KR0140539B1 - Polyamide resin compositions - Google Patents

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Description

Polyamide Resin Composition

The present invention relates to a polyamide resin composition. Polyamide resins are widely used as engineering plastics because of their excellent equilibrium properties, and are widely used, for example, in automobiles and electrical parts. In particular, aromatic polyamide resins composed of aromatic dicarboxylic acids such as terephthalic acid and aliphatic diamines such as hexamethylenediamine have a higher melting point and higher mechanical properties than those of aliphatic polyamide resins, and thus are widely used in a wider field. It is expected to be greatly used.

As the aromatic polyamide resin composition, those containing resins containing reinforcing fibers such as glass fibers in order to further improve heat resistance and causticity have been known.

However, polyamide resins and their compositions have a low fluidity and a high melting point and must be molded at a high temperature near the pyrolysis temperature. In addition, since a large amount of frictional heat is generated when the polyamide resins or their compositions are injection molded and thermally decomposed into low molecular weight resins, there is a disadvantage in that the properties inherently possessed by the polyamide resins or compositions thereof are deteriorated. Therefore, it is difficult to produce molded articles having thin walls or complicated shapes by injection molding, especially because large frictional heat is generated.

As another drawback, aromatic polyamide resin compositions are generally susceptible to breakage when mold release.

Another disadvantage is that the aromatic polyamide resin composition has low fluidity, so that the supply of the composition from the hopper to the molding machine is not smoothly performed at the time of injection or extrusion molding. This is not uniform.

In Japanese Patent Laid-Open No. 61-188457, a polyamide resin composition for thin-walled molded articles is nylon 46, 10 to 80 parts by weight of glass fiber based on 100 parts by weight of resin, and 0.001 to 1 part by weight of 100 parts by weight of resin and glass fiber in total. The inclusion of parts by weight of lubricating products has been introduced. Other thin-walled polyamide resin compositions for molded articles, including nylon 46 and fatty acids of Group I, II or III metals of the bisamide periodic table, polystyrene glycols, aliphatic carboxylic acids having 26 to 32 carbon atoms or derivatives thereof Containing such a lubricant was introduced in Japanese Patent Laid-Open No. 61-188458.

Such conventional documents mention that it improves the moldability of nylon 46 having a high melting point and also prevents the reduction of the molecular weight of the resin during molding. Nylon 46 is also described as a mixture or copolymer of nylon 46 and nylon 66 / 6T (terephthalic acid component) or nylon 66 / 6T / 6I (isophthalic acid component).

However, these conventional polyamide resin compositions contain nylon 46 which is one of aliphatic polyamide resins as a main component. Therefore, the aliphatic polyamide resin composition cannot be expected to significantly improve heat resistance by incorporating a small amount of aromatic polyamide resin into the aliphatic polyamide resin.

Aromatic polyamide resins have a much higher melting point, a much higher molding temperature and a much smaller heat deflection temperature than aliphatic polyamide resins, and aromatic polyamide resins have a different molecular structure from aliphatic polyamide resins. Therefore, there has been no mention of improvement in moldability of the composition containing aromatic polyamide resins as a main component.

Therefore, it is an object of the present invention to provide an aromatic polyamide resin composition which is excellent in fluidity and mold release properties and as a result prevents a decrease in molecular weight during molding. According to the present invention, there is provided a polyamide resin composition comprising the following components.

(A) an aromatic polyamide resin comprising a diamine component (b) comprising an aromatic dicarboxylic acid component as one aliphatic diamine component and an alicyclic diamine component,

(B) 0 to 200 parts by weight of reinforcing fibers per 100 parts by weight of polyamide resin,

(C) at least one additive selected from the group consisting of metal salts of higher fatty acids and derivatives of aliphatic carboxylic acids having from 26 to 32 carbon atoms, wherein said metal is selected from the group consisting of Group I, II and III metals of the periodic table The derivative is selected from the group consisting of acid ester partially combined esters and metal salts and the amount of the additive is in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the polyamide resin.

Commonly used aromatic polyamide resins include a dicarboxylic acid component and a diamine component. The dicarboxylic acid component may be terephthalic acid as the first aromatic dicarboxylic acid component or the other as the second aromatic dicarboxylic acid component or a mixture thereof. Examples of the first aromatic dicarboxylic acid component include isophthalic acid, phthalic acid 2-methyl terephthalic acid or naphthalene dicarboxylic acid component.

However, the dicarboxylic acid component is preferably composed of 40 to 100 mol% of terephthalic acid, 60 to 1 mol% of at least one second aromatic dicarboxylic acid component and an aliphatic dicarboxylic acid component. The isophthalic acid or naphthalene dicarboxylic acid component is particularly good as the second aromatic dicarboxylic acid component and isophthalic acid is the best. The aliphatic dicarboxylic acid component used preferably has 4 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, for example succinic acid, adipic acid, azeranic acid, sebacic acid, decandicarboxylic acid, undecanedicarboxylic acid or dode There is a candicarboxylic acid component, of which adipic acid is particularly preferred.

As described above, the polyamide resins used are formulated in a specific amount of the dicarboxylic acid component and the diamine component, and the final resin composition is excellent in heat resistance, heat resistance, or heat deflection temperature characteristics, and also has tensile strength, elastic strength or wear resistance, A molded article excellent in mechanical properties such as chemical resistance or water resistance can be obtained.

However, if necessary, the resin composition may contain up to 40 mol% of terephthalic acid components, and in addition, 60 mol% of second aromatic dicarboxylic acid components may be contained in the dicarboxylic acid component.

The tribasic polybasic aromatic carboxylic acid component may be used together with the aromatic dicarboxylic acid component in an amount of 10 mol% or less based on the entirety of 2- and 3- or more polybasic carboxylic acid components. Examples of the usable three or more polybasic aromatic carboxylic acid components include trimellitic acid or pyromellitic acid.

As the diamine component, an aliphatic diamine or an alicyclic diamine component or a mixture thereof can be used. The aliphatic diamine component may be linear or branched.

Preferred diamines are linear or branched alkene diamines having 4 to 25 carbon atoms, most preferably 6 to 18 carbon atoms.

Preferred linear alkylene diamine components include, for example, 1, 6-diaminenorexic acid, 1,7-diaminodecane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane Or a 1,12-diaminododecane component. Preferred branched alkene diamine components are, for example, 1,4-diamino-1,1-dimethylbutane, 1,4-diamino-1-ethylbutane, 1,4-diamino-1,2-dimethylbutane , 1,4-diamino-1,3-dimethylbutane, 1,4-diamino-1,4-dimethylbutane, 1,4-diamino-2,3-dimethylbutane, 1,2-diamino- 1-butylethane, 1,6-diamino-1,5-dimethylhexane, 1,6-diamino-1,4-dimethylhexane, 1,6-diamino-3,3-dimethylhexane, 1,6 -Diamino-2,2-dimethylhexane, 1,6-diamino-2,2,4-trimethylhexane, 1,6-diamino-2,4,4-trimethylhexane, 1,6-diamino- 2,3-dimethylheptane, 1,7-diamino-2,4-dimethylheptane, 1,7-diamino-2,5-dimethylheptane, 1,7-diamino-2,2-dimethylheptane, 1 , 8-diamino-1,3-dimethyloctane, 1,8-diamino-1,4-dimethyloctane, 1,8-diamino-2,4-dimethyloctane, 1.8-diamino-3,4- Dimethylotan, 1,8-diamino-4,5-dimethyloctane, 1,8-diamino-2,2-dimethyloctane, 1,8-diamino-3,3-dimethyloctane, 1,8-dia Mino-4,4- Dimethyloctane, 1, 6- diamino-2, 4-diethyl hexane, 1, 9- diamino-5- methyl nonane, etc. are mentioned.

Among the diamines described above, linear alkylene diamine component is preferred, and among them, 1,6-diaminohexane, 1,8-diaminooctane, 1,10-diaminodecane or 1,12-diaminododecane component or two of these The above mixture is particularly good.

The alicyclic diamine component which can then be used is usually 6-25 carbon atoms and contains at least one alicyclic ring. Examples thereof include 1.3-diamino-cyclohexane, 1,4-diamino-cyclohexane, 1,3-bis (aminomethyl) -cyclohexane, isoprondiamine, piperazine, 2,5-dimethylpiperazine , Bis- (4-aminocyclohexyl) methane, bis- (4-aminocyclohexyl (propane, 4,4'-diamino-3,3'-dimethyl dicyclo hexylmethane, 4,4'-diamino- 3,3'-methyl dicyclo hexyl propane, 4,4'-diamino-3,3'-dimethyl-5,5'-dimethyl dicyclo hexylmethane, 4,4 -'- diamino-3,3 ' -Dimethyl-5,5 'dimethyldicyclohexylpropane, α, α'-bis (4-aminocyclohexyl) -p-diisopropylbenzene,

(alpha), (alpha) '-bis (4-aminocyclohexyl) -1, 4- diisopropyl cyclohexane is mentioned.

Among the alicyclic diamine components described above, bis (aminomethyl) cyclohexane, bis (4-aminocyclohexyl) methane or 4,4 -'- diamino-3,3'-dimethyl dischlorohexylmethane is preferable and bis (aminocyclo Hexyl) methane, 1,3-bis (aminocyclohexyl) methane or 1,3-bis (aminomethyl) cyclohexane are best.

According to the present invention, when the dicarboxylic acid component is composed mainly of the terephthalic acid component, more specifically, when the dicarboxylic acid component contains the terephthalic acid component in an amount of 60 mol% or less, the diamine component is composed of the aliphatic diamine component as described above. It is good to be.

More specifically, when the aliphatic diamine component is composed of a carbon chain having 5 to 11 carbon atoms, 50-1 mol% of terephthalic acid component may be contained in the dicarboxylic acid component, and other components include a second aromatic dicarboxylic acid component and an aliphatic dicarboxylic acid. It may be any of the components or mixtures thereof.

More specifically, when composed of a short molded carbon chain having 5 to 7 carbon atoms of an aliphatic diamine component, 50 to 85 mol% of terephthalic acid component may be contained in the dicarboxylic acid component. Therefore, the dicarboxylic acid component may contain 50 to 15 mol% of other dicarboxylic acid components, and the other component may be any of a second aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, or a mixture thereof.

When the aliphatic diamine component is prepared with a carbon chain of 6 to 11 carbon atoms, preferably 6 to 10 carbon atoms, 50 to 100 mol% of the terephthalic acid component is preferably contained in the dicarboxylic acid component. Therefore, the dicarboxylic acid component may contain 50 to 1 mol% of other dicarboxylic acid components, and the other component may be any of a second aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, or a mixture thereof.

On the other hand, when the aliphatic diamine component is composed of a relatively long carbon chain having 10 to 18 carbon atoms, 75 to 100 mol% of the terephthalic acid component is preferably contained in the dicarboxylic acid component. Therefore, the dicarboxylic acid component may contain 25 to 0 mol% of other dicarboxylic acid components, and the other component may be any one of a second aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, or a mixture thereof.

As described above, when the amount of terephthalic acid component, other aromatic dicarboxylic acid component and aliphatic dicarboxylic acid component in the dicarboxylic acid component is specified according to the carbon number in the aliphatic diamine component, the final resin composition is not only moldable, but also the molded article produced therefrom is highly It has heat resistance, high heat deterioration resistance and high heat deflection temperature, and also has excellent mechanical properties such as elastic strength or wear resistance.

The diamine component may contain an aromatic diamine component in addition to the alkylene diamine component. Examples of such aromatic diamine components include m-cidiamine or p-crylene diamine.

The polyamide resin used in the composition of the present invention has an intrinsic viscosity [η] of usually 0.5 dl / g or less and most preferably 0.7 to 3.0 dl / g as measured in concentrated sulfuric acid at 30 ° C.

The polyamide resins mentioned above have already been described, for example, in P. W. Morgan, Polymer Reviews, 10, Condensation Polymers by Interfacial and Solution Methods, Interscience Publishers (1965) or Makeromol. As disclosed in Chem., 47 93-113 (1961), it can be prepared by condensation polymerization in a solution of dicarboxylic acid halide and diamine corresponding to dicarboxylic acid and diamine component. The aforementioned polyamide resin can also be produced by the above-described interfacial method.

The polyamide resin is also prepared by melting method, i.e., polycondensation of aromatic dicarboxylic acid and diamine or polyamide salts thereof corresponding to the aromatic dicarboxylic acid component and diamine component, respectively, in the presence or absence of a solvent such as water. You may. Another method is to prepare an oligomer first by, for example, a solution method and then polycondense the oligomer into a solid phase.

The polyamide resin composition of the present invention may optionally contain reinforcing fibers to have higher heat resistance and rigidity. As the reinforcing fibers, for example, various organic fibers and inorganic fibers such as glass fibers, carbon fibers, potassium titanate fibers, willlastonite, ceramic fibers, metal coated glass fibers, metal carbide fibers or metal fibers may be used. Inorganic fibers are good because of their high heat resistance, in particular glass fibers are good because of the high strengthening effect. The reinforcing fibers can be pretreated as silane binders such as vinyltriethoxysilane, 2-aminopropyltriethoxysilane, 2-glycidoxypropyltrimethoxysilane, and the like.

The reinforcing fibers may be contained in the composition in an amount of usually about 200 parts by weight or less, preferably 150 parts by weight or less, based on 100 parts by weight of the aromatic polyamide resin. If the excess amount is used, the fluidity of the composition is reduced, making molding difficult.

The polyamide resin composition of the present invention contains at least one additive selected from the group consisting of higher fatty acid metal salts and derivatives of aliphatic carboxylic acids having 26 to 32 carbon atoms. The metal is selected from the group consisting of Group I, II and III metals of the periodic table and the derivatives of aliphatic carboxylic acids are selected from the group consisting of acid esters, partially saponified esters and metal salts, preferably alkali or alkaline earth metal salts, The amount is 0.01 to 5 parts by weight based on 100 parts by weight of the polyamide resin.

The translator improves the flowability, melt flow and mold release properties of the final composition in the hopper and also prevents thermal decomposition of polyamide resins into low molecular weight resins. Can be.

Examples of the higher fatty acid metal salts that can be used include metal salts such as lithium, sodium, potassium, magnesium, barium, zinc or aluminum of fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid or bihenic acid. Can be mentioned.

More specifically preferred fatty acid salts include lithium stearate, sodium stearate, calcium stearate, magnesium stearate, lithium 12-hydroxystearate or calcium 12-hydroxystearate.

Derivatives of aliphatic carboxylic acids having 26 to 32 carbon atoms include esters of aliphatic carboxylic acids such as keratinic acid, montanic acid or melicinic acid, and aliphatic polyhydric alcohols, their partial saponification products or metal salts of aliphatic carboxylic acids, preferably alkali or alkaline earth metals. Salts are exemplified.

More specifically preferred examples are the partially potassium saponification products of calcium montanate, sodium montanate, lithium montanate or butyrene glycol esters of montanic acid. The derivatives can be used alone or as a mixture of two or more.

The additive is contained 0.01 to 5 parts by weight, preferably 0.05 to 1 part by weight based on 100 parts by weight of the aromatic polyamide resin. When the amount of the additive is 0.01 parts by weight or less relative to 100 parts by weight of the aromatic polyamide resin, the final resin composition is still poor in moldability, while when it is 5 parts by weight or more, the mechanical properties tend to be lowered.

The composition of the present invention may be prepared by conventional anti-banging, and if desired, other additives such as a freezing stabilizer, a climate stabilizer, a flame retardant, an antistatic agent, a nucleating agent, a colorant, a foaming agent, or a filler do not impair the desirable properties of the composition. It may contain in an amount of.

The present invention will be described in detail with reference to the embodiments. However, the present invention is not limited to the following examples.

[Example 1-9 and Comparative Example 1-4]

A heat resistant aromatic polyamide resin composed of an acid component of 70 mol% of terephthalic acid component, 30 mol% of isophthalic acid component, and a diamine component of 100 mol% of 1,6-diaminohexane was prepared. The prepared resin was found to have a melting point of 325 ° C. as measured by intrinsic viscosity [η] of 1.0 g / ㎗ and DSC method measured in concentrated sulfuric acid at 30 ° C. This polyamide is often referred to later as PA-1.

The amount of 100 parts by weight of polyamide was mixed with the following additives in the amounts as shown in Table 1.

The additive used is abbreviated as follows.

L-1: Lithium stearate S7000 (Sakai Chemical Co., Ltd.)

L-2: Calcium Stearate (Nice Yushisa)

L-3: Magnesium Stearate (Nice Yushisa)

L-4: Calcium 12-hydroxystearate CS600 (Kosei Co., Ltd.)

L05: Calcium Montanate WAX CAW2 (Zust-Japan)

L-6: Sodium Montanate WAX NAW1 (Zust-Japan)

L-7: Lithium Montanate WAX LIX (Just-Japan)

L-8: Partial calcium saponification ester of montanic acid (butst-Japan company) as butylene glycol WAX OP

L-9: Ethylenebisstearyl Amide ALFLOW H50 (Nice Yushisa)

L-10: Polystyrene Glycol PEG 2000 (Wako Junya Kogyo Co., Ltd.)

L-11: Polystyrene Wax WAX PE190 (Zust-Japan)

The mixture was melt kneaded with a single screw extruder (30 mm diameter, 330 ° C.) having an extrusion output of 8 kg / hr to prepare pellets. Table 1 shows the resin pressure at the top of the extruder and the intrinsic viscosity [η] of the pellets. In addition, the pellet was injection molded at 340 by an injection molding machine (IS-50EP, Toshiba Corporation) to calculate mold release characteristics and melt fluidity. The results are shown in Table 1.

The characteristic was measured as follows.

Mold Release Characteristics:

A flat mold of 100 mm x 50 mm x 0.8 mm was used at 120 ° C. A: The molded article was easily released from the mold and no torsion was found. B: Torsion was partially found. C: A severe torsion was found throughout.

Melt Flowability:

Swirl flow was measured with a spiral flow test mold at 70 ° C. The better the total flow, the better the melt flowability.

Absorbent

Samples were immersed in water at 23 ° C. for 24 hours and weight gain was measured according to ASTM D570.

The tensile strength

Measured according to ASTM D638.

Tensile Strength of Absorber:

The samples were immersed in water at 23 ° C. for 24 hours and then the tensile strength was measured as described above.

Annual Deflection Temperature:

It was measured under a load of 18.6 kg / cm 2 in accordance with ASTM D648.

[Comparative Examples 5-6]

A polyamide resin composed of an acid component of 100 mol% of adipic acid and a diamine component of 100 mol% of 1,4-diaminobutane was used. This resin had an intrinsic viscosity [η] of 1.3 dl / g and a melting point of 292 ° C. This resin is sometimes referred to as PA-2.

The polyamide resin was mixed with the above-mentioned additives, and then pellets were formed by a single screw extruder (30 mm diameter, 300 ° C.) having an extrusion amount of 8 kg / hr. The pellets were then injection molded at 320 ° C. with the same injection molding machine as described above, then the mold release properties and melt flowability were calculated.

The results are shown in Table 1.

[Examples 10-17 and Comparative Examples 7-9]

60 parts by weight of PA-1 resin was mixed with 40 parts by weight of glass fiber (03MA486A, manufactured by Asahi Fiberglass K, K) and the additives as shown in Table 2.

The mixture was melted and kneaded in a twin screw vent type (diameter 30 mm, 330 ° C.) at an extrusion amount of 20 kg / hour to prepare pellets. Table 2 shows the power required for the melting and kneading.

The pellets were injection molded in the same manner as in Example 1 to calculate mold separation characteristics and melt fluidity. The results are shown in Table 2.

[Comparative Examples 10-11]

A mixture of 70 parts by weight of PA-2 resin and 30 parts by weight of the same glass fiber and the additives as shown in Table 2 was extruded at a single screw extruder (30 mm, 300 ° C.) at an extrusion amount of 8 kg / hour. Pellets were prepared. Thereafter, the pellets were injection molded at 320 ° C. with the same injection molding machine to calculate mold release characteristics and melt fluidity. The results are shown in Table 2.

[Examples 18-26 and Comparative Examples 12-15]

The heat-resistant aromatic polyamide resin was produced such that its acid component was 60 mol% of terephthalic acid component, adipic acid component 40%, and the diamine component had a composition of 100 mol% of 1,6-diaminohexane. The intrinsic viscosity [η] measured in 30 degreeC concentrated sulfuric acid of the said resin was 1.1 dl / g, and melting | fusing point measured by DSC method was 325 degreeC.

Hereinafter, the polyamide is often named PA-3.

The amount of 100 parts by weight of the polyamide was mixed with the aforementioned additives in the amounts shown in Table 3.

The mixture was melted and kneaded in an extrusion amount of 8 kg / hour with a single screw extruder (30 mm in diameter, 330 ° C.) to prepare pellets. Table 3 shows the pressure of the resin at the top of the extruder and the intrinsic viscosity [?] Of the pellets. In addition, the pellets were injection molded in the same manner as in Example 1 to evaluate the physical properties of the composition. The results are shown in Table 3.

[Examples 27-35 and Comparative Examples 16-18]

An amount of 60 parts by weight of PA-3 resin was mixed with 40 parts by weight of the same glass fiber as described above and the above additives in the amounts shown in Table 4.

The mixture was melted and kneaded in a twin screw exhaust type extruder (diameter 30 mm, 330 ° C.) fh to prepare pellets. The pellets were injection molded in the same manner as in Example 1 to evaluate the physical properties of the composition. The results are shown in Table 4.

Claims (11)

(A) 40 to 100 mole percent terephthalic acid, aromatic dicarboxylic acid other than terephthalic acid, and a dicarboxylic acid component (a) consisting of at least 60 to 0 mole percent aliphatic dicarboxylic acid having 4 to 20 carbon atoms and at least one aliphatic diamine or alicyclic diamine Aromatic polyamide resin comprising diamine component (b); (B) 0 to 200 parts by weight of the fiber reinforcing agent per 100 parts by weight of the polyamide; (C) a polyamide resin composition characterized in that it comprises 0.01 to 5 parts by weight of at least one additive selected from the group consisting of acid esters, partially saponified esters or higher fatty acid metal salts of aliphatic carboxylic acids having 26 to 32 carbon atoms per 100 parts by weight of the polyamide. . The dicarboxylic acid component (a) is composed of 40 to 100 mol% of terephthalic acid and 60 to 0 mol% of aromatic dicarboxylic acids other than terephthalic acid, and the diamine component (b) is at least one aliphatic diamine having 5 to 11 carbon atoms. Polyamide resin composition characterized in that the configuration. The dicarboxylic acid component (a) is composed of 50 to 100 mol% of terephthalic acid, aromatic dicarboxylic acid other than terephthalic acid, and at least 50 to 0 mol% of aliphatic dicarboxylic acids having 4 to 20 carbon atoms, and the diamine component (b). ) Is composed of at least one aliphatic diamine having 5 to 11 carbon atoms. The polyamide resin composition according to any one of claims 1 to 3, wherein the diamine component (b) is composed of at least one aliphatic diamine having 6 to 10 carbon atoms. The dicarboxylic acid component (a) is composed of 75 to 100 mol% of terephthalic acid and 25 to 0 mol% of aromatic dicarboxylic acids other than terephthalic acid, and the diamine component (b) is at least one aliphatic diamine having 10 to 18 carbon atoms. Polyamide resin composition characterized in that the configuration. The polyamide resin composition according to claim 1, wherein the intrinsic viscosity measured in 30 ° C. and concentrated sulfuric acid of the polyamide resin (A) is 0.5 dl / g or more. The polyamide resin composition according to claim 1, wherein the fiber reinforcing agent is glass fiber. The dicarboxylic acid component (a) is composed of 50 to 100 mol% of terephthalic acid and 50 to 0 mol% of aromatic dicarboxylic acids other than terephthalic acid, and the diamine component (b) is at least one aliphatic diamine having 5 to 11 carbon atoms. Polyamide resin composition characterized in that the configuration. The dicarboxylic acid component (a) is composed of 50 to 100 mol% of terephthalic acid and 50 to 0 mol% of dicarboxylic acids other than tefephthalic acid, and the diamine component (b) is at least one aliphatic diamine having 5 to 11 carbon atoms. Polyamide resin composition characterized in that the configuration. The dicarboxylic acid component (a) is composed of 75 to 100 mol% of terephthalic acid, aromatic dicarboxylic acid other than terephthalic acid and at least 25 to 0 mol% of aliphatic dicarboxylic acids having 4 to 20 carbon atoms, and the diamine component (b). ) Is composed of at least one aliphatic diamine having 10 to 18 carbon atoms. A molded article of the polyamide resin composition according to claim 1.