JP2023029319A - Polyamide resin composition and molding - Google Patents

Abstract

To provide a polyamide resin composition which is excellent in flowability, suppresses variation in flowability even in a plurality of times of high temperature processing of approximately 270°C, and is excellent in flame retardancy and mechanical strength when formed into a molding.SOLUTION: A polyamide resin composition contains (a) polyamide, and (b) melamine cyanurate, wherein in the spectrum obtained when the polyamide resin composition is analyzed by 13C-NMR, a ratio M1/M2 of a total area M1 of a peak in a chemical shift of 42.80 ppm or more and 43.05 ppm or lese with respect to a total area M2 of a peak of a chemical shift of 43.10 ppm or more and 43.35 ppm or less is 0.65 or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polyamide resin composition and a molded article.

BACKGROUND ART Polyamide resins have been widely used for various parts such as automobile parts, electronic/electrical parts, industrial machine parts, etc., because they have excellent properties such as molding processability as well as mechanical properties. Due to its excellent toughness, it is used in products with hinges such as connectors and clips. In many cases, these products are required to be flame retardant. In particular, from an environmental point of view, it is desired to use non-halogen flame retardants.

A representative example of such a flame-retardant polyamide resin is a flame-retardant polyamide material using melamine cyanurate, which is used, for example, in connectors, clips, etc. in the electrical and electronic field (see Patent Documents 1 and 2). ). Patent Document 3 proposes a polyamide resin composition using a specific phosphate triester, a higher fatty acid metal salt and a polyhydric alcohol. Further, in Patent Document 4, an attempt is made to improve the toughness by using a polyamide resin composition having a specific molecular weight.

JP-A-53-125459 JP-A-53-031759 JP-A-11-106645 JP 2018-70808 A

In flame-retardant polyamide resins using melamine cyanurate, part of melamine cyanurate reacts with amino groups, which are terminal groups of polyamide, when exposed to high temperature conditions such as extrusion processing, creating a crosslinked structure. By doing so, the molecular weight temporarily increases compared to the polyamide before extrusion. After that, the decomposition reaction progresses during the molding process, and the molecular weight gradually decreases. Therefore, when melamine cyanurate is used in the cross-linking reaction, the flame retardant component is consumed, and the flame retardancy tends to become unstable. Further, when high-temperature processing is performed multiple times, the fluidity of the resin tends to fluctuate as the molecular weight fluctuates. A sudden change in the flow of the resin not only makes it difficult to control the molding conditions, but also leads to the occurrence of burrs on the molded product.

Moreover, in recent years, attention has been paid to the demand for recycling of resin compositions, and a method of remixing used resin compositions with raw materials and processing and molding them again has been adopted. At this time, in the used resin composition to be reused, it is desirable that the fluidity of the used resin composition is stable from the viewpoint of stabilizing processing conditions.

The present invention has been made in view of the above circumstances. Provided are a polyamide resin composition having excellent properties and mechanical strength, and a molded article obtained by molding the polyamide resin composition.

That is, the present invention includes the following aspects.
(1) A polyamide resin composition containing (a) polyamide and (b) melamine cyanurate,
In the spectrum obtained when the polyamide resin composition is analyzed by ¹³ C-NMR, the chemical shift 42.80 ppm or more and 43.05 ppm or less for the total area M2 of the peaks between the chemical shift 43.10 ppm and 43.35 ppm or less A polyamide resin composition having a ratio M1/M2 of the total area M1 of peaks of 0.65 or less.
(2) The proportion of components having a molecular weight of 15,000 or less measured by gel permeation chromatography of the polyamide resin composition is more than 30.0% by mass and 45.0 with respect to the total mass of the polyamide resin composition. % by mass or less, the polyamide resin composition according to (1).
(3) The ratio of components having a molecular weight of 100,000 or more as measured by gel permeation chromatography of the polyamide resin composition is 1.0% by mass or more and 4.0% with respect to the total mass of the polyamide resin composition. The polyamide resin composition according to (1) or (2), which is less than % by mass.
(4) The melt mass flow rate of the polyamide resin composition measured under the conditions of 270° C., 2.16 kg, and a preheating time of 5 minutes is 40 g/10 minutes or more and 65 g/10 minutes or less, (1) to ( The polyamide resin composition according to any one of 3).
(5) Pellets of the polyamide resin composition obtained by pelletizing the melt mass flow rate of the polyamide resin composition after measuring the melt mass flow rate were measured under the conditions of 270 ° C., 2.16 kg, and a preheating time of 5 minutes. The polyamide resin composition according to any one of (1) to (4), which has a melt mass flow rate of 55 g/10 minutes or more and 75 g/10 minutes or less.
(6) The polyamide resin composition according to any one of (1) to (5), wherein the polyamide resin composition has a molecular weight distribution Mw/Mn of 1.70 to 2.00.
(7) (c) The polyamide resin composition according to any one of (1) to (6), further comprising at least one compound selected from the group consisting of polyhydric alcohols and ester derivatives thereof.
(8) The content of the (c) at least one compound selected from the group consisting of polyhydric alcohols and ester derivatives thereof is 0.1 parts by mass or more per 100 parts by mass of the (a) polyamide. The polyamide resin composition according to (7), which is 0 parts by mass or less.
(9) The polyamide resin composition according to any one of (1) to (8), further comprising (d) a higher fatty acid metal salt.
(10) The polyamide according to (9), wherein the content of the higher fatty acid metal salt (d) is 0.05 parts by mass or more and 2.00 parts by mass or less with respect to 100 parts by mass of the polyamide (a). Resin composition.
(11) Any one of (1) to (10), wherein the content of the (b) melamine cyanurate is 2 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the (a) polyamide. Polyamide resin composition according to.
(12) The polyamide resin composition according to any one of (1) to (11), containing 80% by mass or more of polyamide 66 with respect to the total mass of the polyamide (a).
(13) The polyamide resin composition according to (12), wherein the polyamide 66 has a sulfuric acid relative viscosity ηr of 2.50 or more and 2.90 or less.
(14) A molded article obtained by molding the polyamide resin composition according to any one of (1) to (13).
(15) Using a multi-purpose test piece A type obtained by molding the polyamide resin composition in accordance with ISO 3167, using a notched molded body processed in accordance with ISO 2818, it was measured in accordance with ISO 179-1. The molded article according to (14), wherein the molded article has a Charpy impact strength of 2.4 kJ/m ² or more.

According to the polyamide resin composition of the above aspect, the fluidity is excellent, and the fluctuation of the fluidity is suppressed even in multiple high-temperature processing at about 270 ° C., and the flame retardancy and mechanical strength when formed into a molded product. It is possible to provide a polyamide resin composition excellent in The molded article of the above aspect is obtained by molding the polyamide resin composition, and is excellent in flame retardancy and mechanical strength.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

As used herein, "polyamide resin" means a polymer compound having a "--CO--NH--" (amide) bond in its main chain.

<Polyamide resin composition>
The polyamide resin composition of the present embodiment contains (a) polyamide and (b) melamine cyanurate.

In the spectrum obtained when analyzed by ¹³ C-NMR, the peak between the chemical shift of 42.80 ppm and 43.05 ppm is the carbon of the crosslinked component generated by the reaction of the terminal amino group of the polyamide with melamine cyanurate. , chemical shifts between 43.10 and 43.35 ppm are assigned to the carbons adjacent to the terminal amino groups of the polyamide. At this time, the smaller the ratio M1/M2 of the total area M1 of the peaks between the chemical shifts of 42.80 ppm and 43.05 ppm to the total area M2 of the peaks between the chemical shifts of 43.10 ppm and 43.35 ppm and less, the cross-linking Less structure represents less flowability and flow variability.
The M1/M2 is 0.65 or less, preferably 0.50 or less, more preferably 0.35 or less, and even more preferably 0.25 or less.
The M1/M2 is controlled by adjusting the molecular weight of (a) the polyamide used as the raw material, (a) the amino group terminal ratio of the polyamide, setting the barrel temperature of the extruder, the screw rotation speed during melt kneading, and the screw configuration. be able to.

By having the above configuration, the polyamide resin composition of the present embodiment has excellent fluidity, and fluctuations in fluidity are suppressed even in multiple high-temperature processing at about 270 ° C., flame retardancy and mechanical strength. A molded article having excellent properties is obtained. The inventors presume that these characteristics are due to suppression of the reaction between the polyamide and melamine cyanurate during extrusion processing, control of the crosslinking components of the polyamide, and suppression of thermal decomposition of the flame retardant.

Next, each component constituting the polyamide resin composition of the present embodiment will be described in detail below.

[(a) Polyamide]
(a) Polyamides include, for example, polycaprolactam (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylenecyclohexylamide (polyamide 6C), polyhexamethylene methylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecalactam (polyamide 11), polydodecalactam (polyamide 12), polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalate amide (polyamide 6T), polynonanemethylene terephthalamide (polyamide 9T), polydodecamethylene terephthalamide (polyamide 12T), polymetaxylylene adipamide (polyamide MXD6), and copolymerization of two or more of these polyamides and a polyamide copolymer formed by These polyamides may be used alone or in combination of two or more.

Among the above-mentioned materials, polyamide 66 has high moldability and melting point, and is suitable as a material for obtaining parts that require higher heat resistance. When two or more polyamides are used, from the viewpoint of moldability and mechanical properties at high temperatures, (a) polyamide 66 is preferably contained in an amount of 50% by mass or more, preferably 80% by mass, based on the total mass of polyamide. % or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

((a) polymer terminal amount of polyamide)
(a) Polyamide polymer end weights are expressed as mol equivalents per gram. Since the amino terminal groups of (a) polyamide and (b) melamine cyanurate form a crosslinked structure during extrusion, the amount of amino terminal groups and carboxy terminal groups of (a) polyamide used for extrusion is set to a predetermined amount. is preferred. From the viewpoint of fluidity fluctuation, the amount of amino terminal groups is preferably 5 μmol equivalent/g or more and 100 μmol equivalent/g or less, more preferably 10 μmol equivalent/g or more and 80 μmol equivalent/g or less, and 15 μmol equivalent/g or less. More preferably, it is 60 μmol equivalent/g or less.
In addition, the total amount of amino terminus and carboxyl terminus is preferably 70 μmol equivalent/g or more and 175 μmol equivalent/g or less, and 80 μmol equivalent/g or more and 160 μmol equivalent/g or less, from the viewpoint of increasing the processed resin temperature. more preferably 115 μmol equivalent/g or more and 150 μmol equivalent/g or less.
Summarizing these, the ratio of the amino terminal amount to the total amount of the amino terminal amount and the carboxy terminal amount {amino terminal amount/(amino terminal amount + carboxy terminal amount)} is 0.10 or more and less than 0.60. is preferably 0.15 or more and less than 0.50, and more preferably 0.20 or more and less than 0.40.
In addition, when comparing the amino group terminal amounts of the (a) polyamide in the polyamide resin composition and the (a) polyamide before extrusion processing, the amino terminal groups are consumed and are involved in the cross-linking reaction during extrusion processing. is suggested.

((a) Method for measuring polymer terminal amount of polyamide)
(a) Examples of methods for measuring the polymer terminal amount of polyamide include ¹ H-NMR method and titration method. In the ¹ H-NMR method, it can be obtained by integral values of characteristic signals corresponding to each terminal group of the polyamide in the resin composition. In the titration method, the terminal amount of virgin polyamide before extrusion can be determined. For amino terminal groups, a method of titrating a phenol solution of polyamide resin with 0.1N hydrochloric acid, and for carboxy terminal groups, a method of titrating a benzyl alcohol solution of polyamide resin with 0.1N sodium hydroxide, and the like can be mentioned.

((a) Method for adjusting polymer terminal of polyamide)
(a) The terminal of the polyamide polymer can be adjusted to a predetermined terminal concentration during the polymerization of the polyamide, and is not particularly limited, but the group consisting of dicarboxylic acid, monocarboxylic acid, diamine, and monoamine It is preferable to add one or more more selected terminal modifiers. The time at which the terminal modifier is added to the solvent is not particularly limited as long as the terminal modifier fulfills its original function.

Dicarboxylic acids are, for example, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, Azelaic acid, sebacic acid, suberic acid, dodecanedioic acid, eicodioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid , hexahydroterephthalic acid, hexahydroisophthalic acid, diglycolic acid, and the like. These dicarboxylic acids may be used alone or in combination of two or more.

Any monocarboxylic acid may be used as long as it has reactivity with an amino group that may be present at the terminal of the polyamide, and is not limited to the following. Examples include formic acid, acetic acid, propionic acid, butyric acid, and valeric acid. , caproic acid, caprylic acid, lauric acid, tridecyl acid, myristic acid, palmitic acid, stearic acid, pivalic acid, aliphatic monocarboxylic acids such as isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; benzoic acid, aromatic monocarboxylic acids such as toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; These monocarboxylic acids may be used alone or in combination of two or more.

Diamines are not particularly limited, but for example, linear aliphatic diamines such as hexamethylenediamine and pentamethylenediamine; branched aliphatic diamines such as 2-methylpentanediamine and 2-ethylhexamethylenediamine; -aromatic diamines such as phenylenediamine and m-phenylenediamine; and alicyclic diamines such as cyclohexanediamine, cyclopentanediamine and cyclooctanediamine. These diamines may be used alone or in combination of two or more.

Any monoamine may be used as long as it has reactivity with a carboxyl group that may be present at the end of the polyamide, and is not limited to the following. Examples include methylamine, ethylamine, propylamine, butylamine, hexylamine, Aliphatic monoamines such as octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine and dibutylamine; Alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; Aromatic monoamines such as aniline, toluidine, diphenylamine and naphthylamine is mentioned. These monoamines may be used alone or in combination of two or more.

The content of (a) polyamide in the polyamide resin composition of the present embodiment is preferably 50% by mass or more relative to the total mass of the polyamide resin composition, from the viewpoint of moldability and mechanical properties. It is more preferably 80% by mass or more, and even more preferably 90% by mass or more.

(a) The 98% sulfuric acid relative viscosity ηr of polyamide (preferably polyamide 66) is preferably 2.50 or more and 2.90 or less, and 2.57 or more and 2.57 or more, from the viewpoint of fluidity and mechanical properties. It is more preferably 80 or less.
The 98% sulfuric acid relative viscosity ηr can be measured by the method described in Examples below.

[(b) melamine cyanurate]
As used herein, (b) melamine cyanurate is an equimolar reaction product of melamine and cyanuric acid. (b) Melamine cyanurate is obtained by stirring and mixing an aqueous melamine solution and an aqueous cyanuric acid solution at a temperature of, for example, about 90° C. or higher and 100° C. or lower, and then precipitating and filtering the product obtained by the reaction. . The product obtained is a white solid and is preferably pulverized and used in the form of a fine powder.

(b) melamine cyanurate may contain unreacted melamine or cyanuric acid in an amount of 0.001% by mass or more and 0.30% by mass or less relative to the total mass of (b) melamine cyanurate. Such melamine cyanurate is commercially available, and industrially available products can be used as appropriate.

The median diameter (D ₅₀ ) of (b) melamine cyanurate before mixing with (a) polyamide is not particularly limited, but from the viewpoint of dispersibility of melamine cyanurate, it is preferably 1 μm or more and 20 μm or less. 1.5 μm or more and 15 μm or less is more preferable. When the median diameter of the melamine cyanurate is at least the above lower limit, handling becomes easier, and deterioration of the cohesiveness of the melamine cyanurate can be further suppressed. When the median diameter of the melamine cyanurate is equal to or less than the above upper limit, the balance between dispersibility and handling in the polyamide resin composition is excellent.

Here, the median diameter (D ₅₀ ), as defined in JIS Z8901, in the particle size distribution of particles, the mass of particles larger than a certain particle size accounts for 50% by mass of the mass of all particles It is the particle diameter at time and can be measured by a laser diffraction scattering method. Specifically, according to the laser diffraction scattering method, the particle diameter is plotted on the horizontal axis and the frequency (mass) is plotted on the vertical axis. It can be measured as a particle size.

(b) The content of melamine cyanurate is preferably 2 parts by mass or more and 20 parts by mass or less, more preferably 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the polyamide (a). When the content of melamine cyanurate is at least the above lower limit value, flame retardancy is excellent, and when it is at most the above upper limit value, mechanical strength is excellent. Although any known method can be applied to blend melamine cyanurate into polyamide, a method of kneading and blending with an extruder or the like is industrially preferable.

[(c) at least one compound selected from the group consisting of polyhydric alcohols and ester derivatives thereof]
(c) at least one compound selected from the group consisting of polyhydric alcohols and ester derivatives thereof (hereinafter sometimes simply referred to as "(c) compound") is at least one polyalkylene polyhydric alcohol and its It preferably contains a fatty acid ester.
Examples of polyalkylene polyhydric alcohols include glycols such as polyethylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, trimethylene glycol and propylene glycol, 1,4 butanediol, 1,5 pentadiol, 1,6 hexanediol, and the like. diols, glycerin, pentaerythritol, and the like.
Examples of fatty acid esters of polyalkylene polyhydric alcohols include polyalkylene polyhydric alcohols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and serotin. Acids, esters with aliphatic carboxylic acids such as montanic acid, melissic acid, oleic acid and erucic acid, and derivatives thereof, are industrially readily available.
Among them, from the viewpoint of dispersibility of (b) melamine cyanurate, polyethylene glycol or a fatty acid ester of polyethylene glycol is preferable, and a higher fatty acid (12 or more carbon atoms) ester of polyethylene glycol or a derivative thereof is more preferable.
These (c) compounds may be used alone or in combination of two or more.

(c) The content of the compound is preferably 0.1 parts by mass or more and 1.0 parts by mass or less, and 0.1 parts by mass or more and 0.8 parts by mass or less with respect to 100 parts by mass of the (a) polyamide is more preferable. When the content of the compound (c) is at least the above lower limit value, the tensile elongation is excellent, and when it is at most the above upper limit value, the flame retardancy is excellent.

[(d) higher fatty acid metal salt]
(d) Higher fatty acid metal salts are higher fatty acids having 9 or more carbon atoms such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, cerotic acid, montanic acid, melicic acid, oleic acid, and erucic acid. Sodium salts, lithium salts, calcium salts, magnesium salts, zinc salts, aluminum salts and the like of aliphatic carboxylic acids are included. Among these higher fatty acid metal salts, stearic acid metal salts, specifically calcium stearate, magnesium stearate, and zinc stearate, are preferred from the viewpoint of suppressing deterioration in the flame retardancy of the finally obtained polyamide resin composition. , or aluminum stearate are particularly preferred. Calcium stearate or aluminum stearate are most preferred.
These (d) higher fatty acid metal salts may be used alone or in combination of two or more.

(d) The content of the higher fatty acid metal salt is preferably 0.01 parts by mass or more and 5.00 parts by mass or less with respect to 100 parts by mass of the polyamide (a), and 0.05 parts by mass or more and 2.0 parts by mass. It is more preferably not more than parts by mass. (d) When the content of the higher fatty acid metal salt is equal to or more than the above lower limit value, it is excellent in plasticization during molding. On the other hand, when it is equal to or less than the above upper limit, gas generation during molding is further suppressed, and flame retardancy is improved.

[Other ingredients]
Various elastomers commonly used in the polyamide resin composition of the present embodiment within a range that does not impair the effects of the polyamide resin composition of the present embodiment; fillers; flame retardants; titanium white and carbon Pigments and colorants such as black; Hypophosphite metal salts such as sodium hypophosphite; Heat stabilizers typified by hindered phenols, hindered amines, phosphoric acid trialkyl esters and phosphites; Higher fatty acid metal salts, higher Lubricants such as fatty acid amides and higher fatty acid esters; various plasticizers; and various additives such as antistatic agents can be further added.

Examples of fillers include inorganic fibers such as glass fibers and carbon fibers; inorganic fillers such as mica, talc, clay minerals, alumina, silica, and apatite.

Examples of flame retardants include aluminum hydroxide, magnesium hydroxide, zinc borate, zinc stannate, zinc hydroxystannate, ammonium polyphosphate, succinoguanamine, melamine polyphosphate, melamine sulfate, melamine phthalate, and aluminum phosphate. etc.

<Method for producing polyamide resin composition>
The method for producing the polyamide resin composition is not particularly limited, and (a) polyamide, (b) melamine cyanurate, (c) compound, and (d) higher fatty acid metal salt may be melt-kneaded at once. However, from the viewpoint of dispersibility of (b) melamine cyanurate, (b) melamine cyanurate may be melt-kneaded after all the remaining components are melt-kneaded.

(a) The shape of the polyamide is not particularly limited, but it is preferably in the form of pellets. In this case, from the viewpoint of facility simplification, (a) the surface of polyamide pellets was spread with (c) compound, and then (b) melamine cyanurate and (d) higher fatty acid metal salt were spread. It may be melt-kneaded after being blended.

In the method for producing a polyamide resin composition, the method of melt kneading is not particularly limited, but when mixing (a) polyamide, (b) melamine cyanurate, (c) compound, and (d) higher fatty acid metal salt, A method of supplying the material to an extruder using at least one raw material supply device and melt-kneading the material is preferred. For supplying each component to the extruder, separate raw material supply apparatuses may be used, or one raw material supply apparatus may be used.

Although the extruder is not particularly limited, a twin-screw extruder is preferred. Specific examples of the twin-screw extruder include the ZSK series manufactured by COPERION, the TEM series manufactured by Toshiba Machine Co., Ltd., and the TEX series manufactured by The Japan Steel Works, Ltd. The L/D (effective screw length/screw outer diameter) of the twin-screw extruder is preferably 20 or more and 60 or less, more preferably 30 or more and 50 or less. In order to set the molecular weight of (a) polyamide in the resin composition to a specific range, the resin temperature when discharged from the extruder tip nozzle is 15 ° C. or more and 25 ° C. or less higher than the melting point of the main component polyamide. Extrusion is preferably carried out, and can be controlled by the number of screw revolutions of the extruder and the number of kneading blocks (referring to a block in which a plurality of screw elements with high kneading effect called kneading discs are connected).

The method of supplying raw materials to the twin-screw extruder is not particularly limited. A raw material feeder is not particularly limited, and a single-screw feeder, twin-screw feeder, table feeder, rotary feeder, liquid feed pump, or the like can be used. Among them, a loss-in-weight type screw feeder is preferable because there are few fluctuation errors in raw material supply. When a plurality of types of raw materials are charged into one raw material supply device, at least two of the raw materials to be charged may be mixed with a mixer, cone blender, or the like before charging.

<Characteristics of Polyamide Resin Composition>
[Melt Mass Flow Rate (MFR)]
The melt mass flow rate (MFR) of the polyamide resin composition of the present embodiment is 270 ° C. according to JIS K7210-1: 2014, the load is 2.16 kg, the nominal die length is 8.000 mm, the nominal inner diameter is 2.095 mm, These are values measured under the condition of a preheating time of 5 minutes.
From the viewpoint of fluidity, the MFR value of the first time is preferably 40 g/10 minutes or more and 65 g/10 minutes or less, more preferably 45 g/10 minutes or more and 60 g/10 minutes or less.

In addition, the second MFR is measured by pelletizing the pellets obtained by collecting the strands (die ejection) ejected from the die during the first MFR measurement. It is a value measured according to JIS K7210-1:2014 under the conditions of 270° C., load of 2.16 kg, standard die nominal length of 8.000 mm, nominal inner diameter of 2.095 mm, and preheating time of 5 minutes.
From the viewpoint of flow variability and mechanical properties, the second MFR value is preferably 55 g/10 min or more and 75 g/10 min or less, more preferably 60 g/10 min or more and 70 g/10 min or less.

[Molecular Weight of Polyamide Resin Composition]
In the polyamide resin composition of the present embodiment, flame retardancy and fluidity can be further improved by setting specific amounts of components having a molecular weight of 15,000 or less and components having a molecular weight of 100,000 or more. Specifically, from the viewpoint of good fluidity, it is preferable that the component having a molecular weight of 15,000 or less is more than 30.0% by mass and 45.0% by mass or less with respect to the total mass of the polyamide resin composition. More preferably, it is 0.0% by mass or more and 40.0% by mass or less.
In addition, from the viewpoint of fluidity fluctuation, it is preferable that the component having a molecular weight of 100,000 or more is 1.0% by mass or more and less than 4.0% by mass with respect to the total mass of the polyamide resin composition, and 2.0% by mass. It is more preferable that it is not less than 3.5% by mass and not more than 3.5% by mass.

The molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) is preferably 1.70 or more and 2.00 or less, more preferably 1.75 or more and 2.00 or less, from the viewpoint of mechanical properties and molding stability. 00 or less, and more preferably 1.80 or more and 2.00 or less.
In order to set the molecular weight of the polyamide resin composition to a specific amount, for example, it is preferable to control the production conditions during polyamide polymerization, the barrel temperature of the extruder, and the screw rotation speed and screw configuration during melt kneading.

The molecular weight of the polyamide resin composition is obtained by measurement using gel permeation chromatography (GPC).

<Molded body>
The molded article of the present embodiment is obtained by molding the polyamide resin composition.

Since the polyamide resin composition, which is a molding material, has excellent flame retardancy and mechanical strength, the molded article of the present embodiment can be It is suitable as a part or the like.

The molding method is not particularly limited, but examples thereof include injection molding, blow molding, and sheet molding.

In the molded body of this embodiment, a notched molded body obtained by processing the multi-purpose test piece A type obtained by molding the polyamide resin composition in accordance with ISO 3167 in accordance with ISO 2818 is used to conform to ISO 179-1. It is preferable that the Charpy impact strength of the molded body measured by the above method is 2.4 kJ/m ² or more. On the other hand, although the upper limit of the Charpy impact strength is not particularly limited, it can be, for example, 10 kJ/m ² . When the Charpy impact strength of the molded body is within the above range, it is more excellent in mechanical strength.

EXAMPLES Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited only to these examples and comparative examples.
First, raw materials, measurement methods, and evaluation methods used in Examples and Comparative Examples are shown below.

<raw materials>
[(a) Polyamide]
((a-1) Polyamide 66)
15 kg of an aqueous solution containing 50% by mass of a monomer mixture containing equimolar amounts of hexamethylenediamine and adipic acid was prepared, and 0.5% by molar excess of adipic acid was dissolved in the total equimolar salt components. Next, the above monomer aqueous solution was introduced into a 40-L capacity autoclave having a stirring device and an extraction nozzle at the bottom, and the monomer aqueous solution was sufficiently stirred at 50°C. After the inside of the autoclave was sufficiently replaced with nitrogen, the temperature inside the autoclave was raised from 50° C. to about 270° C. while stirring the aqueous monomer solution, and polymerization was carried out. At that time, the pressure inside the autoclave was approximately 1.8 MPa in terms of gauge pressure, and water was discharged out of the system at any time so that the pressure did not exceed 1.8 MPa. Also, the ηr of the polyamide 66 resin was adjusted to about 2.61. After completion of the polymerization in the autoclave, the polyamide 66 resin was discharged from the lower nozzle in the form of strands, and subjected to water cooling and cutting to obtain polyamide 66 in the form of pellets (hereinafter sometimes simply referred to as "a-1"). (VR: 36, ηr: 2.61, Mw/Mn: 1.79, amino terminal group amount: 40 μmol equivalent/g, carboxy terminal group amount: 100 μmol equivalent/g, total amount of amino terminal group amount and carboxy terminal group amount : 140 μmol equivalent/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.29).

((a-2) Polyamide 66)
Polymerize in the same manner as the above (a-1) Polyamide 66, except that 0.2 mol% excess adipic acid is dissolved with respect to all equimolar salt components, and ηr is adjusted to about 2.71. to obtain pellet-like polyamide 66 (VR: 41, ηr: 2.71, Mw/Mn: 1.97, amino terminal group amount: 45 μmol equivalent/g, carboxy terminal group amount: 80 μmol equivalent/g, amino Total amount of terminal groups and carboxy terminal groups: 125 μmol equivalent/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.36).

((a-3) Polyamide 66)
Polymerization was carried out in the same manner as for the polyamide 66 (a-1), except that excess adipic acid was not added, and ηr was adjusted to about 2.81 to obtain polyamide 66 in the form of pellets (VR : 46, ηr: 2.81, Mw/Mn: 2.02, amino terminal group amount: 50 μmol equivalent/g, carboxyl terminal group amount: 60 μmol equivalent/g, total amount of amino terminal group amount and carboxy terminal group amount: 110 μmol equivalent weight/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.45).

((a-4) Polyamide 66)
Polymerization was carried out in the same manner as for the above (a-1) polyamide 66, except that excess adipic acid was not added, and ηr was adjusted to about 2.92 to obtain pellet-like polyamide 66 (VR : 36, ηr: 2.92, Mw/Mn: 2.10, amino terminal group amount: 45 μmol equivalent/g, carboxy terminal group amount: 55 μmol equivalent/g, total amount of amino terminal group amount and carboxy terminal group amount: 100 μmol equivalent weight/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.45).

((a-5) Polyamide 66)
Polymerize in the same manner as the above (a-1) polyamide 66, except that 1.5 mol% excess adipic acid is dissolved with respect to all equimolar salt components, and ηr is adjusted to about 2.47. to obtain pellet-like polyamide 66 (VR: 29, ηr: 2.47, Mw/Mn: 1.98, amino terminal group amount: 45 μmol equivalent/g, carboxy terminal group amount: 120 μmol equivalent/g, amino Total amount of terminal groups and carboxy terminal groups: 165 μmol equivalent/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.27).

((a-6) Polyamide 6)
Polyamide 6: manufactured by Ube Industries, trade name "SF1013A"

((a-7) Polyamide 66)
Polymerization was carried out in the same manner as in (a-1) polyamide 66, except that excess adipic acid was not added and 0.5 mol % excess hexamethylenediamine was dissolved with respect to all equimolar salt components, and ηr was adjusted to about 2.61 to obtain pellet-like polyamide 66 (VR: 36, ηr: 2.61, Mw/Mn: 2.02, amount of amino end groups: 100 μmol equivalent/g, carboxy Terminal group amount: 45 μmol equivalent/g, total amount of amino terminal group and carboxy terminal group: 145 μmol equivalent/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.69).

((a-8) Polyamide 66)
Except that excess adipic acid was not added and 0.2 mol % excess hexamethylenediamine was dissolved with respect to all equimolar salt components, polymerization was carried out in the same manner as the above (a-1) polyamide 66, and ηr was adjusted to about 2.71 to obtain pellet-like polyamide 66 (VR: 41, ηr: 2.71, Mw/Mn: 2.03, amount of amino end groups: 75 μmol equivalent/g, carboxy Amount of terminal groups: 40 μmol equivalent/g Total amount of amino terminal groups and carboxy terminal groups: 115 μmol equivalent/g, amino terminal group amount/(amino terminal group amount + carboxy terminal group amount): 0.65).

[(b) melamine cyanurate]
(b-1): melamine cyanurate, median diameter (D50): 10 μm, manufactured by Nissan Chemical Industries, Ltd. “MC-4500”

[(c) at least one compound selected from the group consisting of polyhydric alcohols and ester derivatives thereof]
(c-1): Polyoxyethylene monolaurate, "Emanone (registered trademark) 1112 (PEM)" manufactured by Kao Corporation
(c-2): Polyethylene glycol, "PEG400 (PEG)" manufactured by Sanyo Kasei Co., Ltd.

[(d) higher fatty acid metal salt]
(d-1): Calcium stearate, manufactured by NOF Corporation "Calcium stearate"

<Method for measuring physical properties>
[Physical properties 1]
(relative viscosity of formic acid)
It was calculated by comparing the viscosity of a solution (soluble matter) prepared by adding raw materials polyamide and polyamide resin composition to formic acid and the viscosity of formic acid itself. Specifically, it was carried out according to ASTM-D789. More specifically, using a solution obtained by dissolving 8.4% by mass of the raw polyamide and the polyamide resin composition in a 90% by mass formic acid (10% by mass of water) solution, the viscosity at 25° C. was measured. By subtracting the viscosity of the formic acid solution alone from the measured viscosity, the formic acid relative viscosity (VR) of the starting polyamide and the polyamide resin composition was obtained.

[Physical properties 2]
(Sulfuric acid relative viscosity)
The 98% sulfuric acid relative viscosity ηr of the raw material polyamide and the polyamide resin composition was measured according to JIS K6920.

[Physical properties 3]
(Median diameter ( _D50 ))
The median diameter of the raw material (b) melamine cyanurate was measured using a laser diffraction particle size distribution analyzer (trade name “SALD-7000” manufactured by Shimadzu Corporation). A measurement sample was prepared by dispersing the sample in pure water, and the measurement was performed using a flow cell. Plot the particle diameter on the horizontal axis and the frequency (mass) on the vertical axis, and the median diameter (D ₅₀ ).

[Physical properties 4]
Quantification of components with a molecular weight of 15,000 or less and components with a molecular weight of 100,000 or more, and molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) were measured by GPC under the following measurement conditions.

(Measurement condition)
Apparatus: "HLC-8320GPC" manufactured by Tosoh Corporation
Detector: differential refractometer (RI)
Solvent: hexafluoroisopropanol (HFIP) in which 0.1 mol % sodium trifluoroacetate is dissolved
Column: manufactured by Tosoh Corporation, two "TSKgel-GMHHR-M", and "G1000HHR"
Based on the elution curve obtained by using one tube connected in series, it was calculated by polymethyl methacrylate (PMMA) conversion.

[Physical properties 5]
(Peak intensity ratio by ¹³ C-NMR)
The peak intensity ratio by ¹³ C-NMR was performed by the following procedure. First, about 300 mg of the polyamide resin composition was dissolved in 10 mL of HFIP, and the insoluble matter was filtered with a 0.45 μm chromatodisk, dried, and the solvent was removed. Furthermore, 200 mg of the dried polyamide resin composition was dissolved in HFIP-d ₂ /CDCl ₃ =4/1 in volume ratio, using 0.8 mL of a solvent, and transferred to a glass sample tube. Using Bruker Biospin Avance 600 (trade name), observation frequency 150.91 MHz, 25° C., lock solvent HFIP-d ₂ , pulse program zgig 30, and 24000 integration times were used. It was calculated from the spectrum obtained when HFIP (71.28 ppm) was used as the chemical shift standard. In the obtained spectrum, the ratio M1 / M2 of the total area M1 of the peaks between the chemical shifts of 42.80 ppm and 43.05 ppm to the total area M2 of the peaks between the chemical shifts of 43.10 ppm and 43.35 ppm and less is calculated. bottom.

[Physical properties 6]
(Quantification of Terminal Amount of Raw Material (a) Polyamide)
It was measured by neutralization titration as follows. 3.0 g of raw material (a) polyamide before extrusion processing is dissolved in 100 mL of a 90% by mass phenol aqueous solution, and the resulting solution is titrated with 0.025 N hydrochloric acid to determine the amino terminal amount (μmol equivalent / g). asked. The endpoint was determined from the pH meter reading.
Regarding the amount of carboxyl terminals ([COOH]), the amount of carboxyl terminals bonded to the polymer terminal of the polyamide was measured by neutralization titration as follows. 4.0 g of raw material (a) polyamide was dissolved in 50 mL of benzyl alcohol, and the resulting solution was titrated with 0.1N NaOH to determine the amount of carboxy terminus (μmol equivalent/g). The endpoint was determined from the color change of the phenolphthalein indicator. [NH ₂ ]+[COOH] and [NH ₂ ]/([NH2]+[COOH]) are calculated from the amino terminal amount ([NH ₂ ]) and the carboxy terminal amount ([COOH]) measured above. bottom.

[Physical properties 7]
(Quantitative determination of end groups of (a) polyamide in polyamide resin composition by ¹ H-NMR)
When melamine cyanurate is contained in the resin composition, the determination of the terminal groups ^of (a) the polyamide in the polyamide resin composition cannot be measured by titration. procedure. First, about 60 mg of the polyamide resin composition was dissolved in 10 mL of HFIP, filtered with a 0.45 μm chromatodisk to remove insoluble matter, and dried to remove the solvent. Next, 60 mg of the polyamide resin composition was dissolved in 1 mL of deuteride sulfate, allowed to stand overnight, and then the resulting solution was transferred to a glass sample tube. Using JEOL RESONANCE's product name "ECS 400", measurement was performed at an observation frequency of 399.78 MHz, 25° C., lock solvent HFIP-d ₂ , pulse program singlepulse, and 256 integration times. It was calculated from the spectrum obtained when sulfuric acid (10.71 ppm) was used as the chemical shift standard. The carboxy terminus amount was determined from the ratio of the peak area of 2.40 ppm originating from the adjacent methylene hydrogen of adipic acid in the main chain and the peak area of 2.65 ppm originating from the adjacent methylene hydrogen of terminal adipic acid. The amino terminal amount was determined from the ratio of the peak area of 3.20 ppm derived from the adjacent methylene hydrogen of hexamethylenediamine in the main chain and the peak area of 2.85 ppm derived from the adjacent methylene hydrogen of hexamethylenediamine at the end. [NH ₂ ]+[COOH] and [NH ₂ ]/([NH ₂ ]+[COOH]) are calculated according to the amino-terminal content ([NH ₂ ]) and carboxy-terminal content ([COOH]) measured above. Calculated.

<Evaluation method>
[Evaluation 1]
(Molding stability (spiral flow length; SFD))
Using an injection molding machine (SE50D manufactured by Sumitomo Heavy Industries, Ltd.), the pellets of each polyamide resin composition are set to a cylinder temperature of 270 ° C. and a mold temperature of 80 ° C., injection for 10 seconds, cooling for 10 seconds, and injection. Injection molding was performed at a speed of 200 mm/s and an injection pressure of 80 MPa using a spiral flow mold having a width of 10 mm and a thickness of 1 mm, and the flow length (spiral flow length; SFD) was measured. The measured flow length (spiral flow length; SFD) was evaluated based on the following evaluation criteria.
Based on the following evaluation criteria, those evaluated as A or B were judged to have good fluidity, and those evaluated as C were judged to be poor.

(Evaluation criteria)
A: flow length of 17.0 cm or more B: flow length of 15.5 cm or more and less than 17.0 cm C: flow length of less than 15.5 cm

[Evaluation 2]
(Melt mass flow rate (MFR))
The first melt mass flow rate (MFR) is 270 ° C according to JIS K7210-1: 2014, the load is 2.16 kg, the nominal die length is 8.000 mm, the nominal inner diameter is 2.095 mm, and the preheating time is 5 minutes. measured below. In addition, the second MFR was measured again at 270° C. under a load of 2.16 kg (under the same conditions as the first time) after collecting the strands discharged during the first MFR measurement, pelletizing them.
The smaller the rate of change between the results of the first and second MFR (2nd/1st), the better.

[Evaluation 3]
(Flame retardance)
Using an injection molding machine (PS40E manufactured by Nissei Plastics Co., Ltd.), the pellets of each polyamide resin composition are set to a molten resin temperature of 270 ° C. and a mold temperature of 80 ° C., and a test piece for UL-94 vertical burning test measurement. was injection molded (thickness: 0.40 mm or 0.80 mm). Using five test pieces with different thicknesses molded in this way, flame retardancy was evaluated based on the UL-94 vertical burning test, and flame retardancy V-0, V-1, V-2, HB was carried out.
In both test pieces with a thickness of 0.40 mm and 0.80 mm, those with a flame retardancy of V-0 are good products, and those with a thickness of 0.40 mm or 0.80 mm are evaluated worse than flame retardancy V-1. judged to be defective.

[Evaluation 4]
(Charpy impact strength)
Using an injection molding machine [PS-40E: manufactured by Nissei Plastics Co., Ltd.], pellets of each polyamide resin composition are injected + holding pressure time 25 seconds, cooling time 15 seconds, mold temperature 80 ° C., molten resin temperature 270. °C and molded specimens of ISO 3167, Multi-Purpose Specimen Type A were molded. The molded specimens of Multi-Purpose Specimen Type A were then processed into notched specimens according to ISO2818. The Charpy impact strength of the obtained notched test piece was measured according to JIS K7111 (ISO179).
The higher the value, the better the mechanical strength was evaluated.

[Evaluation 5]
(tensile strength)
Using an injection molding machine [PS-40E: manufactured by Nissei Plastics Co., Ltd.], pellets of each polyamide resin composition are injected + holding pressure time 25 seconds, cooling time 15 seconds, mold temperature 80 ° C., molten resin temperature 270. °C and molded specimens of ISO 3167, Multi-Purpose Specimen Type A were molded. Using the obtained molded piece, a tensile test was performed at a tensile speed of 50 mm/min according to ISO527, and the tensile strength (MPa) was calculated.
The higher the value, the better the mechanical strength was evaluated.

<Production of Polyamide Resin Composition>
[Example 1]
(Production of polyamide resin composition PA-a1)
(a-1) Polyamide 66, (b-1) melamine cyanurate, (c-1) PEM, and (d-1) calcium stearate are mixed, and using a loss-in-weight feeder, a twin-screw extruder (Toshiba It was supplied to the first supply port of TEM-58SS manufactured by Kikai Co., Ltd., number of barrels: 12). Extrusion was performed at a barrel temperature of 270° C., a discharge rate of 400 kg/hr, and a screw rotation speed of 330 rpm. The extruder screw was equipped with two kneading blocks. The first kneading block was located in extruder barrel #4 and the second kneading block was located in extruder barrel #8. The term "kneading block" as used herein refers to a block in which a plurality of screw elements with a high kneading effect, called kneading disks, are continuous.
Next, the polymer was extruded from the tip nozzle of the extruder in a strand shape, and after measuring the resin temperature, it was cooled with water and cut to obtain pellets of the polyamide resin composition PA-a1.

[Example 2]
(Production of polyamide resin composition PA-a2)
Pellets of the polyamide resin composition PA-a2 were produced in the same manner as in Example 1, except that the barrel temperature was 280°C.

[Examples 3 to 9]
(Production of Polyamide Resin Compositions PA-a3 to PA-a9)
Pellets of the polyamide resin compositions PA-a3 to PA-a9 were produced in the same manner as in Example 1 except that the composition of each component was as shown in Table 1.

[Comparative Example 1]
(Production of polyamide resin composition PA-b1)
Pellets of the polyamide resin composition PA-b1 were produced in the same manner as in Example 1, except that the barrel temperature was 290°C.

[Comparative Example 2]
(Production of polyamide resin composition PA-b2)
Pellets of the polyamide resin composition PA-b2 were produced in the same manner as in Example 1, except that the screw rotation speed of the extruder was changed to 500 rpm.

[Comparative Examples 3 and 6]
(Production of polyamide resin compositions PA-b3 and PA-b6)
Pellets of polyamide resin compositions PA-b3 and PA-b6 were produced in the same manner as in Example 1 except that the barrel temperature was 280° C. and the composition of each component was as shown in Table 4.

[Comparative Examples 4, 5 and 7]
(Production of polyamide resin compositions PA-b4, PA-b5 and PA-b7)
Pellets of polyamide resin compositions PA-b4, PA-b5 and PA-b7 were produced in the same manner as in Example 1 except that the composition of each component was as shown in Table 4.

For each polyamide resin composition obtained, the physical properties of the polyamide resin composition were measured using the methods described above, and various evaluations were performed.
The results are shown in Tables 2 and 5 (physical properties) and Tables 3 and 6 (evaluation).

Polyamide resin compositions PA-a1 to PA containing (a) a polyamide and (b) melamine cyanurate, and having a ratio M1/M2 within a predetermined range in a spectrum obtained by ¹³ C-NMR analysis. -a9 (Examples 1 to 9) was excellent in fluidity, flame retardancy and mechanical strength when molded. Moreover, even after multiple heat cycles, the change in MFR was small, and fluctuations in fluidity were suppressed.

On the other hand, in the polyamide resin compositions PA-b1 to PA-b7 (Comparative Examples 1 to 7), fluidity, suppression of fluctuations in fluidity in multiple high-temperature processing at about 270 ° C., and difficulty when forming a molded product Good combustibility and mechanical strength were not obtained.

According to the polyamide resin composition of the present embodiment, it has excellent fluidity, and fluctuations in fluidity are suppressed even in multiple high-temperature processing at about 270 ° C., and flame retardancy and mechanical properties when formed into a molded product. A polyamide resin composition having excellent strength can be provided. The molded article of the present embodiment is formed by molding the polyamide resin composition, and is excellent in flame retardancy and mechanical strength. It is preferably used as.

Claims (15)

A polyamide resin composition comprising (a) a polyamide and (b) melamine cyanurate,
In the spectrum obtained when the polyamide resin composition is analyzed by ¹³ C-NMR, the chemical shift 42.80 ppm or more and 43.05 ppm or less for the total area M2 of the peaks between the chemical shift 43.10 ppm and 43.35 ppm or less A polyamide resin composition having a ratio M1/M2 of the total area M1 of peaks of 0.65 or less. The ratio of components having a molecular weight of 15,000 or less measured by gel permeation chromatography of the polyamide resin composition is more than 30.0% by mass and 45.0% by mass or less with respect to the total mass of the polyamide resin composition The polyamide resin composition according to claim 1, which is The ratio of components having a molecular weight of 100,000 or more as measured by gel permeation chromatography of the polyamide resin composition is 1.0% by mass or more and less than 4.0% by mass with respect to the total mass of the polyamide resin composition. The polyamide resin composition according to claim 1 or 2. The polyamide resin according to claim 1, wherein the polyamide resin composition has a melt mass flow rate of 40 g/10 minutes or more and 65 g/10 minutes or less measured under conditions of 270°C, 2.16 kg, and a preheating time of 5 minutes. Composition. The melt mass flow of the pellets of the polyamide resin composition obtained by pelletizing the die discharge after measuring the melt mass flow rate of the polyamide resin composition, measured under the conditions of 270 ° C., 2.16 kg, and a preheating time of 5 minutes. 2. The polyamide resin composition according to claim 1, which has a rate of 55 g/10 minutes or more and 75 g/10 minutes or less. 2. The polyamide resin composition according to claim 1, wherein the polyamide resin composition has a molecular weight distribution Mw/Mn of 1.70 to 2.00. 2. The polyamide resin composition according to claim 1, further comprising (c) at least one compound selected from the group consisting of polyhydric alcohols and ester derivatives thereof. The content of at least one compound selected from the group consisting of (c) polyhydric alcohols and ester derivatives thereof is 0.1 parts by mass or more and 1.0 parts by mass with respect to 100 parts by mass of the (a) polyamide The polyamide resin composition according to claim 7, wherein: 2. The polyamide resin composition according to claim 1, further comprising (d) a higher fatty acid metal salt. 10. The polyamide resin composition according to claim 9, wherein the content of the (d) higher fatty acid metal salt is 0.05 parts by mass or more and 2.00 parts by mass or less with respect to 100 parts by mass of the (a) polyamide. . The polyamide resin composition according to claim 1, wherein the content of the (b) melamine cyanurate is 2 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polyamide (a). The polyamide resin composition according to claim 1, comprising 80% by mass or more of polyamide 66 with respect to the total mass of the (a) polyamide. 13. The polyamide resin composition according to claim 12, wherein said polyamide 66 has a sulfuric acid relative viscosity ηr of 2.50 or more and 2.90 or less. A molded article obtained by molding the polyamide resin composition according to claim 1 . Using a notched molded body obtained by molding the polyamide resin composition according to ISO 3167 and processing the multi-purpose test piece A type according to ISO 2818, the molded body measured according to ISO 179-1. 15. The molded article according to claim 14, which has a Charpy impact strength of 2.4 kJ/m ² or more.