JP7310942B2 - Polyamide resin composition - Google Patents

Description

The present invention relates to polyamide resin compositions.

Polyamide resins are known as resins with excellent gas barrier properties, and there is a demand for polyamide resin compositions having gas barrier properties for various applications.

As such a polyamide resin composition, a hydrogen tank liner material composed of a polyamide resin composition containing polyamide 6, a copolyamide and an impact resistant material has been proposed, which has excellent gas barrier properties and excellent impact resistance even at low temperatures. (See, for example, Patent Document 1). On the other hand, 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 the acid anhydride group of the impact resistant agent, and the content of the impact resistant material A polyamide resin composition with a predetermined range has been proposed, and the composition has been shown to be excellent in blow moldability while maintaining a good surface appearance of a molded product (for example, Patent Document 2 ).

JP 2009-191871 A JP 2017-206639 A

Although the molded article of the polyamide resin composition described in Patent Document 1 exhibits certain gas barrier properties, there is a demand for a polyamide resin composition having even better gas barrier properties. Further, from the viewpoint of injection moldability of large-sized molded articles, there is a demand for a polyamide resin composition with improved fluidity.

An object of the present invention is to provide a polyamide resin composition having high fluidity and excellent gas barrier properties when molded.

The present invention relates to the following [1] to [ 16 ].
[1] A polyamide resin composition containing a polyamide resin (A) and an impact resistant material (B), wherein the polyamide resin (A) is an aliphatic homopolyamide resin (A-1) and an aliphatic copolymerized polyamide resin (A -2); 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-1) is 2 in the relative viscosity measured at 25 ° C. .10 to 2.80, and the relative viscosity of the aliphatic copolymerized polyamide resin (A-2) is 2.90 to 3.80.
[2] The polyamide resin composition according to [1], wherein the mass ratio of the aliphatic homopolyamide resin (A-1) and the aliphatic copolymerized polyamide resin (A-2) is 50:50 to 90:10. .
[3] The polyamide resin composition according to [1] or [2], wherein the polyamide resin (A) has a relative viscosity of 2.30 to 3.00.
[4] The polyamide resin composition according to any one of [1] to [3], wherein the polyamide resin (A) has a relative viscosity of 2.45 to 2.80.
[5] The polyamide resin composition according to any one of [1] to [4], wherein the aliphatic homopolyamide resin (A-1) has a relative viscosity of 2.30 to 2.70.
[6] The polyamide resin composition according to any one of [1] to [5], wherein the aliphatic copolyamide resin (A-2) has a relative viscosity of 2.95 to 3.50.
[7] Aliphatic homopolyamide resin (A-1) is one or more selected from the group consisting of polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11 and polyamide 12, [1] to [ 6], the polyamide resin composition according to any one of the above.
[8] The polyamide resin composition according to any one of [1] to [7], wherein the aliphatic homopolyamide resin (A-1) is polyamide 6 and/or polyamide 66.
[9] Any one of [1] to [8], wherein the aliphatic copolyamide resin (A-2) is one or more selected from the group consisting of polyamide 6/66 and polyamide 6/66/12 The polyamide resin composition according to 1.
[10] The polyamide resin composition according to any one of [1] to [9], wherein the aliphatic copolymerized polyamide resin (A-2) is polyamide 6/66.
[11] The polyamide resin composition according to any one of [1] to [10], wherein the impact resistant material (B) is a rubber-like polymer.
[12] The impact resistant material (B) is (ethylene and/or propylene)/α-olefin copolymer and (ethylene and/or propylene)/(α,β-unsaturated carboxylic acid and/or α,β -unsaturated carboxylic acid ester)-based copolymers, and polymers modified with carboxylic acids and/or derivatives thereof, which are one or more selected from the group consisting of any of [1] to [11]. or the polyamide resin composition according to any one of the above.
[13] The impact resistant material (B) is at least one selected from the group consisting of ethylene/α-olefin copolymers and polymers acid-modified with unsaturated carboxylic acids or their acid anhydrides. The polyamide resin composition according to any one of [1] to [12].
[ 14 ] of [1] to [ 13 ], further comprising at least two antioxidants (C) selected from the group consisting of phenolic antioxidants, phosphorus antioxidants and metal halide antioxidants The polyamide resin composition according to any one.
[ 15 ] The polyamide resin composition according to [ 14 ], wherein the mass ratio of the phenolic antioxidant and the phosphorus antioxidant is 1:1 to 10:1.
[ 16 ] Described in [ 14 ] or [ 15 ], wherein the mass ratio of the sum of the phenolic antioxidant and the phosphorus antioxidant to the metal halide antioxidant is 0.1:1 to 10:1 Polyamide resin composition of.

According to the present invention, it is possible to provide a polyamide resin composition having high fluidity and excellent gas barrier properties when molded.

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

The polyamide resin composition of the present invention is a polyamide resin composition comprising a polyamide resin (A) and an impact resistant material (B), wherein the polyamide resin (A) is an aliphatic homopolyamide resin (A-1) and an aliphatic Copolyamide resin (A-2) is included; according to JIS K 6920, 1 g of polyamide resin is dissolved in 100 ml of 96% sulfuric acid, and the relative viscosity measured at 25 ° C. is aliphatic homopolyamide resin (A-1 ) has a relative viscosity of 2.10 to 2.80, and the relative viscosity of the aliphatic copolymerized polyamide resin (A-2) is 2.90 to 3.80.
By setting the relative viscosity of the aliphatic homopolyamide resin (A-1) and the aliphatic copolyamide resin (A-2) to the above range, the polyamide has high fluidity and excellent gas barrier properties when molded. It can be a resin composition.

<Polyamide resin (A)>
The polyamide resin (A) includes an aliphatic homopolyamide resin (A-1) and an aliphatic copolyamide resin (A-2).

(Aliphatic homopolyamide resin (A-1))
The aliphatic homopolyamide resin (A-1) means a polyamide resin in which only one kind of monomer component constitutes the aliphatic polyamide resin. Aliphatic homopolyamide resin (A-1) may consist of at least one of one type of lactam and aminocarboxylic acid which is a hydrolyzate of the lactam, one type of aliphatic diamine and one type of It may also consist of a combination with an aliphatic dicarboxylic acid. Here, when the monomer component constituting the aliphatic polyamide resin is a combination of an aliphatic diamine and an aliphatic dicarboxylic acid, one type of aliphatic diamine and one type of aliphatic dicarboxylic acid are combined to form one monomer. shall be considered an ingredient.

The aliphatic homopolyamide resin (A-1) was obtained by dissolving 1 g of the aliphatic homopolyamide resin (A-1) in 100 ml of 96% sulfuric acid according to JIS K 6920, and having a relative viscosity of 2.0 at 25°C. 10 to 2.80. By setting the relative viscosity of the aliphatic homopolyamide resin (A-1) within the above range, the fluidity of the polyamide resin composition can be increased and the gas barrier properties can be improved. The relative viscosity of the aliphatic homopolyamide resin (A-1) is preferably 2.30-2.70, more preferably 2.40-2.65.

When the aliphatic homopolyamide resin (A-1) contains two or more polyamide resins with different relative viscosities, the relative viscosity of the aliphatic homopolyamide resin (A-1) is preferably measured as described above. However, if the relative viscosity of each polyamide resin and its mixing ratio are known, the average value (average relative viscosity) calculated by summing the values obtained by multiplying each relative viscosity by the mixing ratio is It may be the relative viscosity of the homopolyamide resin (A-1).

Examples of the aliphatic homopolyamide resin (A-1) include an aliphatic homopolyamide resin composed of an aliphatic diamine and an aliphatic dicarboxylic acid, and an aliphatic homopolyamide resin composed of a lactam or aminocarboxylic acid.

Monomer components constituting the aliphatic homopolyamide resin (A-1) include an aliphatic diamine having 2 to 20 carbon atoms, preferably 4 to 12 carbon atoms, and an aliphatic diamine having 2 to 20 carbon atoms, preferably 6 to 12 carbon atoms. and combinations of aliphatic dicarboxylic acids, lactams or aminocarboxylic acids having 6 to 12 carbon atoms, and the like.

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 diamine and the like. 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. acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosandioic acid, and the like.

Combinations of aliphatic diamines and aliphatic dicarboxylic acids include combinations of hexamethylenediamine and adipic acid, combinations of hexamethylenediamine and sebacic acid, combinations of hexamethylenediamine and dodecanedioic acid, and the like. Salt is preferably used.

Lactams include ε-caprolactam, enantholactam, undecanelactam, dodecanelactam, α-pyrrolidone, α-piperidone and the like. From the viewpoint of productivity, the lactam is preferably ε-caprolactam, undecanelactam or dodecanelactam. Aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

Specific examples of the aliphatic homopolyamide resin (A-1) include polycaprolactam (polyamide 6), polyenantholactam (polyamide 7), polyundecanelactam (polyamide 11), polylauryllactam (polyamide 12), and polyhexamethylene. adipamide (polyamide 66), polytetramethylene dodecamide (polyamide 412), polypentamethylene azellamide (polyamide 59), polypentamethylene sebacamide (polyamide 510), polypentamethylene dodecamide (polyamide 512), poly Hexamethylene Azeramide (Polyamide 69), Polyhexamethylene Sebacamide (Polyamide 610), Polyhexamethylene Dodecamide (Polyamide 612), Polynonamethylene Adipamide (Polyamide 96), Polynonamethylene Azeramide (Polyamide 99) , polynonamethylene sebacamide (polyamide 910), polynonamethylene dodecamide (polyamide 912), polydecamethylene adipamide (polyamide 106), polydecamethylene azelamide (polyamide 109), polydecamethylene decamamide (polyamide 1010), polydodecamethylene dodecamide (polyamide 1012), polydodecamethylene adipamide (polyamide 126), polydodecamethylene azelamide (polyamide 129), polydodecamethylene sebacamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1212), polyamide 122, and the like.

From the viewpoint of productivity, the aliphatic homopolyamide resin (A-1) is preferably one or more selected from the group consisting of polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11 and polyamide 12. , polyamide 6 and/or polyamide 66 are particularly preferred.

The aliphatic homopolyamide resin (A-1) may be one or a combination of two or more.

(Aliphatic copolyamide resin (A-2))
The aliphatic copolymerized polyamide resin (A-2) means a polyamide resin in which two or more monomer components constituting the aliphatic polyamide resin are combined. The aliphatic copolymerized polyamide resin (A-2) is a copolymer of two or more selected from the group consisting of combinations of aliphatic diamines and aliphatic dicarboxylic acids, lactams and aminocarboxylic acids. Here, the combination of the aliphatic diamine and the aliphatic dicarboxylic acid is regarded as one type of monomer component in the combination of one type of aliphatic diamine and one type of aliphatic dicarboxylic acid.

The aliphatic copolyamide resin (A-2) is obtained by dissolving 1 g of the aliphatic copolyamide resin (A-2) in 100 ml of 96% sulfuric acid according to JIS K 6920, and measuring the relative viscosity at 25 ° C. 2.90 to 3.80. By setting the relative viscosity of the aliphatic copolymerized polyamide resin (A-2) within the above range, the fluidity of the polyamide resin composition can be increased and the gas barrier property can be improved. The relative viscosity of the aliphatic copolyamide resin (A-2) is preferably 2.95-3.50, more preferably 3.00-3.20.

When the aliphatic copolyamide resin (A-2) contains two or more polyamide resins having different relative viscosities, the relative viscosity of the aliphatic copolyamide resin (A-2) is measured as described above. is preferable, but when the relative viscosity of each polyamide resin and its mixing ratio are known, the average value (average relative viscosity) calculated by summing the values obtained by multiplying each relative viscosity by the mixing ratio, It may be the relative viscosity of the aliphatic copolyamide resin (A-2).

Examples of the aliphatic diamine include those exemplified as raw materials for the aliphatic homopolyamide resin (A-1).

Examples of the aliphatic dicarboxylic acid include those exemplified as raw materials for the aliphatic homopolyamide resin (A-1).

Examples of the lactam include those exemplified as raw materials for the aliphatic homopolyamide resin (A-1). Examples of the aminocarboxylic acid include those exemplified as raw materials for the aliphatic homopolyamide resin (A-1).

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

Specific examples of the aliphatic copolymerized polyamide resin (A-2) include caprolactam/hexamethylenediaminoadipic acid copolymer (polyamide 6/66) and caprolactam/hexamethylenediaminoazelaic acid copolymer (polyamide 6/69). , caprolactam/hexamethylenediaminosebacic acid copolymer (polyamide 6/610), caprolactam/hexamethylenediaminoundecanedicarboxylic acid copolymer (polyamide 6/611), caprolactam/hexamethylenediaminododecanedicarboxylic 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/hexamethylenediaminoadipic acid/hexamethylenediaminosebacic acid copolymer (polyamide 6/66/610), caprolactam/hexamethylenediaminoadipic acid/hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 /66/612), and aliphatic copolymerized polyamide resins such as hexamethylenediaminoadipic acid/caprolactam copolymer (polyamide 66/6).
From the viewpoint of productivity, the aliphatic copolymerized polyamide resin (A-2) is preferably one or more selected from the group consisting of polyamide 6/66 and polyamide 6/66/12. is particularly preferred.

The aliphatic copolyamide resin (A-2) may be one or a combination of two or more.

(Other polyamide resins)
The polyamide resin (A) may contain a polyamide resin (A-3) other than the aliphatic homopolyamide resin (A-1) and the aliphatic copolyamide resin (A-2). Other polyamide resins (A-3) include polyamide resins which are copolymers having functional groups such as alicyclic and aromatic groups on the main chain or side chains. The other polyamide resin (A-3) is preferably a copolyamide resin containing at least two aromatic monomer components, for example.

Examples of aliphatic diamines, aliphatic dicarboxylic acids, lactams and aminocarboxylic acids used as raw materials for other polyamide resins (A-3) include those exemplified for the aliphatic homopolyamide resins (A-1).

Other alicyclic diamines constituting the polyamide resin (A-3) include, for example, cyclohexanediamine, methylcyclohexanediamine, bis(3-methyl-4-aminocyclohexyl)methane, and isophoronediamine. Examples of aromatic diamines constituting other polyamide resins (A-3) include; ,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether and the like.

Other alicyclic dicarboxylic acids constituting the polyamide resin (A-3) include, for example, 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Other aromatic dicarboxylic acids constituting the polyamide resin (A-3) include, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 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, 4,4'-biphenyldicarboxylic acid and the like.

Specific examples of other polyamide resins (A-3) include polycondensates of isophthalic acid/terephthalic acid/hexamethylenediamine/bis(3-methyl-4-aminocyclohexyl)methane, terephthalic acid/2,2,4 - trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine polycondensate, isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-laurolactam polycondensate, isophthalic acid/terephthalate Acid/hexamethylenediamine polycondensate (polyamide 6T/6I), isophthalic acid/2,2,4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine polycondensate, isophthalic acid/terephthalic acid /2,2,4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine polycondensate, polycondensation of isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-laurolactam A body etc. are mentioned.

Specifically, the other polyamide resin (A-3) is preferably composed of 40 to 95 mol % of terephthalic acid component units, 5 to 60 mol % of isophthalic acid component units, and an aliphatic diamine. Other preferred combinations of monomer components constituting the polyamide resin (A-3) include an equimolar salt of hexamethylenediamine and terephthalic acid and an equimolar salt of hexamethylenediamine and isophthalic acid.

The other polyamide resin (A-3) contains 60% by mass or more and 99% by mass or less of units derived from a monomer component composed of an aliphatic diamine, isophthalic acid, and terephthalic acid, and 1 mass of an aliphatic polyamide component unit. % or more and 40 mass % or less.

(Manufacture of polyamide resin)
Examples of polyamide resin production equipment include batch-type reactors, single-vessel or multi-vessel continuous reactors, tubular continuous reactors, single-screw kneading extruders, twin-screw kneading extruders, and other kneading reaction extruders. A known polyamide manufacturing apparatus can be used. As a polymerization method, known methods such as melt polymerization, solution polymerization, and solid phase polymerization can be used, and polymerization can be performed by repeating normal pressure, reduced pressure, and pressurization operations. These polymerization methods can be used alone or in combination as appropriate.

(Polyamide resin (A))
Regarding the relative viscosity of the polyamide resin (A), the relative viscosity of the aliphatic homopolyamide resin (A-1) is 2.10 to 2.80, and the relative viscosity of the aliphatic copolymerized polyamide resin (A-2) is 2. Although it is not particularly limited as long as it is .90 to 3.80, from the viewpoint of the fluidity of the polyamide resin composition, for example, it is preferably 2.30 to 3.00, more preferably 2.45 to 2.80 , more preferably 2.50 to 2.75, and particularly preferably 2.50 to 2.68.

The relative viscosity of the polyamide resin (A) is preferably measured at 25 ° C. by dissolving 1 g of the polyamide resin (A) in 100 ml of 96% sulfuric acid according to JIS K 6920, but the relative viscosity of each polyamide resin And when the mixing ratio is known, the average value (average relative viscosity) calculated by summing the values obtained by multiplying the respective relative viscosities by the mixing ratio may be the relative viscosity of the polyamide resin (A). .

From the viewpoint of low-temperature toughness, the polyamide resin (A) contains the aliphatic homopolyamide resin (A-1) and the aliphatic copolyamide resin (A-2) in 100% by mass of the polyamide resin (A). It is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably 98% by mass or more. It is particularly preferred that the polyamide resin (A) consists only of the aliphatic homopolyamide resin (A-1) and the aliphatic copolyamide resin (A-2). Among them, a mixture of polyamide 6 and polyamide 6/66 is more preferable from the viewpoint of the crystallinity of the polyamide resin (A).

From the viewpoint of low-temperature toughness, the mass ratio of the aliphatic homopolyamide resin (A-1) and the aliphatic copolyamide resin (A-2) is preferably 50:50 to 90:10, more preferably 60:40. ∼85:15 is more preferable, and 70:30 to 80:20 is particularly preferable.

The terminal amino group concentration of the polyamide resin (A) is preferably 30 μmol/g or more, preferably 30 μmol/g or more and 110 μmol/g as the terminal amino group concentration obtained by neutralization titration after dissolving in a mixed solvent of phenol and methanol. The following range is more preferable, and the range of 30 μmol/g or more and 70 μmol/g or less is particularly preferable. Within the above range, molding processability of a molded article using the polyamide resin composition is good.

When the polyamide resin (A) contains two or more types 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 measurement, but each When the terminal amino group concentration and the mixture ratio of the polyamide resin are known, the average value calculated by summing the values obtained by multiplying the respective terminal amino group concentrations by the mixture ratio, the polyamide resin (A) It may be the terminal amino group concentration.

The polyamide resin (A) is preferably contained in an amount of 78 to 94% by mass, more preferably 80 to 92% by mass, based on 100% by mass of the polyamide resin composition. When the content of the polyamide resin (A) is within the above range, molding processability of a molded product using the polyamide resin composition is good.

<Shock resistant material (B)>
The impact resistant material (B) is a component that imparts impact resistance to the polyamide resin composition. A rubber-like polymer is mentioned as an impact-resistant material (B). The impact resistant material (B) preferably has a flexural modulus of 500 MPa or less as measured according to ASTM D-790.

Specific examples of the impact resistant material (B) include (ethylene and/or propylene)/α-olefin copolymer, (ethylene and/or propylene)/(α,β-unsaturated carboxylic acid and/or α, β-unsaturated carboxylic acid ester) copolymers, and the like. These can be used individually by 1 type or in combination of 2 or more types. An ethylene/α-olefin copolymer is preferable as the impact resistant material (B).

The (ethylene and/or propylene)/α-olefin copolymer is a polymer 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-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1 -tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl -1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3 -ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene and the like. These may be used singly or in combination of two or more.

The copolymer may also be a copolymer of polyene such as non-conjugated diene. Non-conjugated dienes include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, 2- methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 4,8-dimethyl-1, 4,8-decatriene (DMDT), dicyclopentadiene, cyclohexadiene, cyclooctadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropylidene-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,5-norbornadiene and the like mentioned. These may be used singly or in combination of two or more.

(Ethylene and/or propylene)/(α,β-unsaturated carboxylic acid and/or α,β-unsaturated carboxylic acid ester) copolymer is ethylene and/or propylene and α,β-unsaturated carboxylic acid and/or a polymer obtained by copolymerizing α,β-unsaturated carboxylic acid ester monomers. α,β-unsaturated carboxylic acid monomers include acrylic acid and methacrylic acid. Examples of α,β-unsaturated carboxylic acid ester monomers include methyl esters, ethyl esters, propyl esters, butyl esters, pentyl esters, hexyl esters, heptyl esters, octyl esters and nonyl esters of these α,β-unsaturated carboxylic acids. esters, decyl esters and the like. These may be used singly or in combination of two or more.

Also, (ethylene and/or propylene)/α-olefin copolymers used as impact resistant materials (B), and (ethylene and/or propylene)/(α,β-unsaturated carboxylic acid and/or α, The β-unsaturated carboxylic acid ester) copolymer is preferably a polymer modified with a carboxylic acid and/or a derivative thereof, and a polymer modified with an unsaturated carboxylic acid or an acid anhydride thereof. is more preferable. By modifying with such a component, a functional group having an affinity for the polyamide resin (A) is included 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, include 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-heptene-2,3-dicarboxylic acid and metal salts of these carboxylic acids, monomethyl maleate, monomethyl itaconate, methyl acrylate, acrylic ethyl acetate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo-[2.2.1]-5-heptene-2,3-dicarboxylic anhydride, maleimide, N-ethylmaleimide, N-butylmaleimide, N-phenylmaleimide, acrylamide , methacrylamide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, glycidyl citraconate, and the like. These can be used singly or in combination of two or more. Among these, maleic anhydride is preferred.

The content of acid anhydride groups in the impact resistant material (B) is preferably more than 25 μmol/g and 200 μmol/g or less, more preferably 35 μmol/g or more and 150 μmol or less, and further preferably 40 μmol/g or more and 110 μmol/g or less. 40 μmol/g or more and 90 μmol or less is particularly preferable. When the content exceeds 25 μmol/g, excessive decrease in melt viscosity of the composition can be suppressed, and the target thickness dimension can be obtained in blow molding. Further, when the content is 200 μmol/g or less, the melt viscosity is not too high, and the load on the extruder can be suppressed to enable good molding. The content of acid anhydride groups possessed by the impact resistant material (B) is determined by neutralization titration with a 0.1 N KOH ethanol solution using a sample solution prepared using toluene and ethanol, using phenolphthalein as an indicator. Measured in

When two or more impact resistant materials having different acid anhydride group contents are used as the impact resistant material (B), the acid anhydride group content in the impact resistant material (B) is determined using toluene and ethanol. Using the prepared sample solution, phenolphthalein is used as an indicator, and it is preferably measured by neutralization titration with a 0.1N KOH ethanol solution. When the mixing ratio is known, the average value calculated by summing the values obtained by multiplying the content of each acid anhydride group by the mixing ratio is also used as the acid anhydride content of the impact resistant material (B). good.

The impact resistant material (B) preferably has an MFR of 0.1 g/10 min or more and 10.0 g/10 min or less measured at a temperature of 230° C. and a load of 2160 g according to 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 body is suppressed. tend to be more uniform. Also, when the MFR is 10.0 g/10 minutes or less, there is a tendency that the drawdown of the parison does not become too large and good blow moldability can be obtained.

The impact resistant material (B) is preferably contained in 100% by mass of the polyamide resin composition in an amount of 5 to 20% by mass, more preferably 6 to 19% by mass, and 7 to 18% by mass. More preferably, it is particularly preferably contained in an amount of 10 to 16% by mass. When the content of the impact resistant material (B) is within the above range, good gas barrier properties are obtained.

<Antioxidant (C)>
The polyamide resin composition preferably further contains an antioxidant (C). The antioxidant (C) is preferably at least one antioxidant selected from the group consisting of organic antioxidants and metal halide antioxidants. It is more preferable to contain at least two antioxidants selected from the group consisting of antioxidants and halogenated metal antioxidants, and at least one selected from phenolic antioxidants and phosphorus antioxidants and halogen It is more preferable to contain a metal oxide antioxidant, and it is particularly preferable to contain all of a phenol antioxidant, a phosphorus antioxidant and a metal halide antioxidant. When the polyamide resin composition contains at least one selected from a phenolic antioxidant and a phosphorus antioxidant and a metal halide antioxidant, both coloring of the resin composition and bleeding out of the antioxidant are prevented. While suppressing, it becomes easy to aim at the improvement in heat resistance.

(Organic antioxidant)
Examples of organic antioxidants include phenol antioxidants, phosphorus antioxidants, thioether antioxidants, and the like. The organic antioxidant is preferably at least one selected from the group consisting of a phenolic antioxidant and a phosphorus antioxidant, and may contain both a phenolic antioxidant and a phosphorus antioxidant. more preferred.

Specific examples of phenolic antioxidants include N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide (Irganox (registered trademark) 1098; BASF Japan Ltd. manufactured by), pentaerythrityl-tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate] (Irganox (registered trademark) 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® GA -80; manufactured by Sumitomo Chemical Co., Ltd.), and at least one selected from the group consisting of these is preferable.The phenolic antioxidant may be used alone or in combination of two or more. .

Specific examples of phosphorus antioxidants include tris (2,4-di-t-butylphenyl) phosphite (Irgafos168; manufactured by BASF Japan Ltd.), bis (2,6-di-t-butyl-4- Methylphenyl) pentaerthritol diphosphite (adekastab (registered trademark) PEP-36; manufactured by ADEKA Corporation) and tetrakis(2,4-di-tert-butylphenoxy)-4,4-bifinyldiphosphine as main Reaction products of bifinyl, phosphorus trichloride and 2,4-di-tert-butylphenol as components (Hostanox (registered trademark) P-EPQ (registered trademark) P; manufactured by Clariant Japan Co., Ltd.) can be mentioned. At least one selected from the group consisting of is preferred. Phosphorus-based antioxidants may be used singly or in combination of two or more.

Specific examples of thioether-based antioxidants include distearyl-3,3-thiodipropionate (Irganox (registered trademark) PS802; manufactured by BASF Japan Ltd.), pentaerythrityl tetrakis (3-laurylthiopropionate). (Sumilizer (registered trademark) TP-D; manufactured by Sumitomo Chemical Co., Ltd.), didodecyl (3,3'-thiodipropionate) (Irganox (registered trademark) PS800; manufactured by BASF Japan Ltd.), and these At least one selected from the group consisting of is preferred. Thioether-based antioxidants may be used singly or in combination of two or more.

The total content of the organic antioxidant is preferably 0.02% by mass or more and 5% by mass or less, and 0.05% by mass or more and 2.0% by mass or less in 100% by mass of the polyamide resin composition. It is more preferable to have

The content of the phenolic antioxidant is preferably 0.01% by mass or more and 5% by mass or less, and 0.05% by mass or more and 2.0% by mass or less in 100% by mass of the polyamide resin composition. is more preferable, and 0.1% by mass or more and 1.5% by mass or less is particularly preferable.
The content of the phosphorus antioxidant is preferably 0.01% by mass or more and 5% by mass or less, and 0.03% by mass or more and 1.5% by mass or less in 100% by mass of the polyamide resin composition. is more preferable, and it is particularly preferable to be 0.05% by mass or more and 1.0% by mass or less.

The mass ratio of the phenolic antioxidant and the phosphorus antioxidant is preferably 1:1 to 10:1, more preferably 2:1 to 8:1, from the viewpoint of preventing bleeding out and coloring the molded product. is more preferable.

(metal halide-based antioxidant)
The metal halide antioxidant is a component that mainly imparts long-term heat resistance. A metal halide antioxidant is a compound of a halogen and a metal. Halogen includes fluorine, chlorine, bromine, iodine and the like. Examples of metals include Group 1 elements (alkali metals), Group 2 elements (alkaline earth metals), Group 3 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) metal.

Examples of the metal halide when the metal is a Group 1 element (alkali metal) include potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium chloride, and the like. In addition, when the metal is a group 11 element (copper group), the metal halide includes cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, Cupric iodide etc. are mentioned. The metal halide antioxidant is more preferably a mixture of cuprous iodide and potassium halide, or a mixture of cuprous bromide and potassium halide. A mixture or a mixture of cuprous bromide and potassium bromide is particularly preferred.

The metal halide antioxidants may be used singly or in combination of two or more.

The content of the metal halide antioxidant is preferably 0.01% by mass or more and 5% by mass or less, and 0.05% by mass or more and 2.0% by mass or less in 100% by mass of the polyamide resin composition. more preferably, and particularly preferably 0.1% by mass or more and 1.0% by mass or less. When the polyamide resin composition contains a copper-based antioxidant in a predetermined amount or more, the shock-resistant material (B) may deteriorate due to copper damage caused by the contact of the impact-resistant material (B) with copper. Also, the coloring of the polyamide resin composition tends to increase. By setting the content of the metal halide antioxidant to 5% by mass or less and using a phenolic antioxidant and/or a phosphorus antioxidant in combination, the impact resistant material (B) is prevented from deteriorating and It becomes easy to suppress coloring of a polyamide resin composition.

The mass ratio of the sum of the phenolic antioxidant and the phosphorus antioxidant to the metal halide antioxidant is 0.1:1 to 10:1 from the viewpoint of preventing bleeding out and coloring the molded product. preferably 0.5:1 to 5:1.
The mass ratio of the phenol antioxidant and the metal halide antioxidant is preferably 0.05:1 to 6:1, more preferably 0.4:1 to 3:1.

<Other ingredients>
The polyamide resin composition can contain other components as long as the effects of the present invention are not impaired. Other components include plasticizers, heat resistant materials, foaming agents, weathering agents, crystal nucleating agents, crystallization accelerators, release agents, lubricants, antistatic agents, flame retardants, flame retardant aids, pigments, dyes, etc. Functionality-imparting agents and the like can be mentioned. The other components are not the polyamide resin (A), the impact resistant material (B) and the antioxidant (C).

The polyamide resin composition preferably contains an inorganic nucleating agent as another component. Examples of inorganic nucleating agents include talc, mica, synthetic mica, glass flakes, non-swelling mica, fullerenes, carbon nanotubes, carbon black, graphite, metal foils, ceramic beads, clay, sericite, zeolite, bentonite, hydroxylated Aluminum, Dolomite, Kaolin, Silica, Fine Silicic Acid, Feldspar Powder, Potassium Titanate, Shirasu Balloon, Calcium Carbonate, Magnesium Carbonate, Barium Sulfate, Calcium Oxide, Aluminum Oxide, Titanium Oxide, Magnesium Oxide, Aluminum Silicate, Silicon Oxide, Magnesium hydroxide, gypsum, novaculite, dawsonite, clay, glass fiber, carbon fiber, graphite fiber, metal fiber, potassium titanate whisker, aluminum borate whisker, magnesium whisker, silicon whisker, wollastonite, sepiolite, slag fiber, Examples include xonolite, elestadite, gypsum fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber and boron fiber.
Among these, talc is preferable from the viewpoint of improving the crystallinity of the polyamide resin and suppressing the gas permeability of nitrogen and hydrogen.

[Method for producing 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 the polyamide resin (A), the impact resistant material (B), the antioxidant (C) and any other component are mixed and used, a single-screw extruder, a twin-screw extruder, a Banbury mixer , a kneader, and a mixing roll are used. For example, using a twin-screw extruder, after blending all the raw materials, a method of melt-kneading, a method of blending a part of the raw materials, melt-kneading, further blending the remaining raw materials and melt-kneading, or a part 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.

[Use of Polyamide Resin Composition]
The polyamide resin composition is not particularly limited, and can be used for producing molded articles using known methods. Specifically, the polyamide resin composition can be used for the production of injection-molded articles by injection molding, the production of blow-molded articles by blow molding, or the production of extruded articles by extrusion molding. Among others, the polyamide resin composition of the present invention is suitable for the production of blow-molded articles by blow molding and the production of extruded articles by extrusion molding.
A method for producing a blow-molded article from a polyamide resin composition by blow molding generally includes forming a parison using a conventional blow molding machine and then performing blow molding. The resin temperature during parison formation is preferably in the range of 10° C. to 70° C. higher than the melting point of the polyamide resin composition.

A method for producing an extruded product from a polyamide resin composition by extrusion molding generally involves co-extrusion with a polyolefin such as polyethylene or another thermoplastic resin, followed by blow molding to obtain a multilayer structure. include. Here, it is also possible to provide an adhesive layer between the polyamide resin composition layer and another thermoplastic resin layer such as polyolefin. When the molded article is a multilayer structure, the polyamide resin composition of the present invention can be used for both the outer layer and the inner layer.

Applications of injection molded products by injection molding, blow molded products by blow molding, or extrusion molded products by extrusion are not particularly limited, but spoilers, air intake ducts, intake manifolds, resonators, fuel tanks, gas tanks, hydraulic oil tanks, Automotive parts such as fuel filler tubes, fuel delivery pipes, various hoses, tubes, and tanks; mechanical parts such as power tool housings and pipes; electric and electronic parts such as tanks, tubes, hoses, and films; parts; furniture parts and the like are preferably mentioned.
Since the polyamide resin composition has excellent gas barrier properties, it is suitably used for moldings that come into contact with gas, such as tanks, tubes, hoses, and films that come into contact with gas.
The type of gas is not particularly limited, but includes hydrogen, nitrogen, oxygen, helium, methane, butane, propane, etc. Gases with low polarity are preferred, and hydrogen and nitrogen are more preferred.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Materials used]
1. Polyamide resin (A)
(1) Aliphatic homopolyamide resin (A-1)
PA6-1: Polyamide 6 (manufactured by Ube Industries, Ltd.: relative viscosity to 96% sulfuric acid = 2.64)
PA6-2: Polyamide 6 (manufactured by Ube Industries, Ltd.: relative viscosity to 96% sulfuric acid = 2.47)
PA6-3: Polyamide 6 (manufactured by Ube Industries, Ltd.: relative viscosity to 96% sulfuric acid = 2.98)
(2) Aliphatic copolyamide resin (A-2)
PA6/66-1: Polyamide 6/66 (manufactured by Ube Industries, Ltd.: relative viscosity to 96% sulfuric acid = 3.04)
PA6/66-2: Polyamide 6/66 (manufactured by Ube Industries, Ltd.: relative viscosity to 96% sulfuric acid = 4.05)

2. Impact resistant material (B)
Maleic anhydride-modified ethylene-butene copolymer (Tafmer (registered trademark) MH5020, manufactured by Mitsui Chemicals, Inc.)

3. Antioxidant (C)
Phenolic antioxidant-1: 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4 , 8,10-tetraoxaspiro[5.5]undecane (manufactured by Sumitomo Chemical Co., Ltd.; Sumilizer (registered trademark) GA-80)
Phenolic antioxidant-2: pentaerythrityl-tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate] (manufactured by BASF Japan Ltd.; Irganox (registered trademark) 1010)
Phosphorus-based antioxidant: tris (2,4-di-t-butylphenyl) phosphite (manufactured by BASF Japan Ltd.; Irgafos168)
Halide metal antioxidant: a mixture of cuprous iodide/potassium iodide = 2/5 (mass ratio)

Examples 1 to 3 and Comparative Example 1
Each component shown in Table 1 was melt-kneaded under the following melt-kneading conditions to prepare the intended polyamide resin composition pellets. The unit of composition in Table 1 is % by mass, and the total polyamide resin composition is 100% by mass.
<Melting kneading conditions>
Use TEX-44 twin screw extruder Cylinder diameter: 44mm
L/D: 35
Screw rotation speed: 120 rpm

[Evaluation method]
1. Hydrogen Gas Permeability Coefficient Using the pellets of Examples 1 to 3 and Comparative Example 1, test pieces having a thickness of 2 mm were produced under the following injection molding conditions.
<Injection molding conditions>
Cylinder temperature: 270°C
Mold temperature: 80°C
Average injection speed in mold: 50mm/sec
Cooling time: 5 seconds

Using the test piece thus obtained, a hydrogen gas permeation test was conducted at 55° C. and 0% RH by adopting a gas chromatographic method according to JIS K7126-1. As a measuring device, GTR-21A-B, serial number GTR-1400120 (manufactured by GTR Tech Co., Ltd.) was used. Gas permeability was evaluated according to the following criteria. Table 1 shows the results.
◯: Hydrogen gas permeability coefficient is less than 3.0×10 ⁻¹⁰ cm ³ cm/(cm ² s cmHg) ×: Hydrogen gas permeability coefficient is 3.0×10 ⁻¹⁰ cm ³ cm/(cm ^{2 )}・s cmHg) or more

2. Nominal Tensile Yield Strain After Heating and Pressing Using the pellets of Examples 1 to 3 and Comparative Example 1, ISOType A test pieces were obtained under the following injection molding conditions. The test piece thus obtained was treated for 2 hours under the conditions of oxygen concentration of 21%, pressure of 0.8 MPa and 180°C. After that, according to ISO 527-2/1A/50, a tensile yield nominal strain test was performed at -60°C and used as an index of heat resistance. The larger the tensile yield nominal strain value after heating and pressurization, the better the low temperature toughness and the better the heat resistance. If the yield point does not appear in the tensile yield nominal strain test, the test piece will continue to stretch in accordance with the tensile stress and then suddenly break, resulting in poor low-temperature toughness and poor heat resistance. The heat resistance of the polyamide resin composition was evaluated according to the following criteria. Table 1 shows the results.
○: Tensile yield nominal strain value is 6.0% or more ×: Tensile yield nominal strain value is less than 6.0% or no yield point

<Injection molding conditions>
Cylinder temperature: 270°C
Mold temperature: 80°C
Average injection speed in mold: 50mm/sec
Cooling time: 5 seconds

3. Fluidity The pellets of Examples 1 to 3 and Comparative Example 1 were subjected to melt mass flow rate (MFR) measurement under conditions of 280°C and a load of 10 kg according to JIS K 7210-1, and used as an index of fluidity. The fluidity of the polyamide resin composition was evaluated according to the following criteria. Table 1 shows the results.
◎: MFR is 80 g/10 min or more ○: MFR is 50 g/10 min or more and less than 80 g/10 min ×: MFR is less than 50 g/10 min

From Table 1, an aliphatic homopolyamide resin (A-1) having a relative viscosity within the range of 2.10 to 2.80 and an aliphatic copolyamide having a relative viscosity within the range of 2.90 to 3.80 It can be seen that Examples 1 to 3 using the polyamide resin (A) containing the resin (A-2) are excellent in hydrogen gas barrier properties and fluidity. It can be seen that Examples 1 to 3 using the polyamide resin (A) having an average relative viscosity in the range of 2.30 to 3.00 are excellent in hydrogen gas barrier properties and fluidity. In addition, since the compositions of Examples 1 to 3 contain at least two antioxidants selected from the group consisting of phenol antioxidants, phosphorus antioxidants, and metal halide antioxidants, Large tensile yield nominal strain after reduction and excellent heat resistance.

Comparative Example 1, in which the aliphatic homopolyamide resin (A-1) has a relative viscosity of more than 2.80 and the aliphatic copolymerized polyamide resin (A-2) has a relative viscosity of more than 3.80, has hydrogen gas barrier properties. and poor liquidity. Moreover, since Comparative Example 1 uses only the metal halide-based antioxidant, it has no yield point in the tensile yield nominal strain test after heating and pressurization, and is inferior in heat resistance.

The polyamide resin composition of the present invention can be used for producing various molded articles by injection molding, extrusion molding, blow molding and the like.

Claims (9)

A polyamide resin composition containing a polyamide resin (A) and an impact resistant material (B),
The polyamide resin (A) contains an aliphatic homopolyamide resin (A-1) and an aliphatic copolymerized polyamide resin (A-2), and the aliphatic homopolyamide resin (A-1 ) and the content of the aliphatic copolyamide resin (A-2) is 80% by mass or more,
According to JIS K 6920, 1 g of polyamide resin is dissolved in 100 ml of 96% sulfuric acid, and the relative viscosity measured at 25 ° C.
The aliphatic homopolyamide resin (A-1) has a relative viscosity of 2.40 to 2.65,
The relative viscosity of the aliphatic copolymerized polyamide resin (A-2) is 3.00 to 3.20,
The polyamide resin (A) has a relative viscosity of 2.45 to 2.80,
The mass ratio of the aliphatic homopolyamide resin (A-1) and the aliphatic copolyamide resin (A-2) is 60:40 to 85:15,
The impact resistant material (B) is an ethylene/α-olefin copolymer acid-modified with an unsaturated carboxylic acid or its acid anhydride,
The content of the polyamide resin (A) in 100% by mass of the polyamide resin composition is 78% by mass or more, and the content of the impact resistant material (B) is 10 to 16% by mass.
Polyamide resin composition. 2. The polyamide resin composition according to claim 1, wherein the impact resistant material (B) is a maleic anhydride-modified ethylene-butene copolymer. The aliphatic homopolyamide resin (A-1) is one or more selected from the group consisting of polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11 and polyamide 12, according to claim 1 or 2. Polyamide resin composition. 4. The polyamide resin composition according to any one of claims 1 to 3, wherein the aliphatic homopolyamide resin (A-1) is polyamide 6 and/or polyamide 66. The polyamide according to any one of claims 1 to 4, wherein the aliphatic copolyamide resin (A-2) is one or more selected from the group consisting of polyamide 6/66 and polyamide 6/66/12. Resin composition. The polyamide resin composition according to any one of claims 1 to 5, wherein the aliphatic copolymerized polyamide resin (A-2) is polyamide 6/66. Any one of claims 1 to 6, further comprising at least two antioxidants (C) selected from the group consisting of phenolic antioxidants, phosphorus antioxidants and metal halide antioxidants. A polyamide resin composition as described. The polyamide resin composition according to claim 7, wherein the mass ratio of the phenolic antioxidant and the phosphorus antioxidant is 1:1 to 10:1. The polyamide resin composition according to claim 7 or 8, wherein the mass ratio of the sum of the phenolic antioxidant and the phosphorus antioxidant to the metal halide antioxidant is 0.1:1 to 10:1. .