Polyamide resin composition, molded article and production method of molded article

Abstract

To provide a polyamide resin composition which is excellent in high-temperature refrigerant resistance, low refrigerant absorbency, low-temperature impact resistance, high-speed moldability, even thickness at extrusion molding, and circumferential direction tensile elongation, and to provide a molded article of the same.SOLUTION: A polyamide resin composition that contains (A) a polyamide resin and (B) a polyolefin resin is such that: when the total amount of (A) and (B) is 100 pts.mass, (B) is 55 pts.mass or less; in 100 pts.mass of (A), 50 pts.mass or more of polyamide having an average carbon atom number of 8 or more per monomer unit is contained; B contains polyolefin having a functional group having responsiveness to the terminal amine of (A) and an ethylene α-olefin copolymer; in a monomer unit constituting (B), a mass ratio of a unit derived from α-olefin is 3-11 mass%; and at least one melting peak of 100°C or more and less than 150°C is exhibited.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyamide resin composition, a molded article, and a method for producing the molded article.

Background Art

[0002] Polyamide resins have properties suitable as engineering plastics, such as excellent mechanical properties, thermal properties, and chemical resistance. Therefore, they are widely used in applications such as mechanical parts, automotive parts, and various electrical and electronic parts, mainly for injection molding. Among them, in electric vehicles (EVs) that are expected to rapidly expand in the future, as cooling pipes through which a refrigerant for cooling a battery passes, small-diameter and long-sized molded articles are required. As small-diameter and long-sized molded articles, it is mainstream to bend a straight tubular primary molded body obtained by extrusion molding and use it as a part. However, generally, polyamide resins are difficult to extrude because of their low melt viscosity and extensibility during melting. In addition, polyamide undergoes hydrolysis by a refrigerant, so there is also a problem of a decrease in strength.

[0003] As a method for imparting flexibility and extrusion moldability while ensuring the chemical resistance of polyamide resins, a method of improving the viscosity by adding a maleic anhydride-modified ethylene-methyl acrylate-maleic anhydride copolymer to a polyamide resin mixture mainly composed of polyamide 6 is known (Patent Document 1). In addition, it is known that a composition obtained by adding polyethylene and an ethylene-propylene-diene copolymer to polyamide 6 / 12 is excellent in extrusion moldability and barrier properties (Patent Document 2). Further, it is known that a polyamide resin obtained by adding a maleic anhydride-grafted ethylene-butene copolymer and low-density linear polyethylene to polyamide 6 is excellent in barrier properties and impact resistance (Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although the compositions described in Patent Documents 1 and 2 can be extrusion-molded, they still have further problems in achieving both high-rate moldability (high-speed moldability) and uniform wall thickness during extrusion molding. In addition, although the composition described in Patent Document 3 is excellent in impact resistance, it is difficult to perform extrusion molding. Furthermore, for the compositions described in Patent Documents 1 and 3, improvement in durability when exposed to automotive coolant water (LLC) is desired.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyamide resin composition excellent in high-temperature refrigerant resistance, low refrigerant absorption, low-temperature impact resistance, high-speed moldability, uniform wall thickness during extrusion molding, and circumferential tensile elongation, and a molded article thereof.

Means for Solving the Problems

[0007] That is, the present invention is as follows. [1] A polyamide resin composition containing (A) a polyamide resin and (B) a polyolefin resin, when the total of the (A) polyamide resin and the (B) polyolefin resin is 100 parts by mass, the total of the (B) polyolefin resin is 55 parts by mass or less, the (A) polyamide resin contains 50 parts by mass or more of a polyamide resin having an average of 8 or more carbon atoms per monomer unit in 100 parts by mass of the (A) polyamide resin, the (B) polyolefin resin contains at least one polyolefin resin having a functional group reactive with the terminal amine of the (A) polyamide resin, and contains at least one ethylene-α-olefin copolymer, Among the monomer units constituting the (B) polyolefin resin, the mass ratio of the monomer units derived from α-olefin is 3% by mass or more and 11% by mass or less, When heated from 23°C at a rate of 20°C / min using a differential scanning calorimeter, it exhibits at least one melting peak between 100°C and less than 150°C, A polyamide resin composition characterized by the above. [2] The polyamide resin composition according to [1], wherein the draw speed at break is 200 mm / s or more. [3] The (B) polyolefin resin contains (B-1) a polyolefin resin having no functional group reactive with the terminal amine of the (A) polyamide resin, and (B-2) a polyolefin resin having a functional group reactive with the terminal amine of the (A) polyamide resin. The polyamide resin composition according to [1] or [2]. [4] The polyamide resin composition according to [3], wherein the weight average molecular weight of the (B-2) component is 80,000 or less. [5] The polyamide resin composition according to [3] or [4], wherein the weight average molecular weight of the (B-1) component exceeds 80,000. [6] The polyamide resin composition according to any one of [3] to [5], wherein the mass ratio of the (B-1) component to the (B-2) component is in the range of (B-1):(B-2) = 1:5 to 5:1. [7] The polyamide resin composition according to any one of [3] to [6], wherein the MFR of the (B-1) component measured at 190°C and 2.16 kg is 0.5 g / 10 min or less, and the MFR of the (B-2) component measured at 190°C and 2.16 kg is 0.5 g / 10 min or more. [8] The polyamide resin composition according to any one of [3] to [7], wherein the (B) polyolefin resin forms a single phase. [9] The polyamide resin composition according to any one of [3] to [8], wherein the dispersion diameter of the (B) polyolefin resin has a ratio of major axis / minor axis of 5.0 or less.

[10] The polyamide resin composition according to any one of [1] to [9], wherein the (B) polyolefin resin contains high-density polyethylene and the weight-average molecular weight of the high-density polyethylene is 100,000 or more.

[11] The polyamide resin composition according to any one of [1] to

[10] , wherein the (B) polyolefin resin contains low-density polyethylene and the weight-average molecular weight of the low-density polyethylene is 80,000 or more.

[12] The polyamide resin composition according to any one of [1] to

[11] , wherein the relative viscosity of sulfuric acid of the (A) polyamide resin is 2.4 or less.

[13] The polyamide resin composition according to any one of [1] to

[12] , further containing 1 to 40 parts by mass of (C) polyphenylene ether with respect to 100 parts by mass of the total of the (A) polyamide resin and the (B) polyolefin resin.

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

[13] , wherein the total content of the (A) polyamide resin and the (B) polyolefin resin is 60 to 100 parts by mass with respect to 100 parts by mass of all resin components.

[15] A molded article using the polyamide resin composition according to any one of [1] to

[14] .

[16] A method for manufacturing a molded article, comprising a step of molding the polyamide resin composition according to any one of [1] to

[14] by an extrusion molding method or a blow molding method.

[17] The molded article according to

[15] , which is a material part for an automobile.

[18] The molded article according to

[15] , which is any one of a brake hose, an air conditioner hose, and a cooling pipe. [Effect of the Invention]

[0008] According to the present invention, it is possible to provide a polyamide resin composition excellent in high-temperature refrigerant resistance, low refrigerant absorption, low-temperature impact resistance, high-speed moldability, uniform wall thickness during extrusion molding, and circumferential tensile elongation, and a molded article thereof.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an exemplification for explaining the present invention, and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist.

[0011] In the present specification, "polyamide" means a polymer having an amide (-NHCO-) group in the main chain.

[0012] ≪Polyamide Resin Composition≫ The polyamide resin composition of the present embodiment is a polyamide resin composition containing (A) a polyamide resin and (B) a polyolefin resin. When the total mass of the above (A) polyamide resin and the above (B) polyolefin resin is 100 parts by mass, the total mass of the above (B) polyolefin resin is 55 parts by mass or less. Among 100 parts by mass of the above (A) polyamide resin, it contains 50 parts by mass or more of a polyamide resin having an average of 8 or more carbon atoms per monomer unit. The above (B) polyolefin resin contains at least one polyolefin resin having a functional group reactive with the terminal amine of the above (A) polyamide resin, and contains at least one ethylene-α-olefin copolymer. Among the monomer units constituting the above (B) polyolefin resin, the mass ratio of the monomer unit derived from α-olefin is 3% by mass or more and 11% by mass or less. When heated from 23 °C at a rate of 20 °C / min using a differential scanning calorimeter, it shows at least one melting peak between 100 °C and less than 150 °C. The polyamide resin composition of the present embodiment may be a composition consisting only of (A) a polyamide resin and (B) a polyolefin resin, or may be a composition consisting only of (A) a polyamide resin, (B) a polyolefin resin, and (C) a polyphenylene ether. Further, these may contain (D) other components.

[0013] According to the polyamide resin composition of the present embodiment, it is possible to provide a polyamide resin composition and a molded article thereof that are excellent in high-temperature refrigerant resistance, low water absorption, low-temperature impact resistance, melt stretchability, extrusion moldability, and circumferential tensile elongation. Hereinafter, each constituent component of the polyamide resin composition of the present embodiment will be described in detail.

[0014] <(A) Polyamide resin> When the total mass of the (A) polyamide resin and the (B) polyolefin resin in the polyamide resin composition of the present embodiment is 100 parts by mass, it is preferable to contain 45 parts by mass or more of the (A) polyamide resin.

[0015] (Relative viscosity of polyamide resin in sulfuric acid) (A) The relative viscosity of the polyamide resin in sulfuric acid is preferably 3.0 or less, more preferably 2.8 or less, still more preferably 2.5 or less, and most preferably 2.4 or less. By the relative viscosity of sulfuric acid being below the above upper limit value, an excessive increase in viscosity due to the reaction with the polyolefin resin can be suppressed, and a polyamide resin composition with more excellent extrusion moldability tends to be obtained. Incidentally, the relative viscosity of sulfuric acid can be measured by a method in accordance with JIS K 6920. The relative viscosity of sulfuric acid can be controlled by adjusting the pressure during the polymerization of the (A) polyamide resin, performing solid-phase polymerization after granulation, or the like.

[0016] Examples of the (A) polyamide resin include, but are not limited to, polyamide resins obtained by condensation polymerization of diamines and dicarboxylic acids, polyamide resins obtained by ring-opening polymerization of lactams, polyamide resins obtained by self-condensation of aminocarboxylic acids, and copolymers obtained by copolymerization of two or more monomers constituting these polyamide resins. These (A) components may be used alone or in combination of two or more.

[0017] The polymerization monomers as raw materials of the (A) polyamide resin will be described in detail below.

[0018] (Diamine) Examples of the diamine include, but are not limited to, aliphatic diamines, alicyclic diamines, aromatic diamines, etc.

[0019] The aliphatic diamine may be a linear saturated aliphatic diamine or a branched-chain saturated aliphatic diamine. Examples of the branched-chain saturated aliphatic diamine include diamines having substituents branched from the main chain.

[0020] The linear saturated aliphatic diamine preferably has 2 to 20 carbon atoms, and examples thereof include ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecamethylenediamine, etc.

[0021] The branched-chain saturated aliphatic diamine preferably has 3 to 20 carbon atoms, and examples thereof include 2-methylpentamethylenediamine (also referred to as "2-methyl-1,5-diaminopentane"), 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 2-methyloctamethylenediamine, 2,4-dimethyloctamethylenediamine, etc.

[0022] Examples of the alicyclic diamine (also referred to as alicyclic diamine) include, but are not limited to, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-cyclopentanediamine, etc.

[0023] Examples of the aromatic diamine include, but are not limited to, metaxylylenediamine, paraxylylenediamine, metaphenylenediamine, orthophenylenediamine, paraphenylenediamine, etc.

[0024] These diamines may be used alone or in combination of two or more.

[0025] (Dicarboxylic acid) Examples of the dicarboxylic acid include, but are not limited to, aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, aromatic dicarboxylic acid, etc.

[0026] The aliphatic dicarboxylic acid may be a linear saturated aliphatic dicarboxylic acid or a branched saturated aliphatic dicarboxylic acid, and those having 3 to 20 carbon atoms are preferred. Examples of such aliphatic dicarboxylic acids include, but are not limited to, malonic acid, dimethylmalonic acid, succinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylglutaric acid, 2,2-diethylsuccinic acid, 2,3-diethylglutaric acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, diglycolic acid, and the like.

[0027] The number of carbon atoms in the alicyclic structure of the alicyclic dicarboxylic acid (also referred to as alicyclic dicarboxylic acid) is not particularly limited, but from the viewpoint of the balance between the water absorption and crystallinity of the resulting (A) polyamide resin, it is preferably 3 or more and 10 or less, more preferably 5 or more and 10 or less.

[0028] The alicyclic dicarboxylic acid may be unsubstituted or may have a substituent. As the substituent, an alkyl group having 1 to 4 carbon atoms is preferred. Examples of the substituent include, but are not limited to, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, and the like.

[0029] Examples of such alicyclic dicarboxylic acids include, but are not limited to, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, and the like.

[0030] Examples of the aromatic dicarboxylic acid include, but are not limited to, aromatic dicarboxylic acids having 8 to 20 carbon atoms which are unsubstituted or substituted with substituents. Examples of the substituent include, but are not limited to, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, a halogen group, an alkylsilyl group having 3 to 10 carbon atoms, a sulfonic acid group, a group having a sulfonate, etc. Examples of the halogen group include a chloro group, a bromo group, etc. Examples of the salt constituting the group having a sulfonate include a sodium salt, etc.

[0031] Examples of such aromatic dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, etc.

[0032] These dicarboxylic acids may be used alone or in combination of two or more.

[0033] (Lactam) Examples of the lactam include, but are not limited to, butyrolactam, pivalolactam, ε-caprolactam, caprylolactam, enantholactam, undecalactam, laurolactam (dodecalactam), etc. Among them, from the viewpoint of polymerization production, ε-caprolactam, undecalactam, or laurolactam (dodecalactam) is preferable. These lactams may be used alone or in combination of two or more.

[0034] (Aminocarboxylic acid) Examples of the aminocarboxylic acid include, but are not limited to, compounds obtained by ring-opening of the above-mentioned lactam, and more specifically, ω-aminocarboxylic acid, α,ω-aminocarboxylic acid, etc.

[0035] The amino carboxylic acid may be an aliphatic amino carboxylic acid or an aromatic amino carboxylic acid. Examples of the aromatic amino carboxylic acid include, but are not limited to, para-aminomethylbenzoic acid.

[0036] From the viewpoint of increasing the crystallinity, the amino carboxylic acid is preferably a linear or branched saturated aliphatic amino carboxylic acid having 4 to 14 carbon atoms and having an ω-position substituted with an amino group. Specific examples of the preferred amino carboxylic acid include, but are not limited to, 6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and the like.

[0037] These amino carboxylic acids may be used alone or in combination of two or more.

[0038] (A) Examples of the polyamide resin include, but are not limited to, polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 116 (polyundecamethylene adipamide), polyamide 1010 (polydecamethylene sebacamide), polyamide 1012 (polydecamethylene dodecamide), polyamide MXD6 (polymetaxylylene adipamide), polyamide 66 / 6I (polyhexamethylene adipamide / polyisophthalic adipamide copolymer), polyamide 6I / 6T (polyisophthalic adipamide / polyterephthalic adipamide copolymer), polyamide 6 / 11 (caprolactam / aminoundecanoic acid copolymer), polyamide 6 / 12 (caprolactam / laurolactam copolymer), polyamide 6 / 66 / 12 (caprolactam / polyhexamethylene adipamide / laurolactam copolymer), polyamide TMHT (trimethylhexamethylene terephthalamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 2Me-5T (poly2-methylpentamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), 2Me-8T (poly2-methyloctamethylene terephthalamide), polyamide 6C (polyhexamethylene cyclohexanedicarboxamide), polyamide 2Me-5C (poly2-methylpentamethylene cyclohexanedicarboxamide), polyamide 9C (polynonamethylene cyclohexanedicarboxamide), 2Me-8C (poly2-methyloctamethylene cyclohexanedicarboxamide), polyamide 10T (polydecamethylene terephthalamide), polyamide 11T (polyundecamethylene terephthalamide), polyamide 12T (polydodecamethylene terephthalamide), polyamide 10C (polydecamethylene cyclohexanedicarboxamide), polyamide 11C (polyundecamethylene cyclohexanedicarboxamide), polyamide 12C (polydodecamethylene cyclohexanedicarboxamide), polyamide 11 (polyundecanamide), polyamide 12 (polydodecanamide), and the like.Among them, as the (A) polyamide resin, from the viewpoints of low-temperature impact resistance and high-temperature refrigerant resistance, polyamide 610, polyamide 612, polyamide 116, polyamide 6 / 11, polyamide 6 / 12, polyamide 6 / 66 / 12, polyamide 1010, polyamide 1012, polyamide 9T, polyamide 2Me-8T, polyamide 9C, 2Me-8C, polyamide 10T, polyamide 11T, polyamide 12T, polyamide 10C, polyamide 11C, polyamide 12C, polyamide 11, and polyamide 12 are preferable, and polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide 6 / 11, polyamide 6 / 12, polyamide 6 / 66 / 12, polyamide 1010, and polyamide 1012 are particularly preferable.

[0039] (Terminal amino group concentration) The terminal amino group concentration of the (A) polyamide resin is not particularly limited, but from the viewpoints of easy reaction with the (B) polyolefin resin and improved high-temperature refrigerant resistance, 20 μmol / g or more is preferable, 30 μmol / g or more is more preferable, 40 μmol / g or more is further preferable, 60 μmol / g or more is particularly preferable, 80 μmol / g or more is more particularly preferable, and 90 μmol / g or more is most preferable. The upper limit value of the terminal amino group concentration of the (A) polyamide resin is not particularly limited, but it can be, for example, 120 μmol / g.

[0040] The terminal carboxy group concentration of the (A) polyamide resin is not particularly limited, but from the viewpoints of excellent high-temperature refrigerant resistance and low metal corrosiveness, 100 μmol / g or less is preferable. The lower limit value of the terminal carboxy group concentration of the (A) polyamide resin is not particularly limited, but it can be, for example, 10 μmol / g.

[0041] Note that the terminal group concentration of the (A) polyamide resin can be measured by neutralization titration, nuclear magnetic resonance analysis, etc. Specifically, it can be measured by the method described in the examples below.

[0042] (Number of carbon atoms per monomer) (A) In 100 parts by mass of the polyamide resin, it is preferably to contain at least 80 parts by mass or more of a polyamide resin having an average of 8 or more carbon atoms per monomer unit, more preferably 90 parts by mass or more, and most preferably 95 parts by mass or more. Further, the (A) polyamide resin may be only a polyamide having an average of 8 or more carbon atoms per monomer unit. When the content of the polyamide having 8 or more carbon atoms per monomer unit is at or above the above lower limit value, the chemical resistance, high-temperature refrigerant resistance, and low-temperature impact resistance of the molded product tend to improve. Also, the upper limit value of the number of carbon atoms per monomer unit of the (A) polyamide resin is preferably 12. When the number of carbon atoms per monomer unit is at or below the above upper limit value, the crystallization temperature and melt stability of the polyamide resin composition increase, and the productivity of the composition and the molded body tends to improve.

[0043] The term "average number of carbon atoms per monomer unit (φ)" is understood to be the number of carbon atoms calculated by dividing the total number of carbon atoms in the monomers used by the number of monomers used. For example, the following examples can be cited. PA6 φ 6 carbon atoms per monomer unit on average [6:1 = 6] PA66 φ 6 carbon atoms per monomer unit on average [(6 + 6):2 = 6] PA612 φ 9 carbon atoms per monomer unit on average [(6 + 12):2 = 9] PA66 / 6I φ 6.5 carbon atoms per monomer unit on average [{(6 + 6)+(6 + 8)}:4 = 6.5].

[0044] (End-capping agent) When producing the (A) polyamide resin, when polymerizing the polymerization monomers, an end-capping agent can be further added for molecular weight adjustment. The end-capping agent is not particularly limited, and known ones can be used.

[0045] Examples of the end-capping agent include, but are not limited to, monocarboxylic acids, monoamines, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, etc. Among these, from the viewpoint of thermal stability, monocarboxylic acids or monoamines are preferred. These end-capping agents may be used alone or in combination of two or more.

[0046] The monocarboxylic acid may be any one having reactivity with an amino group, and examples thereof include aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids, etc. Examples of the aliphatic monocarboxylic acid include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid, etc. Examples of the alicyclic monocarboxylic acid include, but are not limited to, cyclohexanecarboxylic acid, etc. Examples of the aromatic monocarboxylic acid include, but are not limited to, benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, phenylacetic acid, etc. These monocarboxylic acids may be used alone or in combination of two or more.

[0047] The monoamine may be any one having reactivity with a carboxy group, and examples thereof include aliphatic monoamines, alicyclic monoamines, aromatic monoamines, etc. Examples of the aliphatic monoamine include, but are not limited to, methylamine, ethylamine, propylamine, isopropylamine, butylamine, hexylamine, octylamine, decylamine, undecylamine, laurylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, etc. Examples of the alicyclic monoamine include, but are not limited to, cyclohexylamine, dicyclohexylamine, and the like. Examples of the aromatic monoamine include, but are not limited to, aniline, toluidine, diphenylamine, naphthylamine, and the like. These monoamines may be used alone or in combination of two or more.

[0048] Examples of the acid anhydride include, but are not limited to, phthalic anhydride, maleic anhydride, benzoic anhydride, acetic anhydride, hexahydrophthalic anhydride, and the like. These acid anhydrides may be used alone or in combination of two or more.

[0049] Examples of the monoisocyanate include, but are not limited to, phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate, and the like. These monoisocyanates may be used alone or in combination of two or more.

[0050] Examples of the monoacid halide include, but are not limited to, halogen-substituted monocarboxylic acids of monocarboxylic acids such as benzoic acid, diphenylmethane carboxylic acid, diphenylsulfone carboxylic acid, diphenylsulfoxide carboxylic acid, diphenylsulfide carboxylic acid, diphenyl ether carboxylic acid, benzophenone carboxylic acid, biphenyl carboxylic acid, α-naphthalene carboxylic acid, β-naphthalene carboxylic acid, anthracene carboxylic acid, and the like. These monoacid halides may be used alone or in combination of two or more.

[0051] Examples of the monoesters include, but are not limited to, glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin monomontanate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol monobehenate, pentaerythritol monomontanate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monobehenate, sorbitan monomontanate, sorbitan dimontanate, sorbitan trimontanate, sorbitol monopalmitate, sorbitol monostearate, sorbitol monobehenate, sorbitol tribehenate, sorbitol monomontanate, sorbitol dimontanate, and the like. These monoesters may be used alone or in combination of two or more.

[0052] Examples of the monoalcohols include, but are not limited to, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, docosanol, tricosanol, tetracosanol, hexacosanol, heptacosanol, octacosanol, triacontanol (the above-mentioned molar alcohols may be linear or branched), oleyl alcohol, behenyl alcohol, phenol, cresol (o-, m-, or p-isomer), biphenol (o-, m-, or p-isomer), 1-naphthol, 2-naphthol, and the like. These monoalcohols may be used alone or in combination of two or more.

[0053] The mass ratio of the (A) polyamide resin to 100% by mass of the polyamide resin composition of the present embodiment is preferably 40 to 90% by mass, more preferably 50 to 90% by mass, still more preferably 50 to 70% by mass, and particularly preferably 50 to 60% by mass. The mass ratio of the (A) polyamide resin to 100 parts by mass of the total mass of the resin components contained in the polyamide resin composition of the present embodiment is preferably 40 to 90 parts by mass, more preferably 50 to 90 parts by mass, still more preferably 50 to 70 parts by mass, and particularly preferably 50 to 60 parts by mass.

[0054] <(B) Polyolefin resin> The polyamide resin composition of the present embodiment contains at least one polyolefin resin having a functional group reactive with the terminal amine of the (A) polyamide resin from the viewpoints of improving low-temperature impact resistance, high-temperature refrigerant resistance, melt stretchability, and mechanical strength. Further, it contains at least one ethylene-α-olefin copolymer. The polyolefin resin having a functional group reactive with the terminal amine of the above (A) polyamide resin and the above ethylene-α-olefin copolymer may be the same polyolefin resin or different polyolefin resins. For example, it may be an ethylene-α-olefin copolymer having a functional group reactive with the terminal amine of the (A) polyamide resin. Further, the above ethylene-α-olefin copolymer may be a polyolefin resin having no functional group reactive with the (B-1) (A) polyamide resin described later, a modified polyolefin resin having a functional group reactive with the (B-2) (A) polyamide resin, or a polyolefin resin different from these. The above polyolefin resin preferably consists of two or more (preferably two) resins. For example, it may be two types, namely, an ethylene-α-olefin copolymer having a functional group reactive with the terminal amine of the (A) polyamide resin and another olefin resin (preferably a polyethylene resin having no functional group reactive with the terminal amine of the polyamide resin), or two types, namely, a polyolefin resin having a functional group reactive with the terminal amine of the (A) polyamide resin and an ethylene-α-olefin copolymer (preferably an ethylene-α-olefin copolymer having no functional group reactive with the terminal amine of the polyamide resin).

[0055] (B) Examples of the polyolefin resin include, but are not limited to, polyethylene resins, polypropylene resins, ethylene·α-olefin copolymers, and ethylene·α,β-unsaturated carboxylic acid copolymers. These can be used alone or in combination of two or more.

[0056] (Polyethylene resin) Examples of the polyethylene resin include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), etc. Among these, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE) are particularly preferred because they can be obtained at low cost. These polyethylene resins may be used alone or in combination of two or more.

[0057] When using a polyethylene resin, although not limited to the following, from the viewpoints of mechanical strength and resistance to high-temperature refrigerant, it is desirable that the density be 0.89 g / cm 3 or more, more desirably 0.92 g / cm 3 or more, and particularly desirably 0.93 g / cm 3 or more.

[0058] Due to the relationship of maintaining physical properties at the use environment temperature, the melting point of the polyethylene resin is preferably 100°C or higher, more preferably 110°C or higher, still more preferably 115°C or higher, particularly preferably 120°C or higher, and most preferably 125°C or higher. The melting point of the polyethylene resin can be measured by a differential scanning calorimeter or the like. Specifically, it can be measured by the method described in the examples below.

[0059] The polyethylene-based resin preferably contains high-density polyethylene or low-density polyethylene, and more preferably contains high-density polyethylene and low-density polyethylene. Further, the polyethylene-based resin may consist only of high-density polyethylene and low-density polyethylene, or may consist only of high-density polyethylene or low-density polyethylene. The above high-density polyethylene and the above low-density polyethylene may be resins having no functional group reactive with the terminal amine of the (A) polyamide resin. When using high-density polyethylene as the polyethylene-based resin, from the viewpoint of moldability, the weight-average molecular weight is preferably 100,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more. When using low-density polyethylene or linear low-density polyethylene, from the viewpoint of moldability, the weight-average molecular weight is preferably 80,000 or more, more preferably 100,000 or more, and even more preferably 150,000 or more. The weight-average molecular weight of the polyethylene-based resin can be measured by gel permeation chromatography or the like. Specifically, it can be measured by the method described in the examples below.

[0060] (Polypropylene-based resin) Examples of the polypropylene-based resin include homopolypropylene, copolymer resins (including block and random) of propylene and other α-olefins such as butene-1, pentene-1, and hexene-1. Note that the polypropylene-based resin does not include resins containing ethylene as a structural unit.

[0061] (Ethylene·α-olefin copolymer) The ethylene·α-olefin copolymer is a polymer obtained by copolymerizing ethylene and an α-olefin having 3 or more carbon atoms. Note that the ethylene·α-olefin copolymer does not include the above polyethylene-based resin. Examples of α-olefins having 3 or more carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, and the like. These may be used alone or in combination of two or more.

[0062] The ethylene-α-olefin copolymer may also be a copolymer obtained by copolymerizing a polyene such as a non-conjugated diene. Examples of the non-conjugated diene include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 4,8-dimethyl-1,4,8-decatriene, dicyclopentadiene, cyclohexadiene, cyclooctadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,5-norbornadiene, and the like. These may be used alone or in combination of two or more.

[0063] (Ethylene-α,β-unsaturated carboxylic acid copolymer (unsaturated carboxylic acid copolymer)) The ethylene-α,β-unsaturated carboxylic acid copolymer is a polymer obtained by copolymerizing ethylene with an α,β-unsaturated carboxylic acid and / or an α,β-unsaturated carboxylic acid ester monomer. Examples of the α,β-unsaturated carboxylic acid monomer include acrylic acid and methacrylic acid. Examples of the α,β-unsaturated carboxylic acid ester monomer include methyl esters, ethyl esters, propyl esters, butyl esters, etc. of these α,β-unsaturated carboxylic acids. These may be used alone or in combination of two or more.

[0064] (Reactive groups with respect to polyamide resin) (B) The polyolefin resin may include (B-1) a polyolefin resin having no functional group reactive with (A) the polyamide resin, and (B-2) a polyolefin resin having a functional group reactive with (A) the polyamide resin (for example, a modified polyolefin resin having a functional group reactive with (A) the polyamide resin). The above (B-1) is preferably a polyolefin resin having no functional group reactive with the terminal amine of (A) the polyamide resin. The above (B-2) is preferably a polyolefin resin having a functional group reactive with the terminal amine of (A) the polyamide resin.

[0065] (Functional groups having reactivity with (A) the polyamide resin (preferably, functional groups having reactivity with the terminal amine of (A) the polyamide resin)) include carboxy groups, acid anhydride groups, carboxylic acid ester groups, epoxy groups, oxazoline groups, amino groups, maleimide groups, etc.

[0066] (B) These functional groups can be introduced into the polyolefin resin by using known methods. Specifically, there are methods such as copolymerizing a copolymerizable monomer having a functional group during polymerization, introducing a monomer having a functional group as a terminal capping agent during polymerization, and grafting by melt-kneading (B) the polyolefin resin, a monomer having a functional group, and a polymerization initiator. These introduction methods can be used alone or in combination as appropriate.

[0067] Examples of monomers containing these functional groups (for example, functional groups having reactivity with the terminal amine of the (A) polyamide resin) include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, mesaconic acid, citraconic acid, glutaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endo-bicyclo-[2.2.1]-5-heptene-2,3-dicarboxylic acid and metal salts of these carboxylic acids, monomethyl maleate, monomethyl itaconate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, maleic anhydride, maleic anhydride ester, itaconic anhydride, citraconic anhydride, endo-bicyclo-[2,2,1]-5-heptene-2,3-dicarboxylic anhydride, maleimide, N-ethyl maleimide, N-butyl maleimide, N-phenyl maleimide, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, glycidyl citraconate, etc. These can be used alone or in combination of two or more. Component (B-2) preferably contains a maleic anhydride group, and / or a maleic anhydride ester group, and / or a glycidyl group from the viewpoint of reactivity with the (A) polyamide resin.

[0068] (B-2) The mass ratio of the functional group having reactivity contained in the modified polyolefin to 100% by mass of the modified polyolefin (for example, the functional group having reactivity with the terminal amine of the (A) polyamide resin) is preferably 0.3 to 3.0% by mass, more preferably 0.4 to 2.0% by mass, and still more preferably 0.4 to 1.5% by mass. When the mass ratio of the above functional group (for example, acid anhydride group) is at least the above lower limit value, the reactivity with the (A) polyamide resin increases, and the viscosity of the polyamide resin composition can be sufficiently improved. When the mass ratio of the above functional group (for example, acid anhydride group) is within the above upper limit value, it is possible to avoid excessive (A) polyamide resin from reacting per molecule of the (B) polyolefin resin, and a composition excellent in extrusion moldability tends to be obtained.

[0069] In order to suppress uneven wall thickness during molding of the polyamide resin composition, the MFR of the (B-2) component is preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, still more preferably 2.0 g / 10 min or more, particularly preferably 5.0 g / 10 min or more, and most preferably 10.0 g / 10 min or more. From the viewpoint of enhancing the melt extensibility of the polyamide resin composition and enabling molding at a high rate, the MFR of the (B-1) component is preferably 1.0 g / 10 min or less, more preferably 0.6 g / 10 min or less, still more preferably 0.5 g / 10 min or less, and particularly preferably 0.2 g / 10 min or less. The MFR of the polyolefin resin can be measured using a melt indexer or the like at 190 °C and 2.16 kg in accordance with ASTM D1238.

[0070] The weight-average molecular weight of component (B-1) is preferably more than 80,000, more preferably 100,000 or more, even more preferably 150,000 or more, and particularly preferably 200,000 or more. The upper limit of the weight-average molecular weight of component (B-1) is not particularly limited, but can be 1,000,000 or less, 500,000 or less, or 300,000 or less. When the weight-average molecular weight of component (B-1) is within the said range, the draw speed at break of the polyamide resin composition can be adjusted to a suitable range, and the wall thickness uniformity during extrusion molding tends to be good. The weight-average molecular weight of component (B-2) is preferably 80,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. The lower limit of the weight-average molecular weight of component (B-2) is not particularly limited, but can be 10,000 or more, 15,000 or more, or 20,000 or more. When the weight-average molecular weight of component (B-2) is within the said range, the draw speed at break of the polyamide resin composition tends to be adjustable to a suitable range. The weight-average molecular weight of the polyethylene-based resin can be measured by, for example, gel permeation chromatography after separating the component grafted to the polyamide and the component that does not react with the polyamide resin among the (B) polyolefin resins. By measuring the weight-average molecular weight with the component grafted to the polyamide resin as component (B-2) and the component that does not react with the polyamide resin as component (B-1), the weight-average molecular weight of each component can be measured.

[0071] ((Mass ratio of component (B-1) and component (B-2))) From the viewpoint of sufficiently exhibiting the above-mentioned wall thickness non-uniformity suppressing effect and moldability at a high rate, the mass ratio of component (B-1) to component (B-2) is preferably (B-1):(B-2) = 1:5 to 5:1, more preferably (B-1):(B-2) = 1:3 to 3:1, and even more preferably (B-1):(B-2) = 3:7 to 7:3.

[0072] ((Content of (B) polyolefin resin)) When the total of (A) polyamide resin and (B) polyolefin resin is 100 parts by mass, the mass ratio of (B) polyolefin resin is 55 parts by mass or less. Preferably it is 20 parts by mass or more and 54 parts by mass or less, more preferably 30 parts by mass or more and 53 parts by mass or less, still more preferably 35 parts by mass or more and 52 parts by mass or less, and particularly preferably 40 parts by mass or more and 50 parts by mass or less. When the amount of (B) polyolefin resin is within the above range, a polyamide resin composition excellent in extrusion moldability, low-temperature impact resistance, and high-temperature refrigerant resistance tends to be obtained. Also, the mass ratio of (B) polyolefin resin to 100% by mass of the polyamide resin composition of the present embodiment is preferably 55% by mass or less, more preferably 20% by mass or more and 54% by mass or less, still more preferably 30% by mass or more and 53% by mass or less, still more preferably 35% by mass or more and 52% by mass or less, and particularly preferably 40% by mass or more and 50% by mass or less. Also, the mass ratio of (B) polyolefin resin to 100 parts by mass of all resin components contained in the polyamide resin composition of the present embodiment is preferably 55 parts by mass or less, more preferably 20 parts by mass or more and 54 parts by mass or less, still more preferably 30 parts by mass or more and 53 parts by mass or less, still more preferably 35 parts by mass or more and 52 parts by mass or less, and particularly preferably 40 parts by mass or more and 50 parts by mass or less. Also, the ratio of the total mass of (A) polyamide resin and (B) polyolefin resin to 100 parts by mass of the total mass of resin components contained in the polyamide resin composition of the present embodiment is preferably 50 to 100 parts by mass, more preferably 55 to 99 parts by mass, and still more preferably 80 to 95 parts by mass.

[0073] ((B) Polyolefin resin phase uniformity, dispersibility) (B) The polyolefin resin preferably forms a single phase from the viewpoint of exhibiting good moldability and mechanical properties. Forming a single phase means that each component constituting the (B) polyolefin resin preferably does not form an independent domain. The method of observation by an electron microscope for evaluating the single-phase property of the (B) polyolefin resin phase is not limited as long as it can evaluate the single-phase property, but for example, specifically, it can be observed by the method described in the examples. Further, when the (B) polyolefin resin contains the above (B-1) and the above (B-2), it is preferable that the above (B-1) or the above (B-2) does not form an independent domain, and it is more preferable that the (B) polyolefin resin forms a single dispersed phase in the (A) polyamide resin. Among combinations of polyolefin resins, from the viewpoint of forming a single phase and improving compatibility and mechanical properties, a combination of a polyethylene-based resin and an ethylene-α-olefin copolymer is preferable, and a combination of a polyethylene-based resin and an ethylene-α-olefin copolymer in which the mass ratio of monomer units derived from α-olefin is more than 0% by mass and within 20% by mass is more preferable, and a combination of a polyethylene-based resin and an ethylene-α-olefin copolymer in which the mass ratio of monomer units derived from α-olefin is more than 0% by mass and within 15% by mass is particularly preferable.

[0074] The ratio of the major axis to the minor axis of the domain of the (B) polyolefin resin is preferably 7.0 or less, more preferably 5.0 or less, further preferably 4.0 or less, still further preferably 3.5 or less, even more preferably 3.0 or less, and particularly preferably 2.5 or less. The lower limit of the ratio of the major axis to the minor axis is not limited, but for example, it can be 1.1 or more, 1.3 or more, 1.5 or more. Especially in injection molding where the ratio of the major axis to the minor axis tends to be large, due to the properties of the composition in which the ratio of the major axis to the minor axis is kept small, when extrusion molding is performed at a high rate, the ratio of the major axis to the minor axis also becomes small, and a pipe excellent in circumferential tensile elongation tends to be obtained. The major axis and the minor axis of the (B) polyolefin resin can be measured, for example, by the method described in the examples.

[0075] ((B) Mass ratio of monomer units derived from α-olefin among the monomer units constituting the polyolefin resin) The mass ratio of the monomer units derived from α-olefin contained in all the polyolefin resins included as the (B) polyolefin resin to the total mass of the monomer units constituting all the polyolefin resins is expressed as the mass percentage of the total mass of all components of the (B) polyolefin resin being 100% by mass and the ratio of the total mass of the monomer units derived from α-olefin contained in all the polyolefin resins in mass%. From the viewpoint of exhibiting impact resistance, high-temperature refrigerant resistance, and low water absorption, among the monomer units constituting the (B) polyolefin resin, the mass ratio of the monomer units derived from α-olefin is preferably 3% by mass or more and 11% by mass or less, more preferably 3% by mass or more and 10.5% by mass or less, and particularly preferably 5% by mass or more and 10.5% by mass or less. Among the monomer units constituting the (B) polyolefin resin, the mass ratio of the monomer units derived from α-olefin can be measured by nuclear magnetic resonance method or the like. The method is not limited as long as it can measure the mass ratio of the monomer units derived from α-olefin among the monomer units constituting the (B) polyolefin resin. Specifically, for example, it can be measured by the method described in the examples below.

[0076] <(C) Polyphenylene ether> In addition to the above (A) polyamide resin and the above (B) polyolefin resin, the polyamide resin composition of the present embodiment can further contain (C) polyphenylene ether. By containing (C) polyphenylene ether, the polyamide resin composition of the present embodiment tends to be able to adjust the draw speed at break to a suitable range. The resin component contained in the polyamide resin composition of this embodiment may be only the above (A) polyamide resin and the above (B) polyolefin resin, or may be only the above (A) polyamide resin, the above (B) polyolefin resin, and (C) polyphenylene ether, or may further contain other resins. The (C) polyphenylene ether contained in the polyamide composition of this embodiment is a homopolymer and / or copolymer having a repeating structural unit represented by the following general formula (1). [Chemical formula] Here, in general formula (1), O is an oxygen atom, R 1 , R 2 , R 3 and R 4 are each independently hydrogen, halogen, a primary or secondary C 1 -C7 alkyl group, phenyl group, C 1 -C 7 haloalkyl group, C 1 -C 7 aminoalkyl group, C 1 -C 7 hydrocarbyloxy group, or halohydrocarbyloxy group (provided that at least two carbon atoms separate a halogen atom and an oxygen atom).

[0077] Specific examples of the (C) polyphenylene ether include, for example, poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), and further polyphenylene ether copolymers such as copolymers of 2,6-dimethylphenol and other phenols (for example, copolymers with 2,3,6-trimethylphenol and copolymers with 2-methyl-6-butylphenol as described in Japanese Patent Publication No. 52-17880).

[0078] Among these, particularly preferred polyphenylene ethers include poly(2,6-dimethyl-1,4-phenylene ether), a copolymer of 2,6-dimethyl-1,4-phenol and 2,3,6-trimethyl-1,4-phenol, or a mixture thereof.

[0079] Also, the copolymer of 2,6-dimethyl-1,4-phenol and 2,3,6-trimethyl-1,4-phenol is preferably a copolymer containing 10 to 30% by mass of 2,3,6-trimethyl-1,4-phenol, more preferably 15 to 25% by mass, and even more preferably 20 to 25% by mass, based on 100% by mass of the total amount of the polyphenylene ether copolymer.

[0080] (C) The polyphenylene ether is preferably a polyphenylene ether modified with an α,β-unsaturated dicarboxylic anhydride from the viewpoint of compatibility with polyamide. Examples of the α,β-unsaturated dicarboxylic anhydride include maleic anhydride and methyl maleic anhydride, and maleic anhydride is preferred.

[0081] (C) The content of the α,β-unsaturated dicarboxylic anhydride component in the polyphenylene ether is preferably 0.1 to 50% by mass, more preferably 0.2 to 20% by mass, even more preferably 0.3 to 5% by mass, particularly preferably 0.3 to 1% by mass, and most preferably 0.3 to 0.8% by mass, based on 100% by mass of (C) the polyphenylene ether.

[0082] By setting the content of the α,β-unsaturated dicarboxylic anhydride component to 0.1% by mass or more, the compatibility with polyamide is enhanced, and a polyamide composition excellent in mechanical properties such as toughness and rigidity can be obtained. Also, by setting the ratio of the α,β-unsaturated dicarboxylic anhydride component to 50% by mass or less, deterioration of the polyamide composition due to the α,β-unsaturated dicarboxylic anhydride can be prevented.

[0083] When the total of (A) polyamide resin and (B) polyolefin resin is 100 parts by mass, the mass ratio of (C) polyphenylene ether is preferably 1 to 50 parts by mass from the viewpoint of achieving both draw speed at break and low-temperature impact resistance. More preferably, it is 1 part by mass or more and 40 parts by mass or less, still more preferably 5 parts by mass or more and 40 parts by mass or less, still more preferably 10 parts by mass or more and 35 parts by mass or less, and particularly preferably 15 parts by mass or more and 30 parts by mass or less. The ratio of the total mass of (A) polyamide resin, (B) polyolefin resin, and (C) polyphenylene ether to the total mass of 100 parts by mass of the resin components contained in the polyamide resin composition of the present embodiment is preferably 50 to 100 parts by mass, more preferably 80 to 99 parts by mass, still more preferably 85 to 97 parts by mass, and particularly preferably 90 to 95 parts by mass.

[0084] <(D) Other components> In addition to (A) polyamide resin, (B) polyolefin resin, and (C) polyphenylene ether, the polyamide resin composition of the present embodiment can further contain, as needed, (D) other components other than (A) polyamide resin, (B) polyolefin resin, and (C) polyphenylene ether, as long as the effects of the present embodiment are not impaired.

[0085] Examples of (D) other components include, but are not limited to, heat-resistant agents, colorants, ultraviolet absorbers, light degradation inhibitors, plasticizers, lubricants, mold release agents, nucleating agents, flame retardants, and other thermoplastic resins.

[0086] Since the properties of (D) other components are quite different from each other, the suitable content of each component that hardly impairs the effects of the present embodiment varies. And those skilled in the art can easily set the suitable content for each of the above-mentioned other components. For example, in 100% by mass of the polyamide resin composition, the total amount of (D) other components can be 50% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, and 5% by mass or less.

[0087] <Method for producing polyamide resin composition> As a method for producing the polyamide resin composition of the present embodiment, there is no particular limitation as long as it includes a step of melt-kneading a raw material component containing (A) a polyamide resin, (B) a polyolefin resin, and, if necessary, (C) a polyphenylene ether and / or (D) other components.

[0088] Specific examples of the method for melt-kneading the raw material component containing (A) a polyamide resin, (B) a polyolefin resin, and, if necessary, (C) a polyphenylene ether and / or (D) other components include the following. (i) A method in which each component of (A) a polyamide resin, (B) a polyolefin resin, and, if necessary, (C) a polyphenylene ether and / or (D) other components is mixed using a Henschel mixer, a tumbler mixer, etc., and the mixture is supplied to a melt-kneader and melt-kneaded. (ii) Using a single-screw or twin-screw extruder, a part of (A) the polyamide resin, (B) the polyolefin resin, and, if necessary, each component of (C) the polyphenylene ether and / or (D) other components are mixed in advance using a Henschel mixer, a tumbler mixer, etc., and the mixture is fed into the top feed port of the single-screw or twin-screw extruder. The components of (A) the polyamide resin, (B) the polyolefin resin, and, if necessary, (C) the polyphenylene ether and / or (D) other components that were not mixed in the above mixture are mixed in advance using a Henschel mixer, a tumbler mixer, etc., and fed into the side feed port, and then melt-kneaded. Among these, from the viewpoint of improving the mechanical properties, the appearance of the molded body, and the moldability by improving the dispersibility of each component, the production method (ii) is preferred.

[0089] The temperature of the melt-kneading is preferably about 1°C or more and 100°C or less higher than the melting point of the (A) polyamide resin, and more preferably about 10°C or more and 70°C or less higher than the melting point of the (A) polyamide resin.

[0090] The shear rate in the kneader is 100 sec -1The above degree is preferable. Also, the average residence time during kneading is preferably about 0.5 minutes or more and 5 minutes or less.

[0091] As the apparatus for performing melt kneading, any known apparatus may be used. For example, a single-screw or twin-screw extruder, a Banbury mixer, a melt kneader (such as a mixing roll), etc. are preferably used, and a twin-screw extruder is most preferable.

[0092] (Melting peak of the polyamide resin composition) The polyamide resin composition of the present embodiment shows at least one melting peak of 100°C or more and less than 150°C when heated from 23°C at a rate of 20°C / min with a differential scanning calorimeter. Since the melting peak is less than 150°C, the flexibility can be improved and it tends to have excellent impact resistance. Also, since the melting peak is 100°C or more, it tends to have excellent low refrigerant absorbency. The polyamide resin composition preferably shows at least one melting peak of 105°C or more and less than 140°C, more preferably shows at least one melting peak of 110°C or more and less than 140°C, and even more preferably shows at least one melting peak of 120°C or more and less than 140°C.

[0093] (Break draw rate of the polyamide resin composition) The polyamide resin composition preferably shows a break draw rate of 200 mm / s or more, more preferably 250 mm / s or more, even more preferably 300 mm / s or more, still more preferably 400 mm / s or more, particularly preferably 500 mm / s or more, and even more particularly preferably 600 mm / s or more in order to enable high-rate molding while maintaining uniform wall thickness during extrusion molding. The upper limit of the break draw rate is not particularly limited, but it can be, for example, 2000 mm / s or less, 1500 mm / s or less, or 1000 mm / s or less. As a method for adjusting the breaking draw-off speed, for example, there may be mentioned a method of adjusting the molecular weights of the (B-1) component and the (B-2) component as described above, a method of adding an appropriate amount of (C) polyphenylene ether, etc., but it is not limited to these methods.

[0094] The compounding amount of each component when producing the polyamide resin composition of the present embodiment is the same as the content of each component in the polyamide resin composition described above.

[0095] The molded article of the present embodiment is preferably a molded article using the polyamide resin composition of the present embodiment described above. The molded article of the present embodiment can be obtained by a production method including a step of molding the polyamide resin composition of the present embodiment described above by an extrusion molding method or a blow molding method.

[0096] (Circumferential Tension of Hollow Shaped Body of Polyamide Resin Composition) The hollow body molded according to the present embodiment, although not limited, exhibits good tensile elongation when a circumferential tensile test is performed by the method described later. As the tensile elongation in the circumferential tensile test, it is preferably 50% or more, more preferably 100% or more, still more preferably 150% or more, even more preferably 200% or more, and particularly preferably 300% or more. The upper limit of the tensile elongation in the circumferential tensile test is not particularly limited, but can be, for example, 1000% or less, 700% or less, 500% or less.

[0097] The polyamide resin composition of the present embodiment can be extrusion molded to obtain a molded article. Examples of the molding shape include pellet shape, plate shape, fiber shape, strand shape, film or sheet shape, and hollow shape, and it is preferably used as a hollow shaped molded article. Examples of the molded article having a hollow shape include, but are not limited to, various use material parts for automobiles, mechanical industry, electric and electronic, industrial materials, industrial materials, daily and household goods, etc., and can be suitably used. Among them, the molded article of the present embodiment is suitably used for automobile material parts.

[0098] As automotive parts, although not particularly limited, examples include intake system parts, brake system parts, window washer system parts, cooling system parts, and fuel system parts, etc.

[0099] As automotive intake system parts, although not particularly limited, examples include an air intake manifold, an intercooler inlet, etc. As automotive brake system parts, examples include an air brake hose, a brake hose (for brake fluid), etc. As automotive window washer system parts, examples include a washer hose, a washer tank, a washer nozzle, etc. As automotive cooling system parts, although not particularly limited, examples include an outlet pipe, an air conditioner hose, a battery cooling pipe, etc. As automotive fuel system parts, although not particularly limited, examples include a fuel tank, a fuel pump, a fuel tube, and a gasoline tank case, etc. The molded product of this embodiment is preferably any one of a brake hose, an air conditioner hose, and a cooling pipe.

[0100] As the use of the extrusion molded product, although not particularly limited, for example, it is used for tubes, hoses, rods, and hollow molded products, etc.

Example

[0101] Hereinafter, specific examples and comparative examples will be given to explain this embodiment in detail, but this embodiment is not limited to the following examples.

[0102] Hereinafter, each constituent component of the polyamide resin composition used in this example and comparative example will be described.

[0103] <<Constituent components>> <(A) Polyamide resin> (A)-1: Polyamide 612 (PA612) (manufactured by Asahi Kasei, melting point 225°C, model number: 4100, relative viscosity in sulfuric acid: 2.1, terminal amino group concentration 40 μmol / g) (A)-2: Polyamide 610 (PA610) (manufactured by Asahi Kasei, melting point 215 °C, model number: Leona 3100, relative viscosity in sulfuric acid 2.3, terminal amino group concentration 36 μmol / g) (A)-3: Polyamide 612 (PA612) (melting point 215 °C, relative viscosity in sulfuric acid 2.1, terminal amino group concentration 71 μmol / g) (A)-4: Polyamide 6 (PA6) (manufactured by UBE, melting point 222 °C, model number: 1013B, relative viscosity in sulfuric acid 2.4, terminal amino group concentration 46 μmol / g) (A)-5: Polyamide 612 (PA612) (manufactured by Asahi Kasei, melting point 215 °C, model number: Leona 4400, relative viscosity in sulfuric acid 3.6, amino group terminal concentration 14 μmol / g) (A)-6: Polyamide 6 / 12 (PA6 / 12) (manufactured by UBE, melting point 195 °C, model number: 7024B, relative viscosity in sulfuric acid 2.6) (A)-7: Polyamide 612 (PA612) (melting point 215 °C, relative viscosity in sulfuric acid 2.1, terminal amino group concentration 90 μmol / g)

[0104] The melting points of the polyamide resins were measured using a Diamond DSC manufactured by PERKIN-ELMER in accordance with JIS-K7121.

[0105] The relative viscosity of each polyamide resin in 96% sulfuric acid was measured in accordance with JIS-K6920.

[0106] The terminal amino group concentration of each polyamide resin was measured by neutralization titration as follows. First, 3.0 g of the obtained polyamide was dissolved in 100 mL of a 90 mass% aqueous phenol solution. Then, using the obtained solution, titration was performed with 0.025 N hydrochloric acid to determine the terminal amino group concentration (μmol / g). The end point was determined from the indication value of a pH meter.

[0107] The carboxyl group terminal concentration of each polyamide resin was measured by neutralization titration as follows. First, 4.0 g of the obtained polyamide was dissolved in 50 mL of benzyl alcohol. Then, using the obtained solution, titration was performed with 0.1 N NaOH to determine the carboxyl group terminal concentration (μmol / g). The end point was determined from the color change of the phenolphthalein indicator.

[0108] <(B) Polyolefin resin> ((B-1) component) (B-1)-1: High-density polyethylene resin (manufactured by Nippon Polyethylene Co., Ltd., melting point: 128 °C, model number: Novatec HE121, MFR: 0.2 g / 10 min, weight average molecular weight: 214,000) (B-1)-2: High-density polyethylene resin (manufactured by Asahi Kasei, melting point: 135 °C, model number: Suntech HD B891, MFR <0.1 g / 10 min (0.2 g / 10 min, measured at 230 °C, 2.16 kg), weight average molecular weight: 358,000) (B-1)-3: Low-density polyethylene resin (manufactured by Asahi Kasei, melting point: 111 °C, model number: Suntech LD M2004, MFR: 0.4 g / 10 min, weight average molecular weight: 101,200) (B-1)-4: Linear low-density polyethylene resin (manufactured by Prime Polymer Co., Ltd., melting point: 117 °C, model number: Neozex 2006H, MFR: 0.6 g / 10 min, weight average molecular weight: 157,300) (B-1)-5: High-density polyethylene resin (manufactured by Asahi Kasei, melting point: 127 °C, model number:, MFR: 2.5 g / 10 min, weight average molecular weight: 70,900) (B-1)-6: Ethylene-butene copolymer (manufactured by Mitsui Chemicals, Inc., model number: Tafmer DF605, MFR: 0.5 g / 10 min, weight average molecular weight: 174,500) (B-1)-7: High-density polyethylene resin (melting point: 123 °C, MFR: 26 g / 10 min, weight average molecular weight: 50,300) (B-1)-8: Linear low-density polyethylene resin (manufactured by Prime Polymer Co., Ltd., melting point: 98 °C, model number: Evolue SP0540, MFR: 4.0 g / 10 min, weight average molecular weight: 61,000) (B-1)-9: Ethylene-Propylene-Diene Copolymer (MFR: 4.0 g / 10 min, Weight-Average Molecular Weight: 55,000) (Component (B-2)) (B-2)-1: Maleic Anhydride Grafted Ethylene-Butene Copolymer (manufactured by Mitsui Chemicals, Melting Point: 80 °C, Type Number: Tafmer MA9015, MFR: 11 g / 10 min, Acid Modification Rate: 0.75 mass%, Weight-Average Molecular Weight: 29,800) (B-2)-2: Maleic Anhydride Grafted Ethylene-Butene Copolymer (manufactured by Mitsui Chemicals, Melting Point: 70 °C, Type Number: Tafmer MA8510, MFR: 2.4 g / 10 min, Acid Modification Rate: 0.50 mass%, Weight-Average Molecular Weight: 51,500) (B-2)-3: Maleic Anhydride Grafted Ethylene-Butene Copolymer (manufactured by Mitsui Chemicals, Type Number: Tafmer MD715, MFR: 0.5 g / 10 min, Acid Modification Rate: 0.75 mass%, Weight-Average Molecular Weight: 58,400) (B-2)-4: Maleic Anhydride Grafted High-Density Polyethylene (manufactured by Mitsui Chemicals, Melting Point: 135 °C, Type Number: TX-1634, MFR: 1.3 g / 10 min, Acid Modification Rate: 0.60 mass%, Weight-Average Molecular Weight: 85,000) (B-2)-5: Maleic Anhydride Grafted Ethylene-Butene Copolymer (manufactured by Mitsui Chemicals, Type Number: Tafmer MH5020, MFR: 1.2 g / 10 min, Acid Modification Rate: 1.0 mass%, Weight-Average Molecular Weight: 70,600) (B-2)-6: Ethylene-Methyl Acrylate-Maleic Anhydride Copolymer (manufactured by Japan Polyolefins Co., Ltd., Melting Point: 98 °C, Type Number: ET182, MFR: 8.0 g / 10 min, Weight-Average Molecular Weight: 60,100) (B-2)-7: Maleic Anhydride Grafted Ethylene-Propylene-Diene Copolymer (MFR: 4.0 g / 10 min, Acid Modification Rate: 1.0 mass%, Weight-Average Molecular Weight: 51,000) (B-2)-8: Maleic Anhydride Grafted Ethylene-Butene Copolymer (MFR: 0.5 g / 10 min, Acid Modification Rate: 0.50 mass%, Weight-Average Molecular Weight: 124,300)

[0109] The weight-average molecular weight of each polyolefin resin was measured by gel permeation chromatography (GPC) under the following apparatus and conditions. Apparatus: GPC-IR5 manufactured by Polymer Char Detector: RI detector Mobile phase: o-dichlorobenzene (for high-performance liquid chromatography) Flow rate: 1.0 mL / min Column: One UT-807 column manufactured by Showa Denko K.K. Two GMHHR-H(S)HT18393 columns manufactured by Tosoh Corporation were connected in series. Column temperature: 140 °C

[0110] The melting point of each polyolefin resin was measured using a Diamond DSC manufactured by PERKIN-ELMER in accordance with JIS-K7121.

[0111] The MFR of each polyolefin resin was measured using a melt indexer in accordance with ASTM D1238.

[0112] The amount of acid modification of each polyolefin resin (B) was measured by measuring the peak intensity at a wave number of 1780 cm -1 attributed to the carbonyl group by FT-IR and quantified from a calibration curve prepared separately.

[0113] ((C) polyphenylene ether) (C)-1: Maleic anhydride-modified polyphenylene ether (manufactured by Asahi Kasei, model number: Zylon R4919, MFR: 0.51 g / 10 min (measured at 280 °C and 10 kg), glass transition temperature: 214 °C)

[0114] (Synthesis example) ((A)-3: Polyamide 612) The polymerization reaction of polyamide was carried out as follows by the "thermal melt polymerization method" to produce polyamide resin (A)-3. The salt of 1,12-dodecanedioic acid (1050 g) and hexamethylenediamine (540 g) was dissolved in 1400 g of distilled water to prepare a homogeneous aqueous solution of the raw material monomers, and 2.5 g of acetic acid was added thereto as a terminal capping agent. This aqueous solution was charged into an autoclave with an internal volume of 5.4 L and purged with nitrogen. While stirring at a temperature of 110 to 150°C, water vapor was gradually removed to concentrate the solution to a concentration of 70% by mass. Thereafter, the internal temperature was raised to 220°C. At this time, the pressure in the autoclave increased to 1.8 MPa. While maintaining the pressure at 1.8 MPa, the reaction was carried out for 20 minutes until the internal temperature reached 280°C and kept at that pressure for 1 hour. Next, the pressure was reduced over 1 hour and 30 minutes. Thereafter, the inside of the autoclave was maintained under a reduced pressure of 650 torr for 10 minutes using a vacuum device. At this time, the final internal temperature of the polymerization was 265°C. Thereafter, it was pressurized with nitrogen and extruded in a strand shape from the lower spinning nozzle (nozzle), cooled with water, cut, discharged in pellet form, and dried at 80°C under a nitrogen atmosphere for 12 hours to obtain polyamide 612 having a relative viscosity of sulfuric acid of 2.1 and an amino group terminal concentration of 71 μmol / g.

[0115] ((A)-7: Polyamide 612) The polymerization reaction of polyamide was carried out as follows by the "thermal melt polymerization method" to produce polyamide resin (A)-7. The salt of 1,12-dodecanedioic acid (1010 g) and hexamethylenediamine (528 g) was dissolved in 1400 g of distilled water to prepare a homogeneous aqueous solution of the raw material monomers, and 2.0 g of acetic acid was added thereto as a terminal capping agent. This aqueous solution was charged into an autoclave with an internal volume of 5.4 L and purged with nitrogen. While stirring at a temperature of 110 to 150°C, water vapor was gradually removed to concentrate the solution to a concentration of 70% by mass. Thereafter, the internal temperature was raised to 220°C. At this time, the pressure in the autoclave increased to 1.8 MPa. While maintaining the pressure at 1.8 MPa, the reaction was carried out for 20 minutes until the internal temperature reached 280°C and kept at that pressure for 1 hour. Next, the pressure was reduced over 1 hour and 30 minutes. Thereafter, the inside of the autoclave was maintained under a reduced pressure of 650 torr for 20 minutes using a vacuum device. At this time, the final internal temperature of the polymerization was 265°C. Thereafter, it was pressurized with nitrogen, formed into strands from the lower spinning orifice (nozzle), cooled with water, cut, and discharged in pellet form, and then dried at 80°C in a nitrogen atmosphere for 12 hours to obtain polyamide 612 having a relative viscosity of sulfuric acid of 2.1 and an amino group terminal concentration of 90 μmol / g.

[0116] <Physical properties and evaluation methods of the composition> (Manufacture of multi-purpose test pieces) The pellets of the polyamide resin compositions obtained in the examples and comparative examples were dried at 80°C for 8 hours in a reduced-pressure atmosphere to reduce the moisture content in the polyamide resin compositions to 500 ppm or less. Next, the pellets of each polyamide resin composition with adjusted moisture content were molded into multi-purpose test pieces (Type A, dumbbell-shaped tensile test pieces) as molded products using an injection molding machine (NEX-50IV, manufactured by Nissei Plastic Industrial Co., Ltd.) in accordance with ISO3167. The dimensions of the multi-purpose test pieces were as follows: total length ≥ 170 mm, distance between tab portions 109.3 ± 3.2 mm, length of parallel portion 80 ± 2 mm, radius of shoulder 24 ± 1 mm, width of end portion 20 ± 0.2 mm, width of central parallel portion 10 ± 0.2 mm, and thickness 4 ± 0.2 mm. Specific conditions during injection molding were as follows: cylinder speed: 35 mm / second, injection and holding pressure time: 25 seconds, cooling time: 15 seconds, mold temperature: 80°C, and cylinder temperature: 280°C.

[0117] (Manufacture of pipe molded body) The polyamide resin compositions obtained in the examples and comparative examples were dried at 80°C for 8 hours in a reduced-pressure atmosphere to reduce the moisture content in the polyamide resin compositions to 500 ppm or less. Next, the pellets of each polyamide resin composition with adjusted moisture content were molded into a pipe with an outer diameter of 16 mm and an inner diameter of 13 mm using an extrusion molding machine (manufactured by BELLAFORM, BH45-25D). Specific conditions during extrusion molding were as follows: cylinder temperature 240°C, and take-up speed set at 5.0 to 12.0 m / min for molding.

[0118] (Melting peak of polyamide resin composition at 100°C or higher and lower than 150°C) The melting peak of the polyamide resin composition was measured using a Diamond DSC manufactured by PERKIN-ELMER in accordance with JIS-K7121. At this time, the temperature at the peak of the peak observed at 100 °C or higher and less than 150 °C was defined as the melting peak (°C) at 100 °C or higher and less than 150 °C. When multiple melting peaks at 100 °C or higher and less than 150 °C were observed, the peak with the largest melting enthalpy was defined as the melting peak at 100 °C or higher and less than 150 °C.

[0119] (α-olefin ratio (ratio of the component derived from α-olefin among the monomer components constituting the polyolefin resin (B))) Among the monomer components constituting the polyolefin resin (B), the ratio of the component derived from α-olefin was quantified by extracting the polyolefin component from the composition or molded product and analyzing the component by nuclear magnetic resonance method. To 1 g of the pellet, 5 mL of hexafluoroisopropanol (HFIP) and 5 mL of chloroform were added, and the mixture was allowed to stand for 18 hours. The undissolved suspension was separated, and again 5 mL of HFIP and 5 mL of chloroform were added, followed by centrifugation at 3000 rpm for 1 hour to separate the suspension. Centrifugation and recovery of the suspension were repeated three times, and the obtained suspension was vacuum dried to recover a black solid. Next, to 100 mg of the obtained solid, 5 mL of hexafluoroisopropanol (HFIP) and 15 mL of chloroform were added, the suspension was recovered, and the solid was obtained by vacuum drying. 4 mg of this solid was dissolved in deuterated orthodichlorobenzene and 1 1H-NMR measurement was performed. The α-olefin ratio (mass%) was quantified from the integration ratio of the peaks in the range of 1 to 2 ppm and the molecular weight of the constituent monomers.

[0120] (Measurement of draw rate at break) A twin-screw extruder TEM26SX manufactured by Shibaura Machine Co., Ltd. was used. This extruder has a top feed port in the first barrel from the upstream side and a side feed port in the eighth barrel. (Length of the cylinder of the extruder / diameter of the cylinder of the extruder) = 48 (number of barrels: 12). The screw rotation speed was set at 45 rpm and the discharge rate at 3 kg / h, and the polyamide composition was supplied from the side feed port. By adjusting the barrel temperature between 230 and 250 °C, the melt of the polyamide resin composition with the resin temperature adjusted to 260 °C was extruded in the form of strands. Using a Rheotens manufactured by Gottfert, the strand was passed through the circular guide of the lower pulley for tension detection and wound up at a take-up speed of 72 mm / s, and the detected tension was stabilized. After stabilization, winding was carried out while accelerating the take-up speed at an acceleration of 24 m / min 2 and the take-up speed at the time when the strand broke was defined as the breakage take-up speed.

[0121] ((B) Confirmation of the uniformity of the polyolefin resin phase) Pellets of the polyamide resin composition prepared by the method described below were cut in a direction parallel to the flow direction. After trimming this sample, the cutting surface was smoothed using a cryomicrotome (UC6 manufactured by Leica) with a diamond knife. Subsequently, the cutting surface was stained with an aqueous solution of 5 wt% phosphotungstic acid. After staining, the surface 100 nm of the cutting surface was cut off using a cryomicrotome (UC6 manufactured by Leica) with a diamond knife to remove precipitates derived from the staining agent. Using carbon paste, this sample was fixed to the sample stage to obtain an observation sample. Observation was carried out by irradiating the observation sample with an electron beam under the conditions of lens mode High, acceleration voltage 1 kV, and working distance 5 mm using a scanning electron microscope (SU8220 manufactured by Hitachi High-Technologies Corporation). At this time, the detector used was Upper LA100 (backscattered electron image). The viewing angle was adjusted so that the left-right direction of the image was parallel to the flow direction. The components observed with a bright luminance were regarded as the polyamide resin, and the components observed with a dark luminance were regarded as the polyolefin component, and the uniformity of the polyolefin resin phase was evaluated. The uniformity of the polyolefin resin phase was judged according to the following criteria. ○ (Excellent): All the components constituting the (B) polyolefin resin exist as a single phase. × (Poor): Any of the components constituting the (B) polyolefin resin forms a phase independent of the components constituting the other (B) polyolefin resin.

[0122] ((B) Dispersion state of polyolefin resin) Pellets of the polyamide resin composition prepared by the method described below were cut in a direction parallel to the flow direction. After trimming this sample, the cutting surface was smoothed using a diamond knife with a cryomicrotome (UC6 manufactured by Leica). Subsequently, the cut surface was stained with an aqueous solution of 5 wt% phosphotungstic acid. After staining, the surface 100 nm of the cut surface was cut off using a diamond knife with a cryomicrotome (UC6 manufactured by Leica) to remove precipitates derived from the stain. This sample was fixed to a sample stage using carbon paste to obtain an observation sample. Observation was carried out by irradiating the observation sample with an electron beam under the conditions of lens mode High, acceleration voltage 1 kV, and working distance 5 mm using a scanning electron microscope (SU8220 manufactured by Hitachi High-Tech Corporation). At this time, the detector used was Upper LA100 (backscattered electron image). The viewing angle was adjusted so that the left-right direction of the image was parallel to the flow direction. The dispersibility was evaluated with the component observed with a bright luminance as the polyamide resin and the component observed with a dark luminance as the polyolefin component. Components forming the dispersed phase were judged according to the following criteria. (A): In the (B) polyolefin resin, the (A) polyamide resin forms a dispersed phase. (B): In the (A) polyamide resin, the (B) polyolefin resin forms a dispersed phase.

[0123] (Ratio of major axis to minor axis of the dispersion diameter of (B) polyolefin resin) The multi-purpose test pieces of the polyamide resin composition produced by the aforementioned method (injection molding) were cut in a direction parallel to the flow direction. After trimming this sample, the cutting surface was smoothed using a cryomicrotome (UC6 manufactured by Leica) with a diamond knife. Subsequently, the cutting surface was stained with an aqueous solution of 5 wt% phosphotungstic acid. After staining, the surface 100 nm of the cutting surface was cut off using a diamond knife with a cryomicrotome (UC6 manufactured by Leica) to remove the deposits derived from the staining agent. The sample was fixed to a sample stage using carbon paste to obtain an observation sample. The observation sample was irradiated with an electron beam under the conditions of lens mode High, acceleration voltage 1 kV, and working distance 5 mm using a scanning electron microscope (SU8220 manufactured by Hitachi High-Tech Corporation) for observation. At this time, the detector used was Upper LA100 (backscattered electron image). The viewing angle was adjusted so that the left-right direction of the image was parallel to the flow direction. From the obtained image, the components observed with a bright luminance were regarded as the polyamide resin, and the components observed with a dark luminance were regarded as the polyolefin component. By binarization processing, (A) the polyamide resin and (B) the polyolefin resin were separated respectively, and the area per one of the (B) polyolefin resin domains was determined. The number-average area was calculated from all the domains of the (B) polyolefin resin. The area 1.30 μm which has a great influence on the physical properties 2 above 43.3 μm 2 For the (B) polyolefin resin domains in the following range, the number-average of the ratio of the major axis to the minor axis was determined by a known method. As an example, the dispersed state shown in Fig. 1 can be subjected to binarization processing as shown in Fig. 2, and the ratio of its major axis to minor axis (major axis / minor axis) can be determined to be 4.7.

[0124] [Evaluation 1] High-temperature refrigerant resistance The antifreeze of GMW3420 standard, the undiluted DEX-COOL was diluted to 50% with pure water, and the universal test pieces prepared according to the above method for manufacturing multi-purpose test pieces were immersed in an autoclave. The container was immersed in an oil bath at a temperature of 130 °C. After 500 hours, the test pieces were taken out from the container. The liquid adhering to the test pieces was washed with water, wiped off, and then sealed in an aluminum seal bag and stabilized in an environment at 23 °C. The obtained test pieces were tested according to ISO527 at a tensile speed of 50 mm / min, taking the tensile strength of the test pieces immediately after molding as 100% and comparing the strengths. The higher the strength retention rate, the better the strength when in use and the longer the period of use becomes possible.

[0125] [Evaluation 2] Antifreeze absorbency The antifreeze of GMW3420 standard, the undiluted DEX-COOL was diluted to 50% with pure water, and the universal test pieces prepared according to the above method for manufacturing multi-purpose test pieces were immersed in an autoclave. The container was immersed in an oil bath at a temperature of 100 °C. After 500 hours, the test pieces were taken out from the container. The liquid adhering to the test pieces was washed with water, wiped off, and then sealed in an aluminum seal bag and stabilized in an environment at 23 °C. The weight of the obtained test pieces was measured, taking the weight of the same test pieces immediately after molding as 100% and comparing the weight increments. Table 1 shows the ratio of the increased weight to the weight of the test pieces immediately after molding at 100%. The lower the refrigerant absorption amount, the higher the strength in the use environment.

[0126] [Evaluation 3] Low-temperature impact resistance Using the universal test pieces prepared according to the above method for manufacturing multi-purpose test pieces, a Charpy impact test was carried out at -30 °C in accordance with ISO179, and the Charpy impact strength (kJ / m 2 ) was measured. By having excellent low-temperature Charpy impact strength, a molded body that can withstand impacts such as chipping even in cold regions can be obtained.

[0127] [Evaluation 4] High-speed moldability According to the manufacturing method of the above pipe molded body, the number of resin breakages and resin blockages at the die outlet during continuous molding for 2 hours at a cylinder temperature of 240°C and a take-up speed of 20.0 m / min was measured. The fewer the number of resin breakages and resin blockages, the better the high-speed moldability. ◎(Extremely excellent): No resin breakage or resin blockage occurs. ○(Excellent): Resin breakage or resin blockage occurs 1 - 2 times. △(Good): Resin breakage or resin blockage occurs 3 or more times. ×(Poor): Molding cannot be performed at a high rate (20.0 m / min).

[0128] [Evaluation 5] Wall thickness uniformity during extrusion molding According to the manufacturing method of the above pipe molded body, the number of protrusions and depressions with a diameter of 1 mm or more formed on the inner surface or outer surface of a 1 m long pipe molded at a cylinder temperature of 240°C and a take-up speed of 10.0 m / min was measured. The wall thickness of the cross-section of the molded product was measured with calipers, and the maximum value (T max ) and the minimum value (T min ) were obtained. The ratio of the maximum value to the minimum value of the wall thickness (T max / T min ) was calculated, and the wall thickness uniformity was judged according to the following criteria. The smaller the T max / T min , the smaller the variation in wall thickness and the better the extrusion moldability. ◎(Extremely excellent): (T max / T min ) ≤ 1.05 ○(Excellent): 1.05 < (T max / T min ) ≤ 1.10 △(Good): 1.10 < (T max / T min ) < 1.15 ×(Poor): (T max / T min ) ≥ 1.15

[0129] [Evaluation 6] Circumferential tensile elongation According to the manufacturing method of the above pipe molded body, a pipe with an outer diameter of 19 mm and an inner diameter of 16 mm, which was molded at a cylinder temperature of 240°C and a take-up speed of 10.0 m / min, was used. Referring to the test method described in QC / T 798-2008 7.9.2.2, two semi-circular jigs were inserted into the pipe, and the circumferential tensile elongation was determined using a universal testing machine. The greater the tensile elongation, the more excellent the pressure-resistant molded body obtained.

[0130] <Manufacture of Polyamide Resin Composition> [Example 1] (Manufacture of Polyamide Resin Composition E1) A twin-screw extruder TEM26SX manufactured by Shibaura Machine Co., Ltd. was used. From the top feed port, a pre-blended mixture of (A) polyamide resin and (B) polyolefin resin was supplied. The melt-kneaded material extruded from the die head was cooled in a strand shape and pelletized to obtain pellets of polyamide resin composition E1. The types and contents of each component were as described in Table 1.

[0131] [Examples 2, 3, 5 to 10, 12 to 15, 17, 19 to 23] (Manufacture of Polyamide Resin Compositions E2, E3, E5 to E10, E12 to E15, E17, E19 to E23) Pellets of polyamide resin compositions E2, E3, E5 to E10, E12 to E15, E17, E19 to E23 were obtained in the same manner as in Example 1, except that the types and contents of each component were as described in the table.

[0132] [Example 4] (Manufacture of Polyamide Resin Composition E4) A twin-screw extruder TEM26SX manufactured by Shibaura Machine Co., Ltd. was used. From the top feed port, a pre-blended mixture of (A) polyamide resin, (B) polyolefin resin, and (C) modified polyphenylene ether was supplied. The melt-kneaded material extruded from the die head was cooled in a strand shape and pelletized to obtain pellets of polyamide resin composition E4. The types and contents of each component were as described in Table 1.

[0133] [Examples 11, 18] (Production of Polyamide Resin Compositions E11 and 18) Pellets of polyamide resin compositions E11 and E18 were obtained in the same manner as in Example 4, except that the types and contents of the respective components were as described in the table.

[0134] [Comparative Examples 1 - 7] (Production of Polyamide Resin Compositions C1 - 7) Pellets of polyamide resin compositions C1 - 7 were obtained in the same manner as in Example 1, except that the types and contents of the respective components were as described in the table.

[0135] Using the pellets of the polyamide resin compositions obtained in the examples and comparative examples, molded articles were produced by the above method, and various physical properties and evaluations were performed. The evaluation results are shown in the following table.

[0136]

Table 1

[0137]

Table 2

[0138] From the table, it was found that polyamide resin compositions E1 - E15, E17 - E23 (Examples 1 - 15, 17 - 23) are excellent in high - temperature refrigerant resistance, refrigerant absorption, low - temperature impact resistance, melt extensibility, extrusion moldability, and circumferential tensile elongation. For polyamide resin composition C1, the extrusion moldability and circumferential tensile elongation were sufficient, but the high - temperature refrigerant resistance, refrigerant absorption, low - temperature impact resistance, and melt extensibility were insufficient. For polyamide resin composition C2, the low - temperature flexibility and circumferential tensile elongation were sufficient, but the high - temperature refrigerant resistance, refrigerant absorption, melt extensibility, and extrusion moldability were insufficient. For polyamide resin composition C3, the circumferential tensile elongation was sufficient, but all of the high - temperature refrigerant resistance, refrigerant absorption, low - temperature impact resistance, melt extensibility, and extrusion moldability were insufficient. The polyamide resin composition C4 had sufficient high-temperature refrigerant resistance, refrigerant absorption, extensibility during melting, extrusion moldability, and circumferential tensile elongation, but insufficient low-temperature impact resistance. The polyamide resin composition C5 had sufficient low-temperature impact resistance, extrusion moldability, and circumferential tensile elongation, but insufficient extensibility during melting, high-temperature refrigerant resistance, and refrigerant absorption. The polyamide resin composition C6 had sufficient extensibility during melting, extrusion moldability, and circumferential tensile elongation, but insufficient high-temperature refrigerant resistance, refrigerant absorption, and low-temperature impact resistance. The polyamide resin composition C7 had sufficient extensibility during melting, extrusion moldability, circumferential tensile elongation, and low-temperature impact resistance, but insufficient high-temperature refrigerant resistance and refrigerant absorption.

[0139] Therefore, only the composition made of the polyamide molding material having two essential components in the selected proportional amounts according to claim 1 and showing the physical properties defined in claim 1 can satisfy the defined objectives in terms of high-temperature refrigerant resistance, refrigerant absorption, low-temperature impact resistance, extensibility during melting, extrusion moldability, and circumferential tensile elongation. On the other hand, for the polyamide resin compositions C1 to C7 (Comparative Examples 1 to 7), those excellent in all of high-temperature refrigerant resistance, refrigerant absorption, low-temperature impact resistance, extensibility during melting, extrusion moldability, and circumferential tensile elongation could not be obtained.

Industrial Applicability

[0140] According to the polyamide resin composition of the present invention, a polyamide resin composition and / or its molded body excellent in high-temperature refrigerant resistance, low water absorption, low-temperature impact resistance, extensibility during melting, extrusion moldability, and circumferential tensile elongation can be provided. The molded article of the present invention uses the above polyamide composition, and the obtained molded article can be used as a material for various parts such as for automobiles, mechanical industry, electric and electronic, industrial materials, industrial materials, daily and household goods.

Claims

1. A polyamide resin composition comprising (A) a polyamide resin and (B) a polyolefin resin, the total amount of the (B) polyolefin resin is 55 parts by mass or less when the total amount of the (A) polyamide resin and the (B) polyolefin resin is 100 parts by mass, The (A) polyamide resin contains 50 parts by mass or more of a polyamide resin having an average of 8 or more carbon atoms per monomer unit per 100 parts by mass, the polyolefin resin (B) contains at least one polyolefin resin having a functional group reactive with a terminal amine of the polyamide resin (A) and contains at least one ethylene / α-olefin copolymer; Among the monomer units constituting the (B) polyolefin resin, the mass ratio of monomer units derived from α-olefin is 3 mass% or more and 11 mass% or less, When heated at 20° C. / min from 23° C. by a differential scanning calorimeter, it exhibits at least one melting peak at 100° C. or higher and lower than 150° C. A polyamide resin composition comprising:

2. The polyamide resin composition according to claim 1, wherein the take-up speed at break is 200 mm / s or more.

3. The polyamide resin composition according to claim 1, wherein the polyolefin resin (B) comprises: (B-1) a polyolefin resin having no functional group reactive to a terminal amine of the polyamide resin (A); and (B-2) a polyolefin resin having a functional group reactive to a terminal amine of the polyamide resin (A).

4. The polyamide resin composition according to claim 3, wherein the weight average molecular weight of the component (B-2) is 80,000 or less.

5. The polyamide resin composition according to claim 3, wherein the weight average molecular weight of the component (B-1) is more than 80,000.

6. The polyamide resin composition according to claim 3, wherein the mass ratio of the (B-1) component to the (B-2) component is in the range of (B-1):(B-2)=1:5 to 5:

1.

7. The polyamide resin composition according to claim 3, wherein the MFR of the component (B-1) measured at 190°C and 2.16 kg is 0.5 g / 10 min or less, and the MFR of the component (B-2) measured at 190°C and 2.16 kg is 0.5 g / 10 min or more.

8. The polyamide resin composition according to claim 3 , wherein the polyolefin resin (B) forms a single phase.

9. 4. The polyamide resin composition according to claim 3, wherein the ratio of major axis / minor axis of dispersed particles of the polyolefin resin (B) is 5.0 or less.

10. 2. The polyamide resin composition according to claim 1, wherein the polyolefin resin (B) comprises a high-density polyethylene, and the high-density polyethylene has a weight average molecular weight of 100,000 or more.

11. 2. The polyamide resin composition according to claim 1, wherein the polyolefin resin (B) contains a low-density polyethylene, and the low-density polyethylene has a weight average molecular weight of 80,000 or more.

12. 2. The polyamide resin composition according to claim 1, wherein the polyamide resin (A) has a relative viscosity in sulfuric acid of 2.4 or less.

13. The polyamide resin composition according to claim 1, further comprising 1 to 40 parts by mass of (C) polyphenylene ether per 100 parts by mass of the total of the (A) polyamide resin and the (B) polyolefin resin.

14. The polyamide resin composition according to claim 1, wherein the total content of the polyamide resin (A) and the polyolefin resin (B) is 60 to 100 parts by mass per 100 parts by mass of all resin components.

15. A molded article using the polyamide resin composition according to any one of claims 1 to 14.

16. A method for producing a molded article, comprising a step of molding the polyamide resin composition according to any one of claims 1 to 14 by extrusion molding or blow molding.

17. The molded article according to claim 15, which is an automotive material part.

18. The molded article according to claim 15, which is any one of a brake hose, an air conditioning hose, and a cooling pipe.

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