phenol and methanol. The terminal amino group concentration of the aromatic copolymerized polyamide resin (A-3) is preferably 30 μmol / g or more, more preferably 30 μmol / g or more and 50 μmol / g or less.

From the viewpoint of molding processability, the content of the aromatic copolymerized polyamide (A-3) in the polyamide resin (A) is, for example, 5% by mass or more and 30% by mass or less, and 5% by mass or more and 20% by mass or less. Preferably, it is 5% by mass or more and 10% by mass or less, more preferably.

As a specific example of the polyamide resin (A), at least one selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610 and polyamide 612 as the aliphatic homopolyamide (A-1). As the aliphatic copolymerized polyamide (A-2), at least one selected from the group consisting of polyamide 6/66, polyamide 6/12 and polyamide 6/66/12, and aromatic copolymerized polyamide (A-). As 3), a combination with polyamide 6T / 6I is preferably mentioned.
The polyamide resin (A) may contain a polyamide other than the aliphatic homopolyamide (A-1), the aliphatic copolymerized polyamide (A-2) and the aromatic copolymerized polyamide (A-3), but it is contained. It is preferable that there is no such thing.

(Relative viscosity of polyamide resin)
The polyamide resin (A) conforms to JIS K-6920, and 1 g of the polyamide resin is dissolved in 100 ml of 96% concentrated sulfuric acid, and the relative viscosity measured at 25 ° C. is 2.7 or more, and 2.7 or more. It is preferably 0 or less. Further, from the viewpoint of improving the effect of the present invention, 2.7 or more and less than 4.5 is more preferable. When it is 2.7 or more, the melt viscosity of the polyamide composition is not too low, so that the parison shape is particularly well maintained even in extrusion molding during blow molding. Further, when it is 5.0 or less, a uniform wall thickness of the molten resin can be obtained at the time of blow molding without the melt viscosity of the polyamide composition being too high.

Since the polyamide resin (A) contains two or more kinds of polyamide resins having different relative viscositys, the relative viscosity of the polyamide resin (A) is preferably measured as described above, but the relative viscosity of each polyamide resin and its relative viscosity thereof. When the mixing ratio is known, the average value calculated by multiplying each relative viscosity by the mixing ratio may be used as the relative viscosity of the polyamide resin (A).

From the reactivity with the impact resistant material (C), the terminal amino group concentration of the polyamide resin (A) is 30 μmol / g or more as the terminal amino group concentration determined by neutralization titration by dissolving in a mixed solvent of phenol and methanol. There, the range of 30 μmol / g or more and 110 μmol / g or less is preferable, and the range of 30 μmol / g or more and 70 μmol / g or less is more preferable. When it is 30 μmol / g or more, the reactivity with the impact resistant material (C) is good, and the melt viscosity and excellent mechanical properties can be sufficiently obtained. Further, at 110 μmol / g or less, the melt viscosity is not too high and the molding processability is good.

Since the polyamide resin (A) contains two or more kinds of polyamide resins having different terminal amino group concentrations, the terminal amino group concentration in the polyamide resin (A) is preferably measured by the above neutralization pruning, but each of them. When the terminal amino group concentration of the polyamide resin and its mixing ratio are known, the average value calculated by multiplying each terminal amino group concentration by the mixing ratio is the average value of the polyamide resin (A). It may be the terminal amino group concentration.

The polyamide resin (A) is 50 to 80% by mass, preferably 50 to 75% by mass, more preferably 55 to 75% by mass, still more preferably 60 to 75% by mass, particularly preferably 60 to 75% by mass, based on 100% by mass of the polyamide resin composition. Is contained in an amount of 65 to 75% by mass. When the content ratio of the polyamide resin (A) is at least the above lower limit, the gas barrier property is good, and when it is at least the above upper limit, it does not become fragile at low temperatures, so that the mechanical properties and blow moldability are good.

(Olefin-based ionomer (B))
The polyamide resin composition contains an olefin ionomer (B). The olefin ionomer (B) is used as a molding improving material. Examples of the resin of the olefin ionomer (B) include (ethylene and / or propylene) / (α, β-unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) copolymer. The (ethylene and / or propylene) / (α, β-unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) -based copolymer is ethylene and / or propylene and α, β-unsaturated carboxylic acid and / or unsaturated. It is a polymer obtained by copolymerizing a saturated carboxylic acid ester monomer. Examples of the α, β-unsaturated carboxylic acid monomer include acrylic acid and methacrylic acid. Examples of the α, β-unsaturated carboxylic acid ester monomer include methyl ester, ethyl ester, propyl ester, butyl ester, pentyl ester, hexyl ester, heptyl ester, octyl ester, nonyl ester and decyl ester of these unsaturated carboxylic acids. And so on. These may be used individually by 1 type or in combination of 2 or more type. Examples of the metal ion used in the ionomer include Na, K, Cu, Mg, Ca, Ba, Zn, Cd, Al, Fe, Co and Ni. Among these, an ionomer of an ethylene-methacrylic acid copolymer is preferable, and Zn is preferable as a metal ion.

The olefin-based ionomer (B) is contained in an amount of 15 to 20% by mass, preferably 16 to 19% by mass, and more preferably 17 to 18% by mass in 100% by mass of the polyamide resin composition. When the content ratio of the olefin ionomer (B) is in the above range, the surface smoothness and the blow moldability are improved.

(Impact resistant material (C))
The polyamide resin composition contains at least one impact resistant material (C). Examples of the impact resistant material include rubber-like polymers. The impact-resistant material preferably has a flexural modulus of 500 MPa or less as measured in accordance with ASTM D-790.

Specifically, as the impact resistant material (C), (ethylene and / or propylene) / α-olefin copolymer, (ethylene and / or propylene) / (α, β-unsaturated carboxylic acid and / or α, β-Unsaturated carboxylic acid ester) -based copolymers and the like can be mentioned. These can be used alone or in combination of two or more. The impact resistant material (C) is preferably an ethylene / α-olefin copolymer.

The (ethylene and / or propylene) / α-olefin-based copolymer is a copolymer obtained by copolymerizing ethylene and / or propylene with an α-olefin having 3 or more or 4 or more carbon atoms.
Examples of α-olefins having 3 or more carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1 -Tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-hexene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl -1-Pentene, 4-Methyl-1-pentene, 4-Methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3 Examples thereof include -ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene and the like. These may be used individually by 1 type or in combination of 2 or more type.

Further, the copolymer may be a copolymer of a polyene such as a non-conjugated diene. Non-conjugated diene includes 1,4-pentadiene, 1,4-hexadien, 1,5-hexadien, 1,4-octadien, 1,5-octadien, 1,6-octadien, 1,7-octadien, 2- Methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadien, 4-ethylidene-8-methyl-1,7-norbornene, 4,8-dimethyl-1, 4,8-Decatriene (DMDT), dicyclopentadiene, cyclohexadiene, cyclooctadien, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropyriden-2-norbornene, 6-Chloromethyl-5-isopropylidene-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,5-norbornene, etc. Can be mentioned. These may be used individually by 1 type or in combination of 2 or more type.

The (ethylene and / or propylene) / (α, β-unsaturated carboxylic acid and / or α, β-unsaturated carboxylic acid ester) polymer is ethylene and / or propylene and α, β-unsaturated carboxylic acid. And / or a polymer obtained by copolymerizing an α, β-unsaturated carboxylic acid ester monomer. Examples of the α, β-unsaturated carboxylic acid monomer include acrylic acid and methacrylic acid. Examples of the α, β-unsaturated carboxylic acid ester monomer include methyl ester, ethyl ester, propyl ester, butyl ester, pentyl ester, hexyl ester, heptyl ester, octyl ester, and nonyl of these α, β-unsaturated carboxylic acids. Examples include esters and decyl esters. These may be used individually by 1 type or in combination of 2 or more type.

Further, (ethylene and / or propylene) / α-olefin-based copolymer used as the impact resistant material (C), and (ethylene and / or propylene) / (α, β-unsaturated carboxylic acid and / or α, The β-unsaturated carboxylic acid ester) -based copolymer is a polymer modified with a carboxylic acid and / or a derivative thereof, and is an acid-modified polymer with an unsaturated carboxylic acid or an acid anhydride thereof. Is preferable. By modifying with such a component, a functional group having an affinity for the polyamide resin (A) is contained in the molecule.

Examples of the functional group having an affinity for the polyamide resin (A) include a carboxy group, an acid anhydride group, a carboxylic acid ester group, a carboxylic acid metal salt, a carboxylic acid imide group, a carboxylic acid amide group, and an epoxy group. Be done.

Examples of compounds containing these functional groups, namely carboxylic acids and derivatives thereof, are acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, mesaconic acid, citraconic acid, glutaconic acid, cis-4- Cyclohexene-1,2-dicarboxylic acid, endobicyclo- [2.2.1] -5-hepten-2,3-dicarboxylic acid and metal salts of these carboxylic acids, monomethyl maleate, monomethyl itaconic acid, methyl acrylate, Ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconic acid, maleic anhydride , Itaconic anhydride, Citraconic anhydride, Endobicyclo- [2.2.1] -5-heptene-2,3-dicarboxylic acid anhydride, Maleimide, N-ethylmaleimide, N-butylmaleimide, N-phenylmaleimide, Examples thereof include acrylamide, methacrylicamide, glycidyl acrylate, glycidyl methacrylate, glycidyl etaclilate, glycidyl itaconic acid, and glycidyl citraconic acid. These can be used alone or in combination of two or more. Of these, maleic anhydride is preferred.

The content of the acid anhydride group in the impact resistant material (C) is more than 25 μmol / g and less than 100 μmol / g, preferably 35 μmol / g or more and less than 95 μmol / g, and more preferably 40 μmol / g or more and 90 μmol / g or less. When the content exceeds 25 μmol / g, a composition having a high melt viscosity can be obtained, and a target wall thickness dimension can be obtained in blow molding. Further, when the content is less than 100 μmol / g, the melt viscosity is not too high, and the load on the extruder can be suppressed so that the molding process can be performed satisfactorily. The content of the acid anhydride group contained in the impact resistant material (C) is neutralized and titrated with a sample solution prepared using toluene or ethanol, using phenolphthalein as an indicator, and a KOH ethanol solution specified in 0.1. Measured at.

When two or more kinds of impact-resistant materials having different acid anhydride group contents are used as the impact-resistant material (C), the acid anhydride group content in the impact-resistant material (C) is determined by using toluene or ethanol. It is preferable to use the prepared sample solution and measure by neutralization titration with a 0.1N KOH ethanol solution using phenolphthaline as an indicator, but the content of the acid anhydride group of each impact resistant material and When the mixing ratio is known, the average value calculated by multiplying the content of each acid anhydride group by the mixing ratio is also used as the acid anhydride amount of the impact resistant material (C). good.

The impact resistant material (C) preferably has an MFR of 0.1 g / 10 minutes or more and 10.0 g / 10 minutes or less as measured at a temperature of 230 ° C. and a load of 2160 g in accordance with ASTM D1238. When the MFR is 0.1 g / 10 minutes or more, the melt viscosity of the polyamide resin composition does not become too high, for example, it is suppressed that the shape of the parison becomes unstable during blow molding in extrusion molding, and the thickness of the molded product is suppressed. Tends to be more uniform. Further, when the MFR is 10.0 g / 10 minutes or less, the drawdown of the parison does not become too large, and good blow moldability tends to be obtained.

The impact resistant material (C) is contained in an amount of 5 to 10% by mass, preferably 6 to 9% by mass, and more preferably 7 to 8% by mass in 100% by mass of the polyamide resin composition. When the content ratio of the impact resistant material (C) is within the above range, the gas barrier property is good, and the low temperature physical property and the blow moldability are good.

(Melting viscosity, relaxation stress)
The polyamide resin composition has a melt viscosity of 13000 Pa · s or more at a temperature of 250 ° C. and a shear rate of 12 seconds ^-1 , and a relaxation stress at 0.1 seconds at the same temperature of 30 kPa or more. The melt viscosity is preferably 13,000 to 20,000 Pa · s, more preferably 13,000 to 15,000 Pa · s. The higher the relaxation stress, the more desirable it is, so there is no particular upper limit. When the melt viscosity is in the above range, the viewpoint of blow moldability and molding time is good, and when the relaxation stress is in the above range, the viewpoint of blow moldability is good.

(Measurement method of melt viscosity and relaxation stress)
The melt viscosity and relaxation stress were measured by the following methods.
The melt viscosity was measured using a Capillograph 1D formula CC manufactured by Toyo Seiki Co., Ltd. The measurement temperature was 250 ° C., and the orifice was measured using a hole diameter of 1.0 mm and a length of 10 mm (L / D = 10).
The relaxation stress is a stress with an elapsed time of 0.1 s after the sample is sandwiched between measurement cells using a molten viscoelasticity measuring device ARES-G2 manufactured by TA Instruments, strain is applied and stopped while melting the sample under the following conditions. Was measured.
Measurement cell: Parallel plate (φ25 mm)
Distance between parallel plates: 1.5 mm
Melting temperature condition: 250 ° C
Load strain: 100%
When the melt viscosity is in the above range, it is good from the viewpoint of blow moldability and molding time, and when the relaxation stress is in the above range, it is good from the viewpoint of blow moldability.

(D) Heat Resistant Agent The polyamide resin composition preferably contains the heat resistant agent (D). As the heat resistant agent (D), one capable of improving the heat resistance of the polyamide resin can be used, and an organic or inorganic heat resistant agent can be used according to the purpose.

(Inorganic heat resistant agent)
The polyamide resin composition may contain at least one inorganic heat-resistant agent as a heat-resistant agent from the viewpoint of heat welding characteristics and heat-resistant characteristics. The type of inorganic heat resistant agent is a metal compound (salt) belonging to the Group I transition series element, and examples thereof include halides, sulfates, acetates, salicylates, nicotinates and stearate of this metal. Can be mentioned.
Further, the halogenated salt of the alkali metal may be used alone or in combination with the metal compound (salt) belonging to the above-mentioned Group I transition series element.
Specific examples thereof are potassium iodide, sodium iodide or potassium bromide.
Further, it is more effective to use a nitrogen-containing compound such as melamine, benganamin, dimethylolurea or cyanuric acid in combination.
These inorganic heat resistant agents may be used alone or in combination of two or more.

(Organic heat resistant agent)
The polyamide resin composition may contain at least one organic heat-resistant agent as a heat-resistant agent from the viewpoint of heat welding characteristics and heat-resistant characteristics. By containing an organic heat-resistant agent, it is possible to further improve the heat-weldability while maintaining the normal heat aging property, physical properties, melt viscosity and the like even when the interval time becomes long during blow molding. It is considered that this is because, for example, the addition of an organic heat-resistant agent suppresses gelation due to thermal deterioration of the impact-resistant material, thereby suppressing the nucleation action.

Examples of the organic heat-resistant agent include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like.

As the phenolic antioxidant, a hindered phenolic antioxidant is preferable, and a hindered phenol having a t-butyl group at the O-position is more preferable. Specific examples of the hindered phenol having a t-butyl group at the O-position include N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide, pentaerythrityl). -Tetrakiss [3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate ], 3,9-Bis [2- [3- (3-tert-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetra Oxaspiro [5.5] undecane can be mentioned, and at least one selected from the group consisting of these is preferable.

As the phosphorus-based antioxidant, a phosphite ester compound of hindered phenol and a hypophosphorous acid ester compound of hindered phenol are preferable, and a phosphite ester compound of hindered phenol having a t-butyl group at the O-position, O. A hypophosphorous acid ester compound of hindered phenol having a t-butyl group at the position is more preferable, and a phosphite ester compound of hindered phenol having a t-butyl group at the O position is further preferable. Specific examples of the phosphite ester compound of hindered phenol having a t-butyl group at the O-position include tris (2,4-di-t-butylphenyl) phosphite and bis (2,6-di-t). -Butyl-4-methylphenyl) pentaelthritol diphosphite, can be mentioned. Specifically, the hypophosphorous acid ester compound of hindered phenol having a t-butyl group at the O-position is mainly tetrakis (2,4-di-tert-butylphenoxy) -4,4-bifinyldiphosphine. Examples thereof include reaction products of bifinyl, phosphorus trichloride and 2,4-di-tert-butylphenol as components. At least one selected from the group consisting of these is preferable.
Examples of the sulfur-based antioxidant include distearyl-3,3-thiodipropionate, pentaerythrityltetrakis (3-laurylthiopropionate), and didodecyl (3,3'-thiodipropionate). Can be done. At least one selected from the group consisting of these is preferable.

These organic heat resistant agents may be used alone or in combination of two or more.
From the viewpoint of heat-weldability, the polyamide resin composition preferably contains at least one phenolic antioxidant, and contains at least one phenolic antioxidant and at least one phosphorus antioxidant. It is more preferable to contain at least one selected from the group consisting of a hindered phenol having a t-butyl group at the O-position and a subphosphate ester compound of the hindered phenol having a t-butyl group at the O-position. Is more preferable, and it is particularly preferable to contain a subphosphate ester compound of hindered phenol having a t-butyl group at the O-position and hindered phenol having a t-butyl group at the O-position.

The heat resistant agent (D) is preferably contained in 100% by mass of the polyamide resin composition, preferably 0.01 to 3% by mass, more preferably 0.05 to 2% by mass, and further preferably 0.1 to 2% by mass. When the content ratio of the heat resistant agent (D) is within the above range, the heat resistance and the initial physical properties are good.

(Other additives)
Depending on the purpose, the polyamide resin composition may contain dyes, pigments, fibrous reinforcing materials, particulate reinforcing materials, plasticizers, antioxidants (excluding component (D)), heat resistant agents, foaming agents, etc. Functionality-imparting agents such as weather resistant agents, crystal nucleating agents (organic nucleating agents, inorganic nucleating agents such as talc), crystallization accelerators, mold release agents, lubricants, antistatic agents, flame retardants, flame retardant aids, and colorants. Etc. may be appropriately contained. In order to improve the effect of the present invention, the polyamide resin composition preferably contains an antioxidant.
Any additive is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass.

(Manufacturing method of polyamide resin composition)
The method for producing the polyamide resin composition is not particularly limited, and for example, the following method can be applied.
Polyamide resin (A), olefin ionomer (B), and impact resistant material (C) are essential, and for mixing the heat resistant agent (D) and other additives, uniaxial and biaxial Commonly known melt-kneaders such as extruders, Banbury mixers, kneaders, and mixing rolls are used. For example, a method of blending all raw materials and then melt-kneading using a twin-screw extruder, a method of blending some raw materials, then melt-kneading, and then blending the remaining raw materials and then melt-kneading, or a part of them. Any method may be used, such as a method of mixing the remaining raw materials using a side feeder during melt-kneading after blending the raw materials of.

(Use of polyamide resin composition)
The polyamide resin composition can be suitably used as a seamless long liner for a hydrogen tank, which is a seamless liner in which the entire liner is integrally molded by blow molding.

(Seamless long liner for hydrogen tank)
The seamless long liner for hydrogen tanks of the present invention is a seamless liner in which the entire liner is integrally molded by blow molding. For example, the liner is separately molded by an injection method and then welded and joined. Compared to a liner with eyes, it has the advantages of excellent dimensional accuracy, strength, and hydrogen gas barrier property of the liner.
The seamless long liner for a hydrogen tank is a blow-molded product of a polyamide resin composition for blow molding of the seamless long liner for a hydrogen tank.

(Manufacturing method of seamless long liner for hydrogen tank)
In the method for producing a seamless long liner for a hydrogen tank of the present invention, a polyamide resin composition for blow molding of a seamless long liner for a hydrogen tank is used in an accumulator type blow molding machine at a cylinder temperature of 220 to 250 ° C. In, molding is performed in a molding time of 25 minutes or less and an accumulator time of 2 to 20 minutes.
In the present specification, the "cylinder temperature" refers to the temperature of the cylinder 13 in the accumulator type blow molding machine 10, and the "accumulation time" refers to the resin composition 14 melted and kneaded in the accumulator type blow molding machine 10. The time required to store up to a predetermined capacity (capacity for one shot) in Accum 15 after starting extrusion in 15, and the "molding time" means accumulating the resin composition 14 melted and kneaded in the accumulator type blow molding machine 10. It refers to the time from the start of extrusion to 15 until the molded product 19 is taken out. The "molding time" usually includes an accumulating time, a parison extrusion time, a mold closing operation time, a blow-up time, an air circulation time, an exhaust time, a mold opening operation time, and a molded product take-out time. In this specification, the total of blow-up time, air circulation time, and exhaust time is also referred to as cooling time.
In the seamless long liner for hydrogen tank of the present invention, the polyamide resin composition for blow molding of the seamless long liner for hydrogen tank is molded into a seamless long liner for hydrogen tank by using an accumulator type blow molding machine. do. A method of manufacturing a seamless long liner for a hydrogen tank using an accumulator type blow molding machine will be described with reference to the flowchart of FIG. 3 and FIGS. 4 to 6.
The accumulator type blow molding machine 10 has an extruder 11 including a screw 12 and a cylinder 13, and an accumulator 15 including an extrusion cylinder 16.
Using the accumulator type blow molding machine 10, the polyamide resin composition is melted and kneaded in the cylinder 13 of the extruder 11 to obtain the melted and kneaded resin composition 14 (step 1 (S1) in FIG. 3). ..
As shown in FIG. 4, the melted and kneaded resin composition 14 is extruded into Accum 15 by the screw 12 of the extruder 11 and stored up to a predetermined capacity (capacity for one shot) (step 2 (S2) in FIG. 3). .. At that time, the screw rotation speed is not particularly limited, but is preferably 10 to 45 rpm, more preferably 15 to 30 rpm. The accumulator time is 2 to 20 minutes, preferably 2 to 15 minutes, more preferably 2 to 10 minutes. When the accumulator time is within the above range, high cycle molding is possible.

As shown in FIG. 5, immediately after the melted / kneaded resin composition 14 reaches a predetermined capacity in the accumulator 15, the melted / kneaded resin composition 14 in the accumulator 15 is extruded by the extrusion cylinder 16 to form a cylindrical shape. The parison 17 is formed (step 3 (S3) in FIG. 3). The cylinder temperature of the cylinder 13 at that time is 220 to 250 ° C., preferably 220 to 245 ° C., more preferably 225 to 240 ° C., and when the cylinder temperature is in the above range, surface smoothness and mechanical properties are good. Is. The parison extrusion time (time from the start to the end of extrusion of the melted / kneaded resin composition 14 as parison 17) is not particularly limited, but is preferably 3 to 15 seconds.

After that, the parison 17 is sandwiched between the molds 18 and air is blown into the parison to shape the parison 17 inside the mold and form it into a desired shape (step 4 (S4) in FIG. 3). The mold temperature at that time is not particularly limited, but is preferably 20 to 80 ° C.
The molded resin composition is sufficiently cooled by continuously blowing air (step 5 (S5) in FIG. 3). The cooling time is not particularly limited, but is preferably 30 to 300 seconds.
Finally, as shown in FIG. 6, the mold is opened and the molded product 19 is taken out (step 6 (S6) in FIG. 3).
Since the solidification time of the resin is short because the polyamide resin is used, it is necessary to set and manage the time from when the molten resin is started to be extruded as parison 17 until the mold is closed (hereinafter, also referred to as “mold closing time”). The mold closing time is preferably 25 seconds or less, more preferably 2 to 20 seconds. By setting the mold closing time within this range, molding that is advantageous in the dimensional accuracy and strength of the liner is possible.
The molding time is 25 minutes or less, preferably 2 to 20 minutes. When the molding time is within this range, high-cycle molding is possible.
The molded product of the present invention molded by the above molding method is excellent in dimensional accuracy, surface smoothness, mechanical properties, and hydrogen gas barrier property of the molded product.

(Maximum height roughness)
The maximum height roughness (measured length: 20 mm) of the surface of the molded product in the longitudinal direction is preferably 100 μm or less, more preferably 50 μm or less, and the maximum height roughness is defined in JIS B0601. It is defined. When the maximum height roughness is within the above range, the molded product has excellent surface smoothness and does not cause stress concentration, which is effective for maintaining mechanical properties.
The maximum height roughness was measured by measuring the inner surface of a small cut liner with a measurement length of 20 mm in the longitudinal direction using SE500A manufactured by Kosaka Laboratory in accordance with JIS B0601.
In order to obtain the maximum height roughness, a manufacturing method called an accumulator type blow molding is adopted, and a polyamide resin composition for blow molding of the seamless long liner of the hydrogen tank is used at a cylinder temperature of 220 to 250 ° C. It is preferable to mold with an accumulator time of 2 to 20 minutes and a molding time of 25 minutes or less.

(Tensile fracture nominal strain)
Further, the tensile fracture nominal strain according to ISO527-2 / 1BA / 25 is preferably 18% or more, and more preferably 20% or more. When the tensile fracture nominal strain is in the above range, sufficient strength can be maintained even when it comes into contact with a cryogenic gas such as high-pressure hydrogen gas.
For tensile fracture nominal strain, a test piece of ISO standard Type-1BA shape is cut out by cutting in the longitudinal direction of the liner so that the arithmetic average roughness Ra of the cut surface is 6.3a or less, and ISO527-2 / 1BA. According to / 25, the measurement was performed at a test temperature of −60 ° C. using a tensile tester model 5967 manufactured by Instron.
In order to obtain the tensile fracture nominal strain, a manufacturing method called an accumulator type blow molding is adopted, and a polyamide resin composition for blow molding of the seamless long liner of the hydrogen tank is used at a cylinder temperature of 220 to 250 ° C. It is preferable to mold with an accumulator time of 2 to 20 minutes and a molding time of 25 minutes or less.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The methods for evaluating the physical properties of the resins and molded products used in Examples and Comparative Examples are shown below.

[Examples 1 to 3 and Comparative Example 1]
Each component shown in Table 1 is melt-kneaded with a twin-screw kneader TEX44HCT, a cylinder diameter of 44 mm, L / D35 at a cylinder temperature of 250 ° C., a screw rotation of 120 rpm, and a discharge rate of 40 kg / h to obtain a desired polyamide resin composition. Pellets were made.
The unit of the composition in the table is mass%, and the entire resin composition is 100% by mass.
The obtained pellets and the liner molded under the following molding conditions were used for the following characteristic evaluation, and the obtained results are shown in Table 1.

Each component listed in Table 1 is as follows.
(Polyamide resin (A))
The following three components are mixed at a ratio of 10: 4: 1.
Polyamide 6, product name "1030B" Polyamide 6/66 manufactured by Ube Industries, Ltd., product name "5034B", polyamide 6T / 6I manufactured by Ube Industries, Ltd., product name "Grivory G21" manufactured by EMS-CHEMIE (Japan) Co., Ltd.

(Olefin-based ionomer (B))
Ethylene-methacrylic acid copolymer, metal ion: zinc, product name "Himilan (registered trademark) 1706" manufactured by Mitsui Dow Polychemical Co., Ltd.

(Impact resistant material (C))
Maleic anhydride-modified ethylene-butene copolymer, product name "Toughmer (registered trademark) MH5020" manufactured by Mitsui Chemicals, Inc.

(Method for evaluating physical properties of polyamide resin composition)
(1) Melt Viscosity The melt viscosity was measured using Capillograph 1D formula CC manufactured by Toyo Seiki Co., Ltd. according to ISO11443. The melt viscosity was measured at a ^{shear rate of 12 seconds-1} using a measurement temperature of 250 ° C., an orifice with a hole diameter of 1.0 mm and a length of 10 mm (L / D = 10). If the melt viscosity is too low, the drawdown amount becomes large, which is not preferable in terms of blow moldability.
(2) Relaxing stress Using the molten viscoelasticity measuring device ARES-G2 manufactured by TA Instruments, the sample was sandwiched between measurement cells, and strain was applied and stopped while melting the sample under the following conditions, and then the elapsed time was 0.1 s. The stress was measured. If the relaxation stress is too low, the blow moldability will deteriorate.
Measurement cell: Parallel plate (φ25 mm)
Distance between parallel plates: 1.5 mm
Melting temperature condition: 250 ° C
Load strain: 100%

(3) Drawdown amount The drawdown amount was measured by the following method using a single-layer accumulator type blow molding machine. The parison was extruded shortly after the molten resin reached a predetermined amount in the accum. As shown in FIG. 1, the time when extrusion was completed was set to 0 seconds, the drawdown amount every 5 seconds was measured on a long scale, and the value after 30 seconds was defined as the drawdown amount. The smaller the drawdown amount, the higher the parison retention rate and the better the blow moldability.
(I) Blow molding machine (model name of molding machine: JB105 / P50 / AC1L)
Molding machine specifications: Single-layer accumulator type blow molding machine Accumulation capacity: 1 liter Screw diameter: φ50 mm
Die core diameter: φ70 / φ68mm
(Ii) Molding conditions Extruder & die core temperature: 250 ° C
Screw rotation speed: 30 rpm
Accum capacity: 100%

(Evaluation method of 1.2m liner)
The liner evaluations in Examples 1 to 3 and Comparative Example 1 are the results of manufacturing a seamless liner having a diameter of 265 mm × L1200 mm under the following conditions and performing the following molding evaluation.
(1) Liner manufacturing conditions (i) Blow molding machine (model name of molding machine: NB60SII / P90 / AC15S)
Molding machine specifications: Single-layer accumulator type blow molding machine Accumulation capacity: 15 liters Screw diameter: φ90 mm
Die core diameter: φ80 / φ75mm
(Ii) Molding conditions Extruder & die core temperature: 225 to 240 ° C.
Screw rotation speed: 15-30 rpm
Accum capacity: 50%
Mold temperature: 25-30 ° C
Parison extrusion time: 8 to 15 seconds Mold closing time: 2 to 3 seconds Cooling time: 4 minutes Cylinder temperature, accumulator time and molding time are shown in Table 1.

(2) Characteristic evaluation (i) Maximum surface roughness in the longitudinal direction According to JIS B0601, using SE500A manufactured by Kosaka Research Institute, the inner surface of a liner cut out into small pieces is roughened in maximum height with a measurement length of 20 mm in the longitudinal direction. Was measured.
The lower the maximum height roughness, the better the surface smoothness of the molded product, so that stress concentration does not occur, which is effective in maintaining mechanical properties.
(3) Tensile fracture nominal strain As shown in FIG. 2, the ISO standard Type-1BA-shaped test piece is cut in the longitudinal direction of the liner so that the arithmetic average roughness Ra of the cut surface becomes 6.3a or less. It was cut out and measured at a test temperature of −60 ° C. using an Instron tensile tester model 5967 according to ISO527-2 / 1BA / 25. The larger the value of tensile fracture nominal strain, the more advantageous it is against hydrogen leakage due to liner breakage at extremely low temperatures.

ポリアミド樹脂組成物の実施例１〜３のいずれも、ブロー成形性に優れるとともに、表面平滑性に優れ、さらには機械的特性にも優れることがわかる。
実施例１〜３と比較例１とを比較すると、ポリアミド樹脂組成物が、オレフィン系アイオノマーを含まないと、パリソンを保持できず、ブロー成形性が劣ることがわかる。

It can be seen that all of Examples 1 to 3 of the polyamide resin composition are excellent in blow moldability, surface smoothness, and mechanical properties.
Comparing Examples 1 to 3 with Comparative Example 1, it can be seen that if the polyamide resin composition does not contain an olefin ionomer, the parison cannot be retained and the blow moldability is inferior.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a seamless long liner for a hydrogen tank having excellent blow moldability, mechanical properties and surface smoothness.

(1): When parison extrusion is completed (2): 30 seconds after the completion of parison extrusion (3): Maximum roughness measurement sample cutting position in the longitudinal direction of the surface (center of the body)
L1: Initial length of parison L2: Drawdown amount 1: Die core 10: Accumulator type blow molding machine 11: Extruder 12: Screw 13: Cylinder 14: Melted / kneaded resin composition 15: Accum 16: Extrusion cylinder 17: Parison 18: Mold 19: Molded product

Claims (6)

A polyamide resin composition for blow molding of a long liner without seams in a hydrogen tank.
100% by mass of the polyamide resin composition contains 50 to 80% by mass of the polyamide resin (A), 15 to 20% by mass of the olefin ionomer (B), and 5 to 10% by mass of the impact resistant material (C).
A polyamide resin composition in which the composition has a melt viscosity of 13000 Pa · s or more at a temperature of 250 ° C. and a shear rate of 12 seconds- ^{1 and a relaxation stress of 30 kPa or more at 0.1 seconds at the same temperature.} The first aspect of claim 1, wherein the polyamide resin (A) is a polyamide resin composed of an aliphatic homopolyamide (A-1), an aliphatic copolymerized polyamide (A-2), and an aromatic copolymerized polyamide (A-3). Polyamide resin composition for blow molding of seamless long liner of hydrogen tank. A seamless long liner for a hydrogen tank, which is a blow-molded product of the polyamide resin composition for blow molding of the seamless long liner for a hydrogen tank according to claim 1 or 2. The maximum height roughness (measurement length: 20 mm) in the longitudinal direction of the surface is 100 μm or less.
The seamless long liner for a hydrogen tank according to claim 3. The seamless long liner for a hydrogen tank according to claim 3 or 4, wherein the tensile fracture nominal strain according to ISO527-2 / 1BA / 25 is 18% or more. The polyamide resin composition for blow molding of the seamless long liner of the hydrogen tank according to claim 1 or 2 is accumulated using an accumulator type blow molding machine at a cylinder temperature of 220 to 250 ° C. and a molding time of 25 minutes or less. A method for manufacturing a seamless long liner for a hydrogen tank, which comprises molding in 2 to 20 minutes.

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