Polyamide composition and molded article

Abstract

The purpose of the present invention is to provide a polyamide composition which can be molded into a molded body having excellent impact resistance at low temperatures and excellent toughness at low temperatures. The purpose of the present invention is also to provide a molded article having excellent impact resistance at low temperatures and excellent toughness at low temperatures. The polyamide composition contains an aliphatic polyamide and an elastomer comprising a reactive functional group. When the polyamide composition is made to flow at 270 DEG C and then molded into a test piece by injection into a mold at 80 DEG C, the stable fraction of the aliphatic polyamide crystal structure in the test piece is 0.55 or more and less than 1.00. The molded body contains an aliphatic polyamide and an elastomer containing a reactive functional group. The stable fraction of the aliphatic polyamide crystal structure in the molded article is 0.55 or more but less than 1.00. The stable fraction is represented by Sp / (Sp + Mp). And Sp is the peak area derived from the stable crystal in an X-ray diffraction pattern. Mp is a peak area derived from a metastable crystal in an X-ray diffraction pattern.

Description

Technical Field

[0001] The present invention relates to a polyamide composition and a molded article. Background Art

[0002] Polyamides, particularly polyamide 6, are widely used in electrical / electronic components, automotive components, etc. because they have a good balance of mechanical properties, heat resistance, chemical resistance, and moldability. However, since the applications applicable to molded articles made of polyamide alone are limited, performance improvement is often achieved by forming an alloy with other resins (see Patent Document 1). For example, impact resistance is improved by dispersing a modified polyolefin in a polyamide matrix in the form of particles (see Patent Document 2).

[0003] With the increasing attention to environmental issues and greenhouse gas reduction, the required characteristics of molded articles using polyamides are becoming more sophisticated and diverse, and mechanical properties at around -40°C are also being required (see Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a polyamide composition that can be formed into a molded article having excellent impact resistance and excellent toughness at low temperatures. Another object of the present invention is to provide a molded article having excellent impact resistance and excellent toughness at low temperatures.

Means for Solving the Problems

[0006] To solve this problem, the present inventors conducted research and found that the yield strain (specifically, tensile yield strain) of a molded article at a low temperature of -40°C is affected by the crystal structure of the aliphatic polyamide contained in the molded article. In addition, it was also found that the crystal structure of the aliphatic polyamide can be mainly adjusted by an elastomer.

[0007] The present invention has been completed based on the above findings and has the configuration of the following [1]. [1] A polyamide composition, characterized by containing an aliphatic polyamide and an elastomer containing reactive functional groups, When the polyamide composition is injected into a mold at 80°C after being made to flow at 270°C and molded into a test piece, the fraction of the stable form of the aliphatic polyamide crystal structure in the test piece is 0.55 or more and less than 1.00. The fraction of the stable form is represented by S p / (S p + M p ). S p is the peak area derived from the stable form crystals in the X-ray diffraction pattern. M p is the peak area derived from the metastable form crystals in the X-ray diffraction pattern.

[0008] According to [1], by making the polyamide composition contain an elastomer having a reactive functional group, the impact resistance of a molded article made of the polyamide composition can be improved. Specifically, the impact resistance at low temperatures (for example, -40°C) can be improved. Further, by making the elastomer contain a reactive functional group, the compatibility with the aliphatic polyamide can be improved, and as a result, excessive pulsation of strands during the production of the polyamide composition can be suppressed.

[0009] Also, by making the stable fraction (i.e., the stable fraction of the aliphatic polyamide crystal structure in the test piece formed by injecting the polyamide composition after flowing at 270 °C into a mold at 80 °C) 0.55 or more, the toughness of the molded body made of the polyamide composition can be improved. Specifically, the toughness at low temperatures (e.g., -40 °C) can be improved. This will be described below. In polyamide 6, α-type crystals and γ-type crystals are known. In α-type crystals, adjacent molecular chains constituting the α-type crystals are in opposite directions, i.e., arranged antiparallel. The molecular chains constituting the α-type crystals are fully extended and form hydrogen bonds with adjacent molecular chains. In α-type crystals, the lamellae formed by these molecular chains are stacked on top of each other. On the other hand, in γ-type crystals, adjacent molecular chains constituting the γ-type crystals are arranged in parallel. Compared with the molecular chains constituting the α-type crystals, the molecular chains constituting the γ-type crystals exhibit a slightly contracted conformation and form hydrogen bonds with adjacent molecular chains. In γ-type crystals, the folded lamellae formed by these molecular chains are stacked on top of each other. Compared with α-type crystals, γ-type crystals having such a structure are sparser and are crystals with poor stability. In other words, α-type crystals are denser than γ-type crystals and are crystals with excellent stability. It can be said that α-type crystals are more difficult to collapse than γ-type crystals when an external force is applied (e.g., during a tensile test). According to [1], since the stable fraction is 0.55 or more, in the molded body made of the polyamide composition, stable crystals (e.g., when the aliphatic polyamide is polyamide 6, α-type crystals) that are more difficult to collapse than metastable crystals (e.g., when the aliphatic polyamide is polyamide 6, γ-type crystals) to a certain extent or more can be generated. Therefore, the tensile yield strain can be improved. Specifically, the tensile yield strain at low temperatures can be improved. That is, the toughness at low temperatures can be improved. In addition, in such a present specification, improving the tensile yield strain at low temperatures is also expressed as improving the toughness at low temperatures.

[0010] In the present invention, the following constitution of [2] is preferable. [2] The polyamide composition according to [1], wherein the aliphatic polyamide is polyamide 6, the stable crystal is α-type crystal, the metastable crystal is γ-type crystal.

[0011] In addition, the polyamide composition related to [2] can also be expressed in the following way. A polyamide composition, characterized in that it contains polyamide 6 and a polyamide composition containing an elastomer having reactive functional groups, when the polyamide composition is flowed at 270 °C and then injected into a mold at 80 °C to form a test piece, the α-type fraction of the polyamide 6 crystal structure in the test piece is 0.55 or more and less than 1.00, the α-type fraction is α p / (α p +γ p ) represents that α p is the peak area derived from the α-type crystal in the X-ray diffraction pattern, γ p is the peak area derived from the γ-type crystal in the X-ray diffraction pattern.

[0012] In the present invention, the following configurations [3] to [6] are preferred.

[0013] [3] The polyamide composition according to [1] or [2], wherein, based on 100 parts by mass of the total amount of the aliphatic polyamide content and the elastomer content, the content of the elastomer is 1 part by mass to 18 parts by mass.

[0014] According to [3], by making the content of the elastomer 18 parts by mass or less, the excessive pulsation of the strand during the production of the polyamide composition can be further suppressed. In addition, the viscosity when the polyamide composition flows can be prevented from becoming too high. On the other hand, by making the content of the elastomer 1 part by mass or more, the impact resistance of the molded body made of the polyamide composition can be further improved. Specifically, the impact resistance at low temperatures can be further improved.

[0015] [4] The polyamide composition according to any one of [1] to [3], wherein the reactive functional group is at least one selected from an amino group, an epoxy group, and a hydroxyl group.

[0016] According to [4], by making the reactive functional group be at least one selected from an amino group, an epoxy group, and a hydroxyl group, the stable form fraction of the molded body made of the polyamide composition can be improved. The following is an explanation. The reactivity of the amino group, epoxy group, and hydroxyl group with respect to the aliphatic polyamide is not too high. For example, compared with the acid anhydride group, the reactivity of the amino group, epoxy group, and hydroxyl group with respect to the aliphatic polyamide is lower. Therefore, the elastomer containing an amino group, an epoxy group, or a hydroxyl group does not overly hinder the crystallization of the aliphatic polyamide. As a result, compared with using an elastomer containing an acid anhydride group, when using an elastomer containing an amino group, an epoxy group, or a hydroxyl group, it is easier to generate and / or grow stable form crystals. Therefore, by making the reactive functional group be at least one selected from an amino group, an epoxy group, and a hydroxyl group, the stable form fraction of the molded body made of the polyamide composition can be improved.

[0017] [5] The polyamide composition according to any one of [1] to [4], wherein the reactive functional group is at least one of an amino group and an epoxy group.

[0018] According to [5], by making the reactive functional group be at least one of an amino group and an epoxy group, the stable form fraction of the molded body made of the polyamide composition can be improved.

[0019] [6] The polyamide composition according to any one of [1] to [5], wherein when the -40°C tensile yield strain of the test piece is set as X% and the -40°C tensile yield strain of an aliphatic polyamide test piece formed by injecting the aliphatic polyamide after flowing at 270°C into a mold at 80°C is set as Y%, the ratio of X to Y is 0.95 or more.

[0020] The present invention may also have the configuration of the following [7]. [7] A molded article, characterized by containing an aliphatic polyamide and an elastomer containing a reactive functional group, the stable form fraction of the crystal structure of the aliphatic polyamide being 0.55 or more and less than 1.00, the stable form fraction being represented by S p / (S p +M p ), S p being the peak area derived from the stable form crystal in the X-ray diffraction pattern, M p being the peak area derived from the metastable form crystal in the X-ray diffraction pattern.

[0021] According to [7], by making the molded article contain an elastomer having a reactive functional group, the impact resistance can be improved. Specifically, the impact resistance at low temperatures can be improved.

[0022] Moreover, by making the stable fraction (i.e., the stable fraction of the aliphatic polyamide crystal structure in the molded article) 0.55 or more, excellent toughness can be exhibited at low temperatures. This will be described below. In polyamide 6, α-type crystals and γ-type crystals are known. In α-type crystals, adjacent molecular chains constituting the α-type crystals are in opposite directions, i.e., arranged in an antiparallel manner. The molecular chains constituting the α-type crystals are fully extended and form hydrogen bonds with adjacent molecular chains. In α-type crystals, the lamellae formed by these molecular chains are stacked on top of each other. On the other hand, in γ-type crystals, adjacent molecular chains constituting the γ-type crystals are arranged in parallel. Compared with the molecular chains constituting the α-type crystals, the molecular chains constituting the γ-type crystals exhibit a slightly contracted conformation and form hydrogen bonds with adjacent molecular chains. In γ-type crystals, the pleated lamellae formed by these molecular chains are stacked on top of each other. Compared with α-type crystals, γ-type crystals having such a structure are sparser and are less stable crystals. In other words, α-type crystals are denser than γ-type crystals and are crystals with excellent stability. It can be said that α-type crystals are more difficult to collapse than γ-type crystals when an external force is applied (for example, during a tensile test). According to [7], since the stable fraction is 0.55 or more, that is, there are stable crystals (for example, when the aliphatic polyamide is polyamide 6, it is α-type crystals) that are more difficult to collapse than metastable crystals (for example, when the aliphatic polyamide is polyamide 6, it is γ-type crystals) to a certain extent, the tensile yield strain can be increased. Specifically, the tensile yield strain at low temperatures can be increased. That is, the toughness at low temperatures can be improved.

[0023] In the present invention, the following constitution of [8] is preferable. [8] The molded article according to [7], wherein the aliphatic polyamide is polyamide 6, the stable crystal is α-type crystal, the metastable crystal is γ-type crystal.

[0024] In addition, the molded article related to [8] can also be expressed in the following way. A molded article, characterized in that it contains polyamide 6 and an elastomer containing reactive functional groups, the α-fraction of the polyamide 6 crystal structure is 0.55 or more and less than 1.00, the α-fraction is represented by α p / (α p +γ p ), α p is the peak area derived from α-type crystals in the X-ray diffraction pattern, γ p is the peak area derived from γ-type crystals in the X-ray diffraction pattern.

[0025] In the present invention, the following configurations [9] to

[26] are also preferred.

[0026] [9] The polyamide composition according to any one of [1] to [6], wherein the elastomer is a styrene-based thermoplastic elastomer.

[0027]

[10] The polyamide composition according to any one of [1] to [6] and [9], wherein the elastomer is a styrene-butadiene-styrene triblock copolymer (SBS) or a styrene-ethylene-butene-styrene copolymer (SEBS).

[0028]

[11] The polyamide composition according to any one of [1] to [6], [9] and

[10] , wherein the elastomer is a styrene-ethylene-butene-styrene copolymer (SEBS).

[0029]

[12] The polyamide composition according to any one of [1] to [6], wherein the elastomer is an olefin-unsaturated carboxylic acid ester copolymer.

[0030]

[13] The polyamide composition according to

[12] , wherein the unsaturated carboxylic acid ester of the olefin-unsaturated carboxylic acid ester copolymer is glycidyl acrylate or glycidyl methacrylate.

[0031]

[14] The polyamide composition according to any one of [1] to [6],

[12] and

[13] , wherein the elastomer is an ethylene-unsaturated carboxylic acid ester copolymer.

[0032]

[15] The polyamide composition according to any one of [1] to [6] and [9] to

[14] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 30% by mass or more or 50% by mass or more.

[0033]

[16] The polyamide composition according to any one of [1] to [6] and [9] to

[14] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 70% by mass or more or 80% by mass or more.

[0034]

[17] The polyamide composition according to any one of [1] to [6] and [9] to

[14] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 90% by mass or more or 95% by mass or more.

[0035]

[18] The polyamide composition according to any one of [1] to [6] and [9] to

[14] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 97% by mass or more.

[0036]

[19] The polyamide composition according to any one of [1] to [6] and [9] to

[18] , wherein the stable form fraction is 0.60 or more or 0.65 or more.

[0037]

[20] The polyamide composition according to any one of [1] to [6] and [9] to

[18] , wherein the stable form fraction is 0.70 or more or 0.75 or more.

[0038]

[21] The polyamide composition according to any one of [1] to [6] and [9] to

[18] , wherein the stable form fraction is 0.80 or more.

[0039]

[22] The polyamide composition according to any one of [1] to [6] and [9] to

[21] , wherein the stable form fraction is 0.96 or less or 0.95 or less.

[0040]

[23] The polyamide composition according to any one of [1] to [6] and [9] to

[21] , wherein the stable form fraction is 0.94 or less or 0.93 or less.

[0041]

[24] The polyamide composition according to any one of [1] to [6] and [9] to

[21] , wherein the stable form fraction is 0.92 or less or 0.91 or less.

[0042]

[25] The polyamide composition according to any one of [1] to [6] and [9] to

[21] , wherein the stable form fraction is 0.90 or less.

[0043]

[26] A shaped article, characterized in that it is a shaped article obtained by shaping the polyamide composition according to any one of [1] to [6] and [9] to

[25] .

[0044] In the present invention, the following constitutions

[27] to

[43] are also preferred.

[0045]

[27] The shaped article according to [7] or [8], wherein the elastomer is a styrene-based thermoplastic elastomer.

[0046]

[28] The shaped article according to any one of [7], [8] and

[27] , wherein the elastomer is a styrene-butadiene-styrene triblock copolymer (SBS) or a styrene-ethylene-butene-styrene copolymer (SEBS).

[0047]

[29] The shaped article according to any one of [7], [8],

[27] and

[28] , wherein the elastomer is a styrene-ethylene-butene-styrene copolymer (SEBS).

[0048]

[30] The molded article according to [7] or [8], wherein the elastomer is an olefin-unsaturated carboxylic acid ester copolymer.

[0049]

[31] The molded article according to

[30] , wherein the unsaturated carboxylic acid ester of the olefin-unsaturated carboxylic acid ester copolymer is glycidyl acrylate or glycidyl methacrylate.

[0050]

[32] The molded article according to any one of [7], [8],

[30] , and

[31] , wherein the elastomer is an ethylene-unsaturated carboxylic acid ester copolymer.

[0051]

[33] The molded article according to any one of [7], [8],

[27] to

[32] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 30% by mass or more, or 50% by mass or more.

[0052]

[34] The molded article according to any one of [7], [8],

[27] to

[32] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 70% by mass or more, or 80% by mass or more.

[0053]

[35] The molded article according to any one of [7], [8],

[27] to

[32] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 90% by mass or more, or 95% by mass or more.

[0054]

[36] The molded article according to any one of [7], [8],

[27] to

[32] , wherein the total amount of the aliphatic polyamide content and the elastomer content is 97% by mass or more.

[0055]

[37] The molded article according to any one of [7], [8],

[27] to

[36] , wherein the stable fraction is 0.60 or more, or 0.65 or more.

[0056]

[38] The molded article according to any one of [7], [8],

[27] to

[36] , wherein the stable fraction is 0.70 or more, or 0.75 or more.

[0057]

[39] The molded article according to any one of [7], [8],

[27] to

[36] , wherein the stable fraction is 0.80 or more.

[0058]

[40] The molded article according to any one of [7], [8],

[27] to

[39] , wherein the stable fraction is 0.96 or less, or 0.95 or less.

[0059]

[41] The molded article according to any one of [7], [8],

[27] to

[39] , wherein the stable form fraction is 0.94 or less or 0.93 or less.

[0060]

[42] The molded article according to any one of [7], [8],

[27] to

[39] , wherein the stable form fraction is 0.92 or less or 0.91 or less.

[0061]

[43] The molded article according to any one of [7], [8],

[27] to

[39] , wherein the stable form fraction is 0.90 or less.

Advantages of the Invention

[0062] According to the present invention, a polyamide composition capable of forming a molded article having excellent impact resistance and excellent toughness at low temperatures can be provided. According to the present invention, a molded article having excellent impact resistance and excellent toughness at low temperatures can be provided. Detailed Description of the Embodiments

[0063] Hereinafter, the embodiments of the present invention will be described in detail.

[0064] <1. Polyamide Composition> The polyamide composition of the present embodiment contains an aliphatic polyamide. Examples of the aliphatic polyamide include polyamide 6, polyamide 8, polyamide 10, and polyamide 12. Among them, polyamide 6 is preferred.

[0065] Polyamide 6 may be a polyamide resin mainly made from ε-caprolactam and / or 6-aminocaproic acid. Among them, a polyamide resin mainly made from ε-caprolactam is preferred. In polyamide 6, other monomers may also be copolymerized. As such monomers, for example, amino acids such as 11-aminoundecanoic acid, 12-aminododecanoic acid, and p-aminomethylbenzoic acid, lactams such as ω-laurolactam; aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine; aromatic diamines such as m-xylylenediamine and p-xylylenediamine; alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, sodium 5-sulfoisophthalate, hexahydroterephthalic acid, and hexahydroisophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid. Two or more of these may also be copolymerized.

[0066] In 100 mol% of the total amount of monomer units constituting polyamide 6, the total amount of units derived from ε-caprolactam and units derived from 6-aminocaproic acid is preferably 60 mol% or more, more preferably 70 mol% or more, further preferably 80 mol% or more, and still further preferably 90 mol% or more. This may also be 100 mol%. The preferred ranges of the number of units derived from ε-caprolactam and the number of units derived from 6-aminocaproic acid are the same. That is, the description of the total amount of units derived from ε-caprolactam and units derived from 6-aminocaproic acid can be used as the description of the number of units derived from ε-caprolactam and the number of units derived from 6-aminocaproic acid.

[0067] The relative viscosity of the aliphatic polyamide is preferably 1.5 or more, more preferably 2.0 or more, and further preferably 2.5 or more. When it is 1.5 or more, the toughness at low temperatures can be further improved. The relative viscosity of polyamide 6 is preferably 5.0 or less, more preferably 4.5 or less, and further preferably 4.0 or less. When it is 5.0 or less, the excessive decrease in fluidity when melting and flowing the polyamide composition can be suppressed. The relative viscosity is a value measured at 25 °C using 96% sulfuric acid for a 1 g / dL sample (such as polyamide 6) according to JIS K6920-2:2009.

[0068] The polyamide composition of this embodiment further contains an elastomer having reactive functional groups. By making the polyamide composition contain an elastomer having reactive functional groups, the impact resistance of the molded article made of the polyamide composition can be improved. Specifically, the impact resistance at low temperatures (e.g., -40°C) can be improved. Moreover, by making the elastomer contain reactive functional groups, the compatibility with aliphatic polyamides can be improved. As a result, excessive pulsation of the strands during the production of the polyamide composition can be suppressed.

[0069] Examples of the elastomer include diene rubbers such as polybutadiene, polyisoprene, styrene-butadiene random copolymer, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, acrylonitrile-butadiene copolymer, and butadiene-isoprene copolymer. In addition to these, ethylene-propylene random copolymer, ethylene-propylene block copolymer, ethylene-butene random copolymer, ethylene-butene block copolymer, and copolymers of ethylene and α-olefins can also be cited. Ethylene-unsaturated carboxylate copolymers such as ethylene-methyl acrylate and ethylene-butyl acrylate can also be cited. Acrylate-butadiene copolymers such as butyl acrylate-butadiene copolymer can also be cited. Copolymers of ethylene and vinyl fatty acid esters such as ethylene-vinyl acetate, ethylene-propylene-norbornene copolymer, ethylene-propylene-hexadiene copolymer, and other ethylene-propylene non-conjugated diene terpolymers, butene-isoprene copolymer, chlorinated polyethylene, polyamide elastomer, polyester elastomer, etc. can also be cited. In addition, these can be used alone or in combination of two or more.

[0070] Although there is some repetition with the examples of elastomers listed above, from another perspective, examples of elastomers include amide-based thermoplastic elastomers, ester-based thermoplastic elastomers, olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and crosslinked thermoplastic rubbers.

[0071] As the elastomer, a thermoplastic elastomer is preferred, and a styrenic thermoplastic elastomer is more preferred. As the styrenic thermoplastic elastomer, for example, styrene-isoprene diblock copolymer, styrene-butadiene diblock copolymer, styrene-isoprene-styrene triblock copolymer, styrene-butadiene / isoprene-styrene triblock copolymer, styrene-butadiene-styrene triblock copolymer (SBS), and their hydrogenated products (i.e., the products obtained by hydrogenating these copolymers) can be cited. As the hydrogenated product, for example, styrene-ethylene-butene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer, styrene-ethylene-ethylene-propylene-styrene copolymer, and styrene-butene-butadiene-styrene copolymer can be cited. Among them, SBS and SEBS are preferred, and SEBS is more preferred. In addition, these can be used alone or in combination of two or more.

[0072] The melt flow rate (i.e., MFR) of the styrenic thermoplastic elastomer can be, for example, 0.5 g / 10 min or more, 1.0 g / 10 min or more, 1.5 g / 10 min or more, 2.0 g / 10 min or more. The melt flow rate can be, for example, 10.0 g / 10 min or less, 8.0 g / 10 min or less, 6.0 g / 10 min or less. The melt flow rate of the styrenic thermoplastic elastomer is the value measured according to JIS K 7210-1 2014 at 230 °C under a load of 2.16 kg.

[0073] As the elastomer, an olefin-unsaturated carboxylic acid ester copolymer such as an ethylene-unsaturated carboxylic acid ester copolymer is also preferred. This is because the olefin-unsaturated carboxylic acid ester copolymer has excellent compatibility with the aliphatic polyamide and can further suppress the excessive pulsation of the strand during the production of the polyamide composition.

[0074] As the olefin of the olefin-unsaturated carboxylic acid ester copolymer, for example, ethylene and α-olefins having 3 or more carbon atoms can be cited. As the α-olefins having 3 or more carbon atoms, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 1-undecene can be cited. In addition, the number of carbon atoms of the α-olefins having 3 or more carbon atoms can be, for example, 30 or less, 20 or less, 15 or less. Among them, ethylene is preferred. In addition, these can be used alone or in combination of two or more.

[0075] As the unsaturated carboxylic acid ester of the olefin-unsaturated carboxylic acid ester copolymer, for example, unsaturated carboxylic acid esters containing reactive functional groups such as glycidyl acrylate and glycidyl methacrylate can be cited. Among them, glycidyl acrylate is preferred. On the other hand, as other unsaturated carboxylic acid esters (that is, unsaturated carboxylic acid esters other than unsaturated carboxylic acid esters containing epoxy groups), (meth)acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, and tert-butyl methacrylate can be cited. Among them, methyl acrylate and ethyl acrylate are preferred, and methyl acrylate is more preferred. In addition, these can be used alone or two or more of them can be used.

[0076] In 100% by mass of the olefin-unsaturated carboxylic acid ester copolymer, the amount of the unsaturated carboxylic acid ester containing a reactive functional group is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and still more preferably 2% by mass or more. When it is 0.1% by mass or more, the compatibility with the aliphatic polyamide can be further improved, and the impact resistance of the molded body made of the polyamide composition can be further improved. Specifically, the impact resistance at low temperature can be further improved. On the other hand, the amount of the unsaturated carboxylic acid ester containing a reactive functional group is preferably 10% by mass or less, more preferably 7% by mass or less, and still more preferably 5% by mass or less.

[0077] The melt flow rate (i.e., MFR) of the olefin-unsaturated carboxylic acid ester copolymer can be, for example, 0.5 g / 10 min or more, 2.0 g / 10 min or more, 3.0 g / 10 min or more, 4.0 g / 10 min or more, 5.0 g / 10 min or more. The melt flow rate can be, for example, 10.0 g / 10 min or less, 9.0 g / 10 min or less, 8.0 g / 10 min or less. The melt flow rate of the olefin-unsaturated carboxylic acid ester copolymer is a value measured according to JIS K 7210-1 2014 at 190 °C under a load of 21.2 N.

[0078] A reactive functional group is a functional group capable of reacting with an aliphatic polyamide. Specifically, it is a functional group capable of reacting with the functional group of an aliphatic polyamide. For example, as the reactive functional group, for example, amino group, carboxyl group, hydroxyl group, acid anhydride group, epoxy group, isocyanate group, mercapto group, oxazoline group, sulfonic acid group can be cited. Among them, amino group, epoxy group, and hydroxyl group are preferred, and amino group and epoxy group are more preferred. This is because the stability fraction of the molded body made of the polyamide composition can be improved by these reactive functional groups. The following will explain this. The reactivity of amino group, epoxy group, and hydroxyl group with respect to aliphatic polyamide is not too high. For example, compared with the acid anhydride group, the reactivity of amino group, epoxy group, and hydroxyl group with respect to aliphatic polyamide is lower. Therefore, the elastomer containing amino group, epoxy group, or hydroxyl group does not overly hinder the crystallization of aliphatic polyamide. As a result, when using an elastomer containing amino group, epoxy group, or hydroxyl group, it is easier to generate and / or grow stable crystals compared to using an elastomer containing an acid anhydride group. Therefore, by making the reactive functional group be amino group, epoxy group, or hydroxyl group, the stability fraction of the molded body made of the polyamide composition can be improved. In addition, the elastomer can contain one or more of these reactive functional groups.

[0079] As a method for introducing the reactive functional group, for example, a method of copolymerizing a monomer having a reactive functional group and a method of graft polymerization can be cited. For example, by copolymerizing at least an olefin and an unsaturated carboxylic acid ester such as glycidyl acrylate, an olefin-unsaturated carboxylic acid ester copolymer containing an epoxy group can be obtained.

[0080] The content of the elastomer containing a reactive functional group is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and further preferably 10 parts by mass or more, based on 100 parts by mass of the total amount of the aliphatic polyamide content and the elastomer content containing a reactive functional group. When it is 1 part by mass or more, the impact resistance of the molded body made of the polyamide composition can be further improved. Specifically, the impact resistance at low temperature can be further improved. The content of the elastomer containing a reactive functional group is preferably 18 parts by mass or less, more preferably 17 parts by mass or less, further preferably 16 parts by mass or less, and further preferably 15 parts by mass or less. When it is 18 parts by mass or less, it is sometimes possible to further suppress the excessive pulsation of the strands during the production of the polyamide composition. In addition, sometimes it is possible to avoid making the viscosity too high when the polyamide composition flows.

[0081] The elastomer containing a reactive functional group can be dispersed in the polyamide composition of the present embodiment. For example, the elastomer containing a reactive functional group can be dispersed in the form of particles in the continuous phase containing an aliphatic polyamide. In this case, the polyamide composition of the present embodiment can contain a continuous phase containing an aliphatic polyamide and a dispersed phase containing an elastomer containing a reactive functional group.

[0082] The polyamide composition of the present embodiment may also contain components other than aliphatic polyamides and elastomers containing reactive functional groups, such as elastomers without reactive functional groups, light or heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, lubricants, crystal nucleating agents, mold release agents, antistatic agents, halogen-based flame retardants, antimony trioxide, phosphoric acid-based flame retardants, melamine-based flame retardants, inorganic pigments, organic pigments, and dyes. Of course, the polyamide composition of the present embodiment may also contain polyamides other than aliphatic polyamides and various polymers.

[0083] In 100% by mass of the polyamide contained in the polyamide composition of the present embodiment, the amount of the aliphatic polyamide is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably 100% by mass.

[0084] In 100% by mass of the polyamide composition of the present embodiment, the total amount of the content of the aliphatic polyamide and the content of the elastomer containing reactive functional groups is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and further preferably 97% by mass or more. The total amount of the content of the aliphatic polyamide and the content of the elastomer containing reactive functional groups may also be 100% by mass.

[0085] When the polyamide composition of the present embodiment is formed into a test piece (hereinafter sometimes referred to as "polyamide composition test piece"), the stable form fraction of the aliphatic polyamide crystal structure, that is, S p / (S p +M p ) is 0.55 or more and less than 1.00. Here, S p is the peak area derived from the stable form crystal in the X-ray diffraction pattern. M p is the peak area derived from the metastable form crystal in the X-ray diffraction pattern. In addition, the polyamide composition test piece is formed by injecting the polyamide composition of the present embodiment after flowing at 270 °C into a mold at 80 °C. The stable form fraction can be determined by X-ray diffraction.

[0086] By making the stable fraction (i.e., the stable fraction of the aliphatic polyamide crystal structure in the test piece formed by injecting the polyamide composition after flowing at 270 °C into a mold at 80 °C) 0.55 or more, the toughness of the molded article made of the polyamide composition can be improved. Specifically, the toughness at low temperatures (e.g., -40 °C) can be improved. This will be described below. In polyamide 6, α-type crystals and γ-type crystals are known. In α-type crystals, adjacent molecular chains constituting the α-type crystals are in opposite directions, that is, arranged in an antiparallel manner. The molecular chains constituting the α-type crystals are fully extended and form hydrogen bonds with adjacent molecular chains. In α-type crystals, the lamellae formed by these molecular chains are stacked on top of each other. On the other hand, in γ-type crystals, adjacent molecular chains constituting the γ-type crystals are arranged in parallel. Compared with the molecular chains constituting the α-type crystals, the molecular chains constituting the γ-type crystals exhibit a slightly contracted conformation and form hydrogen bonds with adjacent molecular chains. In γ-type crystals, the pleated lamellae formed by these molecular chains are stacked on top of each other. Compared with α-type crystals, γ-type crystals with such a structure are sparser and are less stable crystals. In other words, α-type crystals are denser than γ-type crystals and are crystals with excellent stability. It can be said that α-type crystals are more difficult to collapse than γ-type crystals when an external force is applied (e.g., during a tensile test). According to the present embodiment, since the stable fraction is 0.55 or more, in the molded article made of the polyamide composition, stable crystals (e.g., when the aliphatic polyamide is polyamide 6, it is α-type crystals) that are more difficult to collapse than metastable crystals (e.g., when the aliphatic polyamide is polyamide 6, it is γ-type crystals) can be generated to a certain extent or more. Therefore, the tensile yield strain can be improved. Specifically, the tensile yield strain at low temperatures can be improved. That is, the toughness at low temperatures can be improved.

[0087] The stable fraction is preferably 0.60 or more, more preferably 0.65 or more, further preferably 0.70 or more, further preferably 0.75 or more, further preferably 0.80 or more. The stable fraction can also be, for example, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less.

[0088] For the stability fraction, for example, it can be adjusted by the content of the elastomer containing reactive functional groups, the type of reactive functional groups of the elastomer, the melting temperature during the production of the polyamide composition, the screw speed of the melt kneading during the production of the polyamide composition, the melting temperature when forming the polyamide composition test piece, and the temperature of the mold when forming the polyamide composition test piece. For example, in polyamide 6, the higher the melting temperature when forming the polyamide composition test piece and the temperature of the mold when forming the polyamide composition test piece, the higher the stability fraction. This is because the crystallization temperature of the α-type crystal is higher than that of the γ-type crystal. In addition, the type of reactive functional groups of the elastomer tends to have a relatively large influence on the stability fraction.

[0089] The -40°C tensile yield strain of the polyamide composition test piece is preferably 7.5% or more, more preferably 7.7% or more, and still more preferably 7.8% or more. The -40°C tensile yield strain of the polyamide composition test piece can be, for example, 9.0% or less, 8.5% or less, 8.3% or less.

[0090] Preferably, when the -40°C tensile yield strain of the polyamide composition test piece is set to X% and the -40°C tensile yield strain of the aliphatic polyamide test piece formed by injecting the aliphatic polyamide that has flowed at 270°C into a mold at 80°C is set to Y%, the ratio of X to Y is 0.95 or more. When it is 0.95 or more, it can be said that the -40°C tensile yield strain of the polyamide composition test piece is equivalent to or higher than the -40°C tensile yield strain of the aliphatic polyamide. Therefore, it can be said that the toughness of the molded body made of the polyamide composition, specifically, the toughness at low temperature is equivalent to or higher than that of the molded body made of only the aliphatic polyamide. This ratio is preferably 0.98 or more, more preferably 1.00 or more. This ratio can be, for example, 1.10 or less, 1.07 or less, 1.05 or less, 1.04 or less, 1.03 or less.

[0091] In addition, the -40°C Charpy impact strength of the polyamide composition test piece is preferably 3.0 kJ / m 2 or more.

[0092] The polyamide composition of this embodiment can be manufactured by at least melt-kneading an aliphatic polyamide and an elastomer containing reactive functional groups. For melt-kneading, an extruder (such as a single-screw extruder, a twin-screw extruder), a kneader, a Banbury mixer, a rolling mill, etc. can be used. Among them, an extruder is preferred, and a twin-screw extruder is more preferred.

[0093] For example, the polyamide composition of the present embodiment can be produced by the following method: at least an aliphatic polyamide and an elastomer containing a reactive functional group are melt-kneaded in a twin-screw extruder and then extruded into strands, and the strands are cooled as needed and cut as needed. In addition, as a method of feeding the above components (for example, aliphatic polyamide, elastomer containing a reactive functional group) into the twin-screw extruder, for example, a method of mixing the components with a tumbler, Henschel mixer, etc. and then feeding them into the twin-screw extruder from a hopper all at once, or a method of feeding a part of the components from a side port of the twin-screw extruder can be cited.

[0094] The screw speed of the twin-screw extruder is preferably 50 rpm or more, more preferably 100 rpm or more, and further preferably 150 rpm or more. When it is 50 rpm or more, the reaction between the aliphatic polyamide and the elastomer containing a reactive functional group easily proceeds, so the compatibility can be further improved. On the other hand, the screw speed of the twin-screw extruder is preferably 400 rpm or less, more preferably 300 rpm or less, and further preferably 250 rpm or less. When it is 400 rpm or less, an excessive temperature rise due to shear heating can be suppressed, so the decomposition of the aliphatic polyamide can be suppressed. In addition, the barrel temperature can be set appropriately.

[0095] The screws of the twin-screw extruder can be appropriately combined and used, such as full-flight screws, reverse full-flight screws, orthogonal kneading elements, forward kneading elements, reverse kneading elements, etc. Preferably, a kneading element in the forward conveying direction is added to the screw configuration in the plasticizing region.

[0096] The shape of the polyamide composition of the present embodiment can be set appropriately. The polyamide composition of the present embodiment can be formed into any shape such as pellet form, strand form, powder form, etc. Among them, pellet form is preferred.

[0097] <2. Formed body> The formed body of the present embodiment contains an aliphatic polyamide. Since the description of the aliphatic polyamide is repeated with the above description (that is, the description of the aliphatic polyamide in the polyamide composition), it is omitted. Therefore, the description of the aliphatic polyamide in the polyamide composition can be used as the description of the aliphatic polyamide in the formed body.

[0098] The formed body of the present embodiment contains an elastomer containing a reactive functional group. The description of the excellent elastomer containing a reactive functional group is repeated with the above description (that is, the description of the elastomer containing a reactive functional group in the polyamide composition), so it is omitted. Therefore, the description of the elastomer containing a reactive functional group in the polyamide composition can be used as the description of the elastomer containing a reactive functional group in the formed body. In addition, of course, the description of the content of the elastomer (specifically, the elastomer containing reactive functional groups) in the polyamide composition can also be used as the description of the content of the elastomer (specifically, the elastomer containing reactive functional groups) in the molded article.

[0099] The molded article of the present embodiment may also contain components other than the aliphatic polyamide and the elastomer containing reactive functional groups. For example, an elastomer without reactive functional groups, a light or heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, a lubricant, a crystal nucleating agent, a mold release agent, an antistatic agent, a halogen-based flame retardant, antimony trioxide, a phosphoric acid-based flame retardant, a melamine-based flame retardant, an inorganic pigment, an organic pigment, a dye. Of course, the molded article of the present embodiment may also contain a polyamide other than the aliphatic polyamide, a variety of polymers.

[0100] In 100% by mass of the polyamide contained in the molded article of the present embodiment, the amount of the aliphatic polyamide is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably 100% by mass.

[0101] In 100% by mass of the molded article of the present embodiment, the total amount of the content of the aliphatic polyamide and the content of the elastomer containing reactive functional groups is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and further preferably 97% by mass or more. The total amount of the content of the aliphatic polyamide and the content of the elastomer containing reactive functional groups may also be 100% by mass.

[0102] In the molded article of the present embodiment, the stable fraction of the crystal structure of the aliphatic polyamide is 0.55 or more and less than 1.00. That is, S p / (S p +M p ) is 0.55 or more and less than 1.00. Here, S p is the peak area derived from the stable crystal in the X-ray diffraction pattern. M p is the peak area derived from the metastable crystal in the X-ray diffraction pattern. In addition, the stable fraction can be determined by X-ray diffraction.

[0103] By making the stable form fraction (i.e., the stable form fraction of the aliphatic polyamide crystal structure in the molded article) 0.55 or more, excellent toughness at low temperatures can be exhibited. This will be described below. In polyamide 6, α-type crystals and γ-type crystals are known. In α-type crystals, adjacent molecular chains constituting the α-type crystals are in opposite directions, that is, they are arranged in an antiparallel manner. The molecular chains constituting the α-type crystals are fully extended and form hydrogen bonds with adjacent molecular chains. In α-type crystals, the lamellae formed by these molecular chains are stacked on top of each other. On the other hand, in γ-type crystals, adjacent molecular chains constituting the γ-type crystals are arranged in parallel. Compared with the molecular chains constituting the α-type crystals, the molecular chains constituting the γ-type crystals exhibit a slightly contracted conformation and form hydrogen bonds with adjacent molecular chains. In γ-type crystals, the folded lamellae formed by these molecular chains are stacked on top of each other. Compared with α-type crystals, γ-type crystals having such a structure are sparser and are crystals with poor stability. In other words, α-type crystals are denser than γ-type crystals and are crystals with excellent stability. It can be said that α-type crystals are more difficult to collapse than γ-type crystals when an external force is applied (for example, when a tensile test is performed). According to the present embodiment, the stable form fraction is 0.55 or more, that is, there are stable form crystals (for example, when the aliphatic polyamide is polyamide 6, it is α-type crystals) that are more difficult to collapse than metastable crystals (for example, when the aliphatic polyamide is polyamide 6, it is γ-type crystals) to a certain extent or more. Therefore, the tensile yield strain can be increased, specifically, the tensile yield strain at low temperatures can be increased. That is, the toughness at low temperatures can be improved.

[0104] The stable form fraction is preferably 0.60 or more, more preferably 0.65 or more, further preferably 0.70 or more, further preferably 0.75 or more, further preferably 0.80 or more. The stable form fraction can also be, for example, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less.

[0105] The molded article of the present embodiment can be obtained by molding the polyamide composition of the present embodiment described above. That is, the molded article of the present embodiment can be obtained from the polyamide composition of the present embodiment described above. As the molding method, for example, injection molding, extrusion molding, blow molding, etc. can be cited. Among them, injection molding is preferred.

[0106] Although the melting temperature during the formation of the molded article can be appropriately set according to the type of aliphatic polyamide, it is preferably 15 °C or more higher than the melting point of the aliphatic polyamide. When the aliphatic polyamide is polyamide 6, the melting temperature is preferably 240 °C or more, more preferably 250 °C or more, further preferably 260 °C or more, further preferably 265 °C or more, and further preferably 270 °C or more. When it is 240 °C or more, the generation of unmelted matter and short shot can be reduced. On the other hand, the melting temperature is preferably 300 °C or less, more preferably 290 °C or less, further preferably 285 °C or less, and further preferably 280 °C or less. When it is 300 °C or less, the decomposition of polyamide 6 can be suppressed.

[0107] When forming the molded article with a mold, although the temperature of the mold can be appropriately set according to the type of aliphatic polyamide, in order to promote the crystallization of the aliphatic polyamide, it is preferably 20 °C or more higher than the glass transition temperature of the aliphatic polyamide. The temperature of the mold is more preferably 25 °C or more higher than the glass transition temperature of the aliphatic polyamide, and further preferably 30 °C or more higher than the glass transition temperature. When the aliphatic polyamide is polyamide 6, the temperature of the mold is preferably 70 °C or more, more preferably 75 °C or more, and further preferably 80 °C or more. When it is 70 °C or more, the crystallization can be effectively promoted. The temperature of the mold is preferably 100 °C or less, more preferably 90 °C or less. When it is 100 °C or less, the poor demolding from the mold due to poor curing can be suppressed, and the excessive increase in the molding cycle time due to too low a curing speed can be suppressed.

[0108] The molded article of the present embodiment can be preferably used for mechanical parts, electrical / electronic parts, vehicles (automobiles, railway vehicles, bicycles, etc.), sundry parts, etc. In particular, it can be preferably used for mechanical parts, electrical / electronic parts, vehicles, sundry parts, etc. that may be used at low temperatures.

[0109] The molded article of the present embodiment can be, for example, a pipe, a binding band, a liquid / gas transport pipe, a liquid / gas encapsulation container. In particular, it is preferably a vehicle pipe, a vehicle binding band, a vehicle liquid / gas transport pipe, a vehicle liquid / gas encapsulation container.

Examples

[0110] Examples and comparative examples are listed below to explain the present invention in more detail. Hereinafter, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0111] <1. Raw materials> The following raw materials are used. <1.1. Polyamide> A-1…… "GLAMIDE (registered trademark) T-802" manufactured by Toyobo Co., Ltd. (polyamide 6, relative viscosity 3.3)

[0112] <1.2. Elastomer> B-1…… "Tough Tec (registered trademark) MP10" manufactured by Asahi Kasei Corporation (amino-modified SEBS) B-2…… "BONDFAST (registered trademark) BF-7L" (ethylene-methyl methacrylate glycidyl ester copolymer) manufactured by Sumitomo Chemical Co., Ltd. B-3…… "Tough Tec (registered trademark) M1943" manufactured by Asahi Kasei Corporation (maleic anhydride-modified SEBS) B-4…… "TAFMER (registered trademark) MH5020" manufactured by Mitsui Chemicals, Inc. (maleic anhydride-modified EBR) B-5…… "Tough Tec (registered trademark) H1221" manufactured by Asahi Kasei Corporation (unmodified SEBS)

[0113] <2. Fabrication of Test Specimens> <2.1. Examples 1-4 and Comparative Examples 2-6> Mix polyamide and elastomer in a specified ratio (refer to Table 1). Using a twin-screw extruder Tex25 manufactured by Japan Steel Works, Ltd., melt-knead at a resin temperature of 270°C and a screw rotation speed of 150 rpm, discharge the strands into water, and cut into pellet form. After drying the pellets, using an injection molding machine J-110 manufactured by Japan Steel Works, Ltd., at a resin temperature of 270°C and a mold temperature of 80°C, mold into a 1A-shaped test specimen with a thickness of 4 mm according to JIS K 7161-2 2014.

[0114] <2.2. Comparative Example 1> Except for not blending the elastomer, pellets and 1A-shaped test specimens were manufactured in the same manner as in Example 1.

[0115] <3. Evaluation Method> <3.1. Strand Stability> A case where the pulsation of the strand is so large that it causes continuous strands to be cut, i.e., it is difficult to pelletize, is judged as ×. On the other hand, a case where the pulsation of the strand is at a level that does not interfere with pelletization is judged as 〇.

[0116] <3.2. Melt Flow Rate (MFR)> After drying the pellets, they are filled into the barrel of a plastics melt flow rate instrument and extruded from the die at 280 °C under a load of 10 kg in accordance with ISO 1133, and the MFR, i.e., the melt index (g / 10 min), is determined.

[0117] <3.3. α-form fraction> A specimen is cut from the central part of the Type 1A test piece (i.e., the exact center of the narrower-width part of the Type 1A test piece), and the X-ray diffraction pattern (i.e., the X-ray diffraction curve, X-ray diffraction energy spectrum) of the specimen is obtained by wide-angle X-ray diffraction. The measurement conditions are as follows. Apparatus: Empyrean manufactured by Spectris Ancillary apparatus: Rotating specimen stage X-ray source: CuKα Output: 45 kV, 40 mA Detector: PIXcel3D From the X-ray diffraction pattern, specifically, the X-ray diffraction pattern plotted with the vertical axis as the X-ray intensity (counts per second) and the horizontal axis as 2θ (°), the peak area of the α-form crystal derived from polyamide 6 and the peak area of the γ-form crystal derived from polyamide 6 are determined. Based on these, the α-form fraction is calculated using the following formula. α-form fraction = α p / (α p + γ p ) Here, α p is the peak area of the α-form crystal derived from polyamide 6. γ p is the peak area of the γ-form crystal derived from polyamide 6.

[0118] <3.4. Tensile yield strain> In accordance with JIS K 7161-1 2014, the tensile yield strain of the Type 1A test piece is measured at -40 °C. Specifically, for the Type 1A test piece, after a tensile test is performed at -40 °C, a test speed of 50 mm / min, and a grip distance of 115 mm, the tensile yield strain is determined from the stress-strain curve obtained from the tensile test.

[0119] <3.5. Charpy impact strength> After drying the pellets, they are molded into a notched test piece using an injection molding machine J-110 manufactured by Japan Steel Works, Ltd. at a resin temperature of 270 °C and a mold temperature of 80 °C. At -40 °C, the notched Charpy impact strength is measured in accordance with ISO 179-1. When the notched Charpy impact strength is 3 kJ / m 2 or more, it is marked as 〇, and when it is less than 3 kJ / m 2 it is marked as ×.

[0120]

Table 1

[0121] By using an elastomer having a reactive functional group (specifically, B-1, B-2, B-3, B-4), the -40°C Charpy impact strength can be improved (refer to Comparative Example 1 and Examples 1 to 4 and Comparative Examples 2 to 5).

[0122] By using B-3 and B-4 as the elastomer, although the -40°C tensile yield strain decreases (refer to Comparative Example 1 and Comparative Examples 2 to 4), by using B-1 or B-2, the decrease in the -40°C tensile yield strain can be suppressed (refer to Comparative Example 1 and Examples 1 to 4). According to X-ray diffraction, a larger decrease in the α-form fraction can be observed when using B-3 and B-4 (refer to Comparative Example 1 and Comparative Examples 2 to 4), while no significant decrease in the α-form fraction is observed when using B-1 or B-2 (refer to Comparative Example 1 and Examples 1 to 4). In addition, when using B-5, the strand stability is poor.

Industrial Applicability

[0123] The present invention can provide a polyamide composition and a molded article, and thus is industrially applicable.

Claims

1. A polyamide composition, characterized in that, Containing an aliphatic polyamide and an elastomer containing reactive functional groups, When the polyamide composition is injected into a mold at 80°C after flowing at 270°C to form a test piece, the stable form fraction of the crystal structure of the aliphatic polyamide in the test piece is 0.55 or more and less than 1.00, The stable fraction is represented by S p / (S p +M p ). S p is the peak area from the stable crystal in the X-ray diffraction pattern, M p is the peak area of the metastable crystal in the X-ray diffraction pattern.

2. The polyamide composition according to claim 1, wherein, The aliphatic polyamide is polyamide 6, The stable form crystal is an α-type crystal, The metastable form crystal is a γ-type crystal.

3. The polyamide composition according to claim 1, wherein, Based on a total of 100 parts by mass of the content of the aliphatic polyamide and the content of the elastomer, the content of the elastomer is 1 part by mass to 18 parts by mass.

4. The polyamide composition according to claim 1, wherein, The reactive functional group is at least one selected from an amino group, an epoxy group, and a hydroxyl group.

5. The polyamide composition according to claim 1, wherein, The reactive functional group is at least one of an amino group and an epoxy group.

6. The polyamide composition according to claim 1, wherein, When the -40°C tensile yield strain of the test piece is set as X% and the -40°C tensile yield strain of an aliphatic polyamide test piece formed by injecting the aliphatic polyamide after flowing at 270°C into a mold at 80°C is set as Y%, the ratio of X to Y is 0.95 or more.

7. A shaped body, characterized in that, Containing an aliphatic polyamide and an elastomer containing reactive functional groups, The stable form fraction of the crystal structure of the aliphatic polyamide is 0.55 or more and less than 1.00, The stable fraction is represented by S p / (S p +M p ). S p is the peak area of the stable crystal form in the X-ray diffraction pattern, M p is the peak area of the metastable crystal in the X-ray diffraction pattern.

8. The molded body according to claim 7, wherein, The aliphatic polyamide is polyamide 6, The stable form crystal is an α-type crystal, The metastable form crystal is a γ-type crystal.

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