阅读说明：本技术 管及聚酰胺树脂组合物 (Pipe and polyamide resin composition ) 是由 关口健治 于 2020-02-19 设计创作，主要内容包括：一种管,其包含含有60～80质量％的半芳香族聚酰胺、以及15～40质量％的用具有选自羧基和酸酐基中的至少1种的不饱和化合物改性过的弹性体的层,上述层具有相分离结构,该相分离结构包含含有上述半芳香族聚酰胺的相(A)和含有上述弹性体的相(B),上述相(A)为连续相,上述相(B)为分散在上述相(A)中的分散相,在利用电子显微镜观察上述层的截面而得到的图像中,每100平方μm中存在的长轴直径为2μm以上的上述相(B)的平均个数为1个/100μm～(2)以下；以及一种聚酰胺树脂组合物,是将半芳香族聚酰胺、以及用具有选自羧基和酸酐基中的至少1种的不饱和化合物改性过的弹性体熔融混炼而成的,1g上述弹性体中的羧基和酸酐基的合计浓度为85～250μeq/g。(A pipe comprising a layer containing 60 to 80 mass% of a semi-aromatic polyamide and 15 to 40 mass% of an elastomer modified with an unsaturated compound having at least 1 selected from a carboxyl group and an acid anhydride group, the layer having a phase separation structure comprising a phase (A) containing the semi-aromatic polyamide and a phase (B) containing the elastomer, the phase (A) being a continuous phase, the phase (B) being a dispersed phase dispersed in the phase (A), the phase having a major axis diameter of 2 μm or more being present per 100 μm square in an image obtained by observing a cross section of the layer with an electron microscope(B) The average number of (2) is 1/100. mu.m 2 The following; and a polyamide resin composition obtained by melt-kneading a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having at least 1 kind 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 85 to 250 [ mu ] eq/g.)

1. A pipe comprising a layer containing 60 to 80 mass% of a semi-aromatic polyamide and 15 to 40 mass% of an elastomer modified with an unsaturated compound having at least 1 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, the phase A being a continuous phase, the phase B being a dispersed phase dispersed in the phase A,

in an image obtained by observing a cross section of the layer with an electron microscope, the average number of the phases B having a major axis diameter of 2 μm or more present per 100 μm square is 1/100 μm²The following.

2. The pipe according to claim 1, wherein the layer has a surface roughness Ra of 0.4 μm or less as measured according to JIS B0601 (1982).

3. The tube of claim 1 or 2, wherein the layer is an innermost layer of the tube.

4. The pipe according to any one of claims 1 to 3, wherein the phase-separated structure is a phase-separated structure obtained by reacting the semi-aromatic polyamide with the elastomer.

5. The pipe according to any one of claims 1 to 4, which is a pipe molded from a polyamide resin composition,

the polyamide resin composition is obtained by melt-kneading 60 to 80 mass% of a semi-aromatic polyamide and 15 to 40 mass% of an elastomer modified with an unsaturated compound having at least 1 kind selected from a carboxyl group and an acid anhydride group,

the total concentration of carboxyl groups and acid anhydride groups in 1g of the elastomer is 85 to 250 [ mu ] eq/g.

6. The pipe according to any one of claims 1 to 5, wherein the semi-aromatic polyamide comprises dicarboxylic acid units containing 50 mol% or more of at least 1 selected from terephthalic acid and naphthalenedicarboxylic acid units with respect to the total dicarboxylic acid units, and diamine units containing 60 mol% or more of aliphatic diamine units having 4 to 13 carbon atoms with respect to the total diamine units.

7. The pipe of claim 6, wherein the aliphatic diamine units are at least 1 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 pipe of claim 6, wherein the aliphatic diamine units are units derived from at least 1 selected from the group consisting of 1, 9-nonanediamine and 2-methyl-1, 8-octanediamine.

9. The pipe according to any one of claims 1 to 8, wherein the layer further comprises 0.3 to 5 mass% of a carbodiimide compound.

10. The pipe according to any one of claims 1 to 9, 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 carrying pipe, an air conditioning refrigerant pipe, an oil excavation pipe, or a blow-by pipe.

12. 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 1 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 85 to 250 [ mu ] eq/g.

13. The polyamide resin composition according to claim 12, wherein the semi-aromatic polyamide comprises dicarboxylic acid units containing 50 mol% or more of at least 1 selected from terephthalic acid and naphthalenedicarboxylic acid units based on the total dicarboxylic acid units, and diamine units containing 60 mol% or more of aliphatic diamine units having 4 to 13 carbon atoms based on the total diamine units.

14. The polyamide resin composition according to claim 13, wherein the aliphatic diamine unit is at least 1 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 1 selected from the group consisting of 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 contains 0.3 to 5 mass% of a carbodiimide compound.

17. A method for producing a polyamide resin composition, wherein a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having at least 1 selected from a carboxyl group and an acid anhydride group are melt-kneaded, and then a carbodiimide compound is further added to the mixture, and the mixture is melt-kneaded.

18. The method for producing a polyamide resin composition according to claim 17, wherein the semi-aromatic polyamide is 60 to 80 mass%, the elastomer is 15 to 40 mass%, and the total concentration of carboxyl groups and acid anhydride groups in 1g of the elastomer is 85 to 250 μ eq/g.

Technical Field

The present invention relates to a pipe having excellent heat resistance and also excellent flexibility and moldability.

Background

Polyamide resins are excellent in strength, heat resistance, chemical resistance, and the like, and have been conventionally used for automobile structural parts such as automobile fuel pipes and fuel pipe joints (connectors). For example, the polyamide resin composition is used for a long-life coolant (hereinafter referred to as "LLC") used for cooling an automobile engine, a pipe for circulating a refrigerant for cooling an air conditioner, and the like. Among the above-mentioned pipes, aliphatic polyamides such as polyamide 12, polyamide 11, and polyamide 6 are widely used from the viewpoint of ease of extrusion molding and flexibility, but on the other hand, problems such as insufficient chemical resistance and insufficient heat resistance have been pointed out for these aliphatic polyamides. In particular, in recent years, in order to improve the fuel efficiency of automobiles, the resin formation of pipes through which cooling water, high-temperature gas, and oil flow has been actively studied, and pipes having excellent chemical resistance and heat resistance as compared with conventional pipes have been desired.

It is known that a semi-aromatic polyamide containing an aromatic dicarboxylic acid such as terephthalic acid is generally superior to an aliphatic polyamide in chemical resistance and heat resistance. Semi-aromatic polyamides are generally stiffer than aliphatic polyamides, and it has been proposed to impart flexibility by mixing with a flexibility imparting material such as an elastomer when used as a pipe (see patent documents 1 to 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2006 + 176597

Patent document 2: japanese Special Table 2015-501341

Patent document 3: international publication No. 2017/115699

Disclosure of Invention

Problems to be solved by the invention

However, if the amount of the elastomer added is increased in order to impart sufficient flexibility to the polyamide composition containing a semi-aromatic polyamide, there is pointed out a problem that the pore volume (Japanese patent No. ヤニ) is increased and the moldability such as the surface smoothness is deteriorated.

In view of the problems of the prior art, an object of the present invention is to provide: a pipe having excellent heat resistance and further excellent flexibility and formability; and a polyamide resin composition from which the pipe can be obtained.

Means for solving the problems

The present inventors have conducted intensive studies and, as a result, have found that a pipe having excellent heat resistance possessed by a semi-aromatic polyamide and excellent moldability such as flexibility and surface smoothness can be obtained by molding the semi-aromatic polyamide resin composition obtained by melt-kneading the semi-aromatic polyamide and an elastomer, and further have conducted extensive studies based on the finding, thereby completing the present invention.

Namely, the present invention provides the following [1] and [2 ].

[1] A tube, comprising: a layer comprising 60 to 80 mass% of a semi-aromatic polyamide and 15 to 40 mass% of an elastomer modified with an unsaturated compound having at least 1 selected from the group consisting of 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, the phase (A) being a continuous phase and the phase (B) being a dispersed phase dispersed in the phase (A),

in an image obtained by observing a cross section of the layer with an electron microscope, the average number of the phases (B) having a major axis diameter of 2 μm or more per 100 μm square is 1/100 μm²The following.

[2] A polyamide resin composition obtained by melt-kneading 60 to 80 mass% of a semi-aromatic polyamide and 15 to 40 mass% of an elastomer modified with an unsaturated compound having at least 1 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 85 to 250 [ mu ] eq/g.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: a pipe having excellent heat resistance and further excellent flexibility and formability; and a polyamide resin composition from which the pipe can be obtained.

Detailed Description

The tube of the invention is characterized in that it comprises: a layer comprising 60 to 80 mass% of a semi-aromatic polyamide and 15 to 40 mass% of an elastomer modified with an unsaturated compound having at least 1 selected from the group consisting of 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, the phase (A) being a continuous phase and the phase (B) being a dispersed phase dispersed in the phase (A),

in an image obtained by observing a cross section of the layer with an electron microscope, the average number of the phases (B) having a major axis diameter of 2 μm or more per 100 μm square is 1/100 μm²The following.

The present invention also provides a polyamide resin composition from which the pipe can be obtained. Specifically disclosed is a polyamide resin composition which is obtained by melt-kneading 60-80% by mass of a semi-aromatic polyamide and 15-40% by mass of an elastomer modified with an unsaturated compound having at least 1 selected from a carboxyl group and an acid anhydride group, and which is characterized in that the total concentration of the carboxyl group and the acid anhydride group in 1g of the elastomer is 85-250 [ mu ] eq/g.

By providing a specific concentration of the functional group in the polyamide resin composition containing a semi-aromatic polyamide and an elastomer modified with an unsaturated compound having the functional group, flexibility is imparted to the pipe, and by forming the above form (japanese: モルフォロジー), a pipe having a layer with excellent surface smoothness can be obtained. Further, the semi-aromatic polyamide is contained, thereby imparting heat resistance, which is a characteristic of the pipe.

The polyamide resin composition, pipe and the like of the present invention will be described in more detail below.

In the present specification, the expression "XX to YY" means "XX or more and YY or less". In addition, in the present specification, preferred embodiments of the embodiments are shown, and a combination of 2 or more of the preferred embodiments is also a preferred embodiment. In the case where there are several numerical ranges, the lower limit value and the upper limit value may be selectively combined as a preferable mode.

In addition, an elastomer modified with an unsaturated compound having at least 1 kind selected from a carboxyl group and an acid anhydride group may be simply referred to as "elastomer".

Further, "tube" refers to a tubular structure such as a tube or a hose.

< Polyamide resin composition >

[ semi-aromatic polyamide ]

In the present invention, the semi-aromatic polyamide means: 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, or a polyamide comprising a dicarboxylic acid unit mainly composed of an aliphatic dicarboxylic acid unit and a diamine unit mainly composed of an aromatic diamine unit. The term "as a main component" means 50 to 100 mol%, preferably 60 to 100 mol%, of the total unit.

The polyamide resin composition contains 60-80 mass% of a semi-aromatic polyamide relative to 100 mass% of the polyamide resin composition. If the content of the semi-aromatic polyamide is less than 60% by mass, sufficient heat resistance cannot be exhibited, and if it exceeds 80% by mass, flexibility is poor. The content of the semi-aromatic polyamide is preferably 63 mass% or more, more preferably 65 mass% or more, further preferably 67 mass% or more, and preferably 75 mass% or less.

Among the semi-aromatic polyamides used in the present invention, the semi-aromatic polyamides are preferably polyamides comprising dicarboxylic acid units mainly composed of aromatic dicarboxylic acid units and diamine units mainly composed of aliphatic diamine units, and more preferably semi-aromatic polyamides comprising dicarboxylic acid units containing 50 to 100 mol% of aromatic dicarboxylic acid units and diamine units containing 60 to 100 mol% of aliphatic diamine units having 4 to 13 carbon atoms.

The content of the aromatic dicarboxylic acid unit in the dicarboxylic acid unit is preferably 50 to 100 mol%, more preferably 75 to 100 mol%, and still more preferably 90 to 100 mol%, from the viewpoint of forming a semi-aromatic polyamide having good chemical resistance and heat resistance.

Examples of the aromatic dicarboxylic acid unit include a terephthalic acid unit, a naphthalenedicarboxylic acid unit, an isophthalic acid unit, a1, 4-phenylenedioxydiacetic acid unit, a1, 3-phenylenedioxydiacetic acid unit, a diphenic acid unit, a diphenylmethane-4, 4 ' -dicarboxylic acid unit, a diphenylsulfone-4, 4 ' -dicarboxylic acid unit, and a4, 4 ' -biphenyldicarboxylic acid unit. Examples of the naphthalenedicarboxylic acid unit include units derived from 2, 6-naphthalenedicarboxylic acid, 2, 7-naphthalenedicarboxylic acid and 1, 4-naphthalenedicarboxylic acid, and 2, 6-naphthalenedicarboxylic acid unit is preferable.

Among them, the aromatic dicarboxylic acid unit is preferably a terephthalic acid unit and/or a naphthalenedicarboxylic acid unit. Therefore, the semi-aromatic polyamide preferably contains 50 mol% or more of at least 1 kind of dicarboxylic acid unit selected from terephthalic acid and naphthalenedicarboxylic acid units with respect to the whole dicarboxylic acid units. The content of at least 1 dicarboxylic acid unit selected from terephthalic acid and naphthalenedicarboxylic acid units in all the dicarboxylic acid units is preferably 50 to 100 mol%, more preferably 75 to 100 mol%, and still more preferably 90 to 100 mol%.

The dicarboxylic acid unit constituting the semi-aromatic polyamide may preferably contain a dicarboxylic acid unit other than the aromatic dicarboxylic acid unit in a range of less than 50 mol%. Examples of the other dicarboxylic acid unit include: 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-diethylsuccinic acid, 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 cyclodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2 '-biphenyldicarboxylic acid, 4' -biphenyldicarboxylic acid, diphenylmethane-4, 4 '-dicarboxylic acid, and diphenylsulfone-4, 4' -dicarboxylic acid; etc., and 1 or 2 or more of them may be contained. The content of these other dicarboxylic acid units in the dicarboxylic acid unit is preferably 25 mol% or less, and more preferably 10 mol% or less. The semi-aromatic polyamide used in the present invention may further contain units derived from a polycarboxylic acid such as trimellitic acid, trimesic acid, or pyromellitic acid in a range that enables melt molding.

The semi-aromatic polyamide preferably contains 60 mol% or more of an aliphatic diamine unit having 4 to 13 carbon atoms based on the total diamine units. When a semi-aromatic polyamide containing an aliphatic diamine unit having 4 to 13 carbon atoms in the above ratio is used, a polyamide resin composition having excellent toughness, heat resistance, chemical resistance and lightweight properties can be obtained. The content of the aliphatic diamine unit having 4 to 13 carbon atoms in the diamine unit is preferably 60 to 100 mol%, more preferably 75 to 100 mol%, and still more preferably 90 to 100 mol%.

Examples of the aliphatic diamine unit having 4 to 13 carbon atoms include: 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; branched aliphatic diamines such as 2-methyl-1, 5-pentanediamine, 3-methyl-1, 5-pentanediamine, 2, 4-trimethyl-1, 6-hexanediamine, 2,4, 4-trimethyl-1, 6-hexanediamine, 2-methyl-1, 8-octanediamine and 5-methyl-1, 9-nonanediamine; etc., and 1 or 2 or more of them may be contained.

The above aliphatic diamine unit having 4 to 13 carbon atoms is more preferably at least 1 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, and is more preferably a unit derived from 1, 9-nonanediamine and/or 2-methyl-1, 8-octanediamine, and is further preferably a unit derived from 1, 9-nonanediamine and 2-methyl-1, 8-octanediamine, from the viewpoint of obtaining a polyamide resin composition having further excellent heat resistance, low water absorption and liquid drug resistance. When the aliphatic diamine unit contains both units derived from 1, 9-nonanediamine and 2-methyl-1, 8-octanediamine, the molar ratio of the 1, 9-nonanediamine unit to the 2-methyl-1, 8-octanediamine unit is preferably in the range of from 95/5 to 40/60, more preferably from 90/10 to 40/60, and still more preferably from 80/20 to 40/60, based on the 1, 9-nonanediamine unit/2-methyl-1, 8-octanediamine unit.

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

The semi-aromatic polyamide may further contain an aminocarboxylic acid unit and/or a lactam unit within a range that does not hinder the effect of the present invention.

Examples of the aminocarboxylic acid unit include units derived from 11-aminoundecanoic acid, 12-aminododecanoic acid, and the like, and the aminocarboxylic acid unit may include 2 or more species. The content of the aminocarboxylic acid unit in the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 20 mol% or less, and still more preferably 10 mol% or less, based on 100 mol% of all the monomer units constituting the semi-aromatic polyamide.

The semi-aromatic polyamide may contain a lactam unit within a range not to inhibit the effect of the present invention. Examples of the lactam unit include: the units derived from epsilon-caprolactam, enantholactam, undecanolactam, laurolactam, alpha-pyrrolidone, alpha-piperidone, etc., may contain 2 or more lactam units. The content of the lactam unit in the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 20 mol% or less, and still more preferably 10 mol% or less, based on 100 mol% of all the monomer units constituting the semi-aromatic polyamide.

Typical semi-aromatic polyamides containing 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), poly (nonamethylene terephthalamide) (polyamide 9T), poly (2-methyloctamethylene) terephthalamide (nylon M8T), poly (nonamethylene terephthalamide)/poly (2-methyloctamethylene) terephthalamide copolymer (nylon 9T/M8T), poly (nonamethylene naphthamide) (polyamide 9N), poly (nonamethylene naphthamide)/poly (2-methyloctamethylene) naphthamide copolymer (nylon 9N/M8N), poly (decamethylene terephthalamide) (polyamide 10T), poly (hexamethylene isophthalamide) (polyamide 6I), copolymer of polyamide 6I and polyamide 6T (polyamide 6I/6T), A copolymer of polyamide 6T and polyundecanamide (polyamide 11) (polyamide 6T/11), a copolymer of polyamide 10T and polyundecanamide (polyamide 11) (polyamide 10T/11), and the like.

Of these, at least 1 kind selected from the group consisting of polyamide 10T/11, poly (nonamethylene naphthamide) (polyamide 9N), poly (nonamethylene naphthamide)/poly (2-methyloctamethylene) naphthamide copolymer (nylon 9N/M8N), poly (nonamethylene terephthalamide) (polyamide 9T), poly (nonamethylene terephthalamide)/poly (2-methyloctamethylene) terephthalamide copolymer (nylon 9T/M8T) and poly (decamethylene terephthalamide) (polyamide 10T) is preferable, and poly (nonamethylene naphthamide)/poly (2-methyloctamethylene) naphthamide copolymer (nylon 9N/M8N), poly (nonamethylene terephthalamide)/poly (2-methyloctamethylene) terephthalamide copolymer (nylon 9T/M8T) is more preferable, And at least 1 of polyamide 10T/11, more preferably poly (nonamethylene terephthalamide)/poly (2-methyl octamethylene) terephthalamide copolymer (nylon 9T/M8T).

On the other hand, among the semi-aromatic polyamides, regarding the semi-aromatic polyamides containing a dicarboxylic acid unit containing an aliphatic dicarboxylic acid unit as a main component and a diamine unit containing an aromatic diamine unit as a main component, the aliphatic dicarboxylic acid unit includes a unit derived from the above aliphatic dicarboxylic acid, and 1 or 2 or more of them may be contained. The aromatic diamine unit includes units derived from the aromatic diamine, and may include 1 or 2 or more of them. Other means may be included within a range not to impair the effects of the present invention.

Representative semi-aromatic polyamides comprising dicarboxylic acid units mainly comprising aliphatic dicarboxylic acid units and diamine units mainly comprising aromatic diamine units include polymetaxylylene adipamide (MXD6), polyparaxylylene sebacamide (PXD10), and the like.

The semi-aromatic polyamide of the present invention is preferably capped with a capping agent in an amount of 10 mol% or more of the terminal groups of the molecular chain. When a semi-aromatic polyamide having a terminal capping rate of 10 mol% or more is used, a semi-aromatic polyamide resin composition having more excellent physical properties such as melt stability and hot water resistance can be obtained.

As the end-capping agent, a monofunctional compound having reactivity with a terminal amino group or a terminal carboxyl group can be used. Specific examples thereof include monocarboxylic acids, acid anhydrides, monoisocyanates, monoacyl halides, monoesters, monoalcohols, and monoamines. From the viewpoints of reactivity, stability of the capped end, and the like, a monocarboxylic acid is preferable as the capping agent for the terminal amino group, and a monoamine is preferable as the capping agent for the terminal carboxyl group. From the viewpoint of ease of handling and the like, monocarboxylic acids are more preferable as the end-capping agent.

The monocarboxylic acid used as the end-capping agent is not particularly limited as long as it has reactivity with an amino group, and examples thereof include: aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic 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; mixtures of any of these, and the like. Among them, from the viewpoints of reactivity, stability of the capped end, price, and the like, at least 1 selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid is preferable.

The monoamine used as the end-capping agent is not particularly limited as long as it is reactive with the carboxyl group, and 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; mixtures of any of these, and the like. Among them, at least 1 selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline is preferable from the viewpoints of reactivity, high boiling point, stability of the capped end, cost, and the like.

The semi-aromatic polyamide has intrinsic viscosity [ eta ] measured at 30 deg.C and concentration of 0.2g/dl with concentrated sulfuric acid as solvent_inh]Preferably 0.6dl/g or more, more preferably 0.8dl/g or more, further preferably 0.6dl/g or more, particularly preferably 1.0dl/g or more, and further preferably 2.0dl/g or less, more preferably 1.8dl/g or less, further preferably 1.6dl/g or less. If the intrinsic viscosity [ eta ] of the polyamide_inh]When the content is within the above range, the physical properties such as moldability are further improved. Intrinsic viscosity [ eta ]_inh]Can be determined according to the flowing-down time t of the solvent (concentrated sulfuric acid)₀(second) time t of sample solution flowing down₁(second) and the sample concentration c (g/dl) (i.e., 0.2g/dl) in the sample solution by eta_inh＝[ln(t₁/t₀)]The relation of/c is obtained.

Terminal amino group content ([ NH ]) of semi-aromatic polyamide₂]) Preferably 5 to 60 mu eq/g, more preferably 5 to 50 mu eq/gFurther, it is preferably in the range of 5 to 30. mu. eq/g. If the terminal amino group content ([ NH ]₂]) When the content is 5. mu. eq/g or more, the compatibility of the semi-aromatic polyamide with the elastomer described later is good. Further, if the content of the terminal amino group is 60. mu. eq/g or less, when an acid-modified elastomer described later is used as the elastomer, excessive reaction between the terminal amino group and the modified portion of the elastomer to cause gelation can be avoided.

The terminal amino group content ([ NH ]) as referred to in the specification₂]) The amount of the terminal amino group contained in 1g of the semi-aromatic polyamide (unit: μ eq), can be determined by a neutralization titration method using an indicator.

Contains dicarboxylic acid units and diamine units and has a terminal amino group content ([ NH ]₂]) The semi-aromatic polyamide in the above range can be produced, for example, as follows.

First, a dicarboxylic acid, a diamine, and if necessary, an aminocarboxylic acid, a lactam, a catalyst, and a blocking agent are mixed to produce a nylon salt. In this case, if the molar number (X) of all carboxyl groups and the molar number (Y) of all amino groups contained in the reaction raw materials satisfy the following formula (2),

-0.5≤[(Y-X)/Y]×100≤2.0 (2)

the terminal amino group content ([ NH ]) can be easily produced₂]) The semi-aromatic polyamide is preferably 5 to 60. mu. eq/g. Then, the produced nylon salt is heated to a temperature of 200-250 ℃ to prepare an intrinsic viscosity [ eta ] at 30 ℃ in concentrated sulfuric acid_inh]The prepolymer having a polymerization degree of 0.10 to 0.60dlL/g is further increased to obtain a semi-aromatic polyamide used in the present invention. If the inherent viscosity [ eta ] of the prepolymer_inh]When the amount of the aromatic polyamide is in the range of 0.10 to 0.60dLl/g, the variation in the molar balance between the carboxyl group and the amino group and the decrease in the polymerization rate are small in the stage of increasing the polymerization degree, and a semi-aromatic polyamide having a small molecular weight distribution and further excellent in various performances and moldability can be obtained. In the case of the stage of increasing the polymerization degree by the solid-phase polymerization method, it is preferable to carry out the polymerization under reduced pressure or under inert gas flow, and if the polymerization temperature is in the range of 200 to 280 ℃, the polymerization rate is high and the productivity is excellentColoring and gelation can be effectively suppressed. In addition, in the case of the stage of increasing the polymerization degree by the melt extruder, the polymerization temperature is preferably 370 ℃ or lower, and if polymerization is performed under such conditions, the polyamide is hardly decomposed, and a semi-aromatic polyamide with little deterioration can be obtained.

Examples of the catalyst that can be used for producing the semi-aromatic polyamide include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts and esters thereof. Examples of the salt or ester 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, antimony, etc.; ammonium salts of phosphoric acid, phosphorous acid or hypophosphorous acid; ethyl, isopropyl, butyl, hexyl, isodecyl, octadecyl, decyl, stearyl, phenyl, etc., of phosphoric acid, phosphorous acid, or hypophosphorous acid.

The amount of the catalyst used is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and preferably 1.0% by mass or less, more preferably 0.5% by mass or less, based on 100% by mass of the total mass of the raw materials. If the amount of the catalyst used is not less than the above lower limit, the polymerization proceeds well. If the content is not more than the upper limit, impurities derived from the catalyst are less likely to be generated, and for example, when a polyamide or a polyamide resin composition containing the same is extrusion-molded, problems caused by the impurities can be prevented.

[ Elastomers ]

The polyamide resin composition contains 15-40% 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 content of the elastomer is less than 15% by mass, flexibility is poor, and if it exceeds 40% by mass, it is difficult to exhibit excellent heat resistance.

The content of the elastomer is preferably 19% by mass or more, and more preferably 25% by mass or more, from the viewpoint of imparting flexibility and impact resistance. From the viewpoint of moldability, the content of the elastomer is preferably 35% by mass or less, and more preferably 31% by mass or less.

In addition, as an embodiment of the polyamide resin composition of the present invention, the content of the elastomer may be adjusted according to the flexural modulus of the molded article. From the viewpoint of improving the flexibility of the pipe containing the composition, the content of the elastomer is preferably adjusted to an amount such that the flexural modulus of elasticity of a molded article of the polyamide resin composition measured under the conditions of 23 ℃ and 50% RH in accordance with ISO178 (4 th edition 2001) is 1.8GPa or less, more preferably 1.5GPa or less, and still more preferably 1.2GPa or less. From the viewpoint of functioning as a pipe, the content of the elastomer is preferably adjusted so that the flexural modulus is 0.3GPa or more.

In the present invention, as the elastomer, for example, there can be used: an elastomer obtained by modifying an α -olefin copolymer, (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 or the like") with an unsaturated compound having at least 1 kind selected from a carboxyl group and an acid anhydride group. When the modification is carried out 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, so that the affinity of the interface between the semi-aromatic polyamide phase and the elastomer phase is enhanced, the impact resistance and elongation characteristics are improved, and flexibility is exhibited. Among the above, preferred is a polymer obtained by modifying an α -olefin copolymer with an unsaturated compound having a carboxyl group and/or an acid anhydride group, and more preferred is a polymer obtained by modifying an ethylene-butene copolymer with the unsaturated compound.

Examples of the unsaturated compound having a carboxyl group used for the elastomer modified with an unsaturated compound having a carboxyl group and/or an acid anhydride group include α, β -unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. Examples of the unsaturated compound having an acid anhydride group include dicarboxylic anhydrides having an α, β -unsaturated bond such as maleic anhydride and itaconic anhydride. As the unsaturated compound having a carboxyl group and/or an acid anhydride group, dicarboxylic anhydride having an α, β -unsaturated bond is preferable, and maleic anhydride is more preferable.

The total concentration of the carboxyl group and the acid anhydride group in 1g of the elastomer is preferably 85 to 250. mu. eq/g, more preferably 90 to 220. mu. eq/g, and still more preferably 95 to 210. mu. eq/g. When the content of the carboxyl group and the acid anhydride group is in the above range, a tube having excellent surface appearance can be obtained during extrusion molding, and a tube having excellent surface smoothness can be easily obtained.

The total concentration of the carboxyl group and the acid anhydride group in the polyamide resin composition is difficult to specify because the terminal amino group of the polyamide reacts with the carboxyl group and the acid anhydride group during melt kneading.

Examples of the copolymer include an α -olefin copolymer, an (ethylene and/or propylene)/(α, β -unsaturated carboxylic acid and/or unsaturated carboxylic acid ester) copolymer, an ionomer, and an aromatic vinyl compound/conjugated diene compound block copolymer. These copolymers and the like may be used alone in 1 kind or in combination of 2 or more kinds.

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

Examples of the α -olefin 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-hexene, 4-dimethyl-1-pentene, 1-hexene, 1-decene, 1, decene, 1,4, and 1, one, 4, one, or, one, or a combination of ethylene, one, and a, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene. These may be used in 1 or 2 or more. Among the above, the α -olefin having 3 or more carbon atoms is preferably at least 1 selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene, and more preferably 1-butene.

Further, 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), dicyclopentadiene, cyclohexadiene, cyclooctadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 1, 5-hexadiene, 1, 4-octadiene, 1, 5-octadiene, 4-heptadiene, 7-methyl-1, 7-nonadiene, 4, 8-decatriene (DMDT), dicyclopentadiene, cyclohexadiene, cyclooctadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 2-bis (or mixtures thereof, and the like, Polyene copolymerization of unconjugated dienes such as 6-chloromethyl-5-isopropenyl-2-norbornene, 2, 3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene and 2-propylidene-2, 5-norbornadiene. These may be used in 1 or 2 or more.

The above-mentioned (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 an α, β -unsaturated carboxylic acid and/or unsaturated carboxylic acid ester monomer, and examples of the α, β -unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid and the like, and examples of the α, β -unsaturated carboxylic acid ester monomer include methyl ester, ethyl ester, propyl ester, butyl ester, pentyl ester, hexyl ester, heptyl ester, octyl ester, nonyl ester, decyl ester and the like of these unsaturated carboxylic acids. These may be used in 1 or 2 or more.

The ionomer is a substance in which at least a part of carboxyl groups of the copolymer of an olefin and an α, β -unsaturated carboxylic acid is ionized by neutralization with a metal ion. Ethylene is preferably used as the olefin, and acrylic acid and methacrylic acid are preferably used as the α, β -unsaturated carboxylic acid, but the olefin is not limited to those exemplified herein, and an unsaturated carboxylic acid ester monomer may be copolymerized. The metal ions include alkali metals and alkaline earth metals such as Li, Na, K, Mg, Ca, Sr and Ba, and also include Al, Sn, Sb, Ti, Mn, Fe, Ni, Cu, Zn and Cd. These may be used in 1 or 2 or more.

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 having at least 1 aromatic vinyl compound polymer block and at least 1 conjugated diene polymer block can be used. In the block copolymer, the unsaturated bond in the conjugated diene polymer block may be hydrogenated.

The aromatic vinyl compound polymer block is a polymer block mainly composed of a structural unit derived from an aromatic vinyl compound. Examples of the aromatic vinyl compound in this case include: styrene, alpha-methyl styrene, m-methyl styrene, 2, 4-two methyl styrene, vinyl naphthalene, vinyl anthracene, 4-propyl styrene, 4-cyclohexyl styrene, 4-dodecyl styrene, 2-ethyl-4-benzyl styrene, 4- (phenyl butyl) styrene, they can use 1 or more than 2. The aromatic vinyl compound polymer block may have a structural unit containing a small amount of another unsaturated monomer, as the case may be. The conjugated diene polymer block is a polymer block comprising 1 or 2 or more of 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, and in the hydrogenated aromatic vinyl compound/conjugated diene compound block copolymer, a part or all of unsaturated bond portions in the conjugated diene polymer block are hydrogenated.

The molecular structure of the aromatic vinyl compound/conjugated diene compound block copolymer and the hydrogenated product thereof may be linear, branched, radial, or any combination thereof. Among these, as the aromatic vinyl compound/conjugated diene compound block copolymer and/or the hydrogenated product thereof, a diblock copolymer in which 1 aromatic vinyl compound polymer block and 1 conjugated diene polymer block are linearly bonded, a triblock copolymer in which 3 polymer blocks are linearly bonded in the order of the aromatic vinyl compound polymer block, the conjugated diene polymer block, and the aromatic vinyl compound polymer block, and 1 or 2 or more kinds of hydrogenated products thereof are preferably used, and examples thereof include: unhydrogenated or hydrogenated styrene/butadiene block copolymers, unhydrogenated or hydrogenated styrene/isoprene/styrene block copolymers, unhydrogenated or hydrogenated styrene/butadiene/styrene block copolymers, unhydrogenated or hydrogenated styrene/isoprene/butadiene/styrene block copolymers, and the like.

[ deterioration inhibitor ]

The polyamide resin composition of the present invention may further contain a deterioration inhibitor in order to improve heat aging resistance and hydrolysis resistance.

Examples of the deterioration inhibitor include: antioxidants such as copper-based stabilizers, phenol-based heat stabilizers, phosphorus-based heat stabilizers, and sulfur-based heat stabilizers. The deterioration inhibitor may be a hydrolysis inhibitor such as a carbodiimide compound. These deterioration inhibitors may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The polyamide resin composition preferably contains the deterioration inhibitor in an amount of 0.3 to 5% by mass, more preferably 0.4 to 3% by mass, and still more preferably 0.6 to 2% by mass, based on 100% by mass of the polyamide resin composition. When the content of the deterioration inhibitor is in the above range, a composition having excellent heat aging resistance and hydrolysis resistance and a small amount of gas generated during extrusion molding can be obtained.

The copper-based stabilizer may be used in the form of a mixture of a copper compound and a metal halide, and the polyamide resin composition preferably contains the copper compound and the metal halide in such a ratio 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 further preferably 45/1 or less, more preferably 40/1 or less, further preferably 30/1 or less. When the ratio (halogen/copper) is not less than the lower limit, copper deposition and metal corrosion during molding can be more effectively suppressed. When the ratio (halogen/copper) is not more than the above upper limit, corrosion of a screw of a molding machine and the like can be more effectively suppressed without impairing mechanical properties such as tensile properties of the obtained polyamide resin composition.

Examples of the copper compound include: copper halide, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, and copper complex salts coordinated to chelating agents such as ethylenediamine and ethylenediamine tetraacetic acid. Examples of the copper halide include copper iodide; copper bromides such as cuprous bromide and cupric bromide; copper chloride such as cuprous chloride, and the like. Among these copper compounds, from the viewpoint of excellent heat aging resistance and being capable of suppressing corrosion of metals in a screw and a barrel portion during extrusion, at least 1 selected from copper halides and copper acetates is preferable, at least 1 selected from copper iodides, copper bromides, copper chlorides and copper acetates is more preferable, and at least 1 selected from copper iodides, copper bromides and copper acetates is even more preferable. The copper compound may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

As the metal halide, a metal halide other than copper compounds can be used, and a salt of a metal element of group 1 or group 2 of the periodic table and a halogen is preferable. Examples thereof include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. Among them, from the viewpoint of excellent high-temperature heat resistance such as heat aging resistance and the like of the obtained polyamide resin composition, and the ability to suppress metal corrosion, at least 1 selected from potassium iodide and potassium bromide is preferable, and potassium iodide is more preferable. The metal halide may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

Examples of the phenol-based heat stabilizer include hindered phenol compounds. The hindered phenol compound has a property of imparting heat resistance and light resistance to a resin such as polyamide.

Examples of the hindered phenol compound include: 2, 2-thio-diethylenebis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 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' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxyphenyl) propionamide, triethyleneglycol 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.

The phenol heat stabilizer may be used alone in 1 kind, or may be used in combination in 2 or more kinds. Particularly, 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 preferable.

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, octyldiphenyl phosphite, triisodecyl phosphite, phenyldiisodecyl phosphite, phenylditridecyl phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyl (tridecyl) phosphite, triphenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, tris (nonylphenyl) phosphite, tris (2, 4-di-tert-butylphenyl) phosphite, tris (2, 4-di-tert-butyl-5-methylphenyl) phosphite, tris (butoxyethyl) phosphite, 4' -butylidene-bis (3-methyl-6-tert-butylphenyl-tetratridecyl)) diphosphite Tetra (C12-C15 mixed alkyl) -4,4 ' -isopropylidenediphenyl phosphite, 4 ' -isopropylidenebis (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 ' -butylidenebis (3-methyl-6-tert-butylphenyl) diphosphite, tetra (C1-C15 mixed alkyl) -4,4 ' -isopropylidenediphenyl phosphite, tris (mono-or di-mixed nonylphenyl) phosphite, 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 ' -isopropylidenediphenyl phosphite, bis (octylphenyl) bis (4,4 ' -butylidenebis (3-methyl-6-tert-butylphenyl)). 1, 6-hexanol diphosphite, hexa (tridecyl) -1,1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) diphosphite, tris (4,4 ' -isopropylidenebis (2-tert-butylphenyl)) phosphite, tris (1, 3-stearoyloxyisopropyl) phosphite, 2, 2-methylenebis (4, 6-di-tert-butylphenyl) octyl phosphite, 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-butylbenzo [ d, f ] [1,3,2] -diphosphazepin (Japanese: ジオキサホスフェピン), and the like.

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, 2-bis [ [3- (dodecylthio) -1-oxopropoxy ] methyl ] -1, 3-propanediyl ester, and the like.

Examples of the amine-based heat stabilizer include: 4,4 '-bis (α, α -dimethylbenzyl) diphenylamine (NORAC CD, manufactured by NORAC chemical Co., Ltd.), N' -di-2-naphthyl-p-phenylenediamine (NORAC White, manufactured by NORAC chemical Co., Ltd.), N '-diphenyl-p-phenylenediamine (NORAC DP, manufactured by NORAC chemical Co., Ltd.), N-phenyl-1-naphthylamine (RAC PA, manufactured by NORAC chemical Co., Ltd.), N-phenyl-N' -isopropyl-p-phenylenediamine (NORAC 810-NA, manufactured by NORAC chemical Co., Ltd.), N-phenyl-N '- (1, 3-dimethylbutyl) -p-phenylenediamine (RAC 6C, manufactured by NORAC chemical Co., Ltd.) (NORAC C., Ltd.) (NORAC D, manufactured by NORAC chemical Co., Ltd.) (NORAC DP, manufactured by NORAC chemical Co., Ltd.) (N, N-phenyl-N' - (1, 3-dimethylbutyl) -p-phenylenediamine (NORAC 6C, manufactured by NORAC chemical Co., Ltd.), N-phenyl-N '- (3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine (NORAC G-1, manufactured by NORAC chemical 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-methacryloyloxy-2, 2,6, 6-tetramethylpiperidine, p-phenylenediamine, N-phenyl-N' - (3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, 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-piperidyl) carbonate, bis (2,2,6, 6-tetramethyl-4-piperidyl) oxalate, bis (2,2,6, 6-tetramethyl-4-piperidyl) malonate, Bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6, 6-tetramethyl-4-piperidyl) adipate, bis (2,2,6, 6-tetramethyl-4-piperidyl) terephthalate, 1, 2-bis (2,2,6, 6-tetramethyl-4-piperidyloxy) ethane, α' -bis (2,2,6, 6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6, 6-tetramethyl-4-piperidyl) toluylene-2, 4-dicarbamate, bis (2,2,6, 6-tetramethyl-4-piperidyl) hexamethylene-1, 6-dicarbamate, and mixtures thereof, Tris (2,2,6, 6-tetramethyl-4-piperidyl) benzene-1, 3, 5-tricarboxylate, tris (2,2,6, 6-tetramethyl-4-piperidyl) benzene-1, 3, 4-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, 1,2,3, 4-butanetetracarboxylic acid, 1,2,2,6, 6-pentamethyl-4-piperidinol, β, β ', β' -tetramethyl-3, 9- [2,4, and condensates of 8, 10-tetraoxaspiro [5.5] undecane ] diethanol.

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

[ chemical formula 1]

In the above general formula (I), X₁Represents a 2-valent hydrocarbon group. Examples of the hydrocarbon group include a chain aliphatic group, an aliphatic group having an alicyclic structure, and a group having an aromatic ring. The number of carbon atoms of the chain aliphatic group is 1 or more, preferably 1 to 20, more preferably 6 to 18, and the number of carbon atoms of the aliphatic group having an alicyclic structure and the group having an aromatic ring is preferably 5 or more, more preferably 6 to 20, and further preferably 6 to 18. The hydrocarbon group may have a substituent such as an amino group, a hydroxyl group, or an alkoxy group.

The polycarbodiimide may be an aliphatic polycarbodiimide, an aromatic polycarbodiimide, or a mixture thereof. Among them, aliphatic polycarbodiimides are more preferable from the viewpoint of chemical resistance and molding processability of the molded article obtained.

The aliphatic polycarbodiimide preferably has X which has a repeating unit represented by the general formula (I)₁A polycarbodiimide which is a chain aliphatic group or an aliphatic group having an alicyclic structure. X₁More preferably a group selected from an alkylene group having 3 to 18 carbon atoms, a 2-valent group represented by the following general formula (II), and a 2-valent group represented by the following general formula (III), and still more preferably a 2-valent group represented by the following general formula (III).

[ chemical formula 2]

In the above general formula (II) and general formula (III), R¹～R⁵Each independently represents a single bond or an alkylene group having 1 to 8 carbon atoms. R in the general formula (II)¹And R²Preferably a single bond. R in the general formula (III)³And R⁵Preferably a single bond, R⁴Preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms.

[ other ingredients ]

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 required.

Examples of other types of polymers include: polyether resins such as polyacetal and polyphenylene ether; polysulfone resins such as polysulfone and polyethersulfone; polythioether resins such as polyphenylene sulfide and polythioether sulfone; polyketone resins such as polyetheretherketone and polyallylether; polyacrylonitrile, polymethacrylonitrile, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, methacrylonitrile-butadiene-styrene copolymers and other polynitrile resins; polymethacrylate-based resins such as polymethyl methacrylate and polyethyl methacrylate; polyethylene ester resins such as polyvinyl acetate; polyvinyl chloride resins such as polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinylidene chloride copolymer, and vinylidene chloride-methacrylate copolymer; cellulose resins such as cellulose acetate and cellulose butyrate; fluorine-based resins such as polyvinylidene fluoride, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer; a polycarbonate-based resin; polyimide resins such as thermoplastic polyimide, polyamideimide, and polyetherimide; a thermoplastic polyurethane resin; and the like.

Examples of the filler include: fibrous fillers such as glass fibers, powdery fillers such as calcium carbonate, wollastonite, silica alumina, titanium dioxide, potassium titanate, magnesium hydroxide, and molybdenum disulfide; hydrotalcite, glass flakes, mica, clay, montmorillonite, kaolin, and other platy fillers.

The crystal nucleating agent is not particularly limited as long as it is a crystal nucleating agent generally used as a crystal nucleating agent for polyamides, and examples thereof include talc, calcium stearate, aluminum stearate, barium stearate, zinc stearate, antimony oxide, magnesium oxide, and any mixture thereof. Among them, talc is preferable in view of the effect of increasing the crystallization rate of polyamide. The crystallization nucleating agent may be treated with a silane coupling agent, a titanium coupling agent, or the like for the purpose of improving compatibility with the polyamide.

The colorant is not particularly limited, and may be appropriately selected from inorganic or organic pigments and dyes according to the use of the polyamide resin composition. As a colorant to be blended in the polyamide resin composition used for the chemical liquid transport tube, black inorganic pigments such as carbon black, lamp black, acetylene black, bone black, thermal black, channel black, furnace black, and titanium black are exemplified as preferable colorants.

The antistatic agent is not particularly limited, and may be an organic antistatic agent or an inorganic antistatic agent. Examples of the organic antistatic agent include: lithium ion salts, quaternary ammonium salts, ionic liquid, and other ionic compounds; and electron conductive high molecular compounds such as polythiophene, polyaniline, polypyrrole, and polyacetylene. Examples of the inorganic antistatic agent include: metal oxide-based conductive agents such as ATO, ITO, PTO, GZO, antimony pentoxide, and zinc oxide; carbon-based conductive agents such as carbon nanotubes and fullerenes. From the viewpoint of heat resistance, inorganic antistatic agents are preferred. Carbon black as a colorant may also function as an antistatic agent.

The plasticizer is not particularly limited as long as it is a plasticizer generally used as a plasticizer for polyamide, and examples thereof include: benzene sulfonic acid alkylamide compounds, toluene sulfonic acid alkylamide compounds, hydroxybenzoic acid alkyl ester compounds, hydroxybenzoic acid alkylamide compounds, and the like.

The lubricant is not particularly limited as long as it is a lubricant generally used as a lubricant for polyamide, and 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, polyolefin waxes, and the like. The fatty acid amide compound is preferable because it has an excellent external lubricating effect, for example, stearic acid amide, palmitic acid amide, methylene bis stearamide, ethylene bis stearamide, and the like.

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 still more preferably 5% by mass or less, based on 100% by mass of the polyamide resin composition.

[ Process for producing Polyamide resin composition ]

By providing the method for producing a polyamide resin composition of the present invention with a 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 obtained resin composition is excellent in flexibility and impact resistance.

The temperature and time at the time of melt kneading may be appropriately adjusted depending on the melting point of the semi-aromatic polyamide to be used, and from the viewpoint of suppressing deterioration of the polymerizability of the elastomer, the melt kneading temperature is preferably 380 ℃ or less, more preferably 370 ℃ or less, and still more preferably 360 ℃ or less. The melt kneading time is preferably about 1 to 5 minutes.

The method of melt-kneading is not particularly limited, and a method capable of uniformly mixing the semi-aromatic polyamide, the elastomer and the other components can be preferably employed, and a single-screw extruder, a twin-screw extruder, a kneader, a banbury mixer and the like are preferable, and a twin-screw extruder is more preferable from the viewpoint of good dispersibility of the elastomer and industrial productivity.

When a component that reacts with the terminal group of the semi-aromatic polyamide or the modified portion of the elastomer, such as a carbodiimide compound, is added as the deterioration inhibitor, the semi-aromatic polyamide and the elastomer are melt-kneaded and then the deterioration inhibitor is added, whereby the reaction between the semi-aromatic polyamide and the elastomer during melt-kneading can be prevented from being inhibited by the deterioration inhibitor. That is, the following method for producing a polyamide resin composition is preferable: the semi-aromatic polyamide and the elastomer modified with an unsaturated compound having at least 1 selected from the group consisting of a carboxyl group and an acid anhydride group are melt-kneaded, and then a carbodiimide compound is further added thereto to perform melt-kneading.

Specifically, when a twin-screw extruder is used as the melt kneading apparatus, it is preferable that a mixture obtained by dry-blending the semi-aromatic polyamide, the elastomer, and other components added as needed is fed from a first feed opening at the root of the twin-screw extruder, and the deterioration inhibitor is fed from a second feed opening provided between a first kneading section and a second kneading section provided in the screw. In this case, the deterioration inhibitor may be dry-blended with the semi-aromatic polyamide and then charged, if necessary.

< pipe >

[ method for producing tube ]

The pipe of the present invention is preferably a pipe molded from the polyamide resin composition.

The method for producing the tube of the present invention is not particularly limited, and known methods such as extrusion molding and blow molding can be used. Examples thereof include: a method (coextrusion method) in which melt extrusion is performed using an extruder corresponding to the number of layers or the number of materials, and the layers are simultaneously stacked in or out of a mold; or a method (coating method) in which a single-layer tube is produced in advance and the resins are integrated and laminated on the outside sequentially using an adhesive as needed.

In the case of manufacturing a pipe having a corrugated region, a pipe having a straight pipe shape is first formed, and then molding is performed, whereby a predetermined corrugated shape can be formed.

[ constitution of tube ]

The outer diameter of the pipe is designed in consideration of the flow rate of the fluid flowing inside. In addition, the wall thickness of the tube is designed to: the thickness of the pipe can maintain the required breaking pressure of the pipe without increasing the permeability of the internal matters, and can maintain the flexibility with good assembling operation and vibration resistance in use. The preferred pipe has an outer diameter of 2.5 to 300mm and a wall thickness of 0.5 to 30 mm.

The pipe of the present invention may comprise at least one layer containing the polyamide resin composition described in the present invention, and may be a single layer or 2 or more layers as necessary. In the case where the pipe is composed of 2 or more layers, the layer containing the polyamide resin composition is preferably the innermost layer of the pipe in order to reduce the flow path resistance of the fluid flowing inside and reduce unnecessary residues.

In the case of a multilayer pipe, the material constituting the other layer is not particularly limited, and a thermoplastic resin is preferable from the viewpoint of the formability of the pipe.

The thermoplastic resin may be appropriately selected in consideration of the use of the pipe, adhesion to an adjacent layer, and the like. Specifically, examples thereof include: polyester resins such as polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyethylene isophthalate; fluorine-based resins 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 saponified products (EVOH); polyether resins such as polyacetal and polyphenylene sulfide; and polyamide resins such as semi-aromatic polyamides and aliphatic polyamides.

(form)

The pipe of the present invention comprises a layer containing 60 to 80 mass% of the above-mentioned semi-aromatic polyamide and 15 to 40 mass% of the above-mentioned elastomer, and the layer has a phase separation structure comprising a phase (A) containing the semi-aromatic polyamide and a phase (B) containing the elastomer, the phase (A) being a continuous phase and the phase (B) being a dispersed phase dispersed in the phase (A). The layer exhibits a so-called sea-island structure in which the phase (a) is a sea phase and the phase (B) is an island phase, and thus can exhibit excellent flexibility and moldability while exhibiting favorable properties of each phase. The phase separation structure is a phase separation structure obtained by reacting a semi-aromatic polyamide with an elastomer.

The "phase (a) containing a semi-aromatic polyamide" means a phase containing more than 50 mass% of a semi-aromatic polyamide in the phase, and the "phase (B) containing an elastomer" means a phase containing more than 50 mass% of an elastomer in the phase.

In addition, in the electron microscope observation layer cross section obtained by the image, per 100 square micron in 100 exists the major axis diameter of 2 micron above the phase (B) average number is 1/100 micron²The number of the particles is preferably 0.5/100. mu.m²Hereinafter, the closer to 0 pieces/100. mu.m²The more preferred. If the above average number exceeds 1/100. mu.m²The following is poor in surface smoothness, and may cause flow path resistance of the fluid flowing inside the pipe, thereby causing residue inside the pipe.

The above average number (number/100 μm)²) Is a value calculated as follows: the total number of the phases (B) having a major axis diameter of 2 μm or more in any 6 divisions of 10 μm × 10 μm in the cross section (cut) of the layer when the tube was cut into a wafer was measured by a field emission scanning electron microscope (FE-SEM), and the total number was divided by the total area (10 μm × 10 μm × 6 divisions).

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

(surface roughness (arithmetic average roughness Ra))

In order to reduce the flow path resistance of the fluid flowing inside and reduce unnecessary residues, the surface of the pipe is preferably a smooth surface without irregularities. Specifically, the surface roughness Ra of the layer measured in accordance with JIS B0601(1982) is preferably 0.4 μm or less, more preferably 0.35 μm or less, and still more preferably 0.3 μm or less.

(flexural modulus of elasticity)

The tube of the present invention has excellent flexibility.

Specifically, the flexural modulus at 23 ℃ measured in accordance with ISO178 (4 th edition of 2001) when the polyamide resin composition of the present invention used for a pipe is injection molded into a test piece having a thickness of 4mm is preferably 1.8GPa or less, more preferably 1.7GPa or less, and still more preferably 1.6GPa or less. In addition, the flexural modulus is preferably 0.3GPa or more from the viewpoint of not impairing the function as a pipe.

The flexural modulus can be specifically determined by the method described in examples.

(Heat distortion temperature)

The tube of the present invention has excellent heat resistance. The use of the polyamide resin composition of the present invention which maintains the excellent heat resistance of the semi-aromatic polyamide enables the pipe to easily exhibit its heat resistance.

The heat distortion temperature is, specifically, preferably 70 ℃ or higher, more preferably 90 ℃ or higher, and even more preferably 100 ℃ or higher, as measured in accordance with ISO75 (3 rd edition in 2013) when the polyamide resin composition of the present invention used for a pipe is injection molded into a test piece having a thickness of 4 mm. The upper limit of the heat distortion temperature is not limited as long as the function as a tube and the effect of the present invention are not impaired.

The heat distortion temperature can be specifically determined by the method described in examples.

[ use ]

The pipe obtained in the present invention has excellent chemical resistance and heat resistance because the pipe contains the polyamide resin composition as a main component, and also has excellent moldability and flexibility because the polyamide resin composition contains a specific amount of an elastomer and the content of an unsaturated compound having a carboxyl group and/or an acid anhydride group in the elastomer is in a specific range.

Therefore, the resin composition can be used for automobile parts, internal combustion engine applications, crude oil excavation, transportation applications, electric and electronic parts, medical applications, food, homes, office supplies, building material-related parts, and the like. In particular, since chemical resistance and heat resistance are excellent, there are fuel tubes such as a feed tube, a return tube, an evaporation tube, a fuel feed tube, an ORVR tube, a reserve tube, and an exhaust tube; an oil pipe, an oil excavating pipe, a brake pipe, a pipe for a window cleaning liquid, an engine coolant (LLC) pipe, a tank pipe, a urea solution delivery pipe, a cooler pipe for cooling water, refrigerant, etc., a pipe for air conditioning refrigerant, a heater pipe, a load heating pipe, a floor heating pipe, a pipe for infrastructure supply, a pipe for fire extinguisher and fire extinguishing equipment, a pipe for medical cooling equipment, ink, paint dispersion pipe, a blow-by pipe (japanese: ブローバイチューブ), and other drug solution pipes. In particular, the resin composition can be suitably used as an engine coolant pipe, a urea water pipe, a fuel pipe, an oil excavating pipe, and a blow-by pipe.

Examples

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

The physical properties of examples, comparative examples and production examples were measured by the following methods.

Intrinsic viscosity

The semi-aromatic polyamide (sample) obtained in production example was subjected to the following equation using concentrated sulfuric acid as a solvent to determine the intrinsic viscosity (dl/g) at a concentration of 0.2g/dl and a temperature of 30 ℃.

η_inh＝[ln(t₁/t₀)]/c

In the above relation, eta_inhDenotes intrinsic viscosity (dl/g), t₀The flow-down time (sec) of the solvent (concentrated sulfuric acid) is shown by t₁The flow-down time (sec) of the sample solution is shown, and c represents the concentration (g/dl) of the sample in the sample solution (i.e., 0.2 g/dl).

Melting Point

The melting point of the semi-aromatic polyamide obtained in production example was measured by using a differential scanning calorimetry apparatus "DSC 7020" manufactured by Hitachi High-TechScience, Inc.

Melting points were determined according to ISO11357-3(2011 version 2). Specifically, the sample (polyamide) was heated from 30 ℃ to 340 ℃ at a rate of 10 ℃/min under a nitrogen atmosphere, and held at 340 ℃ for 5 minutes to completely melt the sample, and then cooled to 50 ℃ at a rate of 10 ℃/min and held at 50 ℃ for 5 minutes. The melting point (. degree.C.) was defined as the peak temperature of the melting peak occurring when the temperature was again raised to 340 ℃ at a rate of 10 ℃ per minute, and when there were a plurality of melting peaks, the melting point (. degree.C.) was defined as the peak temperature of the melting peak on the highest temperature side.

Concentration of terminal amino group

1g of the semi-aromatic polyamide obtained in production example was dissolved in 35mL of phenol, and 2 was mixed therewithA sample solution was prepared using mL of methanol. The content of terminal amino groups ([ NH ] of the semi-aromatic polyamide was measured by titration with 0.01N aqueous hydrochloric acid using thymol blue as an indicator₂]The unit: μ eq/g).

Total concentration of carboxyl groups and/or acid anhydride groups of the elastomer

The total concentration of the carboxyl group and the acid anhydride group was determined by dissolving 1g of the elastomer in 170mL of toluene and further adding 30mL of ethanol, and titrating the thus-prepared sample solution with 0.1N KOH/ethanol solution using phenolphthalein as an indicator.

Preparation of tubes

The polyamide resin compositions obtained in examples and comparative examples were melted at an extrusion temperature of 300 ℃ by connecting a single-layer crosshead die to a single-screw extruder (DHS40-25, phi 40mm, L/D28, full-flight screw, compression ratio 3) of IKG corporation, and molded into tubular bodies. Then, the tube was cooled in a vacuum forming (Japanese: サイジング) tank of controlled dimensions and pulled at a speed of 10 m/min to prepare a tube having an inner diameter of 6mm and an outer diameter of 8 mm.

Morphology observation (average number of dispersed phases (B) having a major axis diameter of 2 μm or more)

The tube produced in the above manner was cut in the radial direction, trimmed on the surface using a cryomicrotome (ULTRACUT UC-S/FC-S manufactured by LEICA), and the cut surface was dyed with ruthenium tetroxide, then treated with osmium coating, and observed with a field emission scanning electron microscope (Regulus 8220 manufactured by Hitachi High-Technologies), to obtain an image (FE-SEM image).

The components constituting each phase were identified by energy dispersive X-ray analysis during the FE-SEM observation.

In the 3500-magnification image obtained by the above method, the major axis diameter (major axis dispersion diameter) of the dispersed phase (B) observed in 6 divisions of 100 square μm (10 μm × 10 μm) was measured, and the average number of dispersed phases (B) (number/100 μm × 6 divisions) having a major axis diameter of 2 μm or more was calculated by dividing the total number of dispersed phases (B) having a major axis diameter of 2 μm or more by the total area (10 μm × 10 μm × 6 divisions)²)。

Surface roughness (arithmetic average roughness Ra) (formability)

The pipe of a predetermined length produced by the above method was cut in half in the longitudinal direction, and the roughness of the inner surface in the longitudinal direction was measured. The measurement was carried out by using a surface roughness measuring instrument (SE700) of Katsukawa institute, K.K., in accordance with JIS B0601(1982) (speed 0.1 mm/sec, measurement length 1.25 mm). The measurement was performed 3 times for each tube, and the average value was defined as a measurement value.

Preparation of test piece

The polyamide resin compositions obtained in examples and comparative examples were molded using an injection molding machine (clamping force: 100 ton, screw diameter: φ 32mm) manufactured by Sumitomo heavy mechanical industries, to give multipurpose test pieces of type A1 (dumbbell type test pieces described in JISK 7139; 4mm thick, 170mm in total length, 80mm in parallel portion length, and 10mm in parallel portion width) at a cylinder temperature 20 to 30 ℃ higher than the melting point of the semi-aromatic polyamide and a mold temperature of 140 ℃ using a T-runner mold. Then, rectangular parallelepiped test pieces (dimensions: length × width × thickness: 80mm × 10mm × 4mm) were cut out from the multipurpose test pieces, and used as test pieces for evaluation of flexural modulus and heat distortion temperature.

Flexural modulus of elasticity (flexibility)

The flexural modulus (GPa) at 23 ℃ and 50% RH was measured using the test piece prepared by the above method, using an Autograph (manufactured by Shimadzu corporation) according to ISO178 (4 th edition 2001).

Heat distortion temperature (Heat resistance)

The test piece produced by the above method was used to measure the heat distortion temperature (. degree.C.) according to ISO75 (3 rd edition 2013) using HDT tester "S-3M" manufactured by Toyo Seiki Seisaku-Sho K.K.).

Production example 1[ production of semi-aromatic Polyamide A-1 ]

9870.6g (59.42 mol) of terephthalic acid, a mixture of 1, 9-nonanediamine and 2-methyl-1, 8-octanediamine [50/50 (molar ratio)]9497.4g (60.00 mol), 142.9g (1.17 mol) of benzoic acid, 19.5g (0.1 mass% based on the total mass of the raw materials) of sodium hypophosphite monohydrate and 5 liters of distilled water were charged into an autoclave having an internal volume of 40 liters, and nitrogen substitution was carried out. The mixture was stirred at 100 ℃ for 30 minutes, and the temperature inside the autoclave was raised to 220 ℃ over 2 hours. At this time, the pressure inside the autoclave was increased to 2 MPa. After continuing the reaction for 2 hours in this state, the temperature was raised to 230 ℃ and then maintained at 230 ℃ for 2 hours, and the reaction was carried out while gradually removing water vapor and maintaining the pressure at 2 MPa. Then, the pressure was reduced to 1MPa for 30 minutes, and the reaction was further continued for 1 hour to obtain an intrinsic viscosity [. eta. ]]0.2dL/g of prepolymer. This was pulverized into a particle size of 2mm or less using a flake crusher (Japanese: フレーククラッシャー) manufactured by Hosokawa Micron Co., Ltd., and dried at 100 ℃ under reduced pressure for 12 hours, and then solid-phase polymerized at 230 ℃ and 13Pa (0.1mmHg) for 10 hours to obtain a white polyamide resin (polyamide 1). Polyamide 1 comprising 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)), had a melting point of 265 ℃ and an intrinsic viscosity [. eta._inh]1.20dL/g, terminal amino group concentration ([ NH ]₂]) It was 15. mu. eq/g.

Examples 1,2 and 2 (production of Polyamide resin compositions)

The semi-aromatic polyamide shown in Table 1, the elastomer, the deterioration inhibitor C-3, the lubricant, and the dye were mixed in advance at a predetermined mass ratio, and charged into an upstream feed port of a twin-screw extruder ("TEM-26 SS", Toshiba mechanical Co., Ltd.). The deterioration inhibitor C-1 is fed from the middle part feed inlet of the first kneading part and the second kneading part of the screw, and melt-kneaded at a cylinder temperature of 300 to 320 ℃ to knead and extrude, and then cooled and cut to produce a polyamide resin composition in the form of pellets. Test pieces and pipes for various physical property evaluations were produced using the pellets, and various evaluations were performed by the methods described above. The results are shown in Table 1.

Example 3 and comparative example 1

The semi-aromatic polyamide shown in Table 1, an elastomer, a deterioration inhibitor C-2 or C-3, a lubricant and a dye were previously mixed at a predetermined mass ratio, and the mixture was fed into an upstream feed port of a twin-screw extruder ("TEM-26 SS", Toshiba mechanical Co., Ltd.) at one time, and melt-kneaded at a cylinder temperature of 300 to 320 ℃ to knead and extrude the mixture, and then cooled and cut to produce a pellet-shaped polyamide resin composition. Test pieces and pipes for various physical property evaluations were produced using the pellets, and various evaluations were performed by the methods described above. The results are shown in Table 1.

The components shown in table 1 are as follows.

< semi-aromatic polyamide A-1 >

Semi-aromatic polyamide A-1 obtained in production example 1

< elastomer B-1 >

Elastomer obtained by modifying ethylene-butene copolymer with maleic anhydride (TAFMER MH5010, manufactured by Mitsui chemical Co., Ltd.; concentration of acid anhydride group: 50. mu. eq/g)

< elastomer B-2 >

Elastomer obtained by modifying ethylene-butene copolymer with maleic anhydride (TAFMER MH5020, manufactured by Mitsui chemical Co., Ltd., acid anhydride group concentration: 100. mu. eq/g)

< elastomer B-3 >

Elastomer obtained by modifying ethylene-butene copolymer with maleic anhydride (TAFMER MH5040, manufactured by Mitsui chemical Co., Ltd., acid anhydride group concentration: 200. mu. eq/g)

< elastomer B-4 >

Elastomer obtained by modifying ethylene-propylene copolymer with maleic anhydride (TAFMER MP0620, manufactured by Mitsui chemical Co., Ltd.; concentration of acid anhydride group: 100. mu. eq/g)

< deterioration inhibitor C-1 >

Alicyclic polycarbodiimide (manufactured by Nisshinbo Chemical Co., Ltd., CARBODILITE HMV-15CA)

< deterioration inhibitor C-2 >

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

< deterioration inhibitor C-3 >

Hindered phenol compound (Sumilizer GA-80, manufactured by Sumitomo chemical Co., Ltd.)

< Lubricant D-1 >

Polyolefin wax (LICOCENEPE MA4221, manufactured by Clariant Chemicals)

< Lubricant D-2 >

Montanic acid wax (LICOWAX OP, Clariant Chemicals)

< dye E-1 >

Carbon black (Mitsubishi chemical corporation, #980B)

[ Table 1]

As is apparent from Table 1, the pipes of examples 1 to 3 both had a low flexural modulus and high surface smoothness while maintaining the heat resistance of the semi-aromatic polyamide. The tube of comparative example 1 had high heat resistance and surface smoothness, but insufficient flexibility. In addition, the pipe of comparative example 2 was excellent in heat resistance and flexibility, but the average number of coarse dispersed phases (B) having a major axis diameter of 2 μm or more was 3, and the surface smoothness was insufficient.

It is presumed that when the content of the unsaturated compound having a carboxyl group and/or an acid anhydride group in the elastomer is set to a specific range, the affinity between the elastomer and the polyamide is increased, the coagulation of the elastomer which causes the surface smoothness to be impaired during extrusion molding and the separation of the orifice grease are suppressed, and a pipe having excellent surface smoothness can be obtained even in a composition containing a large amount of the elastomer.