Polyamide resin composition and molded article

Abstract

The object of the present invention is to provide a polyamide resin composition that offers excellent high-temperature refrigerant resistance, flexibility, and low-temperature impact resistance, enables the provision of a tube molded article that does not leak at 100°C, and exhibits excellent high-speed extrusion moldability. [Solution] The polyamide resin composition of the present invention is a polyamide resin composition comprising (A) a polyamide resin and (B) a polyolefin resin, The (A) polyamide resin and the (B) polyolefin resin are characterized in that, with respect to a total mass of 100 parts by mass of the (A) polyamide resin and the (B) polyolefin resin, the mass ratio of the (A) polyamide resin is 20 parts by mass or more and 50 parts by mass or less, and the mass ratio of the (B) polyolefin resin is 50 parts by mass or more and 80 parts by mass or less, and when heated from 23°C to 20°C / min using a differential scanning calorimeter, at least one melting peak is shown at 80°C or more and less than 150°C, the viscosity parameter shown below is 1.2 or more and less than 4.0, and the (A) polyamide resin forms the matrix. Viscosity parameter: (ΦA × ηB) / (ΦB × ηA)

Description

[Technical Field]

[0001] This invention relates to polyamide resin compositions and molded articles. [Background technology]

[0002] Polyamide resins possess excellent mechanical, thermal, and chemical resistance properties, making them suitable as engineering plastics. Therefore, they are widely used in applications such as mechanical and automotive parts, and various electrical and electronic components, primarily for injection molding. In particular, in the rapidly expanding field of electric vehicles (EVs), there is a demand for long, thin molded parts for cooling pipes through which refrigerants cool the batteries. Polyamide resins and rubber materials are widely used in these pipes due to their heat resistance and toughness. However, rubber materials, when used alone, lack sufficient strength, especially in high-temperature ranges (around 80°C), leading to problems such as leakage at high temperatures. On the other hand, polyamide resins generally have less flexibility than rubber, making them unsuitable for applications requiring assembly flexibility or vibration absorption.

[0003] A known method for imparting flexibility to polyamide resins involves adding crosslinked high-density polyethylene to polyamide 12 (Patent Document 1). Another known method involves adding crosslinked brominated isobutyl rubber to a polyamide resin mixture mainly composed of polyamide 6 / 66 (Patent Document 2). Furthermore, a method is known in which a crosslinked ethylene-1-butene copolymer is added to polyamide 6 (Patent Document 3). Furthermore, a method is known in which high-viscosity polyethylene and impact-resistant materials are added to polyamide 6 (Patent Document 4). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2009-270024 [Patent Document 2] Patent No. 6294948 [Patent Document 3] Japanese Patent Publication No. 2023-78137 [Patent Document 4] Patent No. 4703962 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The composition described in Patent Document 1 is unsuitable for use in areas requiring assembly flexibility and vibration absorption due to its poor flexibility and impact resistance. Furthermore, while the compositions described in Patent Documents 2, 3, and 4 are excellent in flexibility and impact resistance, they lack sufficient strength at high temperatures, leading to problems such as liquid leakage at 80°C, the operating temperature of EVs.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a polyamide resin composition and a molded article thereof that is excellent in high-temperature refrigerant resistance, flexibility, and low-temperature impact resistance, and that does not leak at 100°C, and that produces little residue during extrusion molding and is excellent in high-speed extrusion moldability. [Means for solving the problem]

[0007] In other words, the present invention is as follows. [1] A polyamide resin composition comprising (A) a polyamide resin and (B) a polyolefin resin, With respect to a total mass of 100 parts by mass of the (A) polyamide resin and the (B) polyolefin resin, the mass ratio of the (A) polyamide resin is 20 parts by mass or more and 50 parts by mass or less, and the mass ratio of the (B) polyolefin resin is 50 parts by mass or more and 80 parts by mass or less. When heated at 20°C / min from 23°C using a differential scanning calorimeter, at least one melting peak is observed between 80°C and 150°C. The viscosity parameters shown below are between 1.2 and 4.0, A polyamide resin composition characterized in that the (A) polyamide resin forms a matrix. Viscosity parameter: (ΦA × ηB) / (ΦB × ηA) ηA: The (A) polyamide component obtained by the method described above, at 280°C and 400 s -1 Shear viscosity at shear rate ΦA: The volume ratio of the polyamide resin component obtained by dividing the weight fraction of the polyamide resin component by the specific gravity of the polyamide resin component. ηB: (B) Polyolefin component obtained by the method described above, at 280°C and 400s -1 Shear viscosity at shear rate ΦB: The volume ratio of the polyolefin resin component obtained by dividing the weight fraction of the polyolefin resin component by the specific gravity of the polyolefin component. [2] The polyamide resin composition according to [1], characterized in that at least a portion of the (B) polyolefin resin is crosslinked. [3] The polyamide resin composition according to [1] or [2], characterized in that, in thermogravimetric analysis (TGA), the peak at 150°C to 300°C is 0.05% or more. [4] (E) A polyamide resin composition according to any one of [1] to [3], characterized by further comprising an antioxidant. [5] The polyamide resin composition according to [4], characterized in that the (E) antioxidant is added after the (B) polyolefin resin that becomes a crosslinking reaction product and (C) crosslinking material have been kneaded. [6] The polyamide resin composition according to any one of [1] to [5], characterized in that the (B) polyolefin resin includes a polyolefin resin having a functional group that is reactive to the terminal amino group of the (A) polyamide resin. [7] The polyamide resin composition according to any one of [1] to [6], characterized in that when heated at 23°C to 20°C / min using a differential scanning calorimeter, it shows at least one melting peak of 80°C or higher and less than 150°C. 〔8〕The polyamide resin composition according to any one of 〔2〕to 〔7〕, wherein at least a part of the (B) polyolefin resin is crosslinked using a (C) crosslinking agent. 〔9〕The polyamide resin composition according to any one of 〔2〕to 〔8〕, wherein at least a part of the (B) polyolefin resin is crosslinked using a (D) crosslinking aid. 〔10〕The (B) polyolefin resin contains monomer units derived from at least one α-olefin, The polyamide resin composition according to any one of 〔1〕to 〔9〕, wherein the mass ratio of the monomer units derived from the α-olefin among the monomer units constituting the (B) polyolefin resin is 3% by mass or more and 20% by mass or less. 〔11〕The polyamide resin composition according to any one of 〔1〕to 〔10〕, wherein the weight average molecular weight of the polyolefin resin component in the polyamide resin composition is 1,000,000 or more. 〔12〕A molded article comprising the polyamide resin composition according to any one of 〔1〕to 〔11〕. 〔13〕The molded article according to 〔12〕, which is any one of a brake hose, an air conditioner hose, an oil hose, or a cooling pipe.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a polyamide resin composition and a molded article thereof that are excellent in high-temperature refrigerant resistance, flexibility, low-temperature impact resistance, do not cause liquid leakage at 100 °C, have less melt fracture during extrusion molding, and are excellent in high-speed extrusion molding properties.

Embodiments for Carrying Out the Invention

[0009] 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.

[0010] In the present specification, "polyamide" means a polymer having an amide (-NHCO-) group in the main chain.

[0011] [Polyamide resin composition] The polyamide resin composition of this embodiment is (A) A polyamide resin and (B) a polyolefin resin, and the polyamide resin composition contains Based on 100 parts by mass of the total mass of the (A) polyamide resin and the (B) polyolefin resin, the mass ratio of the (A) polyamide resin is 20 parts by mass or more and 50 parts by mass or less, and the mass ratio of the (B) polyolefin resin is 50 parts by mass or more and 80 parts 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 of 80°C or more and less than 150°C. The viscosity parameter shown below is 1.2 or more and less than 4.0. The (A) polyamide resin forms a matrix, which is a feature. Viscosity parameter: (ΦA × ηB) / (ΦB × ηA) ηA: The shear viscosity of the (A) polyamide component at a shear rate of 280°C and 400 s obtained by the above-mentioned method. -1 at the shear rate ΦA: The volume ratio of the (A) polyamide resin component obtained by dividing the weight fraction of the (A) polyamide resin component by the specific gravity of the (A) polyamide component. ηB: The shear viscosity of the (B) polyolefin component at a shear rate of 280°C and 400 s obtained by the above-mentioned method. -1 at the shear rate ΦB: The volume ratio of the (B) polyolefin resin component obtained by dividing the weight fraction of the (B) polyolefin resin component by the specific gravity of the (B) polyolefin component.

[0012] The polyamide resin composition of this embodiment may consist only of (A) a polyamide resin and (B) a polyolefin resin, or it may consist only of (A) a polyamide resin, (B) a polyolefin resin and (C) a crosslinking agent, or it may consist only of (A) a polyamide resin, (B) a polyolefin resin, (C) a crosslinking agent, (D) a crosslinking aid and (E) an antioxidant, and these may further contain (F) other components.

[0013] The polyamide resin composition of this embodiment provides excellent resistance to high-temperature refrigerants, flexibility, and low-temperature impact resistance, and enables the provision of tube molded articles that do not leak at 100°C, and produces less residue during extrusion molding, resulting in excellent high-speed extrusion moldability. The following describes in detail each component of the polyamide resin composition of this embodiment.

[0014] <(A) Polyamide resin> The polyamide resin composition of this embodiment contains 20 to 50 parts by mass of (A) polyamide resin with respect to 100 parts by mass of the total mass of (A) polyamide resin and (B) polyolefin resin. From the viewpoint of ensuring that the polyamide resin forms the matrix, the mass proportion of (A) polyamide resin must be 20 parts by mass or more, preferably 25 parts by mass or more, and more preferably 30 parts by mass or more. On the other hand, from the viewpoint of obtaining sufficient flexibility derived from the polyolefin resin, the mass proportion of (A) polyamide resin must be 50 parts by mass or less, preferably 45 parts by mass or less, and most preferably 40 parts by mass or less.

[0015] Furthermore, from a similar viewpoint, the mass ratio of (A) polyamide resin to 100 parts by mass of the total mass of resin components contained in the polyamide resin composition of this embodiment is preferably 20 to 50 parts by mass, more preferably 25 to 45 parts by mass, and even more preferably 30 to 40 parts by mass. Furthermore, the mass ratio of (A) polyamide resin to 100% by mass of the polyamide resin composition of this embodiment is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and even more preferably 30 to 40% by mass.

[0016] (Relative viscosity of polyamide resin with sulfuric acid) The sulfuric acid relative viscosity of the (A) polyamide resin is preferably 1.5 to 3.0, more preferably 1.7 to 2.8, even more preferably 1.9 to 2.5, and most preferably 2.0 to 2.4. When the sulfuric acid relative viscosity is below the above upper limit, it becomes easier to use the (A) polyamide resin as a matrix even if the degree of crosslinking of the (B) polyolefin resin is low, and a polyamide resin composition with better extrusion moldability tends to be obtained. Furthermore, when the sulfuric acid relative viscosity is above the above lower limit, a polyamide resin composition with excellent resistance to high-temperature refrigerants tends to be obtained. The relative viscosity of sulfuric acid can be measured by a method compliant with JIS K 6920. The relative viscosity of sulfuric acid can be controlled by (A) adjusting the pressure during polymerization of the polyamide resin or by performing solid-phase polymerization after granulation, although this is not limited to the following.

[0017] The (A) polyamide resin is not limited to the following, but examples include 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 individually or in combination of two or more.

[0018] The polymer monomers that serve as raw materials for the polyamide resin (A) described above will be explained in detail below. (Diamine) Examples of diamines, though not limited to those listed below, include aliphatic diamines, alicyclic diamines, and aromatic diamines.

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

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

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

[0022] The aforementioned alicyclic diamines (also written as alicyclic diamines) are not limited to the following, but examples include 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, and 1,3-cyclopentanediamine.

[0023] The aforementioned aromatic diamines are not limited to the following, but examples include metaxylylenediamine, paraxylylenediamine, metaphenylenediamine, orthophenylenediamine, and paraphenylenediamine.

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

[0025] (Dicarboxylic acid) The aforementioned dicarboxylic acid is not limited to the following, but examples include 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 preferably has 3 to 20 carbon atoms. Examples of such aliphatic dicarboxylic acids are, 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, dodecanediic acid, tetradecanediic acid, hexadecanedioic acid, octadecanediic acid, eicosanedioic acid, and diglycolic acid.

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

[0028] The alicyclic dicarboxylic acid may be unsubstituted or substituted. A alkyl group having 1 to 4 carbon atoms is preferred as the substituent. Examples of substituents, though not limited to those listed below, include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups.

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

[0030] The aforementioned aromatic dicarboxylic acid is not limited to the following, but examples include unsubstituted or substituted aromatic dicarboxylic acids having 8 to 20 carbon atoms. The substituents are not limited to the following, but examples include alkyl groups having 1 to 6 carbon atoms, aryl groups having 6 to 12 carbon atoms, arylalkyl groups having 7 to 20 carbon atoms, halogen groups, alkylsilyl groups having 3 to 10 carbon atoms, sulfonic acid groups, and groups having sulfonates. Examples of halogen groups include chloro groups and bromo groups. Examples of salts constituting groups having sulfonates include sodium salts.

[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, and 5-sodium sulfoisophthalic acid.

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

[0033] (Lactam) The lactams mentioned above are not limited to the following, but examples include butyrolactam, pivalolactam, ε-caprolactam, capryloractam, enantractam, undecanelactam, and laurolactam (dodecanelactam). Among these, ε-caprolactam, undecanelactam, or laurolactam (dodecanelactam) are preferred from the viewpoint of polymerization production. These lactams may be used individually or in combination of two or more.

[0034] (aminocarboxylic acid) The aminocarboxylic acid mentioned above is not limited to the following, but examples include compounds in which the above-mentioned lactam has been ring-opened, and more specifically, ω-aminocarboxylic acid, α,ω-aminocarboxylic acid, etc.

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

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

[0037] These aminocarboxylic acids may be used individually or in combination of two or more types.

[0038] Furthermore, the polyamide resin (A) is not limited to the following, but examples include: polyamide 610 (polyhexamethylene sebamid), polyamide 612 (polyhexamethylene dodecamide), polyamide 116 (polyundecamethylene adipamide), polyamide 1010 (polydecamethylene sebamid), polyamide 1012 (polydecamethylene dodecamide), polyamide MXD6 (polymetaxylylene adipamide), and polyamide 66 / 6I (polyhexamethylene adipamide / polyisophthal adipamide). Polyamide 6I / 6T (polyisophthaladipamide / polyterephthaladipamide copolymer), polyamide 6 / 11 (caprolactam / aminoundecanoic acid copolymer), polyamide 6 / 12 (caprolactam / laurolactam copolymer), polyamide 6 / 6 / 12 (caprolactam / polyhexamethyleneadipamide / laurolactam copolymer), polyamide TMHT (trimethylhexamethyleneterephthalamide), polyamide 6T (polyhexamethyleneterephthalamide), polyamide 2Me-5T (Po Polyamide 9T (polynonamethylene terephthalamide), 2Me-8T (poly2-methyloctamethylene terephthalamide), polyamide 6C (polyhexamethylene cyclohexanedicalboxamide), polyamide 2Me-5C (poly2-methylpentamethylene cyclohexanedicalboxamide), polyamide 9C (polynonamethylene cyclohexanedicalboxamide), 2Me-8C (poly2-methyloctamethylene cyclohexanedicalboxamide), polyamide Examples include polyamide 10T (polydecamethylene terephthalamide), polyamide 11T (polyundecamethylene terephthalamide), polyamide 12T (polydodecamethylene terephthalamide), polyamide 10C (polydecamethylene cyclohexanedicalboxamide), polyamide 11C (polyundecamethylene cyclohexanedicalboxamide), polyamide 12C (polydodecamethylene cyclohexanedicalboxamide), polyamide 11 (polyundecanamide), and polyamide 12 (polydodecaneamide).In particular, (A) as polyamide resins, from the viewpoint of low-temperature impact resistance and high-temperature refrigerant resistance, polyamide 610, polyamide 612, polyamide 116, polyamide 6 / 11, polyamide 6 / 12, polyamide 6 / 6 / 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 preferred, polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide 6 / 11, polyamide 6 / 12, polyamide 6 / 66 / 12, polyamide 1010, and polyamide 1012 are more preferred, and polyamide 610, polyamide 612, polyamide 11, polyamide 6 / 11, polyamide 6 / 12, polyamide 6 / 66 / 12, polyamide 1010, and polyamide 1012 are particularly preferred.

[0039] The terminal amino group concentration of the polyamide resin (A) is not particularly limited, but is preferably 20 μmol / g or more, more preferably 30 μmol / g or more, even more preferably 40 μmol / g or more, particularly preferably 60 μmol / g or more, and most preferably 80 μmol / g or more, as it facilitates reaction with the polyolefin resin (B) and improves resistance to high temperatures and coolants. The upper limit of the terminal amino group concentration of the polyamide resin (A) is not particularly limited, but can be, for example, 120 μmol / g.

[0040] The terminal carboxyl group concentration of the (A) polyamide resin is not particularly limited, but is preferably 100 μmol / g or less due to its excellent resistance to high temperatures and low metal corrosion. The lower limit of the terminal carboxyl group concentration of the (A) polyamide resin is not particularly limited, but can be, for example, 10 μmol / g.

[0041] The end group concentration of (A) polyamide resin can be measured by neutralization titration or nuclear magnetic resonance spectroscopy. Specifically, it can be measured by the method described in the examples below.

[0042] (Number of carbon atoms per monomer) Preferably, in 100 parts by mass of the (A) polyamide resin, at least 50 parts by mass of polyamide resin having an average of 8 or more carbon atoms per monomer unit is included, more preferably 60 parts by mass or more, and most preferably 80 parts by mass or more. Alternatively, the (A) polyamide resin may consist only of polyamide having an average of 8 or more carbon atoms per monomer unit. When the content of polyamide having 8 or more carbon atoms per monomer unit is above the above lower limit, the chemical resistance, high temperature refrigerant resistance, and low temperature shock resistance of the molded product tend to improve. Furthermore, (A) it is preferable that the upper limit of the number of carbon atoms per monomer unit of the polyamide resin is 12. When the number of carbon atoms per monomer unit is below the above upper limit, the crystallization temperature and melt stability of the polyamide resin composition tend to be higher, and the productivity of the composition and molded articles tends to improve.

[0043] Here, 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 monomer used by the number of monomers used. For example, consider the following: PA6 φ has an average of 6 carbon atoms per monomer unit [6:1=6] PA66 φ has an average of 6 carbon atoms per monomer unit [(6+6):2=6] PA612 φ has an average of 9 carbon atoms per monomer unit [(6+12):2=9] PA66 / 6I φ contains an average of 6.5 carbon atoms per monomer unit. [{(6+6)+(6+8)}:4=6.5].

[0044] (Terminal encapsulant) During the production of the polyamide resin (A) described above, an end-capturing agent may be further added to adjust the molecular weight when polymerizing the monomers. This end-capturing agent is not particularly limited, and known agents can be used.

[0045] The end-captive agents mentioned above are not limited to the following, but examples include monocarboxylic acids, monoamines, acid anhydrides, monoisocyanates, monoacid halides, monoesters, and monoalcohols. Among these, monocarboxylic acids or monoamines are preferred from the viewpoint of thermal stability. These end-captive agents may be used individually or in combination of two or more.

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

[0047] The monoamine can be any monoamine that is reactive with a carboxyl group, and examples include aliphatic monoamines, alicyclic monoamines, aromatic monoamines, etc. Examples of aliphatic monoamines include, but are not limited to, methylamine, ethylamine, propylamine, isopropylamine, butylamine, hexylamine, octylamine, decylamine, undecylamine, laurylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, and dibutylamine. Examples of alicyclic monoamines include, but are not limited to, cyclohexylamines and dicyclohexylamines. Examples of aromatic monoamines include, but are not limited to, aniline, toluidine, diphenylamine, and naphthylamine. These monoamines may be used individually or in combination of two or more.

[0048] The aforementioned acid anhydrides are not limited to the following, but examples include phthalic anhydride, maleic anhydride, benzoic anhydride, acetic anhydride, and hexahydrophthalic anhydride. These acid anhydrides may be used individually or in combination of two or more.

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

[0050] The aforementioned monoacid halides are not limited to the following, but include, for example, halogen-substituted monocarboxylic acids such as benzoic acid, diphenylmethanecarboxylic acid, diphenylsulfoncarboxylic acid, diphenylsulfoxidecarboxylic acid, diphenylsulfidecarboxylic acid, diphenylethercarboxylic acid, benzophenonecarboxylic acid, biphenylcarboxylic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, and anthracenecarboxylic acid. These monoacid halides may be used individually or in combination of two or more.

[0051] Examples of the aforementioned monoesters include, but are not limited to, glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin monomonantate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol monobehenate, pentaerythritol monomonantate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monobehenate, sorbitan monomonantate, sorbitan dimonantate, sorbitan trimonantate, sorbitol monopalmitate, sorbitol monostearate, sorbitol monobehenate, sorbitol tribehenate, sorbitol monomonantate, and sorbitol dimonantate. These monoesters may be used individually or in combination of two or more.

[0052] The aforementioned monoalcohols are not limited to the following, but examples include 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 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, etc. These monoalcohols may be used individually or in combination of two or more.

[0053] (B) Polyolefin resin The polyamide resin composition of this embodiment includes (B) polyolefin resin from the viewpoint of improving flexibility, low-temperature impact resistance, and melt-induced elongation. Here, the (B) polyolefin resin includes a polyolefin resin containing at least one monomer unit derived from an α-olefin, and may consist only of a polyolefin resin containing at least one monomer unit derived from an α-olefin. The α-olefin-derived monomer unit may be one type or a combination of multiple types.

[0054] The (B) polyolefin resin has a mass percentage of α-olefin-derived monomer units among its constituent monomer units of 3% by mass or more and 20% by mass or less, preferably 5 to 17% by mass, and more preferably 7 to 15% by mass. The mass percentage of α-olefin-derived monomer units among the constituent monomer units of the (B) polyolefin resin can be measured by the method described in the examples below.

[0055] Preferably, the (B) polyolefin resin is crosslinked in at least a portion of it. When the (B) polyolefin resin is crosslinked, even in a resin composition like this embodiment where the content ratio of (A) polyamide resin is relatively small, the (A) polyamide resin tends to form a matrix, and the composition tends to have excellent resistance to liquid leakage at high temperatures and resistance to high-temperature refrigerants.

[0056] The (B) polyolefin resin preferably includes a polyolefin resin having a functional group that is reactive with the (A) polyamide resin, and more preferably includes a resin having a functional group that is reactive with the terminal amino groups of the (A) polyamide resin.

[0057] The (B) polyolefin resin preferably includes a polyolefin resin having a melting point of 80°C or higher.

[0058] The (B) polyolefin resin may consist of two or more (preferably only two) resins, although this is not limited to the following. The two resins may be, for example, an ethylene-α-olefin copolymer having a functional group that is reactive to the terminal amino groups of the (A) polyamide resin, and a crystalline olefin resin that is not reactive to the terminal amino groups of the (A) polyamide resin and has a melting point of 80°C or higher. Alternatively, there may be two types: a crystalline olefin resin having a functional group that is reactive to the terminal amino groups of the (A) polyamide resin and exhibiting a melting point of 80°C or higher, and an ethylene-α-olefin copolymer that is not reactive to the terminal amino groups of the (A) polyamide resin. If the (B) polyolefin resin contains two or more components, some of the components may be crosslinked, or all of the components may be crosslinked. From the viewpoint of preventing poor dispersion in the polyamide composition, it is preferable that all components are crosslinked.

[0059] The polyolefin resin (B) mentioned above is not limited to the following, but specifically, examples include polyethylene resins, polypropylene resins, ethylene-α-olefin copolymers, and ethylene-α,β-unsaturated carboxylic acid copolymers. These can be used individually or in combination of two or more.

[0060] (Polyethylene resin) Examples of polyethylene resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). Among these, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE) are more preferred because they are readily available at low cost, with HDPE and LDPE being even more preferred. These polyethylene resins may be used individually or in combination of two or more types.

[0061] When using the aforementioned polyethylene resin, the density is 0.89 g / cm³, but is not limited to the following.3 The above is desirable from the viewpoint of mechanical strength and resistance to high-temperature refrigerants, with a density of 0.92 g / cm³. 3 It is even more desirable that the density be 0.93 g / cm³ or higher. 3 It is especially desirable that the above conditions be met.

[0062] The melting point of the polyethylene resin is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, even more preferably 115°C or higher, particularly preferably 120°C or higher, and most preferably 125°C or higher, in order to maintain physical properties at the ambient temperature of use. The melting point of the polyethylene resin can be measured using a differential scanning calorimeter or the like. Specifically, it can be measured by the method described in the examples below.

[0063] The polyethylene resin preferably contains high-density polyethylene or low-density polyethylene, and more preferably contains both high-density polyethylene and low-density polyethylene. Alternatively, the polyethylene resin may consist only of high-density polyethylene and low-density polyethylene, or only of high-density polyethylene or low-density polyethylene. The high-density polyethylene and low-density polyethylene may be resins that do not have functional groups that react with the terminal amine groups of the (A) polyamide resin. When high-density polyethylene is used as the polyethylene 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. Furthermore, 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 polyethylene resins can be measured by methods such as gel permeation chromatography. Specifically, it can be measured by the method described in the examples below.

[0064] (Polypropylene resin) Examples of the aforementioned polypropylene resins include homopolypropylene, copolymer resins of propylene with other α-olefins such as butene-1, pentene-1, and hexene-1 (including block and random types). Note that the polypropylene resins do not include resins containing ethylene as a structural unit.

[0065] (Ethylene-α-olefin copolymer) The ethylene-α-olefin copolymer is a polymer obtained by copolymerizing ethylene with an α-olefin having 3 or more carbon atoms. The ethylene-α-olefin copolymer shall not contain the polyethylene-based resin mentioned above. 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, and 12-ethyl-1-tetradecene. These can be used individually or in combination of two or more types.

[0066] Furthermore, the ethylene-α-olefin copolymer may be copolymerized with polyenes such as non-conjugated dienes. Examples of non-conjugated dienes 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, and dicyclopentadiene. Examples include 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, and 2-propenyl-2,5-norbornadiene. From the viewpoint of having superior high-temperature refrigerant resistance, flexibility, and low-temperature impact resistance, ethylene-propylene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer are preferred, with ethylene-butene copolymer being more preferred. The above-mentioned ethylene-α-olefin copolymer may be used alone or in combination of two or more types.

[0067] (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 α,β-unsaturated carboxylic acid monomers include acrylic acid and methacrylic acid. Examples of α,β-unsaturated carboxylic acid ester monomers include methyl esters, ethyl esters, propyl esters, and butyl esters of these α,β-unsaturated carboxylic acids. These may be used individually or in combination of two or more.

[0068] (Reactive groups for polyamide resins) The (B) polyolefin resin may also include a modified polyolefin resin having a functional group that is reactive with the polyamide resin (preferably a functional group that is reactive with the terminal amino group of the (A) polyamide resin). Examples of functional groups that are reactive with (A) polyamide resin (preferably functional groups that are reactive with terminal amino groups of (A) polyamide resin) include carboxyl groups, acid anhydride groups, carboxylate eryl groups, epoxy groups, oxazoline groups, amino groups, maleimide groups, and the like.

[0069] These functional groups can be introduced into the (B) polyolefin resin using known methods. Specifically, these methods include copolymerizing copolymerizable monomers having functional groups during polymerization, introducing monomers having functional groups as end-captives during polymerization, and grafting by melt-kneading the (B) polyolefin resin, monomers having functional groups, and polymerization initiator. These introduction methods can be used individually or in appropriate combinations, and grafting can also be performed simultaneously with the crosslinking reaction described later.

[0070] Examples of monomers containing these functional groups (for example, (A) functional groups that are reactive to the terminal amino groups of polyamide resins) 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, endobicyclo-[2.2.1]-5-heptene-23nocarboxylic acid and metal salts of these carboxylic acids, monomethyl maleate, monomethyl itaconic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methacrylic acid Examples include methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, maleic anhydride, maleic anhydride ester, itaconate anhydride, citraconic anhydride, endobicyclo-[2,2,1]-5-heptene-2,3-dicarboxylic acid anhydride, maleimide, N-ethyl maleimide, N-butyl maleimide, N-phenyl maleimide, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, and glycidyl citraconic acid. These can be used individually or in combination of two or more. The modified polyolefin resin having a functional group that is reactive with the polyamide resin (preferably a functional group that is reactive with the terminal amino group of the polyamide resin (A)) preferably contains a maleic anhydride group, a maleic anhydride ester group, and / or a glycidyl group, from the viewpoint of reactivity with the polyamide resin (A).

[0071] The mass percentage of reactive functional groups (for example, functional groups that react with terminal amino groups of (A) polyamide resin) contained in 100% by mass of the modified polyolefin resin is preferably 0.3 to 3.0% by mass, more preferably 0.4 to 2.0% by mass, and even more preferably 0.4 to 1.5% by mass. When the mass percentage of the above functional groups (for example, acid anhydride groups, maleic acid groups, etc.) is above the lower limit, the reactivity with the (A) polyamide resin is increased, and the compatibility between the (A) polyamide resin and the (B) polyolefin resin can be sufficiently improved. When the mass percentage of the above functional groups (for example, acid anhydride groups, maleic acid groups, etc.) is below the upper limit, it is possible to avoid the reaction of an excess amount of (A) polyamide resin per molecule of the (B) polyolefin resin, and a composition with excellent extrusion moldability tends to be obtained.

[0072] The weight-average molecular weight of the (B) polyolefin resin is preferably greater than 50,000, more preferably 65,000 or more, even more preferably 80,000 or more, and particularly preferably 100,000 or more. When the weight-average molecular weight of the (B) polyolefin resin component is within this range, the crosslinking required to form the (A) polyamide resin matrix is ​​reduced, and a resin composition with superior fluidity and tensile elongation tends to be obtained. The weight-average molecular weight of polyethylene resins can be measured, for example, by dissolving only the polyolefin resin composition from a polyamide resin composition and then using gel permeation chromatography.

[0073] From the viewpoint of further improving high-temperature refrigerant resistance, flexibility, low-temperature impact resistance, and high-speed extrusion moldability, the (B) polyolefin resin is preferably a combination of a polyethylene resin (preferably a polyethylene resin with a melting point of 80°C or higher, more preferably HDPE or LDPE with a melting point of 80°C or higher) and a modified polyolefin resin having a functional group that reacts to the terminal amino groups of the (A) polyamide resin (preferably an ethylene-α-olefin copolymer having a maleic acid group, more preferably an ethylene-butene copolymer having a maleic acid group), a combination of a polyethylene resin (preferably a polyethylene resin with a melting point of 80°C or higher, more preferably HDPE or LDPE with a melting point of 80°C or higher) and an ethylene-α-olefin copolymer (preferably an ethylene-butene copolymer), or only a modified polyolefin resin having a functional group that reacts to the terminal amino groups of the (A) polyamide resin (preferably an ethylene-α-olefin copolymer having a maleic acid group, more preferably an ethylene-butene copolymer having a maleic acid group).

[0074] ((B) Polyolefin resin content) When the total amount of the (A) polyamide resin and the (B) polyolefin resin is 100 parts by mass, the mass proportion of the (B) polyolefin resin is preferably 50 to 80 parts by mass, more preferably 55 to 75 parts by mass, and even more preferably 60 to 70 parts by mass. When the amount of the (B) polyolefin resin is within the above range, a polyamide resin composition with excellent extrusion moldability, low-temperature impact resistance, and high-temperature refrigerant resistance tends to be obtained.

[0075] Furthermore, the mass ratio of the (B) polyolefin resin to 100% by mass of the polyamide resin composition of this embodiment is preferably 50 to 80% by mass, more preferably 55 to 75% by mass, and even more preferably 60 to 70% by mass. Furthermore, the mass ratio of (B) polyolefin resin to 100 parts by mass of the total resin components contained in the polyamide resin composition of this embodiment is preferably 50 to 80 parts by mass, more preferably 55 to 75 parts by mass, and even more preferably 60 to 70 parts by mass.

[0076] Furthermore, 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 this embodiment is preferably 50 to 100 parts by mass, more preferably 55 to 99 parts by mass, and even more preferably 80 to 95 parts by mass. The above resin components may consist only of (A) polyamide resin and (B) polyolefin resin.

[0077] ((B) Uniformity and dispersibility of the polyolefin resin phase) Furthermore, from the viewpoint of exhibiting good moldability and mechanical properties, it is preferable that the (B) polyolefin resin forms a single phase. Forming a single phase means that each component constituting the (B) polyolefin resin does not form independent domains. The observation method using an electron microscope that can evaluate the unity of the (B) polyolefin resin phase is not limited, but for example, observation can be performed using the method described in the examples. Among the aforementioned combinations of polyolefin resins, a combination of polyethylene resin and ethylene-α-olefin copolymer is preferred from the viewpoint of forming a single phase and improving compatibility and mechanical properties. A combination of polyethylene resin and ethylene-α-olefin copolymer in which the mass percentage of monomer units derived from α-olefin is greater than 0% by mass and within 20% by mass is more preferred. A combination of polyethylene resin and ethylene-α-olefin copolymer in which the mass percentage of monomer units derived from α-olefin is greater than 0% by mass and within 15% by mass is particularly preferred.

[0078] ((B) Mass percentage of monomer units derived from α-olefins among the monomer units constituting the polyolefin resin) The mass ratio of α-olefin-derived monomer units contained in all polyolefin resins to the total mass of monomer units constituting all polyolefin resins included in the (B) polyolefin resin is expressed as mass%, with the total mass of all components of the (B) polyolefin resin being 100% by mass, and the ratio of the total mass of α-olefin-derived monomer units contained in all polyolefin resins being expressed in mass%. From the viewpoint of exhibiting impact resistance, high-temperature refrigerant resistance, and low water absorption, the mass percentage of α-olefin-derived monomer units among the monomer units constituting (B) polyolefin resin is preferably 3% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 17% by mass or less, and particularly preferably 7% by mass or more and 15% by mass or less. The mass percentage of α-olefin-derived monomer units among the monomer units constituting the (B) polyolefin resin can be measured by methods such as nuclear magnetic resonance spectroscopy. While the method is not limited to any method capable of measuring the mass percentage of α-olefin-derived monomer units among the monomer units constituting the (B) polyolefin resin, it can be measured by, for example, the method described in the examples below.

[0079] <(C) Crosslinking of (B) polyolefin resin using crosslinking agents and / or (D) crosslinking aids> The polyamide resin composition of this embodiment is a polyamide resin composition comprising (A) a polyamide resin and (B) a polyolefin resin, wherein at least a portion of the (B) polyolefin resin may be crosslinked. The (B) polyolefin resin is preferably crosslinked using (C) a crosslinking agent, and more preferably using (D) a crosslinking aid. The (B) polyolefin resin is more preferably crosslinked using both (C) a crosslinking agent and (D) a crosslinking aid.

[0080] ((C) Crosslinking agent) The crosslinking agent used during the aforementioned crosslinking is not particularly limited and any known agent can be used. Examples of crosslinking agents include radical initiators, such as persulfates like potassium persulfate and ammonium persulfate, various organic peroxides as exemplified below, such as alkyl hydroperoxide peroxides like t-butyl hydroperoxide and cumene hydroperoxide, diacyl peroxide peroxides like benzoyl peroxide and lauroyl peroxide, dialkyl peroxide peroxides like di-t-butyl peroxide and t-butyl peroxylaurate, and azo compound peroxides like 2,2'-azobisisobutyronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile. Of these, organic peroxides are preferred for dynamic crosslinking of polyethylene resins because they have the ability to extract hydrogen from polyethylene resins. Dialkyl peroxide peroxides that efficiently extract hydrogen are more preferred, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane is particularly preferred from the viewpoint of reaction rate at processing temperature. The amount of crosslinking agent used is preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of (B) polyolefin resin.

[0081] ((D) Crosslinking agent) To promote crosslinking, the crosslinking aid can be further added. The crosslinking aid typically contains multiple unsaturated groups such as allyl or acrylic acid esters. The aid can be, for example, N,N'-(m-phenylene) dimaleamide, trimethylolpropane trimethyl acrylate, tetraallyloxyethane, triallyl cyanurate, tetramethylene diacrylate, or polyethylene oxide glycol dimethacrylate. From the viewpoint of reactivity and thermal stability, the use of triallyl cyanurate (TAIC) is preferred. The amount of the aid used is preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of (B) polyolefin resin.

[0082] ((E) Antioxidant) To achieve the optimal crosslinking amount and obtain resistance to thermal aging, antioxidants can also be added. Antioxidants are useful for controlling the crosslinking reaction because they can quench the radical species, which are the active species in the crosslinking reaction, and stop the reaction. Useful antioxidants include, but are not limited to, phosphate ester antioxidants, hindered phenol antioxidants, amine antioxidants, or mixtures of two or more of these compounds. Due to their high effectiveness in improving the thermal stability of polyamide resin compositions, the use of N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]hinderedphenol, sold by BASF Japan as Irganox 1098, 3-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionic acid-n-octadecyl, sold as Irganox 1076, and 2,2-bis[[[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]oxy]methyl]propane-1,3-diol 1,3-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], sold as Irganox 1010, is particularly preferred. (B) The proportion of the antioxidant compound in 100 parts by mass of polyolefin resin is preferably 0.01 to 5 parts by mass, more preferably 0.3 to 2.0 parts by mass, and most preferably 0.5 to 1.0 part by mass.

[0083] From the viewpoint of preventing deactivation due to reaction with the crosslinking material (C) and thermal history, it is preferable that the antioxidant (E) is not added at the same time as the crosslinking reaction product of the polyolefin resin (B) and the crosslinking material (C), and it is particularly preferable that these components (B) and (C) are added after they have been kneaded together. Furthermore, even when a portion of the antioxidant (E) is added simultaneously with the crosslinking reaction product (B) from the polyolefin resin and (C) the crosslinking material for purposes such as controlling the crosslinking reaction, it is preferable to add the antioxidant (E) after these have been kneaded.

[0084] (Method for performing cross-linking reactions) The method for carrying out the crosslinking reaction is not particularly limited, as long as it includes a step of holding raw material components containing (B) polyolefin resin and, if necessary, (C) a crosslinking agent and / or (D) a crosslinking aid at a high temperature. For example, a method may be used in which the raw material components are mixed using a Henschel mixer, tumbler mixer, etc., as necessary, and then kneaded using a single-screw or twin-screw extruder, Banbury mixer, pressure kneader, or open roll. From the viewpoint of productivity and ease of kneading with polyamide resin, it is preferable to carry out the crosslinking reaction by melt kneading in a single-screw or twin-screw extruder, and it is particularly preferable to carry out the crosslinking reaction by melt kneading in a twin-screw extruder.

[0085] <(F) Other ingredients> In addition to using (A) polyamide resin, (B) polyolefin resin, and (C) crosslinking agent and / or (D) crosslinking aid as described above, the polyamide resin composition of this embodiment may further contain (F) other components as needed, to the extent that it does not impair the effects of this embodiment.

[0086] The aforementioned (F) other components are components other than the above-mentioned (A) polyamide resin, (B) polyolefin resin, (C) crosslinking agent, and (D) crosslinking aid, and examples include heat-resistant agents, colorants, ultraviolet absorbers, photodegradation inhibitors, plasticizers, lubricants, mold release agents, nucleating agents, flame retardants, and other thermoplastic resins.

[0087] Since the aforementioned (F) other components each have significantly different properties, the suitable content of each component that does not impair the effects of this embodiment varies. A person skilled in the art can easily determine the suitable content of each of the aforementioned other components, but for example, the total amount of (F) other components in 100% by mass of the polyamide resin composition can be 50% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less.

[0088] (Viscosity parameters) The polyamide resin composition of this embodiment contains, in addition to the above-described (A) polyamide resin, (B) polyolefin resin, and, optionally added, (C) crosslinking agent, (D) crosslinking aid, and (F) other components, and satisfies the following relationship for the viscosity parameter: (ΦA×ηB) / (ΦB×ηA), which is an evaluation index for the phase structure and dispersibility of the polyamide resin composition. 1.2 ≤ (ΦA×ηB) / (ΦB×ηA) < 4.0 Here, ηA is the shear viscosity at a shear rate of 400 s at 280 °C of the (A) polyamide component determined by the above-described method, and ΦA is the volume ratio of the (A) polyamide resin component obtained by dividing the weight fraction of the (A) polyamide resin component by the specific gravity of the (A) polyamide component. ηB is the shear viscosity at a shear rate of 400 s at 280 °C of the (B) polyolefin component determined by the above-described method, and ΦB is the volume ratio of the (B) polyolefin resin component obtained by dividing the weight fraction of the (B) polyolefin resin component by the specific gravity of the (B) polyolefin component. -1 The shear viscosity at a shear rate of 400 s at 280 °C of the (A) polyamide component, and ΦA is the volume ratio of the (A) polyamide resin component obtained by dividing the weight fraction of the (A) polyamide resin component by the specific gravity of the (A) polyamide component. ηB is the shear viscosity at a shear rate of 400 s at 280 °C of the (B) polyolefin component, and ΦB is the volume ratio of the (B) polyolefin resin component obtained by dividing the weight fraction of the (B) polyolefin resin component by the specific gravity of the (B) polyolefin component. -1 By satisfying the above relationship for the viscosity parameter of the polyamide resin composition of this embodiment, the polyamide component can be surely used as the matrix component, and good dispersibility, and thus liquid leakage resistance and high-temperature refrigerant resistance can be obtained.

[0089] From the same viewpoint, the viscosity parameter is preferably 1.5 or more, more preferably 2.0 or more. Also, the viscosity parameter is preferably less than 3.5, more preferably less than 3.0.

[0090] <Method for producing polyamide resin composition> The method for producing the polyamide resin composition of this embodiment is not particularly limited as long as it includes a step of melt-kneading raw material components containing (A) polyamide resin, (B) polyolefin resin, and, optionally added, (C) crosslinking agent, (D) crosslinking aid, and (F) other components.

[0091] ​The following are specific examples of methods for melt-kneading raw material components, which include (A) polyamide resin, (B) polyolefin resin, and (C) crosslinking agents, (D) crosslinking aids, and (F) other components, which are added as needed. (i) A method of mixing raw material components including (A) polyamide resin, (B) polyolefin resin, and (C) crosslinking agent, (D) crosslinking aid, and (F) other components as needed, using a Henschel mixer, tumbler mixer, etc., and supplying the mixture to a melt kneader for melt kneading. (ii) A method of melt-mixing in which raw material components including (A) polyamide resin, (B) polyolefin resin, and (C) crosslinking agent, (D) crosslinking aid, and (F) other components, which are added as needed, are mixed in a single-screw or twin-screw extruder using a Henschel mixer, tumbler mixer, etc., and the mixture is supplied to the top feed port of the single-screw or twin-screw extruder, and the components of (A) polyamide resin, (B) polyolefin resin, and (C) crosslinking agent and / or (D) crosslinking aid and / or (F) other components that were not mixed in the above mixture are pre-mixed using a Henschel mixer, tumbler mixer, etc., and supplied to the side feed port. (iii) Using a single-screw or twin-screw extruder, the raw material components, including (B) polyolefin resin and (C) crosslinking agent, (D) crosslinking aid, and (F) other components, which are added as needed, are mixed using a Henschel mixer, tumbler mixer, etc., and the mixture is supplied to the top feed port of the single-screw or twin-screw extruder. The components of (A) polyamide resin, (B) polyolefin resin, and (C) crosslinking agent and / or (D) crosslinking aid and / or (F) other components that are not mixed in the above mixture are pre-mixed using a Henschel mixer, tumbler mixer, etc., and supplied to the side feed port for melt kneading. A method of mixing the obtained mixture with (A) polyamide resin and / or (F) other components using a Henschel mixer, tumbler mixer, etc., and supplying the mixture to a melt kneader at the top feed port of a single-screw or twin-screw extruder, and melt kneading. Among these, method (ii) or (iii) is preferred in order to improve the dispersibility of each component and to further promote the crosslinking reaction.

[0092] The temperature during melt mixing is preferably 1°C to 100°C higher than the melting point of the polyamide resin (A), and more preferably 10°C to 70°C higher than the melting point of the polyamide resin (A). Furthermore, when kneading only components that do not contain (A) polyamide resin, a temperature approximately 1°C to 200°C higher than the melting point of (B) polyolefin resin is preferred, a temperature approximately 50°C to 150°C higher than the melting point of (B) polyolefin resin is more preferred, and a temperature approximately 70°C to 130°C higher than the melting point of (B) polyolefin resin is particularly preferred.

[0093] The shearing rate in the mixer is 100 sec. -1 The above is preferable. Furthermore, the average residence time during mixing is preferably between 0.5 minutes and 5 minutes.

[0094] Any known apparatus may be used for melt-kneading, such as a single-screw or twin-screw extruder, a Banbury mixer, or a melt-kneader (mixing roll, etc.), with a twin-screw extruder being the most preferred.

[0095] (Weight-average molecular weight of polyolefin resin component in polyamide resin composition) In the polyamide resin composition of this embodiment, the weight-average molecular weight of the polyolefin resin component is preferably 1,000,000 or more, and more preferably 3,000,000 or more. The weight-average molecular weight being 1,000,000 or higher tends to ensure that (A) polyamide resin can be reliably used as the matrix resin, and it tends to exhibit excellent high-temperature properties and superior resistance to liquid leakage at 80°C and 100°C. The weight-average molecular weight of the polyolefin resin component in the polyamide resin composition can be measured, for example, by the method described in the examples.

[0096] (Melting peak of polyamide resin composition) The polyamide resin composition of this embodiment exhibits at least one melting peak between 80°C and 150°C when heated at 20°C / min from 23°C using a differential scanning calorimeter. A melting peak below 150°C improves structural flexibility and tends to result in superior impact resistance. Furthermore, a melting peak above 80°C tends to reduce the likelihood of leakage in high-temperature ranges. The polyamide resin composition preferably exhibits at least one melting peak between 105°C and 140°C, and particularly preferably at least one melting peak between 110°C and 140°C.

[0097] (Breakdown take-up rate of polyamide resin composition) The polyamide resin composition preferably exhibits a take-up rate of 200 mm / s or more, more preferably 250 mm / s or more, even more preferably 300 mm / s or more, even more preferably 400 mm / s or more, particularly preferably 500 mm / s or more, and most 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 take-up rate is not particularly limited, but for example it can be 2000 mm / s or less, 1500 mm / s or less, or 1000 mm / s or less. Methods for adjusting the fracture and take-up rate include, for example, adjusting the molecular weights of components (A) and (B) as described above, and controlling the degree of crosslinking of component (B) by adjusting the amount and position of addition of components (C) and (D), but are not limited to these methods.

[0098] The molded article of this embodiment is preferably a molded article containing the polyamide resin composition of this embodiment described above. The molded article of this embodiment can be obtained by a manufacturing method that includes a step of molding the polyamide resin composition of this embodiment described above by extrusion molding or blow molding.

[0099] The polyamide resin composition of this embodiment can be extruded to produce molded articles. Examples of molded shapes include pellets, plates, fibers, strands, films or sheets, and hollow shapes, with hollow molded articles being particularly preferred. While not limited to the following, hollow molded articles can be suitably used as material components for various applications such as automobiles, machinery, electrical and electronic equipment, industrial materials, daily necessities, and household goods. Among these, the molded articles of this embodiment are particularly suitable for use as material components in automobiles.

[0100] Automotive parts are not limited to these, but examples include intake system parts, brake system parts, windshield washer system parts, cooling system parts, and fuel system parts.

[0101] Automotive intake system components are not limited to those mentioned above, but examples include air intake manifolds, intercooler inlets, etc. Automotive brake system components include air brake hoses, brake hoses (for brake fluid), etc. Automotive window washer system components include washer hoses, washer tanks, washer nozzles, etc. Automotive cooling system components are not limited to those mentioned above, but examples include outlet pipes, air conditioning hoses, battery cooling pipes, etc. Automotive fuel system components are not limited to those mentioned above, but examples include fuel tanks, fuel pumps, fuel tubes, and gasoline tank cases, etc. The molded product of this embodiment is preferably a brake hose, an air conditioning hose, or a cooling pipe.

[0102] The applications of extruded products are not particularly limited, but they are used, for example, in tubes, hoses, rods, and hollow molded products. [Examples]

[0103] The embodiment will be described in detail below with reference to specific examples and comparative examples, but this embodiment is not limited to the following examples.

[0104] The following describes the individual components of the polyamide resin compositions used in this example and comparative example.

[0105] <<Components>> ((A) Polyamide resin) (A)-1: Polyamide 612 (PA612) (manufactured by Asahi Kasei, melting point 225°C, model number: 4100, relative viscosity of sulfuric acid: 2.1, terminal amino group concentration 40 μmol / g) (A)-2: Polyamide 6 (PA6) (UBE Corporation, melting point 222°C, model number: 1013B, relative viscosity of sulfuric acid 2.4, terminal amino group concentration 46 μmol / g) (A)-3: Polyamide 12 (PA12) (Manufactured by UBE, melting point 189°C, model number: 3030U, relative viscosity of sulfuric acid 1.8)

[0106] The melting points of each polyamide resin were measured using a Diamond DSC manufactured by PERKIN-ELMER, in accordance with JIS-K7121.

[0107] The 96% sulfuric acid relative viscosity of each polyamide resin was measured according to JIS-K6920.

[0108] The amino group end-terminus 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% by mass phenol aqueous solution. Next, the resulting solution was titrated with 0.025 N hydrochloric acid to determine the amino group end-terminus concentration (μmol / g). The endpoint was determined from the pH meter reading.

[0109] The carboxyl group end-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. Next, the resulting solution was titrated with 0.1 N NaOH to determine the carboxyl group end-concentration (μmol / g). The endpoint was determined by the color change of phenolphthalein indicator.

[0110] ((B) Polyolefin resin) (B-1) Component (B)-1: High-density polyethylene resin (manufactured by Nippon Polyethylene Co., Ltd., melting point: 128℃, model number: Novatec HE121, MFR: 0.2g / 10min, weight-average molecular weight: 214,000) (B)-2: Low-density polyethylene resin (manufactured by Asahi Kasei, melting point: 111℃, model number: Suntech LD M2004, MFR: 0.4g / 10min, weight-average molecular weight: 101,200) (B)-3: Low-density polyethylene resin (manufactured by Asahi Kasei, melting point: 112℃, model number: Suntech LD M2270, MFR: 7.0g / 10min, weight-average molecular weight: 81,800) (B)-4: Ethylene-butene copolymer (manufactured by Mitsui Chemicals, model number: Tafmer DF605, MFR: 0.5g / 10min, weight-average molecular weight: 174,500) (B)-5: Ethylene-propylene-diene copolymer (MFR: 4.0 g / 10 min, weight-average molecular weight: 55,000) (B)-6: Grafted ethylene-butene maleate copolymer (manufactured by Mitsui Chemicals, Inc., melting point: 82°C, model number: Tafmer MA9015, MFR: 11g / 10min, acid denaturation rate: 0.75% by mass, weight-average molecular weight: 29,800) (B)-7: Grafted ethylene-butene maleate copolymer (manufactured by Mitsui Chemicals, Inc., melting point: 70°C, model number: Tafmer MA8510, MFR: 2.4g / 10min, acid denaturation rate: 0.50% by mass, weight-average molecular weight: 51,500) (B)-8: Grafted ethylene-butene maleate copolymer (manufactured by Mitsui Chemicals, Inc., melting point: 62°C, model number: Tafmer MH7020, MFR: 0.7g / 10min, acid denaturation rate: 1.0% by mass) (B)-9: Grafted ethylene-butene maleate copolymer (manufactured by Mitsui Chemicals, Inc., melting point: 52°C, model number: Tafmer MH5020, MFR: 0.6g / 10min, acid denaturation rate: 1.0% by mass) (B)-10: Maleic acid grafted high-density polyethylene (manufactured by Mitsui Chemicals, Inc., melting point: 135°C, model number: TX-1634, MFR: 1.3g / 10min, acid denaturation rate: 0.60% by mass, weight-average molecular weight: 85,000) (B)-11: Grafted ethylene-propylene-diene copolymer (MFR: 4.0 g / 10 min, acid denaturation rate: 1.0% by mass, weight-average molecular weight: 51,000)

[0111] ((C) Crosslinking agent) (C)-1:2,5-Dimethyl-2,5-bis(t-butylperoxy)hexane (Model number: Perhexa 25B-40, CAS number: 78-63-7, manufactured by NOF Corporation, diluted with silica to a purity of 40% by weight)

[0112] ((D) Crosslinking agent) (D)-1: Triallyl isocyanate (Model number: Tyke M-60, CAS number 1025-15-6, manufactured by Mitsubishi Chemical Corporation, diluted with calcium silicate to a purity of 60% by weight)

[0113] ((E) Antioxidant) (E)-1:2,2-Bis[[[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]oxy]methyl]propane-1,3-diol 1,3-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Model number: Irganox1010, CAS number: 6683-19-8, manufactured by BASF Japan)

[0114] The weight-average molecular weight of each polyolefin resin was measured by gel permeation chromatography (GPC) using the following apparatus and conditions. Equipment: Polymer Char GPC-IR5 Detector: RI detector Mobile phase: o-dichlorobenzene (for high-performance liquid chromatography) Flow rate: 1.0mL / min Column: UT-807 manufactured by Showa Denko Corporation x 1 Two Tosoh Corporation GMHHR-H(S)HT18393 tubes are connected in series. Column temperature: 140℃

[0115] The weight-average molecular weight of the polyolefin resin components in the polyamide resin compositions described in the Examples and Comparative Examples was measured by gel permeation chromatography (GPC) using the following apparatus and conditions for components dissolved in the following solvent, sample concentration, sample dissolution temperature, and sample dissolution time, and evaluated according to the following criteria. Here, the sample weight below refers to the weight of the polyolefin resin component in the polyamide resin composition, and the actual amount to be weighed is the amount including the polyamide resin component. (For example, for a composition with 60 parts of polyolefin resin component and 40 parts of polyamide resin component, the weight of the polyamide composition would be 4 mg / 0.6 = 6.67 mg.) Solvent: o-dichlorobenzene (for high-performance liquid chromatography) Sample concentration: 4 mg of sample (as polyolefin resin component) / 8 mL of solvent Sample dissolution temperature: 140℃ Sample dissolution time: 60 minutes Equipment: Polymer Char GPC-IR5 Detector: RI detector Mobile phase: o-dichlorobenzene (for high-performance liquid chromatography) Flow rate: 1.0mL / min Column: UT-807 manufactured by Showa Denko Corporation x 1 Two Tosoh Corporation GMHHR-H(S)HT18393 tubes are connected in series. Column temperature: 140℃ ◎ (Excellent): The weight-average molecular weight of the soluble portion is 3,000,000 or more. ○ (Good): The weight-average molecular weight of the soluble component is 1,000,000 or more. × (Poor): The weight-average molecular weight of the soluble portion is less than 1,000,000.

[0116] The melting points of each polyolefin resin were measured using a Diamond DSC manufactured by PERKIN-ELMER, in accordance with JIS-K7121.

[0117] The MFR of each polyolefin resin was measured in accordance with ASTM D1238, using a melt indexer at 190°C with a load of 2.16 kg.

[0118] The acid modification level of each polyolefin resin (B) is attributed to the carbonyl group at wavenumber 1780 cm⁻¹ using FT-IR. -1 The peak intensity was measured and quantified using a calibration curve prepared separately.

[0119] <Physical properties and evaluation methods of the composition> (Manufacturing of multi-purpose test specimens) The polyamide resin composition pellets obtained in the examples and comparative examples were dried under reduced pressure at 80°C for 8 hours to reduce the moisture content of the polyamide resin composition to 500 ppm or less. Then, the pellets of each polyamide resin composition with adjusted moisture content were molded as multipurpose test specimens (Type A, dumbbell-shaped tensile test specimens) using an injection molding machine (NEX-50IV, manufactured by Nissei Plastic Co., Ltd.) in accordance with ISO 3167. The dimensions of the multipurpose test specimen were as follows: total length ≥ 170 mm, distance between tabs 109.3 ± 3.2 mm, length of parallel section 80 ± 2 mm, radius of shoulder section 24 ± 1 mm, width of end section 20 ± 0.2 mm, width of central parallel section 10 ± 0.2 mm, and thickness 4 ± 0.2 mm. The specific injection molding conditions were: injection and holding pressure time: 25 seconds, cooling time: 15 seconds, mold temperature: 80°C, cylinder temperature: 280°C.

[0120] (Manufacturing of pipe-shaped bodies) The polyamide resin compositions obtained in the examples and comparative examples were dried under reduced pressure at 80°C for 8 hours to reduce the moisture content of the polyamide resin compositions to 500 ppm or less. Next, the pellets of each polyamide resin composition with adjusted moisture content were molded into pipes with an outer diameter of 16 mm and an inner diameter of 13 mm using an extrusion molding machine (BELLAFORM, BH45-25D). Specifically, the extrusion molding conditions were set to a cylinder temperature of 240°C and a take-up speed of 5.0 to 12.0 m / min.

[0121] (Melting peak of polyamide resin composition at temperatures between 80°C and 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. The temperature at which the peaks observed in the range of 80°C to less than 150°C reached their peak was defined as the melting peak (°C) between 80°C and 150°C. If multiple melting peaks were observed between 80°C and 150°C, the peak with the largest enthalpy of melting was designated as the melting peak between 80°C and 150°C. In the table, temperatures below 150°C are expressed as Tm(°C).

[0122] (α-olefin ratio (the proportion of α-olefin-derived components among the monomer components constituting polyolefin resin (B))) The proportion of α-olefin-derived components among the monomer components constituting polyolefin resin (B) was quantified by extracting polyolefin components from the composition or molded product and analyzing those components by nuclear magnetic resonance spectroscopy. 5 mL of hexafluoroisopropanol (HFIP) and 5 mL of chloroform were added to 1 g of pellet, and the mixture was allowed to stand for 18 hours. Undissolved suspended matter was separated, and another 5 mL of HFIP and 5 mL of chloroform were added. Centrifugation was performed at 3000 rpm for 1 hour, and the suspended matter was separated again. The centrifugation and suspension recovery process was repeated three times, and the resulting suspended matter was vacuum-dried to obtain a black solid. Next, 5 mL of hexafluoroisopropanol (HFIP) and 15 mL of chloroform were added to 100 mg of the obtained solid, the suspended matter was recovered, and the mixture was vacuum-dried to obtain a solid. 4 mg of this solid was dissolved in deuterated orthodichlorobenzene, and 1H-NMR measurement was performed at 140°C. The α-olefin ratio (mass%) was quantified from the integral ratio of peaks in the range of 1-2 ppm and the molecular weight of the constituent monomers.

[0123] (Method for filtering out (A) polyamide component from polyamide resin composition) A solvent mixture of hexafluoroisopropanol (HFIP) and chloroform (1:1) was added to the pellet and allowed to stand for 18 hours. Undissolved suspended matter was separated, and chloroform (1:1) was added again. The mixture was centrifuged at 3000 rpm for 1 hour to separate the suspended matter. This centrifugation and suspension recovery process was repeated three times. Methanol was added to the resulting filtrate, and the insoluble matter was filtered off to recover the solid.

[0124] (Method for filtering out (B) polyamide component from polyamide resin composition) A solvent mixture of hexafluoroisopropanol (HFIP) and chloroform in a 1:1 ratio was added to the pellet, and the mixture was allowed to stand for 18 hours. Undissolved suspended solids were separated, and a solvent mixture of chloroform in a 1:3 ratio was added again. The mixture was then centrifuged at 3000 rpm for 1 hour, and the suspended solids were separated. This centrifugation and collection of suspended solids was repeated three times, and the collected suspended solids were obtained by vacuum drying.

[0125] (Shear viscosity of component A ηA) The shear viscosity ηA of component A was measured by isolating the (A) polyamide component from the composition or molded product and measuring its shear viscosity using a capillograph. After thoroughly vacuum-drying the solid obtained from the polyamide resin composition according to the (A) method for filtering out the polyamide component, a NETZSCH Japan Co., Ltd. twin capillary RH-7 (using a flat die with a bore diameter of 15 mm and a die hole diameter of 1.0 mm) was subjected to a process at 280°C for 400 seconds. -1 The shear viscosity at the shear rate was measured, and the shear viscosity ηA of component A was obtained by applying Bagley and Rabinowitsch corrections.

[0126] (Shear viscosity of component B ηB) The shear viscosity ηB of component B was measured by separating the (B) polyolefin component from the composition or molded product and measuring the shear viscosity of that component using a capillary graph. The solid obtained according to the (B) method for filtering out polyolefin components from the polyamide resin composition was thoroughly vacuum-dried, and then subjected to a NETZSCH Japan Co., Ltd. Twin Capillograph RH-7 (using a flat die with a bore diameter of 15 mm and a die hole diameter of 1.0 mm) at 280°C for 400 s. -1 The shear viscosity at the shear rate was measured, and the shear viscosity ηB of component B was obtained by applying Bagley and Rabinowitsch corrections.

[0127] (Specific gravity of each component) The specific gravity of each component at 23°C was measured using a known method for the solids obtained according to the respective filtering methods for (A) the polyamide component and (B) the polyolefin component, and this was used in the calculation of the viscosity parameter (ΦA×ηB) / (ΦB×ηA) described later.

[0128] (Viscosity parameter: (ΦA × ηB) / (ΦB × ηA)) From the ηA and ηB obtained as described above, the viscosity parameter (ΦA × ηB) / (ΦB × ηA) was calculated as an evaluation index for the phase structure and dispersibility of the polyamide resin composition. Furthermore, ΦA above is the volume ratio of (A) polyamide resin component obtained by dividing the weight fraction of (A) polyamide resin component by the specific gravity of (A) polyamide resin component, and ΦB above is the volume ratio of (B) polyolefin resin component obtained by dividing the weight fraction of (B) polyolefin resin component by the specific gravity of (B) polyolefin resin component.

[0129] (Measurement of pull-up speed at break) A twin-screw extruder, model TEM26SX, manufactured by Shibaura Machine Co., Ltd., was used. This extruder has a top feed port on the first barrel from the upstream side and a side feed port on the eighth barrel. The ratio (length of the extruder cylinder / diameter of the extruder cylinder) is 48 (number of barrels: 12). The screw rotation speed was set to 45 rpm and the discharge rate to 3 kg / hour, and the polyamide composition was supplied from the side feed port. By adjusting the barrel temperature between 230 and 250°C, the molten polyamide resin composition, whose resin temperature was adjusted to 260°C, was extruded in strand form. Using Gottfert Rheotens, this strand was passed through the circular guide of the tension-sensing pulley below and wound up at a pull-up speed of 72 mm / second to stabilize the detected tension. After stabilization, the flow rate was set to 24 m / min. 2 The winding was performed while accelerating the winding speed, and the winding speed at the moment the strand broke was defined as the winding speed at the time of breakage.

[0130] (Measurement of high-temperature physical properties) The tensile modulus (GPa) of the above multipurpose test specimen was measured in accordance with ISO 527 using an Instron universal material testing machine (capacity: 100kN, model: 5582) in a constant temperature chamber set to 80°C.

[0131] (Thermogravimetric analysis (TGA) peak) To evaluate the retention stability of the polyamide resin composition, peaks were obtained in the thermogravimetric change using thermogravimetric analysis (TGA). Specifically, in each example, the weight increment (percentage difference from the 100 wt% point) observed between 150°C and 300°C was measured using a thermogravimetric analysis (TGA) instrument. Each sample was thoroughly dried by vacuum drying, and a TGA-DTA8122 (manufactured by Rigaku Corporation) was used for the TGA, with the temperature increased from 30°C to 20°C / min under atmospheric conditions (i.e., without nitrogen purging). The initial weight was set to 100 wt%, and the weight increment (percentage difference from the 100 wt% point) observed between 150°C and 300°C was measured and expressed as a percentage peak in the thermogravimetric analysis (TGA). The thermogravimetric analysis (TGA) peak is preferably 0.05% or higher, more preferably 0.10% or higher, even more preferably 0.15% or higher, and particularly preferably 0.20% or higher. The larger the thermogravimetric analysis (TGA) peak, the less molten metal was produced during extrusion molding. There is no particular upper limit to the thermogravimetric analysis (TGA) peak, but it can be, for example, 1.0% or less, or 0.5% or less.

[0132] (Confirmation of matrix components in polyamide resin compositions) Pellets of polyamide resin composition prepared using the method described later were cut in a direction parallel to the flow direction. After trimming the sample, the cut surface was smoothed using a diamond knife in a cryomicrotome (Leica UC6). Subsequently, the cut surface was stained with a 5 wt% phosphotungstic acid aqueous solution. After staining, the surface of the cut surface was cut to a depth of 100 nm using a diamond knife in a cryomicrotome (Leica UC6) to remove precipitates derived from the stain. The sample was fixed to the sample stage using carbon paste and used as the observation sample. The observation sample was irradiated with an electron beam using a scanning electron microscope (Hitachi High-Tech Corporation SU8220) under the conditions of lens mode High, acceleration voltage 1 kV, and working distance 5 mm, and observed. At this time, an Upper LA100 detector was used (backscattered electron image). The field of view angle was adjusted so that the left-right direction of the image was parallel to the flow direction. The dispersibility was evaluated by identifying the components observed with bright brightness as polyamide resin and the components observed with dark brightness as polyolefin components. The components forming the matrix phase were determined based on the following criteria. (A): (A) Polyamide resin contains (B) polyolefin resin in a dispersed phase. (B): (A) polyamide resin forms a dispersed phase in (B) polyolefin resin.

[0133] [Evaluation 1] High temperature refrigerant resistance A general-purpose test specimen, prepared according to the above-described method for manufacturing multi-purpose test specimens, was immersed in a 50% diluted solution of DEX-COOL antifreeze (GMW3420 standard) with pure water. The container was placed in an oil bath at 130°C, and after 500 hours, the test specimen was removed from the container. The liquid adhering to the test specimen was washed off with water and wiped dry, then sealed in an aluminum seal bag and stabilized at 23°C. The obtained test specimens were tested at a tensile speed of 50 mm / min according to ISO 527, and the tensile strength of the test specimen immediately after molding was set to 100%, and the strength was compared. Specimens that had lost their shape after immersion were considered unmeasurable. A higher strength retention rate indicates superior strength during use and the ability to use the specimen for a longer period.

[0134] [Evaluation 2] Bending modulus Universal test specimens, prepared according to the above-described method for manufacturing multipurpose test specimens, were subjected to bending tests at 23°C in accordance with ISO 178, and the flexural modulus (GPa) was measured. A lower flexural modulus results in a molded body with superior assembly properties and vibration absorption. A flexural modulus below 0.7 GPa was considered to indicate superior flexibility.

[0135] [Rating 3] Low-temperature impact resistance Using a universal test specimen prepared according to the above-described method for manufacturing multipurpose test specimens, a Charpy impact test was performed at -30°C in accordance with ISO 179, and the Charpy impact strength (kJ / m²) was determined. 2 The following was measured: ) Excellent low-temperature Charpy impact strength allows for the production of molded bodies that can withstand impacts such as chipping even in cold climates. In the table, (C) indicates that the specimen fractured completely, and (P) indicates that the specimen fractured partially.

[0136] [Evaluation 4] Presence or absence of leakage at 80°C and 100°C In the resin pipes obtained in the examples and comparative examples, connectors were press-fitted, and a 50% by volume aqueous solution of ethylene glycol was placed inside the pipe, sealing the pipe with the aqueous solution. These pipes were then heated in ovens at 80°C and 100°C for 250 hours, respectively. After treatment, the pipes were checked for leakage from the connector. The absence of shape collapse and leakage indicates that a more reliable pipe product can be obtained. ◎ (Excellent): No liquid leakage occurs from the connector. ○ (Excellent): More than 70% of the solution remains, but there are signs of leakage at the connector. △ (Good): The remaining solution level is less than 70%, and there are signs of leakage at the connector. × (Defective): Connector is disconnected / Pipe does not maintain its shape

[0137] [Rating 5] High-speed extrusion moldability Following the above-described method for manufacturing pipe molded bodies, the number of times resin breaks and resin jams occurred at the die exit 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. A lower number of resin breaks and resin jams indicates superior high-speed molding performance. ◎ (Excellent): No resin breakdown or clogging occurs. ○ (Excellent): Resin depletion and resin clogging occurred only 1-2 times. △ (Good): Resin depletion or resin clogging occurred 3 or more times. × (Defective): Unable to mold at high rates (20.0 m / min)

[0138] [Evaluation 6] Amount of adhesive residue during extrusion molding The amount of molded plastic residue generated was measured when the pipe was continuously molded for 2 hours at a cylinder temperature of 240°C and a pull-up speed of 10.0 m / min, according to the above-described method for manufacturing pipe molded bodies. ◎ (Excellent): Eye discharge amount is 10g or less. ○ (Good): Eye discharge amount is between 10g and 30g. × (Poor): Eye discharge amount is 30g or more

[0139] <Manufacturing of polyamide resin compositions> [Example 1] (Manufacturing of polyamide resin composition E1) A twin-screw extruder TEM26SX manufactured by Shibaura Machine Co., Ltd. was used. A pre-blended mixture of (B) polyolefin resin, (C) crosslinking agent, and (D) crosslinking aid was supplied from the top feed port. Furthermore, a pre-blended mixture of (A) polyamide resin and (E) antioxidant was supplied from the side feed port located in the fifth barrel. The molten mixture extruded from the die head was cooled into strands and pelletized to obtain pellets of polyamide resin composition E1. The types and contents of each component are as shown in Table 1.

[0140] [Examples 2-16, Comparative Examples 1, 4-10] (Manufacturing of polyamide resin compositions E2-E16, C1, 4-10) Except for the types and content of each component being as shown in the table, pellets of polyamide resin compositions E2-E16, C1, 4-10 were obtained using the same method as in Example 1.

[0141] [Example 17] (Manufacturing of polyamide resin composition E17) A twin-screw extruder TEM26SX manufactured by Shibaura Machine Co., Ltd. was used. A pre-blended mixture of (B) polyolefin resin, (C) crosslinking agent, (D) crosslinking aid, and (E) antioxidant was supplied from the top feed port. Furthermore, a pre-blended mixture of (A) polyamide resin was supplied from the side feed port located in the fifth barrel. The molten mixture extruded from the die head was cooled into strands and pelletized to obtain pellets of polyamide resin composition E17. The types and contents of each component are as shown in Table 1.

[0142] [Comparative Examples 2, 3] Pellets of polyamide resin compositions C2 and C3 were obtained using the same method as in Example 17, except that the types and contents of each component were as shown in the table.

[0143] Using the polyamide resin compositions pellets obtained in the examples and comparative examples, molded articles were manufactured by the method described above, and various physical properties were evaluated. The evaluation results are shown in the table below.

[0144] [Table 1]

[0145] Table 1 shows that polyamide resin compositions E1 to E17 (Examples 1 to 17) are excellent in high-temperature refrigerant resistance, flexibility, and low-temperature impact resistance, and enable the provision of tube molded articles that do not leak at 100°C. Furthermore, they provide polyamide resin compositions and molded articles thereof that produce less internal buildup during extrusion molding and have excellent high-speed extrusion moldability. On the other hand, with C1 to C10, it was not possible to obtain a polyamide resin composition or molded article thereof that would enable the provision of a tube molded article with excellent high-temperature refrigerant resistance, flexibility, and low-temperature impact resistance, and that would not leak at 100°C, while also exhibiting low condensation during extrusion molding and excellent high-speed extrusion moldability.

[0146] Therefore, only a polyamide molding material having two essential components in selected proportional amounts according to claim 1, and exhibiting the physical properties specified in claim 1, can satisfy the specified objectives in terms of high-temperature refrigerant resistance, flexibility, low-temperature impact resistance, and also in terms of liquid leakage resistance and high-speed extrusion moldability of the tube molded body. On the other hand, none of the polyamide resin compositions C1 to C8 (Comparative Examples 1 to 8) exhibited excellent high-temperature refrigerant resistance, flexibility, or low-temperature impact resistance, nor did any of them demonstrate superior performance in terms of liquid leakage resistance or high-speed extrusion moldability of the tube molded body. [Industrial applicability]

[0147] The polyamide resin composition of the present invention provides a tubular molded article that exhibits excellent high-temperature refrigerant resistance, flexibility, and low-temperature impact resistance, and does not leak at high temperatures. Furthermore, it provides a polyamide resin composition and a molded article thereof that exhibits low condensation during extrusion molding and excellent high-speed extrusion moldability. The molded article of the present invention uses the above polyamide composition, and the resulting molded article can be used as a material for various parts for automobiles, machinery, electrical and electronic equipment, industrial materials, industrial supplies, daily necessities, and household goods.

Claims

1. A polyamide resin composition comprising (A) a polyamide resin and (B) a polyolefin resin, With respect to a total mass of 100 parts by mass of the (A) polyamide resin and the (B) polyolefin resin, the mass ratio of the (A) polyamide resin is 20 parts by mass or more and 50 parts by mass or less, and the mass ratio of the (B) polyolefin resin is 50 parts by mass or more and 80 parts by mass or less. When heated at 20°C / min from 23°C using a differential scanning calorimeter, at least one melting peak is observed between 80°C and 150°C. The viscosity parameters shown below are between 1.2 and 4.0, A polyamide resin composition characterized in that the (A) polyamide resin forms a matrix. Viscosity parameter: (ΦA × ηB) / (ΦB × ηA) ηA: The (A) polyamide component obtained by the method described above, at 280°C and 400 s －１ Shear viscosity at shear rate ΦA: The volume ratio of the polyamide resin component obtained by dividing the weight fraction of the polyamide resin component by the specific gravity of the polyamide resin component. ηB: The (B) polyolefin component obtained by the method described above, at 280°C and 400 s －１ Shear viscosity at shear rate ΦB: The volume ratio of the polyolefin resin component obtained by dividing the weight fraction of the polyolefin resin component by the specific gravity of the polyolefin component.

2. The polyamide resin composition according to claim 1, characterized in that at least a portion of the (B) polyolefin resin is crosslinked.

3. The polyamide resin composition according to claim 1, characterized in that, in thermogravimetric analysis (TGA), the peak at 150°C to 300°C is 0.05% or more.

4. (E) The polyamide resin composition according to claim 1, further comprising an antioxidant.

5. The polyamide resin composition according to claim 4, characterized in that the (E) antioxidant is added after the (B) polyolefin resin that becomes a crosslinking reaction product and (C) crosslinking material have been kneaded together.

6. The polyamide resin composition according to claim 1, characterized in that the (B) polyolefin resin includes a polyolefin resin having a functional group that is reactive to the terminal amino group of the (A) polyamide resin.

7. The polyamide resin composition according to claim 1, characterized in that when heated at 23°C to 20°C / min using a differential scanning calorimeter, it exhibits at least one melting peak of 80°C or higher and less than 150°C.

8. The polyamide resin composition according to claim 2, characterized in that at least a portion of the (B) polyolefin resin is crosslinked using (C) a crosslinking agent.

9. The polyamide resin composition according to claim 2, characterized in that at least a portion of the (B) polyolefin resin is crosslinked using (D) a crosslinking aid.

10. The (B) polyolefin resin contains at least one monomer unit derived from an α-olefin, The polyamide resin composition according to claim 1, characterized in that, of the monomer units constituting the (B) polyolefin resin, the mass percentage of monomer units derived from the α-olefin is 3% by mass or more and 20% by mass or less.

11. The polyamide resin composition according to claim 1, characterized in that the weight-average molecular weight of the polyolefin resin component in the polyamide resin composition is 1,000,000 or more.

12. A molded article characterized by comprising the polyamide resin composition described in any one of claims 1 to 11.

13. The molded article according to claim 12, characterized in that it is one of a brake hose, an air conditioning hose, an oil hose, or a cooling pipe.

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