Tube and polyamide resin composition

Abstract

A tube comprising a layer containing 60 to 80% by mass of a semi-aromatic polyamide and 15 to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, wherein the layer has a phase-separated structure comprising a phase (A) containing the semi-aromatic polyamide and a phase (B) containing the elastomer, wherein the phase (A) is a continuous phase and the phase (B) is a dispersed phase dispersed in the phase (A), and in an image obtained by observing a cross section of the layer using an electron microscope, the average number of phases (B) having a major axis diameter of 2 μm or more per 100 μm2 is 1 per 100 μm. 2 The following; and a polyamide resin composition, which is formed by melt-kneading a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, wherein the total concentration of the carboxyl group and the acid anhydride group in 1g of the above elastomer is 85 to 250μeq / g.

Description

Technical Field

[0001] The present invention relates to a pipe having excellent heat resistance, flexibility, and formability. Background Art

[0002] Polyamide resins are excellent in strength, heat resistance, and chemical resistance, and have long been used in automotive components such as fuel piping and fuel piping joints (connectors) for automobiles. For example, polyamide resin compositions are also used in pipes for circulating refrigerants such as long-lasting coolants (hereinafter referred to as "LLC") used to cool automobile engines and air conditioners. Among these pipes, aliphatic polyamides such as polyamide 12, polyamide 11, and polyamide 6 are widely used from the perspective of ease and flexibility of extrusion molding. However, these aliphatic polyamides have also been pointed out to have problems such as insufficient chemical resistance and insufficient heat resistance. In particular, in recent years, in order to improve the fuel efficiency of automobiles, the resinification of pipes through which cooling water, high-temperature gas, and oil flow is being actively studied, and pipes with excellent chemical resistance and heat resistance compared to conventional pipes are desired.

[0003] Semi-aromatic polyamides containing aromatic dicarboxylic acids such as terephthalic acid are generally known to have superior chemical and heat resistance compared to aliphatic polyamides. Since semi-aromatic polyamides are generally more rigid than aliphatic polyamides, it has been proposed to impart flexibility to semi-aromatic polyamides by mixing them with a flexibility-imparting material such as an elastomer when used as tubes (see Patent Documents 1 to 3).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-176597

[0007] Patent Document 2: Japanese Patent Application No. 2015-501341

[0008] Patent Document 3: International Publication No. 2017 / 115699 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, increasing the amount of elastomer added to impart sufficient flexibility to a polyamide composition containing a semi-aromatic polyamide has been pointed out to cause problems with moldability, such as increased pore fat accumulation and associated deterioration in surface smoothness.

[0011] Therefore, in view of the problems of the conventional art, an object of the present invention is to provide a tube having excellent heat resistance and excellent flexibility and moldability, and a polyamide resin composition from which the tube can be obtained.

[0012] Means for solving problems

[0013] The present inventors conducted intensive research and found that by molding a polyamide resin composition obtained by melt-kneading a semi-aromatic polyamide and an elastomer, a tube having excellent heat resistance, flexibility, surface smoothness, and other excellent moldability can be obtained. Based on this finding, the inventors conducted further research and completed the present invention.

[0014] That is, the present invention provides the following [1] and [2].

[0015] [1] A tube comprising: a layer containing 60 to 80% by mass of a semi-aromatic polyamide and 15 to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group;

[0016] The layer has a phase-separated structure comprising a phase (A) containing the semi-aromatic polyamide and a phase (B) containing the elastomer, wherein the phase (A) is a continuous phase and the phase (B) is a dispersed phase dispersed in the phase (A).

[0017] In an image obtained by observing a cross section of the layer using an electron microscope, the average number of the phase (B) having a major axis diameter of 2 μm or more per 100 μm² was 1 / 100 μm. 2 the following.

[0018] [2] A polyamide resin composition obtained by melt-kneading 60 to 80% by mass of a semi-aromatic polyamide and 15 to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, wherein the total concentration of the carboxyl group and the acid anhydride group in 1 g of the elastomer is 85 to 250 μeq / g.

[0019] Effects of the Invention

[0020] According to the present invention, there can be provided: a tube having excellent heat resistance and excellent flexibility and moldability; and a polyamide resin composition from which the tube can be obtained. DETAILED DESCRIPTION

[0021] The pipe of the present invention is characterized in that it comprises: a layer containing 60 to 80% by mass of a semi-aromatic polyamide and 15 to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group;

[0022] The layer has a phase-separated structure comprising a phase (A) containing the semi-aromatic polyamide and a phase (B) containing the elastomer, wherein the phase (A) is a continuous phase and the phase (B) is a dispersed phase dispersed in the phase (A).

[0023] In an image obtained by observing a cross section of the layer using an electron microscope, the average number of the phase (B) having a major axis diameter of 2 μm or more per 100 μm² was 1 / 100 μm. 2 the following.

[0024] The present invention also provides a polyamide resin composition from which the aforementioned tube can be obtained. Specifically, the polyamide resin composition of the present invention is characterized in that it is prepared by melt-kneading 60 to 80% by mass of a semi-aromatic polyamide and 15 to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, wherein the total concentration of the carboxyl and acid anhydride groups in 1 gram of the elastomer is 85 to 250 μeq / g.

[0025] By including the aforementioned functional groups at a specific concentration in a polyamide resin composition comprising a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having the aforementioned functional groups, flexibility is imparted to the tube. Furthermore, by forming the aforementioned morphology, a tube having a layer with excellent surface smoothness can be obtained. Furthermore, the inclusion of the semi-aromatic polyamide imparts heat resistance, a characteristic characteristic of the tube.

[0026] Hereinafter, the polyamide resin composition, pipe, etc. of the present invention will be described in more detail.

[0027] It should be noted that, in this specification, the description "XX to YY" means "XX or greater and YY or less." Furthermore, in this specification, preferred embodiments are described, and combinations of two or more preferred embodiments are also preferred embodiments. Regarding items indicated by numerical ranges, when there are multiple numerical ranges, their lower and upper limits may be selectively combined to provide preferred embodiments.

[0028] In addition, an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group may be simply referred to as an "elastomer".

[0029] In addition, the "tube" refers to a cylindrical structure such as a pipe or a hose.

[0030] <Polyamide resin composition>

[0031] [Semi-aromatic polyamide]

[0032] In the present invention, a semi-aromatic polyamide refers to a polyamide comprising dicarboxylic acid units primarily composed of aromatic dicarboxylic acid units and diamine units primarily composed of aliphatic diamine units, or a polyamide comprising dicarboxylic acid units primarily composed of aliphatic dicarboxylic acid units and diamine units primarily composed of aromatic diamine units. Here, "main component" means constituting 50 to 100 mol%, preferably 60 to 100 mol%, of all units.

[0033] The polyamide resin composition contains 60 to 80% by mass of a semi-aromatic polyamide relative to 100% by mass of the polyamide resin composition. If the content of the semi-aromatic polyamide is less than 60% by mass, sufficient heat resistance may not be exhibited. If the content exceeds 80% by mass, flexibility may be poor. The content of the semi-aromatic polyamide is preferably 63% by mass or greater, more preferably 65% ​​by mass or greater, even more preferably 67% by mass or greater, and preferably 75% by mass or less.

[0034] The semi-aromatic polyamide used in the present invention is preferably a polyamide comprising a dicarboxylic acid unit mainly composed of an aromatic dicarboxylic acid unit and a diamine unit mainly composed of an aliphatic diamine unit, and more preferably a semi-aromatic polyamide comprising a dicarboxylic acid unit containing 50 to 100 mol % of an aromatic dicarboxylic acid unit and a diamine unit containing 60 to 100 mol % of an aliphatic diamine unit having 4 to 13 carbon atoms.

[0035] From the viewpoint of forming a semi-aromatic polyamide having excellent chemical resistance and heat resistance, the content of the aromatic dicarboxylic acid units in the dicarboxylic acid units is preferably in the range of 50 to 100 mol %, more preferably in the range of 75 to 100 mol %, and even more preferably in the range of 90 to 100 mol %.

[0036] Examples of the aromatic dicarboxylic acid unit include terephthalic acid unit, naphthalene dicarboxylic acid unit, isophthalic acid unit, 1,4-phenylenedioxydiacetic acid unit, 1,3-phenylenedioxydiacetic acid unit, biphenylcarboxylic acid unit, diphenylmethane-4,4'-dicarboxylic acid unit, diphenylsulfone-4,4'-dicarboxylic acid unit, and 4,4'-biphenylcarboxylic acid unit. Examples of the naphthalene dicarboxylic acid unit include units derived from 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, and 1,4-naphthalene dicarboxylic acid, with 2,6-naphthalene dicarboxylic acid unit being preferred.

[0037] Among these, the aromatic dicarboxylic acid units are preferably terephthalic acid units and / or naphthalene dicarboxylic acid units. Therefore, the semi-aromatic polyamide preferably contains 50 mol% or more of at least one dicarboxylic acid unit selected from terephthalic acid and naphthalene dicarboxylic acid units relative to all dicarboxylic acid units. The content of at least one dicarboxylic acid unit selected from terephthalic acid and naphthalene dicarboxylic acid units in all dicarboxylic acid units is preferably in the range of 50 to 100 mol%, more preferably in the range of 75 to 100 mol%, and even more preferably in the range of 90 to 100 mol%.

[0038] The dicarboxylic acid units constituting the semi-aromatic polyamide may preferably contain dicarboxylic acid units other than the aromatic dicarboxylic acid units in an amount of less than 50 mol%. Examples of the other dicarboxylic acid units include: units derived from aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, dimethylmalonic acid, 2,2-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, and trimethyladipic acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,2′-biphenyldicarboxylic acid, 4,4′-biphenyldicarboxylic acid, diphenylmethane-4,4′-dicarboxylic acid, and diphenylsulfone-4,4′-dicarboxylic acid. One or more of these may be contained. The content of these other dicarboxylic acid units in the dicarboxylic acid units is preferably 25 mol% or less, more preferably 10 mol% or less. The semi-aromatic polyamide used in the present invention may further contain units derived from polycarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid within a melt-moldable range.

[0039] Furthermore, the semi-aromatic polyamide preferably contains 60 mol% or more of aliphatic diamine units having 4 to 13 carbon atoms relative to the total diamine units. Using a semi-aromatic polyamide containing aliphatic diamine units having 4 to 13 carbon atoms in this ratio can produce a polyamide resin composition having excellent toughness, heat resistance, chemical resistance, and lightness. The content of aliphatic diamine units having 4 to 13 carbon atoms in the diamine units is preferably in the range of 60 to 100 mol%, more preferably in the range of 75 to 100 mol%, and even more preferably in the range of 90 to 100 mol%.

[0040] Examples of the aliphatic diamine units having 4 to 13 carbon atoms include units derived from linear aliphatic diamines such as 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and 1,13-tridecanediamine; and branched aliphatic diamines such as 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, and 5-methyl-1,9-nonanediamine. The present invention may contain one or more of these units.

[0041] The aliphatic diamine units having 4 to 13 carbon atoms are more preferably at least one selected from the group consisting of units derived from 1,4-butanediamine, 1,6-hexanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine. From the perspective of obtaining a polyamide resin composition having further excellent heat resistance, low water absorption, and chemical liquid resistance, units derived from 1,9-nonanediamine and / or 2-methyl-1,8-octanediamine are more preferred, and 1,9-nonanediamine units and 2-methyl-1,8-octanediamine units are even more preferred. When the aliphatic diamine units contain units derived from both 1,9-nonanediamine and 2-methyl-1,8-octanediamine, the molar ratio of the 1,9-nonanediamine units to the 2-methyl-1,8-octanediamine units is preferably in the range of 1,9-nonanediamine units / 2-methyl-1,8-octanediamine units = 95 / 5 to 40 / 60, more preferably in the range of 90 / 10 to 40 / 60, and even more preferably in the range of 80 / 20 to 40 / 60.

[0042] The diamine units constituting the semi-aromatic polyamide may preferably contain less than 40 mol% of other diamine units other than aliphatic diamine units having 4 to 13 carbon atoms. Examples of these other diamine units include units derived from aliphatic diamines having 3 or fewer carbon atoms, such as ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, and 2-methyl-1,3-propylenediamine; alicyclic diamines such as cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine; and aromatic diamines such as p-phenylenediamine, m-phenylenediamine, xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, and 4,4'-diaminodiphenylether. The content of these other diamine units in the diamine units is preferably 25 mol% or less, and more preferably 10 mol% or less.

[0043] The semi-aromatic polyamide may further contain an aminocarboxylic acid unit and / or a lactam unit within a range not inhibiting the effects of the present invention.

[0044] Examples of the aminocarboxylic acid units include units derived from 11-aminoundecanoic acid and 12-aminododecanoic acid, and the aminocarboxylic acid units may contain two or more types. The content of the aminocarboxylic acid units in the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to 100 mol% of all monomer units constituting the semi-aromatic polyamide.

[0045] The semi-aromatic polyamide may contain lactam units within a range that does not impair the effects of the present invention. Examples of such lactam units include units derived from ε-caprolactam, enantholactam, undecanoic acid, laurolactam, α-pyrrolidone, and α-piperidone. The semi-aromatic polyamide may contain two or more lactam units. The content of lactam units in the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to 100 mol% of all monomer units constituting the semi-aromatic polyamide.

[0046] Representative examples of semi-aromatic polyamides comprising a dicarboxylic acid unit mainly composed of an aromatic dicarboxylic acid unit and a diamine unit mainly composed of an aliphatic diamine unit having 4 to 13 carbon atoms include polytetramethylene terephthalamide (polyamide 4T), polypentamethylene terephthalamide (polyamide 5T), polyhexamethylene terephthalamide (polyamide 6T), polynonamethylene terephthalamide (polyamide 9T), poly(2-methyloctamethylene) terephthalamide (nylon M8T), polynonamethylene terephthalamide / poly(2-methyloctamethylene) terephthalamide copolymer (nylon M8T), and poly(2-methyloctamethylene) terephthalamide copolymer (nylon M8T). Nylon 9T / M8T), polynonamethylene naphthalamide (polyamide 9N), polynonamethylene naphthalamide / poly(2-methyloctamethylene) naphthalamide copolymer (nylon 9N / M8N), polydecamethylene terephthalamide (polyamide 10T), polyhexamethylene isophthalamide (polyamide 6I), copolymer of polyamide 6I and polyamide 6T (polyamide 6I / 6T), copolymer of polyamide 6T and polyundecanamide (polyamide 11) (polyamide 6T / 11), and copolymer of polyamide 10T and polyundecanamide (polyamide 11) (polyamide 10T / 11), etc.

[0047] Among them, preferably selected from polyamide 10T / 11, poly nonamethylene naphthalamide (polyamide 9N), poly nonamethylene naphthalamide / poly (2-methyloctamethylene) naphthalamide copolymer (nylon 9N / M8N), poly nonamethylene terephthalamide (polyamide 9T), poly nonamethylene terephthalamide / poly (2-methyloctamethylene) terephthalamide copolymer (nylon 9T / M8T) and polydecamethylene terephthalamide (polyamide 10T). At least one of the polyamides is preferably selected from the group consisting of polynonamethylene naphthalamide / poly(2-methyloctamethylene)naphthalamide copolymer (nylon 9N / M8N), polynonamethylene terephthalamide / poly(2-methyloctamethylene)terephthalamide copolymer (nylon 9T / M8T), and polyamide 10T / 11, and further preferably polynonamethylene terephthalamide / poly(2-methyloctamethylene)terephthalamide copolymer (nylon 9T / M8T).

[0048] On the other hand, among semi-aromatic polyamides, those containing dicarboxylic acid units having aliphatic dicarboxylic acid units as the main component and diamine units having aromatic diamine units as the main component, the aliphatic dicarboxylic acid units include units derived from the above-mentioned aliphatic dicarboxylic acids, and the polyamide may contain one or more of these. Furthermore, the aromatic diamine units include units derived from the above-mentioned aromatic diamines, and the polyamide may contain one or more of these. Furthermore, other units may be contained within a range that does not hinder the effects of the present invention.

[0049] Representative semi-aromatic polyamides containing a dicarboxylic acid unit mainly composed of an aliphatic dicarboxylic acid unit and a diamine unit mainly composed of an aromatic diamine unit include poly(m-xylylene adipamide) (MXD6) and poly(p-xylylene sebacate) (PXD10).

[0050] The semi-aromatic polyamide of the present invention preferably has at least 10 mol% of its molecular chain terminal groups capped with an end-capping agent. Using a semi-aromatic polyamide with an end-capping ratio of 10 mol% or more can produce a semi-aromatic polyamide resin composition having even better properties such as melt stability and hot water resistance.

[0051] As the end-capping agent, a monofunctional compound that is reactive with the terminal amino group or the terminal carboxyl group can be used. Specifically, monocarboxylic acids, acid anhydrides, monoisocyanates, monoacyl halides, monoesters, monoalcohols, monoamines, etc. can be mentioned. From the viewpoints of reactivity and stability of the end-capping terminal, monocarboxylic acids are preferably used as the end-capping agent for the terminal amino group, and monoamines are preferably used as the end-capping agent for the terminal carboxyl group. From the viewpoints of ease of operation, monocarboxylic acids are more preferably used as the end-capping agent.

[0052] The monocarboxylic acid used as the end-capping agent is not particularly limited as long as it is reactive with amino groups. Examples include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, octanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclopentanecarboxylic acid and cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthoic acid, β-naphthoic acid, methylnaphthoic acid, and phenylacetic acid; and mixtures thereof. Among these, at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, octanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid is preferred from the perspectives of reactivity, stability of the end-capping, and price.

[0053] The monoamine used as the end-capping agent is not particularly limited as long as it is reactive with carboxyl groups. Examples thereof include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine; and mixtures thereof. Among these, at least one selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline is preferred from the perspectives of reactivity, high boiling point, stability of the end-capping, and price.

[0054] The intrinsic viscosity [η] of semi-aromatic polyamide was measured at a concentration of 0.2 g / dl and a temperature of 30°C using concentrated sulfuric acid as a solvent. inh ] is preferably 0.6 dl / g or more, more preferably 0.8 dl / g or more, particularly preferably 1.0 dl / g or more, and is preferably 2.0 dl / g or less, more preferably 1.8 dl / g or less, and further preferably 1.6 dl / g or less. If the intrinsic viscosity [η inh ] is within the above range, the physical properties such as moldability are further improved. Intrinsic viscosity [η inh ] can be calculated by η based on the flow time t0 (seconds) of the solvent (concentrated sulfuric acid), the flow time t1 (seconds) of the sample solution, and the sample concentration c (g / dl) in the sample solution (i.e., 0.2 g / dl). inh =[ln(t1 / t0)] / c is obtained.

[0055] The terminal amino group content ([NH2]) of the semi-aromatic polyamide is preferably 5 to 60 μeq / g, more preferably 5 to 50 μeq / g, and even more preferably 5 to 30 μeq / g. A terminal amino group content ([NH2]) of 5 μeq / g or greater provides excellent compatibility between the semi-aromatic polyamide and the elastomer described below. Furthermore, a terminal amino group content of 60 μeq / g or less prevents gelation due to excessive reaction between the terminal amino groups and the modified portion of the elastomer, as described below, when the acid-modified elastomer is used as the elastomer.

[0056] The terminal amino group content ([NH 2 ]) referred to in this specification refers to the amount of terminal amino groups contained in 1 g of the semi-aromatic polyamide (unit: μeq), and can be determined by a neutralization titration method using an indicator.

[0057] The semi-aromatic polyamide comprising a dicarboxylic acid unit and a diamine unit and having a terminal amino group content ([NH2]) within the above range can be produced, for example, as follows.

[0058] First, dicarboxylic acid, diamine, and, if necessary, aminocarboxylic acid, lactam, catalyst, and end-capping agent are mixed to produce nylon salt. In this case, if the number of moles (X) of all carboxyl groups and the number of moles (Y) of all amino groups contained in the above-mentioned reaction raw materials satisfy the following formula (2),

[0059] -0.5≤[(YX) / Y]×100≤2.0 (2)

[0060] Then, the semi-aromatic polyamide with a terminal amino group content ([NH2]) of 5 to 60 μeq / g is easily produced, which is preferred. Next, the generated nylon salt is heated to a temperature of 200 to 250°C and the intrinsic viscosity [η inh ] is 0.10 to 0.60 dl / g, and further polymerization degree is increased, thereby obtaining the semi-aromatic polyamide used in the present invention. inh ] is within the range of 0.10 to 0.60 dl / g, the deviation of the molar balance between the carboxyl group and the amino group and the decrease in the polymerization rate in the high polymerization stage are small, and a semi-aromatic polyamide with a small molecular weight distribution, various properties, and better formability can be obtained. In the case of the stage of high polymerization by solid phase polymerization, it is preferably carried out under reduced pressure or in the circulation of an inert gas. If the polymerization temperature is within the range of 200 to 280°C, the polymerization rate is high, the productivity is excellent, and coloring and gelation can be effectively suppressed. In addition, in the case of the stage of high polymerization using a melt extruder, the polymerization temperature is preferably below 370°C. If the polymerization is carried out under such conditions, the polyamide is almost not decomposed, and a semi-aromatic polyamide with little deterioration can be obtained.

[0061] Examples of catalysts that can be used in the production of semi-aromatic polyamides include phosphoric acid, phosphorous acid, hypophosphorous acid, or salts or esters thereof. Examples of such salts or esters include salts of phosphoric acid, phosphorous acid, or hypophosphorous acid with metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony; ammonium salts of phosphoric acid, phosphorous acid, or hypophosphorous acid; and ethyl, isopropyl, butyl, hexyl, isodecyl, octadecyl, decyl, stearyl, and phenyl esters of phosphoric acid, phosphorous acid, or hypophosphorous acid.

[0062] The usage amount of above-mentioned catalyst is preferably more than the 0.01 mass % with respect to the gross mass 100 mass % of raw material, more preferably more than the 0.05 mass %, in addition, is preferably below the 1.0 mass %, more preferably below the 0.5 mass %.If the usage amount of catalyst is more than the above-mentioned lower limit, then polymerization is carried out well.If for below the above-mentioned upper limit, then be difficult for producing the impurity coming from catalyst, for example, when by polyamide or the polyamide resin composition extrusion molding containing it, can prevent the undesirable condition caused by above-mentioned impurity.

[0063] [Elastomer]

[0064] The polyamide resin composition contains 15 to 40% by mass of an elastomer modified with an unsaturated compound having a carboxyl group and / or an acid anhydride group, relative to 100% by mass of the polyamide resin composition. If the elastomer content is less than 15% by mass, the flexibility is poor, while if it exceeds 40% by mass, it is difficult to exhibit excellent heat resistance.

[0065] From the viewpoint of imparting flexibility and impact resistance, the elastomer content is preferably 19% by mass or more, more preferably 25% by mass or more. Furthermore, from the viewpoint of formability, the elastomer content is preferably 35% by mass or less, more preferably 31% by mass or less.

[0066] In one embodiment of the polyamide resin composition of the present invention, the elastomer content can be adjusted based on the flexural modulus of a molded article. To improve the flexibility of a tube comprising the composition, the elastomer content is preferably adjusted so that the flexural modulus of the polyamide resin composition molded article, as measured in accordance with ISO 178 (2001, 4th edition) at 23°C and 50% RH, is 1.8 GPa or less, more preferably 1.5 GPa or less, and even more preferably 1.2 GPa or less. Furthermore, to ensure proper function as a tube, the elastomer content is preferably adjusted so that the flexural modulus is 0.3 GPa or greater.

[0067] In the present invention, as an elastomer, for example, an elastomer modified with an α-olefin copolymer, an (ethylene and / or propylene) / (α,β-unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) copolymer, an ionomer, or an aromatic vinyl compound / conjugated diene compound block copolymer (hereinafter sometimes referred to as "copolymer, etc.") with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group can be used. When modified with such an unsaturated compound, the terminal amino group of the semi-aromatic polyamide reacts with the carboxyl group and / or acid anhydride group of the modified component, which is a component of the elastomer, thereby increasing the affinity between the semi-aromatic polyamide phase and the elastomer phase, improving impact resistance and elongation properties, and exhibiting flexibility. Among the above, a polymer modified with an unsaturated compound having a carboxyl group and / or anhydride group is preferred, and a polymer modified with an ethylene-butene copolymer with the unsaturated compound is more preferred.

[0068] Examples of unsaturated compounds having a carboxyl group used in elastomers modified with unsaturated compounds having a carboxyl group and / or anhydride group include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. Examples of unsaturated compounds having an anhydride group include dicarboxylic anhydrides having an α,β-unsaturated bond, such as maleic anhydride and itaconic anhydride. Unsaturated compounds having a carboxyl group and / or anhydride group are preferably dicarboxylic anhydrides having an α,β-unsaturated bond, with maleic anhydride being more preferred.

[0069] The total concentration of carboxyl groups and acid anhydride groups per gram of the elastomer is preferably in the range of 85 to 250 μeq / g, more preferably in the range of 90 to 220 μeq / g, and even more preferably in the range of 95 to 210 μeq / g. When the content of carboxyl groups and acid anhydride groups is within this range, a tube having excellent surface appearance and excellent surface smoothness can be easily obtained during extrusion molding.

[0070] It should be noted that the total concentration of the carboxyl groups and acid anhydride groups in the polyamide resin composition is difficult to specify because the terminal amino groups of the polyamide react with the carboxyl groups and acid anhydride groups during the melt kneading process.

[0071] Examples of the copolymers include α-olefin copolymers, (ethylene and / or propylene) / (α,β-unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) copolymers, ionomers, and aromatic vinyl compound / conjugated diene compound block copolymers. These copolymers may be used alone or in combination of two or more.

[0072] Examples of the α-olefin copolymer include copolymers of ethylene and an α-olefin having 3 or more carbon atoms, and copolymers of propylene and an α-olefin having 4 or more carbon atoms. The α-olefin copolymer is preferably a copolymer of ethylene and an α-olefin having 3 or more carbon atoms.

[0073] 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. One or more of these can be used. Among the above, the α-olefin having 3 or more carbon atoms is preferably at least one selected from propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, and 1-butene is more preferred.

[0074] In addition, 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 (DMDT), bicyclopentadiene, Polyene copolymerization of non-conjugated dienes such as pentadiene, 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-propylene-2,5-norbornadiene. These can be used alone or in combination.

[0075] The (ethylene and / or propylene) / (α,β-unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) copolymer is a polymer obtained by copolymerizing ethylene and / or propylene with α,β-unsaturated carboxylic acid and / or unsaturated carboxylic acid ester monomers. Examples of the α,β-unsaturated carboxylic acid monomers include acrylic acid and methacrylic acid. Examples of the α,β-unsaturated carboxylic acid ester monomers include methyl esters, ethyl esters, propyl esters, butyl esters, pentyl esters, hexyl esters, heptyl esters, octyl esters, nonyl esters, and decyl esters of these unsaturated carboxylic acids. These may be used alone or in combination.

[0076] The ionomer is a copolymer of an olefin and an α,β-unsaturated carboxylic acid in which at least a portion of the carboxyl groups are ionized by neutralization with a metal ion. Ethylene is preferably used as the olefin, and acrylic acid or methacrylic acid is preferably used as the α,β-unsaturated carboxylic acid. However, these are not limited to the examples listed here, and unsaturated carboxylic acid ester monomers may also be copolymerized. Furthermore, the metal ions include alkali metals and alkaline earth metals such as Li, Na, K, Mg, Ca, Sr, and Ba, as well as Al, Sn, Sb, Ti, Mn, Fe, Ni, Cu, Zn, and Cd. One or more of these may be used.

[0077] In addition, the aromatic vinyl compound / conjugated diene compound block copolymer is a block copolymer comprising an aromatic vinyl compound polymer block and a conjugated diene polymer block, and a block copolymer comprising at least one aromatic vinyl compound polymer block and at least one conjugated diene polymer block can be used. In addition, in the above-mentioned block copolymer, the unsaturated bonds in the conjugated diene polymer block can be hydrogenated.

[0078] The aromatic vinyl compound-based polymer block is a polymer block composed primarily of structural units derived from aromatic vinyl compounds. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, vinylnaphthalene, vinylanthracene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, and 4-(phenylbutyl)styrene. One or more of these may be used. Furthermore, the aromatic vinyl compound-based polymer block may, depending on the circumstances, have structural units containing a small amount of other unsaturated monomers. The conjugated diene polymer block is a polymer block formed from one or more conjugated diene compounds such as butadiene, chloroprene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 4-methyl-1,3-pentadiene, and 1,3-hexadiene. In the hydrogenated aromatic vinyl compound / conjugated diene compound block copolymer, part or all of the unsaturated bonds in the conjugated diene polymer block are hydrogenated.

[0079] The molecular structure of the aromatic vinyl compound / conjugated diene compound-based block copolymer and its hydrogenated product may be linear, branched, radial, or any combination thereof. Among them, as the aromatic vinyl compound / conjugated diene compound-based block copolymer and / or its hydrogenated product, preferably used are a diblock copolymer in which one aromatic vinyl compound-based polymer block and one conjugated diene-based polymer block are linearly bonded, a triblock copolymer in which three polymer blocks are linearly bonded in the order of aromatic vinyl compound-based polymer block-conjugated diene-based polymer block, and one or more of their hydrogenated products, and examples thereof include unhydrogenated or hydrogenated styrene / butadiene block copolymers, unhydrogenated or hydrogenated styrene / isoprene block copolymers, unhydrogenated or hydrogenated styrene / isoprene / styrene block copolymers, unhydrogenated or hydrogenated styrene / butadiene / styrene block copolymers, and unhydrogenated or hydrogenated styrene / isoprene / butadiene / styrene block copolymers.

[0080] [Degradation inhibitor]

[0081] The polyamide resin composition of the present invention may further contain a degradation inhibitor in order to improve its heat aging resistance and hydrolysis resistance.

[0082] Examples of degradation inhibitors include antioxidants such as copper stabilizers, phenolic heat stabilizers, phosphorus heat stabilizers, and sulfur heat stabilizers. Examples of degradation inhibitors include hydrolysis inhibitors such as carbodiimide compounds. These degradation inhibitors may be used alone or in combination of two or more.

[0083] The polyamide resin composition preferably contains 0.3 to 5 mass% of a degradation inhibitor, more preferably 0.4 to 3 mass%, and even more preferably 0.6 to 2 mass%, relative to 100 mass% of the polyamide resin composition. When the degradation inhibitor content is within the above range, a composition having excellent heat aging resistance and hydrolysis resistance and low gas generation during extrusion molding can be obtained.

[0084] The copper stabilizer can be used in the form of a mixture of a copper compound and a metal halide. For the ratio of the copper compound to the metal halide in the polyamide resin composition, it is preferred that the copper compound and the metal halide be contained in the polyamide resin composition in such a manner that the ratio of the total molar amount of halogen to the total molar amount of copper (halogen / copper) is 2 / 1 to 50 / 1. The above ratio (halogen / copper) is preferably 3 / 1 or more, more preferably 4 / 1 or more, further preferably 5 / 1 or more, and preferably 45 / 1 or less, more preferably 40 / 1 or less, further preferably 30 / 1 or less. When the ratio (halogen / copper) is above the above lower limit, copper precipitation and metal corrosion during molding can be more effectively suppressed. When the ratio (halogen / copper) is below the above upper limit, corrosion of the screw of the molding machine, etc. can be more effectively suppressed without damaging the mechanical properties such as tensile properties of the obtained polyamide resin composition.

[0085] Examples of copper compounds include copper halides, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, and copper complexes coordinated with chelating agents such as ethylenediamine and ethylenediaminetetraacetic acid. Examples of the copper halides include copper iodide, copper bromides such as cuprous bromide and cupric bromide, and cupric chlorides such as cuprous chloride. Among these copper compounds, from the perspective of excellent heat aging resistance and the ability to suppress metal corrosion of the screw and barrel during extrusion, at least one selected from copper halides and copper acetate is preferred, more preferably at least one selected from copper iodide, copper bromide, copper chloride, and copper acetate, and even more preferably at least one selected from copper iodide, copper bromide, and copper acetate. One copper compound may be used alone or in combination of two or more.

[0086] As the metal halide, a metal halide that is not a copper compound can be used, preferably a salt of a metal element from Group 1 or Group 2 of the periodic table and a halogen. For example, potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium chloride, etc. can be mentioned. Among them, from the perspective of excellent high-temperature heat resistance such as heat aging resistance of the obtained polyamide resin composition and the ability to suppress metal corrosion, at least one selected from potassium iodide and potassium bromide is preferred, and potassium iodide is more preferred. The metal halide can be used alone or in combination of two or more.

[0087] Examples of phenolic heat stabilizers include hindered phenol compounds, which have the property of imparting heat resistance and light resistance to resins such as polyamide.

[0088] Examples of the hindered phenol compound include 2,2-thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, hexamethylenebis(3-(3,5-di-tert-butyl- 4-hydroxyphenyl) propionate), 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, and the like.

[0089] The phenolic heat stabilizer may be used alone or in combination of two or more. In particular, from the viewpoint of improving heat resistance, 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane is preferred.

[0090] Examples of the phosphorus-based heat stabilizer include monosodium phosphate, disodium phosphate, trisodium phosphate, sodium phosphite, calcium phosphite, magnesium phosphite, manganese phosphite, pentaerythritol-type phosphite compounds, trioctyl phosphite, trilauryl phosphite, octyl diphenyl phosphite, triisodecyl phosphite, phenyl diisodecyl phosphite, phenyl ditridecyl phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, triphenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and tris(2,4-di-tert-butyl-5-methylphenyl) phosphite. , tris(butoxyethyl) phosphite, 4,4'-butylene-bis(3-methyl-6-tert-butylphenyl-tetra(tridecyl)) diphosphite, tetra(C12-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphite, 4,4'-isopropylidene bis(2-tert-butylphenyl) bis(nonylphenyl) phosphite, tris(biphenyl) phosphite, tetra(tridecyl)-1,1,3-tris(2-methyl-5-tert-butyl-4-hydroxyphenyl)butane diphosphite, tetra(tridecyl)-4,4'-butylene bis(3-methyl-6-tert-butylphenyl) diphosphite, tetra(C1-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphites, tris(mono- and di-mixed nonylphenyl) phosphites, 4,4'-isopropylidenebis(2-tert-butylphenyl)bis(nonylphenyl) phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tris(3,5-di-tert-butyl-4-hydroxyphenyl) phosphite, hydrogenated 4,4'-isopropylidene diphenyl polyphosphite, bis(octylphenyl)bis(4,4'-butylidenebis(3-methyl-6-tert-butylphenyl))1,6-hexanol diphosphite, hexadecyl-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl) diphosphite, tris(4,4'-isopropylidenebis(2-tert-butylphenyl) )) phosphite, tris (1,3-stearyloxyisopropyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, 2,2-methylenebis (3-methyl-4,6-di-tert-butylphenyl) -2-ethylhexyl phosphite, tetrakis (2,4-di-tert-butyl-5-methylphenyl) -4,4'-biphenylene diphosphite, tetrakis (2,4-di-tert-butylphenyl) -4,4'-biphenylene diphosphite, 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] - diphosphapin (Japanese: ジオキサホスフエピン) and the like.

[0091] Examples of the sulfur-based heat stabilizer include distearyl 3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate), 2-mercaptobenzimidazole, didodecyl 3,3'-thiodipropionate, ditridecyl 3,4'-thiodipropionate, and 2,2-bis[[3-(dodecylthio)-1-oxopropoxy]methyl]-1,3-propanediyl ester.

[0092] Examples of amine-based heat stabilizers include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (e.g., "NOCRAC CD" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N,N'-di-2-naphthyl-p-phenylenediamine (e.g., "NOCRAC White" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N,N'-diphenyl-p-phenylenediamine (e.g., "NOCRACDP" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N-phenyl-1-naphthylamine (e.g., "NOCRAC PA" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N-phenyl-N'-isopropyl-p-phenylenediamine (e.g., "NOCRAC 810-NA" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (e.g., "NOCRAC 6C", etc.), N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine ("NOCRAC G-1" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(phenylacetoxy)-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4 -cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-(ethylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(cyclohexylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(phenylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethyl-4-piperidinyl)- ) carbonate, bis(2,2,6,6-tetramethyl-4-piperidinyl) oxalate, bis(2,2,6,6-tetramethyl-4-piperidinyl) malonate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) adipate, bis(2,2,6,6-tetramethyl-4-piperidinyl) terephthalate, 1,2-bis(2,2,6,6-tetramethyl-4-piperidinyloxy)ethane, α, α'-bis(2,2,6,6-tetramethyl-4-piperidinyloxy)-p-xylene, bis(2,2,6,6-tetramethyl-4-piperidinyl)toluene-2,4-dicarbamate, bis(2,2,6,6-tetramethyl-4-piperidinyl)hexamethylene-1,6-dicarbamate, tris(2,2,6,6-tetramethyl-4-piperidinyl)benzene-1,3,5-tricarboxylate, tris(2,2,6,6-tetramethyl-4-piperidinyl)benzene-1,3,5-tricarboxylate4-tricarboxylate, 1-[2-{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy}butyl]-4-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]2,2,6,6-tetramethylpiperidine, condensation product of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, and β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]undecane]diethanol, etc.

[0093] Examples of the carbodiimide compound include monocarbodiimide and polycarbodiimide, and polycarbodiimide is preferred from the viewpoint of heat resistance. More specifically, polycarbodiimide is preferably a compound having a repeating unit represented by the following general formula (I).

[0094] [Chemical Formula 1]

[0095]

[0096] In the general formula (I), X1 represents a divalent hydrocarbon group. Examples of such hydrocarbon groups include chain aliphatic groups, aliphatic groups containing an alicyclic structure, and groups containing an aromatic ring. The chain aliphatic group has 1 or more carbon atoms, preferably 1 to 20, and more preferably 6 to 18 carbon atoms. The aliphatic group containing an alicyclic structure and the group containing an aromatic ring have 5 or more carbon atoms, more preferably 6 to 20, and even more preferably 6 to 18 carbon atoms. The hydrocarbon group may have a substituent such as an amino group, a hydroxyl group, or an alkoxy group.

[0097] Examples of the polycarbodiimide include aliphatic polycarbodiimide, aromatic polycarbodiimide, and mixtures thereof. Of these, aliphatic polycarbodiimide is more preferred from the viewpoint of chemical resistance and molding processability of the resulting molded article.

[0098] The aliphatic polycarbodiimide is preferably a polycarbodiimide having a repeating unit represented by the general formula (I) above, wherein X1 is a chain aliphatic group or an aliphatic group containing an alicyclic structure. X1 is more preferably a group selected from an alkylene group having 3 to 18 carbon atoms, a divalent group represented by the following general formula (II), and a divalent group represented by the following general formula (III). Even more preferably, it is a divalent group represented by the following general formula (III).

[0099] [Chemical Formula 2]

[0100]

[0101] In the above general formula (II) and general formula (III), R 1 ~R 5 Each independently represents a single bond or an alkylene group having 1 to 8 carbon atoms. 1 and R2 Preferably, it is a single bond. 3 and R 5 Preferably, a single bond, R 4 An alkylene group having 1 to 6 carbon atoms is preferred, and an alkylene group having 1 to 3 carbon atoms is more preferred.

[0102] [Other ingredients]

[0103] The polyamide resin composition of the present invention may contain other components such as other types of polymers, fillers, crystal nucleating agents, colorants, antistatic agents, plasticizers, lubricants, flame retardants, and flame retardant aids as needed.

[0104] Examples of other types of polymers include polyether resins such as polyacetal and polyphenylene ether; polysulfone resins such as polysulfone and polyethersulfone; polysulfide resins such as polyphenylene sulfide and polysulfide ethersulfone; polyketone resins such as polyetheretherketone and polyallyletherketone; polynitrile resins such as polyacrylonitrile, polymethacrylonitrile, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, and methacrylonitrile-butadiene-styrene copolymer; polymethacrylate resins such as polymethyl methacrylate and polyethyl methacrylate; polyethylene ester resins such as polyvinyl acetate; and polyvinylidene chloride. , polyvinyl chloride, vinyl chloride-vinylidene chloride copolymer, vinylidene chloride-methacrylate copolymer and other polyvinyl chloride resins; cellulose acetate, cellulose butyrate and other cellulose resins; polyvinylidene fluoride, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, polytrifluorochloroethylene, ethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer and other fluorine resins; polycarbonate resins; thermoplastic polyimide, polyamide-imide, polyetherimide and other polyimide resins; thermoplastic polyurethane resin; etc.

[0105] Examples of fillers include fibrous fillers such as glass fiber; powdered fillers such as calcium carbonate, wollastonite, silica, silica alumina, alumina, titanium dioxide, potassium titanate, magnesium hydroxide, and molybdenum disulfide; and flaky fillers such as hydrotalcite, glass flakes, mica, clay, montmorillonite, and kaolin.

[0106] The crystallization nucleating agent is not particularly limited as long as it is a crystallization nucleating agent commonly used for polyamides. Examples thereof include talc, calcium stearate, aluminum stearate, barium stearate, zinc stearate, antimony oxide, magnesium oxide, and any mixtures thereof. Among them, talc is preferred because it has a greater effect of increasing the crystallization rate of polyamide. To improve compatibility with polyamide, the crystallization nucleating agent may be treated with a silane coupling agent, a titanium coupling agent, or the like.

[0107] The colorant is not particularly limited and can be appropriately selected from inorganic or organic pigments and dyes depending on the intended use of the polyamide resin composition. Preferred colorants for use in polyamide resin compositions for liquid drug delivery tubes include black inorganic pigments such as carbon black, lamp black, acetylene black, bone black, thermal black, channel black, furnace black, and titanium black.

[0108] There are no particular limitations on antistatic agents, and they can be either organic or inorganic. For example, organic antistatic agents include ionic compounds such as lithium ion salts, quaternary ammonium salts, and ionic liquids; and electron-conductive polymers such as polythiophene, polyaniline, polypyrrole, and polyacetylene. Inorganic antistatic agents include metal oxide conductive agents such as ATO, ITO, PTO, GZO, antimony pentoxide, and zinc oxide; and carbon conductive agents such as carbon nanotubes and fullerenes. Inorganic antistatic agents are preferred from the perspective of heat resistance. It should be noted that carbon black, as a colorant, can also function as an antistatic agent.

[0109] The plasticizer is not particularly limited as long as it is a plasticizer commonly used as a plasticizer for polyamide, and examples thereof include benzenesulfonic acid alkylamide compounds, toluenesulfonic acid alkylamide compounds, hydroxybenzoic acid alkyl ester compounds, and hydroxybenzoic acid alkylamide compounds.

[0110] The lubricant is not particularly limited as long as it is a lubricant commonly used as a lubricant for polyamides. Examples thereof include higher fatty acid compounds, hydroxy fatty acid compounds, fatty acid amide compounds, alkylene bis fatty acid amide compounds, fatty acid lower alcohol ester compounds, metal soap compounds, and polyolefin waxes. Fatty acid amide compounds, such as stearic acid amide, palmitic acid amide, methylene bis stearic acid amide, and ethylene bis stearic acid amide, are preferred because they have excellent external lubricity.

[0111] The content of these other components in the polyamide resin composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less, relative to 100% by mass of the polyamide resin composition.

[0112] [Method for producing polyamide resin composition]

[0113] Since the method for producing a polyamide resin composition of the present invention includes the step of melt-kneading the mixture containing the semi-aromatic polyamide and the elastomer, the terminal groups of the semi-aromatic polyamide and the modified portion of the elastomer react with each other during melt-kneading, and the resulting resin composition has excellent flexibility and impact resistance.

[0114] The temperature and time during the melt kneading can be appropriately adjusted depending on the melting point of the semi-aromatic polyamide used, etc. From the viewpoint of suppressing deterioration of the polymerizability of the elastomer, the melt kneading temperature is preferably 380°C or lower, more preferably 370°C or lower, and even more preferably 360°C or lower. The melt kneading time is preferably about 1 to 5 minutes.

[0115] The melt-kneading method is not particularly limited. A method that can uniformly mix the semi-aromatic polyamide, elastomer and the above-mentioned other components can be preferably adopted, preferably a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, etc. From the viewpoint of good dispersibility of the elastomer and industrial productivity, a twin-screw extruder is more preferred.

[0116] When a component such as a carbodiimide compound that reacts with the terminal groups of a semi-aromatic polyamide or the modified portion of an elastomer is added as a degradation inhibitor, the degradation inhibitor can be added after the semi-aromatic polyamide and the elastomer are melt-kneaded. This prevents the degradation inhibitor from inhibiting the reaction between the semi-aromatic polyamide and the elastomer during melt kneading. Specifically, a preferred method for producing a polyamide resin composition is one in which a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group are melt-kneaded, and then a carbodiimide compound is added and melt-kneaded.

[0117] Specifically, when a twin-screw extruder is used as the melt-kneading device, it is preferred that a mixture of the semi-aromatic polyamide, the elastomer, and other components added as needed be dry-blended and fed from a first feed port at the base of the twin-screw extruder, and the degradation inhibitor be fed from a second feed port provided between the first and second kneading sections of the screws. In this case, the degradation inhibitor may be fed after dry-blending with the semi-aromatic polyamide, if necessary.

[0118] <Tube>

[0119] [Method for manufacturing pipe]

[0120] The pipe of the present invention is preferably a pipe formed from the above-mentioned polyamide resin composition.

[0121] The method for producing the tube of the present invention is not particularly limited, and known methods such as extrusion and blow molding can be used. For example, a method in which melt extrusion is performed using an extruder appropriate for the number of layers or the number of materials, followed by simultaneous lamination inside or outside a mold (coextrusion) or a method in which a single-layer tube is preliminarily produced and, if necessary, an adhesive is applied to the outer surface to integrate the resin and then laminate the tube (coating).

[0122] When manufacturing a tube having a corrugated region, a straight tube is first formed and then molded to form a predetermined corrugated shape.

[0123] [Tube structure]

[0124] The outer diameter of the tube is designed taking into account the flow rate of the fluid flowing inside. Furthermore, the wall thickness of the tube is designed to maintain the required burst pressure without increasing the permeability of the contents, while also maintaining a degree of flexibility that allows for ease of assembly and good vibration resistance during use. The outer diameter of the tube is preferably 2.5 to 300 mm, and the wall thickness is 0.5 to 30 mm.

[0125] The pipe of the present invention only needs to include at least one layer containing the polyamide resin composition described in the present invention, and may be a single layer or two or more layers as needed. When the pipe is composed of two or more layers, the layer containing the polyamide resin composition is preferably the innermost layer of the pipe in order to reduce flow resistance of the fluid flowing therein and to reduce unnecessary residues.

[0126] In the case of a multilayer tube, the material constituting the other layers is not particularly limited, but thermoplastic resins are preferred from the viewpoint of tube formability.

[0127] Thermoplastic resins can be appropriately selected in consideration of the application of the tube, adhesion to adjacent layers, etc. Specifically, examples include polyester resins such as polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyethylene isophthalate; fluororesins such as ethylene-tetrafluoroethylene copolymer (ETFE), vinylidene fluoride polymer (PVDF), polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer; polyolefin resins such as polyethylene, polypropylene, polystyrene, and ethylene-vinyl acetate copolymer saponification product (EVOH); polyether resins such as polyacetal and polyphenylene sulfide; and polyamide resins such as semi-aromatic polyamide and aliphatic polyamide.

[0128] (form)

[0129] The tube of the present invention comprises a layer containing 60-80% by mass of the semi-aromatic polyamide and 15-40% by mass of the elastomer. This layer has a phase-separated structure comprising a phase (A) containing the semi-aromatic polyamide and a phase (B) containing the elastomer, wherein phase (A) is a continuous phase and phase (B) is a dispersed phase dispersed within phase (A). The layer exhibits a so-called sea-island structure, in which phase (A) is a sea phase and phase (B) is an island phase. This allows for the properties of each phase to be effectively utilized, resulting in excellent flexibility and moldability. Furthermore, the phase-separated structure is formed by the reaction of the semi-aromatic polyamide and the elastomer.

[0130] The “semi-aromatic polyamide-containing phase (A)” refers to a phase containing more than 50% by mass of a semi-aromatic polyamide, and the “elastomer-containing phase (B)” refers to a phase containing more than 50% by mass of an elastomer.

[0131] In an image obtained by observing a cross section of the layer using an electron microscope, the average number of the phase (B) having a major axis diameter of 2 μm or more per 100 μm² was 1 / 100 μm². 2 less than 0.5 / 100 μm, more preferably 0.5 / 100 μm 2 Below, the closer to 0 / 100μm 2 If the above average number exceeds 1 / 100μm 2 If the thickness is less than 0.05, the surface smoothness is poor, causing flow resistance of the fluid flowing inside the tube and possibly causing residue to form inside the tube.

[0132] The above average number (number / 100μm 2 ) is a value calculated as follows: for the cross-section (cut) of the above-mentioned layer when the tube is cut into discs, the total number of the above-mentioned phase (B) with a major axis diameter of 2 μm or more in any 6 partitions of 10 μm×10 μm is measured using a field emission scanning electron microscope (FE-SEM), and the value is calculated by dividing the total number by the total area (10 μm×10 μm×6 partitions).

[0133] The phase (B) having a major axis diameter of 2 μm or more can be measured based on an image obtained using a field emission scanning electron microscope or the like using conventional image analysis software.

[0134] (Surface roughness (arithmetic mean roughness Ra))

[0135] To reduce flow resistance of the fluid flowing therein and to minimize unnecessary residue, the surface of the tube is preferably smooth and free of irregularities. Specifically, the surface roughness Ra of the layer, as measured in accordance with JIS B 0601 (1982), is preferably 0.4 μm or less, more preferably 0.35 μm or less, and even more preferably 0.3 μm or less.

[0136] (Flexural modulus)

[0137] The tube of the present invention has excellent flexibility.

[0138] Specifically, when the polyamide resin composition of the present invention used in a pipe is injection-molded into a 4 mm thick test piece, the flexural modulus at 23°C, as measured in accordance with ISO 178 (4th edition, 2001), is preferably 1.8 GPa or less, more preferably 1.7 GPa or less, and even more preferably 1.6 GPa or less. Furthermore, in order to maintain the function of the pipe, the flexural modulus is preferably 0.3 GPa or more.

[0139] Specifically, the flexural modulus can be determined by the method described in Examples.

[0140] (Heat Deflection Temperature)

[0141] The pipe of the present invention has excellent heat resistance. This pipe can easily exhibit its heat resistance by using the polyamide resin composition of the present invention while maintaining the excellent heat resistance of the semi-aromatic polyamide.

[0142] Specifically, the heat deformation temperature, measured in accordance with ISO 75 (2013, 3rd edition), when the polyamide resin composition of the present invention used in the pipe is injection-molded into a 4 mm thick test piece, is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. The upper limit of the heat deformation temperature is not particularly limited as long as the function of the pipe and the effects of the present invention are not impaired.

[0143] Specifically, the heat deformation temperature can be determined by the method described in Examples.

[0144] [use]

[0145] The tube obtained in the present invention has a polyamide resin composition as its main component and therefore exhibits excellent chemical resistance and heat resistance. In addition, since the polyamide resin composition contains a specific amount of an elastomer and the concentration of the unsaturated compound having a carboxyl group and / or anhydride group in the elastomer is within a specific range, it also has excellent moldability and flexibility.

[0146] Therefore, it can be used in automotive parts, internal combustion engines, crude oil drilling, transportation, electrical and electronic components, medical, food, household and office supplies, and building material-related parts. Due to its excellent chemical and heat resistance, it can be used in fuel pipes such as feed pipes, return pipes, evaporator pipes, fuel filling pipes, ORVR pipes, reserve pipes, and exhaust pipes; oil pipes, oil drilling pipes, brake pipes, window washer fluid pipes, engine coolant (LLC) pipes, tank pipes, urea solution delivery pipes, cooler pipes for cooling water and refrigerants, air conditioning refrigerant pipes, heater pipes, load heating pipes, floor heating pipes, infrastructure supply pipes, fire extinguisher and fire extinguishing equipment pipes, medical cooling equipment pipes, ink and paint dispensing pipes, blowby pipes, and other liquid medicine pipes. It is particularly suitable for engine coolant pipes, urea water pipes, fuel pipes, oil drilling pipes, and blowby pipes.

[0147] Example

[0148] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

[0149] The physical properties in Examples, Comparative Examples, and Production Examples were measured by the following methods.

[0150] Intrinsic viscosity

[0151] The intrinsic viscosity (dl / g) of the semi-aromatic polyamide (sample) obtained in the production example was determined using concentrated sulfuric acid as a solvent at a concentration of 0.2 g / dl and a temperature of 30°C according to the following relationship.

[0152] η inh =[ln(t1 / t0)] / c

[0153] In the above relationship, η inh represents the intrinsic viscosity (dl / g), t0 represents the flow time (seconds) of the solvent (concentrated sulfuric acid), t1 represents the flow time (seconds) of the sample solution, and c represents the concentration of the sample in the sample solution (g / dl) (i.e., 0.2 g / dl).

[0154] Melting point

[0155] The melting point of the semi-aromatic polyamide obtained in the production example was measured using a differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Co., Ltd.

[0156] The melting point was measured in accordance with ISO 11357-3 (2011, 2nd edition). Specifically, under a nitrogen atmosphere, a sample (polyamide) was heated from 30°C to 340°C at a rate of 10°C / min, held at 340°C for 5 minutes, and completely melted. The sample was then cooled to 50°C at a rate of 10°C / min and held at 50°C for 5 minutes. The melting point (°C) was determined by measuring the peak temperature of the melting peak that appeared when the temperature was again raised to 340°C at a rate of 10°C / min. If multiple melting peaks were present, the peak temperature of the highest melting peak was used as the melting point (°C).

[0157] Terminal amino concentration

[0158] A sample solution was prepared by dissolving 1 g of the semi-aromatic polyamide obtained in the production example in 35 mL of phenol and mixing it with 2 mL of methanol. The terminal amino group content ([NH2], unit: μeq / g) of the semi-aromatic polyamide was measured by titration with 0.01 N aqueous hydrochloric acid using thymol blue as an indicator.

[0159] Total concentration of carboxyl groups and / or anhydride groups in the elastomer

[0160] 1 g of the elastomer was dissolved in 170 mL of toluene, and 30 mL of ethanol was added. The sample solution prepared in this manner was titrated with a 0.1 N KOH / ethanol solution using phenolphthalein as an indicator to determine the total concentration of carboxyl groups and acid anhydride groups.

[0161] The Making of a Tube

[0162] The polyamide resin compositions obtained in the Examples and Comparative Examples were melted at an extrusion temperature of 300°C using a single-screw extruder (DHS40-25, φ40 mm, L / D = 28, full-flight screw, compression ratio 3) from IKG Corporation and formed into a tubular body. The extruder was then cooled in a vacuum sizing tank for dimensional control and pulled at a speed of 10 m / min to produce a tube having an inner diameter of 6 mm and an outer diameter of 8 mm.

[0163] Morphological observation (average number of dispersed phases (B) with a major axis diameter of 2 μm or more)

[0164] The tube produced by the above method was cut radially and surface trimmed using a freezing ultrathin microtome (ULTRACUTUC-S / FC-S manufactured by LEICA). The cut surface was stained with ruthenium tetroxide and then coated with osmium. The surface was observed using a field emission scanning electron microscope (Regulus 8220 manufactured by Hitachi High-Technologies Co., Ltd.) to obtain an image (FE-SEM image).

[0165] In addition, the components constituting each phase were identified by performing energy dispersive X-ray analysis during the above-mentioned FE-SEM observation.

[0166] In the image obtained by the above method at a magnification of 3500 times, the major axis diameter (major axis dispersion diameter) of the dispersed phase (B) confirmed in 6 sections of 100 square μm (10 μm × 10 μm) was measured, and the total number of dispersed phases (B) with a major axis diameter of 2 μm or more was divided by the total area (10 μm × 10 μm × 6 sections) to calculate the average number of dispersed phases (B) with a major axis diameter of 2 μm or more (pieces / 100 μm). 2 ).

[0167] Surface roughness (arithmetic mean roughness Ra) (formability)

[0168] A tube of a predetermined length, prepared by the above method, was cut in half along the longitudinal direction, and the inner surface roughness along the longitudinal direction was measured. Measurements were performed using a surface roughness measuring machine (SE700) manufactured by Kosaka Laboratory Co., Ltd. in accordance with JIS B0601 (1982) (speed 0.1 mm / s, measurement length 1.25 mm). Each tube was measured three times, and the average value was used as the measured value.

[0169] Production of test pieces

[0170] Using an injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. (clamping force: 100 tons, screw diameter: φ32 mm), the polyamide resin compositions obtained in the Examples and Comparative Examples were molded using a T-type runner mold at a cylinder temperature 20 to 30°C higher than the melting point of the semi-aromatic polyamide and a mold temperature of 140°C. Multipurpose test piece type A1 (dumbbell-shaped test piece according to JISK 7139; 4 mm thick, 170 mm total length, 80 mm parallel portion length, 10 mm parallel portion width) was prepared. A rectangular parallelepiped test piece (dimensions: length × width × thickness = 80 mm × 10 mm × 4 mm) was then cut from the multipurpose test piece to serve as a test piece for evaluating the flexural modulus and heat distortion temperature.

[0171] Flexural modulus (flexibility)

[0172] The test piece prepared by the above method was used to measure the flexural modulus (GPa) at 23° C. and 50% RH using Autograph (manufactured by Shimadzu Corporation) in accordance with ISO 178 (4th edition, 2001).

[0173] Heat deformation temperature (heat resistance)

[0174] The heat deformation temperature (° C.) of the test piece prepared by the above method was measured in accordance with ISO 75 (2013 3rd edition) using an HDT tester “S-3M” manufactured by Toyo Seiki Seisaku-sho, Ltd.

[0175] Production Example 1 [Production of Semi-aromatic Polyamide A-1]

[0176] 9870.6 g (59.42 mol) of terephthalic acid, 9497.4 g (60.00 mol) of a 50 / 50 molar ratio mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, 142.9 g (1.17 mol) of benzoic acid, 19.5 g of sodium hypophosphite monohydrate (0.1 mass % relative to the total mass of the raw materials), and 5 liters of distilled water were placed in a 40-liter autoclave and purged with nitrogen. The autoclave was stirred at 100°C for 30 minutes, and the temperature inside the autoclave was raised to 220°C over 2 hours. At this point, the pressure inside the autoclave reached 2 MPa. After continuing the reaction for 2 hours, the temperature was raised to 230°C, and then the temperature was maintained at 230°C for 2 hours. The reaction was continued while gradually removing water vapor and maintaining the pressure at 2 MPa. Next, the pressure was reduced to 1 MPa over 30 minutes, and the reaction was continued for 1 hour to obtain a prepolymer having an intrinsic viscosity [η] of 0.2 dL / g. This was crushed to a particle size of 2 mm or less using a flake crusher manufactured by Hosokawa Micron Co., Ltd., dried at 100°C under reduced pressure for 12 hours, and then solid-phase polymerized at 230°C and 13 Pa (0.1 mmHg) for 10 hours to obtain a white polyamide resin (polyamide 1). Polyamide 1 contains terephthalic acid units, 1,9-nonanediamine units, and 2-methyl-1,8-octanediamine units (1,9-nonanediamine units / 2-methyl-1,8-octanediamine units = 50 / 50 (molar ratio)), has a melting point of 265°C, and an intrinsic viscosity [η inh ] is 1.20 dL / g, and the terminal amino group concentration ([NH2]) is 15 μeq / g.

[0177] Example 1, Example 2, Comparative Example 2 (Production of Polyamide Resin Composition)

[0178] The semi-aromatic polyamide, elastomer, degradation inhibitor C-3, lubricant, and dye listed in Table 1 were premixed in the specified mass ratio and fed into the upstream feed port of a twin-screw extruder ("TEM-26SS" manufactured by Toshiba Machine Co., Ltd.). Degradation inhibitor C-1 was fed through the feed port between the first and second kneading sections of the screws. The mixture was melt-kneaded at a barrel temperature of 300-320°C, kneaded, extruded, cooled, and cut to produce pelletized polyamide resin compositions. These pellets were used to prepare test pieces and tubes for evaluating various physical properties, and various evaluations were performed using the methods described above. The results are shown in Table 1.

[0179] Example 3, Comparative Example 1

[0180] The semi-aromatic polyamide, elastomer, degradation inhibitor C-2 or C-3, lubricant, and dye listed in Table 1 were premixed at a specified mass ratio and fed all at once into the upstream feed port of a twin-screw extruder ("TEM-26SS" manufactured by Toshiba Machine Co., Ltd.). The mixture was melt-kneaded at a barrel temperature of 300-320°C, kneaded, extruded, cooled, and cut to produce pellets of a polyamide resin composition. These pellets were used to prepare test pieces and tubes for evaluating various physical properties, and various evaluations were performed using the methods described above. The results are shown in Table 1.

[0181] In addition, each component shown in Table 1 is as follows.

[0182] <Semi-aromatic polyamide A-1>

[0183] Semi-aromatic polyamide A-1 obtained in Production Example 1

[0184] <Elastomer B-1>

[0185] Elastomer obtained by modifying an ethylene-butene copolymer with maleic anhydride (TAFMERMH5010 manufactured by Mitsui Chemicals, Inc., anhydride group concentration: 50 μeq / g)

[0186] <Elastomer B-2>

[0187] Elastomer obtained by modifying an ethylene-butene copolymer with maleic anhydride (TAFMERMH5020 manufactured by Mitsui Chemicals, Inc., anhydride group concentration: 100 μeq / g)

[0188] <Elastomer B-3>

[0189] Elastomer obtained by modifying an ethylene-butene copolymer with maleic anhydride (TAFMERMH5040 manufactured by Mitsui Chemicals, Inc., anhydride group concentration: 200 μeq / g)

[0190] <Elastomer B-4>

[0191] Elastomer obtained by modifying ethylene-propylene copolymer with maleic anhydride (manufactured by Mitsui Chemicals, Inc., TAFMERMP0620, anhydride group concentration: 100 μeq / g)

[0192] <Degradation Inhibitor C-1>

[0193] Alicyclic polycarbodiimide (CarbodiLite HMV-15CA, manufactured by Nisshinbo Chemical Co., Ltd.)

[0194] <Degradation Inhibitor C-2>

[0195] Copper stabilizer (manufactured by PolyAd Services, KG HS01-P, molar ratio: halogen / copper = 10 / 1)

[0196] <Degradation Inhibitor C-3>

[0197] Hindered phenol compound (Sumitomo Chemical Co., Ltd., SUMILIZER GA-80)

[0198] <Lubricant D-1>

[0199] Polyolefin wax (manufactured by Clariant Chemicals, LICOCENEPE MA4221)

[0200] <Lubricant D-2>

[0201] Montanic acid wax (manufactured by Clariant Chemicals, LICOWAX OP)

[0202] <Dye E-1>

[0203] Carbon black (Mitsubishi Chemical Corporation, #980B)

[0204] [Table 1]

[0205]

[0206] As shown in Table 1, the tubes of Examples 1 to 3 achieve both a low flexural modulus and high surface smoothness while maintaining the heat resistance inherent in semi-aromatic polyamide. The tube of Comparative Example 1, while high in heat resistance and surface smoothness, lacks sufficient flexibility. Furthermore, the tube of Comparative Example 2, while excellent in heat resistance and flexibility, has an average number of 3 coarse dispersed phases (B) with a major axis diameter of 2 μm or greater, indicating insufficient surface smoothness.

[0207] It is speculated that by setting the concentration of the unsaturated compound having a carboxyl group and / or anhydride group in the elastomer to a specific range, the affinity between the elastomer and the polyamide is increased, and the coagulation of the elastomer that causes the deterioration of the surface smoothness during extrusion molding and the detachment as pore fat accumulation are suppressed. As a result, a tube with excellent surface smoothness can be obtained even in a composition containing a large amount of elastomer.

Claims

1. A tube comprising a layer containing 60% to 80% by mass of a semi-aromatic polyamide and 19% to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, The layer has a phase separation structure including a phase A containing the semi-aromatic polyamide and a phase B containing the elastomer, wherein the phase A is a continuous phase and the phase B is a dispersed phase dispersed in the phase A. In an image obtained by observing a cross section of the layer using an electron microscope, the average number of the phase B having a major axis diameter of 2 μm or more per 100 μm² was 1 / 100 μm. 2 the following, The total concentration of the carboxyl groups and the acid anhydride groups in 1 g of the elastomer is 95 μeq / g to 210 μeq / g.

2. The tube according to claim 1, wherein The surface roughness Ra of the layer measured in accordance with JIS B 0601 (1982) is 0.4 μm or less.

3. The tube according to claim 1, wherein Said layer is the innermost layer of the tube.

4. The tube according to claim 1, wherein The phase separation structure is a phase separation structure formed by the reaction of the semi-aromatic polyamide and the elastomer.

5. The tube according to claim 1, which is a tube formed from a polyamide resin composition. The polyamide resin composition is prepared by melt-kneading 60 to 80% by mass of a semi-aromatic polyamide and 19 to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group.

6. The tube according to any one of claims 1 to 5, wherein The semi-aromatic polyamide comprises dicarboxylic acid units and diamine units, wherein the dicarboxylic acid units comprise 50 mol % or more of at least one selected from terephthalic acid and naphthalene dicarboxylic acid units relative to all dicarboxylic acid units, and the diamine units comprise 60 mol % or more of aliphatic diamine units having 4 to 13 carbon atoms relative to all diamine units.

7. The tube according to claim 6, wherein The aliphatic diamine unit is at least one selected from the group consisting of units derived from 1,4-butanediamine, 1,6-hexanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine.

8. The tube according to claim 6, wherein The aliphatic diamine unit is a unit derived from at least one selected from 1,9-nonanediamine and 2-methyl-1,8-octanediamine.

9. The tube according to any one of claims 1 to 5, wherein The layer further contains 0.3% to 1.0% by mass of a carbodiimide compound. 10 . The tube according to claim 1 , which is an extrusion-molded body or a blow-molded body.

11. The pipe according to claim 10, which is a fuel pipe, an engine coolant pipe, a urea solution delivery pipe, an air conditioning refrigerant pipe, an oil drilling pipe, or a blowby gas pipe.

12. A polyamide resin composition, which is obtained by melt-kneading 60% to 80% by mass of a semi-aromatic polyamide and 19% to 40% by mass of an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, wherein the total concentration of the carboxyl group and the acid anhydride group in 1g of the elastomer is 95μeq / g to 210μeq / g.

13. The polyamide resin composition according to claim 12, wherein The semi-aromatic polyamide comprises dicarboxylic acid units and diamine units, wherein the dicarboxylic acid units comprise 50 mol % or more of at least one selected from terephthalic acid and naphthalene dicarboxylic acid units relative to all dicarboxylic acid units, and the diamine units comprise 60 mol % or more of aliphatic diamine units having 4 to 13 carbon atoms relative to all diamine units.

14. The polyamide resin composition according to claim 13, wherein The aliphatic diamine unit is at least one selected from the group consisting of units derived from 1,4-butanediamine, 1,6-hexanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine.

15. The polyamide resin composition according to claim 13, wherein The aliphatic diamine unit is a unit derived from at least one selected from 1,9-nonanediamine and 2-methyl-1,8-octanediamine.

16. The polyamide resin composition according to any one of claims 12 to 15, wherein The polyamide resin composition further includes 0.3% to 1.0% by mass of a carbodiimide compound.

17. A method for producing a polyamide resin composition, wherein: After melt-kneading a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having at least one selected from a carboxyl group and an acid anhydride group, a carbodiimide compound is further added and melt-kneaded. The semi-aromatic polyamide accounts for 60 to 80% by mass, the elastomer accounts for 19 to 40% by mass, and the total concentration of carboxyl groups and acid anhydride groups in 1 g of the elastomer is 95 to 210 μeq / g.

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