JP2011057930A - Impact-resistant polyamide resin composition - Google Patents

Abstract

Provided is a polyamide resin composition having excellent impact resistance and excellent performance such as low water absorption, heat resistance, chemical resistance, mechanical properties and dimensional stability.
A polyamide (A) comprising a diamine unit containing 70 mol% or more of paraxylylenediamine units and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit having 6 to 18 carbon atoms and a modified polyolefin ( An impact resistant polyamide resin composition comprising 0.5 to 50 parts by mass of a modified polyolefin (B) with respect to 100 parts by mass of the polyamide (A), the polyamide resin composition comprising B).
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Description

The present invention relates to a polyamide resin composition comprising a specific polyamide resin composition and a modified olefin, a polyamide resin composition obtained by further adding a filler to the polyamide resin composition, and a molded article comprising these polyamide resin compositions. About. More specifically, the present invention relates to a polyamide composition having excellent impact resistance and various properties such as low water absorption, heat resistance, chemical resistance, mechanical properties, and dimensional stability. The polyamide resin composition of the present invention is useful as a material for industrial, industrial, and household products such as automobile parts, electrical and electronic parts, and machine parts, and particularly for various parts used under high heat conditions such as automobile engine room parts. It can be preferably used.

Aliphatic polyamides typified by nylon 6 and nylon 66 have excellent properties such as heat resistance, chemical resistance, rigidity, wear resistance, and moldability, and have been used in many applications as engineering plastics. It was. However, it cannot always be said that the dry strength immediately after molding or the impact strength at low temperature is sufficient. For such problems, alloying with polyolefins has been studied and used in practice. On the other hand, it has been pointed out that there are problems such as heat resistance and low dimensional stability due to water absorption in applications such as automobile parts exposed to high temperatures. In particular, in recent years, there has been a tendency for heat resistance to increase in applications for electrical and electronic parts that use surface mounting technology and electrical parts in engine rooms, and it has become difficult to use conventional polyamides. Therefore, it has been desired to develop a polyamide having excellent heat resistance, dimensional stability, and mechanical properties.

In response to these requirements, semi-aromatic polyamides called 6T-based polyamides based on polyamides composed of 1,6-hexanediamine and terephthalic acid, which have a higher melting point than conventional polyamides, have begun to be used as new engineering plastics. It was. However, 6T-based polyamide has a problem that it is inferior in impact strength as compared with a conventional polyamide. On the other hand, a method has been proposed in which impact resistance is improved by alloying a semi-aromatic polyamide such as 6T polyamide with a rubber component (see, for example, Patent Documents 1 and 2). However, the polyamide composed of 1,6-hexanediamine and terephthalic acid has a melting point of around 370 ° C., and it is necessary to carry out melt molding at a temperature higher than the decomposition temperature of the polymer. Therefore, in practice, it is put to practical use with a composition whose melting point has been lowered to about 320 ° C., which is a practical temperature range for polyamide, by copolymerizing about 30 to 40 mol% of adipic acid, isophthalic acid, ε-caprolactam, etc. Has been. Such copolymerization of the third to fourth components is effective for lowering the melting point, but on the other hand, it leads to a decrease in crystallization speed and ultimate crystallinity. Not only the physical properties such as chemical properties and dimensional stability are lowered, but also there is a concern that productivity is lowered due to the extension of the molding cycle. In addition, since the viscosity is likely to decrease during melt residence, there is a difficulty in moldability.

JP 60-144362 A JP-A-4-270761

The object of the present invention is to provide a polyamide resin composition that solves the above-mentioned problems and is excellent in impact resistance and excellent in various properties such as low water absorption, heat resistance, chemical resistance, mechanical properties, and dimensional stability. It is in.

As a result of intensive studies, the present inventors have found that a polyamide composed of a diamine component mainly composed of paraxylylenediamine and a dicarboxylic acid component mainly composed of a linear aliphatic dicarboxylic acid having 6 to 18 carbon atoms, and a modification It has been found that a resin composition comprising polyolefin is excellent in impact resistance and various properties such as low water absorption, heat resistance, chemical resistance, mechanical properties, and dimensional stability.

That is, the present invention relates to a polyamide (A) and a modified polyolefin comprising a diamine unit containing 70 mol% or more of paraxylylenediamine units and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit having 6 to 18 carbon atoms. It is a polyamide resin composition containing (B), and relates to an impact-resistant polyamide resin composition containing 0.5 to 50 parts by mass of modified polyolefin (B) with respect to 100 parts by mass of polyamide (A). The present invention also relates to a molded article comprising the polyamide resin composition.

The polyamide resin composition of the present invention is a compact and thin molded product that requires high crystallization speed, ultimate crystallinity and low water absorption, automotive headlight reflectors that require heat resistance and rigidity, engine room It can be suitably used for various parts used under high heat conditions such as parts. Moreover, it can be molded into a film, sheet, or tube, and can be suitably used for industrial, industrial and household products.

The polyamide resin composition of the present invention contains a polyamide (A) composed of a diamine unit and a dicarboxylic acid unit, which will be described later, and a modified polyolefin (B). Here, the diamine unit refers to a structural unit derived from the raw material diamine component, and the dicarboxylic acid unit refers to a structural unit derived from the raw material dicarboxylic acid component.

The polyamide (A) is a polyamide comprising a diamine unit containing 70 mol% or more of paraxylylenediamine units and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit having 6 to 18 carbon atoms. The paraxylylenediamine unit in the diamine unit is preferably 80 mol% or more, more preferably 90 mol% or more, and most preferably 100 mol%. 80 mol% or more is preferable, as for a C6-C18 linear aliphatic dicarboxylic acid unit in a dicarboxylic acid unit, 90 mol% or more is more preferable, and 100 mol% is the most preferable.

The polyamide (A) is obtained by polycondensing a diamine component containing 70 mol% or more of paraxylylenediamine and a dicarboxylic acid component containing 70 mol% or more of a linear aliphatic dicarboxylic acid having 6 to 18 carbon atoms.

The starting diamine component used for the polyamide (A) contains 70 mol% or more of paraxylylenediamine, more preferably 80 mol% or more, particularly preferably 90 mol% or more, and 100 mol%. Most preferred. By making paraxylylenediamine in the diamine component 70 mol% or more, the resulting polyamide resin composition has a high melting point and high crystallinity, and various polyamide resin compositions having excellent heat resistance, chemical resistance, etc. It can use suitably for a use. If the paraxylylenediamine concentration in the diamine component of the raw material is less than 70 mol%, the heat resistance and chemical resistance are lowered, which is not preferable.

As raw material diamine components other than paraxylylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 2-methyl -1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 5 -Aliphatic diamines such as methyl-1,9-nonanediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, etc. Aromatic aliphatic diamines such as diamine and metaxylylenediamine, or a mixture of these There does not can be exemplified as being limited thereto.

The raw material dicarboxylic acid component used for the polyamide (A) contains 70 mol% or more of a linear aliphatic dicarboxylic acid having 6 to 18 carbon atoms, more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Preferably, 100 mol% is most preferable. Polyamide obtained by adjusting the straight chain aliphatic dicarboxylic acid having 6 to 18 carbon atoms to 70 mol% or more exhibits fluidity at the time of melt processing, high crystallinity, low water absorption, heat resistance, chemical resistance, molding It can be suitably used for various applications as a polyamide having excellent processability and dimensional stability. When the concentration of the straight-chain aliphatic dicarboxylic acid having 6 to 18 carbon atoms in the raw material dicarboxylic acid component is less than 70 mol%, the heat resistance, chemical resistance and molding processability are deteriorated.

Examples of the linear aliphatic dicarboxylic acid having 6 to 18 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, Examples include hexadecanedioic acid. Among them, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid are preferable, and sebacic acid and azelaic acid are particularly preferable. If an aliphatic dicarboxylic acid having 5 or less carbon atoms is used in place of these, the melting point and boiling point of the dicarboxylic acid are low, so that the reaction molar ratio of the diamine and the dicarboxylic acid collapses during the polycondensation reaction. This is not preferred because the mechanical properties and thermal stability of the resulting polyamide are lowered. When an aliphatic dicarboxylic acid having 19 or more carbon atoms is used, a polyamide having stable properties can be obtained, but this is not preferable because the melting point is greatly lowered and heat resistance cannot be obtained.

As raw material dicarboxylic acids other than straight chain aliphatic dicarboxylic acids having 6 to 18 carbon atoms, malonic acid, succinic acid, 2-methyladipic acid, trimethyladipic acid, 2,2-dimethylglutaric acid, 2,4-dimethylglutaric acid 3,3-dimethylglutaric acid, 3,3-diethylsuccinic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid, 2, Examples thereof include, but are not limited to, 6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, or a mixture thereof.

In addition to the diamine component and dicarboxylic acid component, lactams such as ε-caprolactam and laurolactam, and aliphatic aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid are also used as copolymerization components as long as the effects of the present invention are not impaired. it can.

A small amount of a monofunctional compound having reactivity with the terminal amino group or carboxyl group of the polyamide may be added as a molecular weight modifier during the polycondensation of the polyamide (A). The compounds that can be used include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, benzoic acid, and toluyl Acids, aromatic monocarboxylic acids such as naphthalenecarboxylic acid, aliphatic monoamines such as butylamine, amylamine, isoamylamine, hexylamine, heptylamine and octylamine, araliphatic monoamines such as benzylamine and methylbenzylamine, or these Although a mixture can be illustrated, it is not limited to these.

When a molecular weight modifier is used during the polycondensation of the polyamide (A), the preferred amount varies depending on the reactivity, boiling point, reaction conditions, etc. of the molecular weight modifier used. It is about 0.1-10 mass% with respect to the sum total of an acid component.

There are several indicators of the degree of polymerization of polyamide, but the relative viscosity is generally used. In the polyamide (A), the preferred relative viscosity is 1.8 to 4.2, more preferably 1.9 to 3.5, and particularly preferably 2.0 to 3.0. When the relative viscosity of the polyamide (A) is less than 1.8, the fluidity of the melted polyamide (A) tends to be unstable and the appearance of the molded product may be deteriorated. On the other hand, if the relative viscosity of the polyamide (A) exceeds 4.2, the melt viscosity of the polyamide (A) may be too high and the molding process may become unstable. The relative viscosity here refers to the drop time (t) measured by dissolving 1 g of polyamide in 100 mL of 96% sulfuric acid at 25 ° C. with a Canon Fenceke viscometer, and the drop of 96% sulfuric acid itself measured in the same manner. It is a ratio of time (t0) and is represented by the following formula (1).
Relative viscosity = t / t0 (1)

The polyamide (A) preferably has a number average molecular weight (Mn) in the range of 10,000 to 50,000 in the gel permeation chromatography (GPC) measurement, and is preferably in the range of 14,000 to 30,000. Particularly preferred. By setting Mn in the range of 10,000 to 50,000, the mechanical strength in the case of forming a molded article is stable, and the mold has a suitable melt viscosity that provides good workability in terms of moldability. Further, the dispersity (weight average molecular weight / number average molecular weight = Mw / Mn) is preferably in the range of 1.5 to 5.0, and particularly preferably in the range of 1.5 to 3.5. By setting the degree of dispersion in the above range, the fluidity at the time of melting and the stability of the melt viscosity are increased, and the workability of melt kneading and melt molding is improved. Also, the toughness is good, and various physical properties such as water absorption resistance, chemical resistance, and heat aging resistance are also good.

Polyamide (A) is (a) polycondensation in the molten state, (b) so-called solid phase polymerization in which a low molecular weight polyamide is obtained by polycondensation in the molten state and then heat-treated in the solid phase, (c) in the molten state After obtaining a low molecular weight polyamide by polycondensation, it can be obtained by a known polyamide synthesis method such as extrusion polymerization in which a high molecular weight is obtained in a molten state using a kneading extruder.

Although the polycondensation method in the molten state is not particularly limited, a method in which an aqueous solution of a nylon salt of a diamine component and a dicarboxylic acid component is heated under pressure and polycondensed in a molten state while removing water and condensed water, Examples thereof include a method in which a diamine component is directly added to a dicarboxylic acid in a molten state and polycondensed in an atmosphere of atmospheric pressure or steam. When polymerizing by directly adding diamine to the molten dicarboxylic acid, the diamine component is continuously added to the molten dicarboxylic acid phase in order to keep the reaction system in a uniform liquid state, so as not to fall below the melting point of the resulting oligoamide and polyamide. The polycondensation proceeds while controlling the reaction temperature.

The polyamide obtained by melt polycondensation is once taken out, pelletized, and dried before use. In order to further increase the degree of polymerization, solid phase polymerization may be performed. As a heating device used in drying or solid phase polymerization, a continuous heating drying device, a rotary drum type heating device called a tumble dryer, a conical dryer, a rotary dryer or the like, and a rotary blade inside a nauta mixer are used. Although a conical heating apparatus provided with can be used suitably, a well-known method and apparatus can be used without being limited to these. Particularly in the case of solid-phase polymerization of polyamide, a batch heating apparatus is preferably used because it can seal the inside of the system and easily proceed with polycondensation in a state where oxygen that causes coloring is removed. It is done.

In the polycondensation system of the polyamide (A), a phosphorus atom-containing compound may be added as a catalyst for the polycondensation reaction and an antioxidant for preventing the polyamide from being colored by oxygen present in the polycondensation total. Phosphorus atom-containing compounds to be added include alkaline earth metal salts of hypophosphorous acid, alkali metal salts of phosphoric acid, alkaline earth metal salts of phosphoric acid, alkali metal salts of pyrophosphoric acid, alkaline earth metal salts of pyrophosphoric acid And alkali metal salts of metaphosphoric acid and alkaline earth metal salts of metaphosphoric acid. Specifically, calcium hypophosphite, sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, magnesium phosphate, dimagnesium hydrogen phosphate , Magnesium dihydrogen phosphate, calcium phosphate, dicalcium hydrogen phosphate, calcium dihydrogen phosphate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, sodium pyrophosphate, potassium pyrophosphate, magnesium pyrophosphate, pyro Examples thereof include, but are not limited to, calcium phosphate, lithium pyrophosphate, sodium metaphosphate, potassium metaphosphate, magnesium metaphosphate, calcium metaphosphate, lithium metaphosphate, or a mixture thereof.

The addition amount of the phosphorus atom-containing compound added to the polycondensation system of the polyamide (A) is preferably 50 to 400 ppm in terms of the phosphorus atom concentration in the polyamide (A), and more preferably 60 to 350 ppm. Is preferable, and it is especially preferable that it is 70-300 ppm. When the phosphorus atom concentration is less than 50 ppm, the effect as an antioxidant cannot be sufficiently obtained, and the polyamide resin composition tends to be colored, which is not preferable. In addition, when the phosphorus atom concentration exceeds 400 ppm, the gelation reaction of the polyamide resin composition is promoted, and foreign matters that may be caused by the phosphorus atom-containing compound may be mixed in the molded product, and the appearance of the molded product may be This is not preferable because it tends to deteriorate.

Moreover, it is preferable to add a polymerization rate adjusting agent in combination with the phosphorus atom-containing compound in the polycondensation system of polyamide (A). To prevent coloring of the polyamide during polycondensation, it is necessary to have a sufficient amount of phosphorus atom-containing compound, but there is a risk of causing gelation of the polyamide, so polymerization is also performed to adjust the amidation reaction rate. It is preferable to coexist with a speed regulator. Examples of the polymerization rate adjusting agent include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal acetates and alkaline earth metal acetates, and alkali metal hydroxides and alkali metal acetates are preferable. Polymerization rate regulators include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lithium acetate, sodium acetate, acetic acid Examples include, but are not limited to, potassium, rubidium acetate, cesium acetate, magnesium acetate, calcium acetate, strontium acetate, barium acetate, or mixtures thereof.

When a polymerization rate modifier is added to the polycondensation system, the gram equivalent ratio of the phosphorus atom-containing compound and the polymerization rate modifier (= [gram equivalent of polymerization rate modifier] / [gram equivalent of phosphorus atom-containing compound]) is In the case of 0.4 to 1.0, more preferably 0.5 to 0.95, and particularly preferably 0.6 to 0.9. The effect of suppressing the amidation reaction promoting effect of the phosphorus atom-containing compound may be insufficient, and the gel in the polyamide may increase. On the other hand, if it exceeds 1.0, the effect of promoting the amidation reaction of the phosphorus atom-containing compound is excessively suppressed, the progress of polycondensation is delayed, the thermal history during polyamide production may increase, and the polyamide gel may increase. Therefore, it is not preferable.

The polyamide resin composition of the present invention contains a modified polyolefin (B) as a constituent component other than the polyamide (A). As the modified polyolefin (B), a polyolefin modified by copolymerization with an α, β-unsaturated carboxylic acid or its ester or a metal salt derivative, or a carboxylic acid or an acid anhydride introduced into the polyolefin is modified. Quality ones can be used. Specifically, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 4-methyl-1-pentene copolymer, ethylene / 1-hexene copolymer, ethylene / 1-octene copolymer , Ethylene / 1-decene copolymer, propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / 4-methyl-1-pentene copolymer, propylene / 1-hexene copolymer, propylene / 1-octene copolymer, propylene / 1-decene copolymer, propylene / 1-dodecene copolymer, ethylene / propylene / 1,4-hexadiene copolymer, ethylene / propylene / dicyclopentadiene copolymer, ethylene 1-butene / 1,4-hexadiene copolymer, ethylene / 1-butene / 5-ethylidene-2-norbornene copolymer Although, and others are not limited thereto.

The polyamide resin composition of the present invention comprises the above-mentioned polyamide (A) and modified polyolefin (B), and the blending amount of the modified polyolefin (B) is 0.5 to 50 mass with respect to 100 parts by mass of the polyamide (A). Parts, preferably 1 to 45 parts by mass, particularly preferably 5 to 40 parts by mass. When the compounding amount of the modified polyolefin is 0.5 parts by mass or less with respect to 100 parts by mass of the polyamide resin, there is little improvement effect such as mechanical strength and thermal properties, and when the compounding amount of the modified polyolefin exceeds 50 parts by mass. The characteristics of the polyamide resin composition, such as a decrease in heat resistance, are not preferable.

A filler can be blended in the polyamide resin composition of the present invention as necessary. When these fillers are used in an amount of 1 to 200 parts by mass based on 100 parts by mass of the resin composition of the present invention, it is preferable because of balance of moldability, mechanical properties, thermal deformability and the like. The blending amount is more preferably 1 to 150 parts by mass, and particularly preferably 2 to 100 parts by mass with respect to 100 parts by mass of the resin composition. As the filler, fillers having various forms such as powder, fiber and cloth can be used.

As powder filler, silica, alumina, titanium oxide, zinc oxide, boron nitride, talc, mica, potassium titanate, calcium silicate, magnesium sulfate, aluminum borate, asbestos, glass beads, carbon black, graphite, disulfide Examples include molybdenum and polytetrafluoroethylene.

The fibrous filler is obtained from polyparaphenylene terephthalamide resin, polymetaphenylene terephthalamide resin, polyparaphenylene isophthalamide resin, polymetaphenylene isophthalamide resin, or a condensate of diaminodiphenyl ether and terephthalic acid or isophthalic acid. Examples thereof include organic fibrous fillers such as wholly aromatic polyamide fibers such as fibers and wholly aromatic liquid crystal polyester fibers; and inorganic fibrous fillers such as glass fibers, carbon fibers, and boron fibers. These fibrous fillers may be secondarily processed into a cloth shape or the like.

These fillers can be used alone or in combination. Particularly, it is preferable to use a combination of the above powder filler and the above fibrous filler because a thermoplastic resin composition excellent in moldability, surface aesthetics, mechanical properties, and heat resistance can be obtained. . Moreover, the thing surface-treated with the silane coupling agent or the titanium coupling agent etc. can also be used as these fillers. Use of a filler whose surface is treated with such a coupling agent is preferable because the resulting molded article has excellent mechanical properties. As the silane coupling agent, an aminosilane coupling agent is particularly preferable.

The polyamide resin composition of the present invention includes an antioxidant such as a copper-based antioxidant, a hindered phenol-based antioxidant, a hindered amine-based antioxidant, and a thio-based antioxidant within a range that does not impair the effects of the present invention. , Colorants, light stabilizers, lubricants, crystallization agents, matting agents, heat stabilizers, weathering stabilizers, UV absorbers, nucleating agents, plasticizers, flame retardants, antistatic agents, anti-coloring agents, gelation Various additives generally used for polymer materials such as inhibitors, or other polymers can be blended, but the invention is not limited to these.

The production method of the polyamide resin composition of the present invention is not particularly limited, and the polyamide (A), the modified polyolefin (B), and other additives and resins as necessary in any order and using a conventional apparatus. For example, it can be produced by a melt-kneading method using an ordinary vent type extruder or an apparatus similar thereto.

The polyamide resin composition of the present invention can be applied with known molding methods such as injection molding, blow molding, extrusion molding, compression molding, stretching, and vacuum molding. Engineering plastics such as engine mounts, engine covers, torque control levers, window regulators, headlight reflectors, door mirror stays and other automotive parts, connectors, switches, capacitors, capacitors and other molded parts such as capacitors, and films , Sheet, hollow container, tube, etc., and can be suitably used for industrial materials, industrial materials, household goods, and the like.

Claims (10)

  Including polyamide (A) and modified polyolefin (B) comprising a diamine unit containing 70 mol% or more of paraxylylenediamine units and a dicarboxylic acid unit containing 70 mol% or more of a linear aliphatic dicarboxylic acid unit having 6 to 18 carbon atoms It is a polyamide resin composition, Comprising: The impact-resistant polyamide resin composition containing 0.5-50 mass parts of modified polyolefin (B) with respect to 100 mass parts of polyamide (A).   The impact-resistant polyamide resin composition according to claim 1, wherein the linear aliphatic dicarboxylic acid unit is at least one selected from an azelaic acid unit, a sebacic acid unit, an undecanedioic acid unit, and a dodecanedioic acid unit.   The impact-resistant polyamide resin composition according to claim 1 or 2, wherein the linear aliphatic dicarboxylic acid unit is at least one selected from sebacic acid units and azelaic acid units.   The polyamide (A) is a polyamide comprising a diamine unit containing 90 mol% or more of paraxylylenediamine units and a dicarboxylic acid unit containing 90 mol% or more of at least one selected from sebacic acid units and azelaic acid units. 4. The impact-resistant polyamide resin composition according to any one of 3 above.   The impact-resistant polyamide resin composition according to any one of claims 1 to 4, wherein the polyamide (A) has a relative viscosity in the range of 1.8 to 4.2.   The number average molecular weight (Mn) in the gel permeation chromatography measurement of the polyamide (A) is in the range of 10,000 to 50,000, and the dispersity (weight average molecular weight / number average molecular weight = Mw / Mn) is 1.5. It is the range of -5.0, The impact-resistant polyamide resin composition in any one of Claims 1-5.   The impact-resistant polyamide resin composition according to any one of claims 1 to 6, comprising 1 to 200 parts by mass of a filler with respect to 100 parts by mass in total of the polyamide (A) and the modified polyolefin (B).   A molded article comprising the polyamide resin composition according to any one of claims 1 to 7.   The molded article according to claim 8, wherein the molded article is an automotive part.   The molded article according to claim 8, wherein the molded article is an electrical component or an electronic component.