Semi-aromatic polyamide resin, polyamide resin composition, and method for producing semi-aromatic polyamide resin

Abstract

This semi-aromatic polyamide resin contains a diamine unit and a dicarboxylic acid unit. The diamine unit contains 60-100 mol% of an aliphatic diamine unit having 7-13 carbon atoms with respect to 100 mol% of the diamine unit, the dicarboxylic acid unit contains 60-100 mol% of an aromatic dicarboxylic acid unit with respect to 100 mol% of the carboxylic acid unit, and the semi-aromatic polyamide resin has an inherent viscosity ηinh measured at 30°C in concentrated sulfuric acid of 1.6-3.0 dl / g, a terminal amino group content [NH2] of 10-70 μ-equivalent / g, a terminal carboxyl group content [COOH] of 10-90 μ-equivalent / g, and a ratio [NH2] / [COOH] of the terminal amino group content [NH2] to the terminal carboxyl group content [COOH] of 0.1 or more and less than 1.0.

Description

Semi-aromatic polyamide resin, polyamide resin composition, and method for producing semi-aromatic polyamide resin

[0001] The present invention relates to a semi-aromatic polyamide resin, a polyamide resin composition, and a method for producing the semi-aromatic polyamide resin. More specifically, the present invention relates to a semi-aromatic polyamide resin having excellent fatigue resistance and retention stability during melt processing, a polyamide resin composition containing the semi-aromatic polyamide resin, and a method for producing the semi-aromatic polyamide resin.

[0002] Resin materials such as polyamide resins are widely used in parts used in automobiles, industrial machinery, and other applications. Many resin products have also been put to practical use in sliding components such as gears. In recent years, there has been a trend toward product development aimed at miniaturizing and increasing the output of sliding components, particularly gears. To achieve these goals, it is necessary to increase the torque and rotational speed applied to sliding components, specifically gears. Therefore, sliding components, specifically gears, are required to be used in higher-load environments than before, and there is an increasing demand for resin materials with high fatigue resistance that can withstand high loads. Furthermore, such resin materials are also required to have lower water absorption to prevent problems caused by poor meshing due to dimensional changes caused by water absorption.

[0003] Semi-aromatic polyamide resins derived from long-chain aliphatic diamines, such as polynonamethylene terephthalamide (hereinafter also referred to as PA9T) and polydecamethylene terephthalamide (hereinafter also referred to as PA10T), have excellent properties such as heat resistance, rigidity, and sliding properties, as well as high dimensional stability due to their low water absorption. Therefore, they are widely used in sliding components, specifically gears. However, the fatigue resistance of semi-aromatic polyamide resins is inferior to that of aliphatic polyamide resins, and therefore, there is a need for improved fatigue resistance in semi-aromatic polyamide resins.

[0004] Furthermore, resin materials used in sliding components, specifically gears, are required to have stability during melt processing such as kneading and molding, i.e., retention stability. Resin materials with poor retention stability experience a decrease in resin viscosity due to molecular chain scission caused by heat generated during melt processing. This not only reduces mechanical properties such as fatigue resistance, but also leads to poor appearance due to the occurrence of discoloration, voids, and bumps.

[0005] A commonly known method for improving the fatigue resistance of semi-aromatic polyamide resins is to increase the molecular weight of the resin. For example, Patent Document 1 discloses a polyamide resin with a specific viscosity number, in which the difference between the amino terminal group concentration and the carboxyl terminal group concentration is within a predetermined range, as an example of a semi-aromatic polyamide resin with an increased molecular weight. Patent Document 2 discloses a semi-aromatic polyamide resin in which the relationship between the amino terminal group concentration, the carboxyl terminal group concentration, and the terminal concentration of amino groups blocked with carboxylic acid is controlled within a predetermined range. Patent Document 3 discloses a semi-aromatic polyamide resin having improved compatibility, in which the ratio of the amino terminal group concentration to the carboxylic acid terminal group concentration is within a predetermined range in a semi-aromatic polyamide primarily composed of terephthalic acid and 1,10-decanediamine.

[0006] Furthermore, semi-aromatic polyamide resins with improved retention stability have also been studied. Patent Document 4 discloses that a polyamide resin with excellent retention stability can be obtained by setting the amount of terminal amino groups in a semi-aromatic polyamide resin within a specific range and further setting the value obtained by dividing the amount of terminal amino groups by the amount of terminal carboxyl groups to a predetermined value or more.

[0007] JP 2015-199873 A, International Publication No. 2021 / 065205, JP 2016-94508 A, International Publication No. 2006 / 098434

[0008] However, the fatigue resistance and retention stability of high molecular weight semi-aromatic polyamide resins are not clarified in any of Patent Documents 1 to 3. Patent Document 4 describes a semi-aromatic polyamide resin with excellent retention stability, but the examples are limited to the disclosure of a semi-aromatic polyamide resin with an intrinsic viscosity [η] of around 1.2 dl / g, and there is no description of a semi-aromatic polyamide resin with a higher intrinsic viscosity, i.e., a semi-aromatic polyamide resin with a high molecular weight and excellent retention stability.

[0009] Recently, in our research into increasing the molecular weight of semi-aromatic polyamide resins, we discovered that high-molecular-weight semi-aromatic polyamide resins have poor retention stability during melt processing and lack fatigue resistance. In particular, semi-aromatic polyamide resins have a high melting point, which means that they are easily decomposed during melt processing at high temperatures.

[0010] Therefore, an object of the present invention is to provide a semi-aromatic polyamide resin which has excellent fatigue resistance and retention stability during melt processing, and which has a high molecular weight.

[0011] As a result of intensive research to solve the above problems, the present inventors have conceived the following invention and found that the above problems can be solved.

[0012] [1] A semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the diamine units contain 60 to 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms relative to 100 mol% of the diamine units, and the dicarboxylic acid units contain 60 to 100 mol% of aromatic dicarboxylic acid units relative to 100 mol% of the carboxylic acid units, and wherein the inherent viscosity η measured in concentrated sulfuric acid at 30°C is ｉｎｈ is 1.6 to 3.0 dl / g, and the amount of terminal amino groups [NH ２ ] is 10 to 70 μ equivalents / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μ equivalents / g, and the amount of terminal amino groups [NH ２ ] to the amount of terminal carboxyl groups [COOH], [NH ２[2] The semi-aromatic polyamide resin according to [1], wherein the aliphatic diamine unit having 7 to 13 carbon atoms is at least one selected from the group consisting of 1,10-decanediamine unit, 1,9-nonanediamine unit, and 2-methyl-1,8-octanediamine unit. [3] The semi-aromatic polyamide resin according to [1], wherein the inherent viscosity η ｉｎｈ [4] The semi-aromatic polyamide resin according to [1] or [2], wherein the inherent viscosity η is 1.7 to 2.5 dl / g. ｉｎｈ [5] The semi-aromatic polyamide resin according to any one of [1] to [3], wherein the amount of terminal amino groups [NH ２ [6] The semi-aromatic polyamide resin according to any one of [1] to [4], wherein the amount of terminal amino groups [NH ２ [7] The semi-aromatic polyamide resin according to any one of [1] to [6], wherein the amount of terminal carboxyl groups [COOH] is 30 to 80 μequivalents / g. [8] The semi-aromatic polyamide resin according to any one of [1] to [6], wherein the amount of terminal carboxyl groups [NH ２

[10] The semi-aromatic polyamide resin according to any one of [1] to [7], wherein the ratio of [COOH] to [COOH] is 0.2 to 0.9. [9] A polyamide resin composition comprising the semi-aromatic polyamide resin according to any one of [1] to [6] and a crystal nucleating agent.

[10] The polyamide resin composition according to [9], comprising 0.01 to 10 parts by mass of the crystal nucleating agent per 100 parts by mass of the semi-aromatic polyamide resin.

[11] A polyamide resin composition comprising the semi-aromatic polyamide resin according to any one of [1] to

[10] and an antioxidant.

[12] The polyamide resin composition according to

[11] , comprising 0.01 to 5 parts by mass of the antioxidant per 100 parts by mass of the semi-aromatic polyamide resin.

[13] A polyamide resin composition containing a semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the diamine units contain 60 to 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms relative to 100 mol% of the diamine units, and the dicarboxylic acid units contain 60 to 100 mol% of aromatic dicarboxylic acid units relative to 100 mol% of the carboxylic acid units, and the semi-aromatic polyamide resin has a weight average molecular weight Mw of 40,000 to 90,000 in terms of polymethyl methacrylate as measured by gel permeation chromatography (GPC), and a terminal amino group amount [NH ２ ] is 10 to 70 μ equivalents / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μ equivalents / g, and the amount of terminal amino groups [NH ２ ] to the amount of terminal carboxyl groups [COOH], [NH ２] / [COOH] is 0.1 or more and less than 1.0.

[14] The polyamide resin composition according to

[13] , which contains at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, a sliding property improver, and a lubricant.

[15] The polyamide resin composition according to

[14] , which contains 0.01 to 10 parts by mass of at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, a sliding property improver, and a lubricant, per 100 parts by mass of the semi-aromatic polyamide resin.

[16] A molded article made of the polyamide resin composition according to any one of [9] to

[15] .

[17] The molded article according to

[16] , which is a sliding member.

[18] The molded article according to

[17] , which is a gear.

[19] A method for producing a semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, comprising: a first reaction step of polycondensing raw materials containing an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent to obtain a primary polycondensation reaction product; and a second reaction step of solid-state polymerizing the primary polycondensation reaction product to obtain the semi-aromatic polyamide resin, wherein the ratio x / y of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials is greater than 1.01 and 1.03 or less, and the amount of the end-capping agent contained in the raw materials is 0.1 to 1.5 mol % relative to 100 mol % of the diamine contained in the raw materials.

[0013] According to the present invention, it is possible to provide a semi-aromatic polyamide resin that has excellent fatigue resistance and retention stability during melt processing and has a high molecular weight, and a polyamide resin composition containing the semi-aromatic polyamide resin.

[0014] The following describes an example of an embodiment of the present invention (hereinafter, sometimes referred to as "this embodiment"). However, the embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. Furthermore, although preferred embodiments are shown in this specification, combinations of two or more of the individual preferred embodiments are also preferred. For matters indicated as numerical ranges, when there are several numerical ranges, the lower and upper limits can be selectively combined to form a preferred embodiment. In this specification, when a numerical range is described as "XX to YY," it means "XX or more and YY or less." Furthermore, in this specification, "units" (where "~" indicates a monomer) means "a structural unit derived from ~," for example, "dicarboxylic acid units" means "structural units derived from dicarboxylic acids," and "diamine units" means "structural units derived from diamines."

[0015] [Semi-aromatic polyamide resin] The semi-aromatic polyamide resin of this embodiment contains diamine units and dicarboxylic acid units. In this embodiment, the diamine units contain 60 to 100 mol % of diamine units derived from an aliphatic diamine having 7 to 13 carbon atoms relative to 100 mol % of the diamine units, and the dicarboxylic acid units contain 60 to 100 mol % of dicarboxylic acid units derived from an aromatic dicarboxylic acid relative to 100 mol % of the dicarboxylic acid units.

[0016] (Diamine Units) The diamine units contain 60 to 100 mol % of aliphatic diamine units having 7 to 13 carbon atoms, relative to 100 mol % of the diamine units. The aliphatic diamine units having 7 to 13 carbon atoms may be linear diamine units and / or branched diamine units. In other words, the aliphatic diamine units having 7 to 13 carbon atoms may be at least one type selected from the group consisting of linear diamine units and branched diamine units. The aliphatic diamine units having 7 to 13 carbon atoms may contain only one type of linear diamine unit or branched diamine unit, or may contain both linear diamine units and branched diamine units.

[0017] Examples of the linear diamine unit include diamine units derived from at least one selected from the group consisting of 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and 1,13-tridecanediamine.

[0018] Examples of the branched diamine unit include 2-butyl-2-ethyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, and 4,5-dimethyl-1,8-octanediamine. and 2,4-diethyl-1,6-hexanediamine.

[0019] From the viewpoints of low water absorbency and heat resistance, the aliphatic diamine unit having 7 to 13 carbon atoms is preferably a diamine unit derived from at least one selected from the group consisting of 1,9-nonanediamine, 1,10-decanediamine, and 2-methyl-1,8-octanediamine, and more preferably a diamine unit derived from 1,9-nonanediamine and / or a diamine unit derived from 2-methyl-1,8-octanediamine. That is, the aliphatic diamine unit having 7 to 13 carbon atoms is more preferably a diamine unit derived from at least one selected from the group consisting of 1,9-nonanediamine and 2-methyl-1,8-octanediamine. From the viewpoints of low water absorbency and heat resistance, the aliphatic diamine unit having 7 to 13 carbon atoms is preferably a diamine unit derived from 1,9-nonanediamine and a diamine unit derived from 2-methyl-1,8-octanediamine. When the aliphatic diamine units having 7 to 13 carbon atoms contain both diamine units derived from 1,9-nonanediamine and diamine units derived from 2-methyl-1,8-octanediamine, the molar ratio thereof (diamine units derived from 1,9-nonanediamine / diamine units derived from 2-methyl-1,8-octanediamine) is preferably in the range of 95 / 5 to 40 / 60, and more preferably in the range of 90 / 10 to 50 / 50.

[0020] The diamine units contain 60 to 100 moles of the aliphatic diamine units having 7 to 13 carbon atoms relative to 100 moles of the diamine units. From the viewpoints of mechanical properties and heat resistance, the diamine units preferably contain 70 to 100 moles, more preferably 80 to 100 moles, and even more preferably 90 to 100 moles, of the aliphatic diamine units having 7 to 13 carbon atoms. The diamine units may contain 100 moles of the aliphatic diamine units having 7 to 13 carbon atoms.

[0021] The diamine units may contain diamine units derived from diamines other than aliphatic diamine units, provided that the effects of the present invention are not impaired. Examples of diamine units derived from other diamines include diamine units derived from at least one diamine selected from the group consisting of alicyclic diamines and aromatic diamines. Examples of diamine units derived from alicyclic diamines include diamine units derived from at least one diamine selected from the group consisting of cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornanedimethylamine, and tricyclodecanedimethyldiamine. Examples of diamine units derived from aromatic diamines include diamine units derived from at least one diamine selected from the group consisting of p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, and 4,4'-diaminodiphenylether. The diamine units may contain only one or more diamine units derived from these other diamines. The content of the diamine units derived from the other diamines in the diamine units is less than 40 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to 100 mol% of the diamine units. The content of the diamine units derived from the other diamines in the diamine units is preferably 0 mol% or more and less than 40 mol%, more preferably 0 mol% or more and 30 mol% or less, even more preferably 0 mol% or more and 20 mol% or less, and even more preferably 0 mol% or more and 10 mol% or less, relative to 100 mol% of the diamine units. The content of the diamine units derived from the other diamines in the diamine units may be 0 mol%.

[0022] (Dicarboxylic Acid Unit) The dicarboxylic acid unit contains 60 to 100 mol % of aromatic dicarboxylic acid units relative to 100 mol % of dicarboxylic acid units.

[0023] Examples of the aromatic dicarboxylic acid unit include dicarboxylic acid units derived from at least one selected from the group consisting of terephthalic acid, isophthalic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,3-furandicarboxylic acid, 2,4-furandicarboxylic acid, and 2,5-furandicarboxylic acid. Only one type of structural unit derived from these aromatic dicarboxylic acid units may be contained, or two or more types may be contained.

[0024] From the viewpoints of mechanical properties, heat resistance, reactivity with diamines, and the like, the aromatic dicarboxylic acid unit is preferably an aromatic dicarboxylic acid unit derived from terephthalic acid.

[0025] The proportion of the aromatic dicarboxylic acid units contained in the dicarboxylic acid units is 60 mol% or more relative to 100 mol% of the dicarboxylic acid units. From the viewpoints of mechanical properties and heat resistance, the proportion of the aromatic dicarboxylic acid units is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more. The proportion of the aromatic dicarboxylic acid units contained in the dicarboxylic acid units may be 100 mol%. The dicarboxylic acid units preferably contain 70 to 100 mol%, more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol% of aromatic dicarboxylic acid units relative to 100 mol% of the dicarboxylic acid units.

[0026] The dicarboxylic acid unit may contain a dicarboxylic acid unit derived from a dicarboxylic acid other than an aromatic dicarboxylic acid, provided that the effects of the present invention are not impaired. Examples of such other dicarboxylic acids include aliphatic dicarboxylic acids and alicyclic dicarboxylic acids. Examples of the dicarboxylic acid unit derived from an aliphatic dicarboxylic acid include a dicarboxylic acid unit derived from at least one selected from the group consisting of 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. Examples of the dicarboxylic acid unit derived from an alicyclic dicarboxylic acid include a dicarboxylic acid unit derived from at least one selected from the group consisting of 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid.

[0027] The dicarboxylic acid unit may contain only one type of dicarboxylic acid unit derived from these other dicarboxylic acids, or may contain two or more types. The content of the dicarboxylic acid units derived from the other dicarboxylic acids contained in the dicarboxylic acid unit is less than 40 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to 100 mol% of the dicarboxylic acid unit. The content of the dicarboxylic acid units derived from the other dicarboxylic acids in the dicarboxylic acid unit is preferably 0 mol% or more and less than 40 mol%, more preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 20 mol% or less, and even more preferably 0 mol% or more and 10 mol% or less, relative to 100 mol% of the dicarboxylic acid unit. The content of the diamine units derived from the other dicarboxylic acids in the dicarboxylic acid unit may be 0 mol%.

[0028] The ratio of the diamine units and the dicarboxylic acid units in 100 mol% of the semi-aromatic polyamide resin of this embodiment (the ratio of the total number of moles of dicarboxylic acid units and diamine units to the number of moles of all structural units constituting the polyamide resin) is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and may be 95 mol% or more, or even 100 mol%. By having the total ratio of diamine units and dicarboxylic acid units in the above range, a semi-aromatic polyamide resin with better mechanical properties and heat resistance can be obtained. The ratio of the diamine units and the dicarboxylic acid units in 100 mol% of the semi-aromatic polyamide resin of this embodiment (the ratio of the total number of moles of dicarboxylic acid units and diamine units to the number of moles of all structural units constituting the polyamide resin) is preferably 70 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, even more preferably 90 mol% or more and 100 mol% or less, and may be 95 mol% or more and 100 mol% or less, or even 100 mol%.

[0029] (Aminocarboxylic Acid Unit) In addition to the diamine unit and the dicarboxylic acid unit, the semi-aromatic polyamide resin of this embodiment may further contain an aminocarboxylic acid unit. Examples of the aminocarboxylic acid unit include an aminocarboxylic acid unit derived from at least one selected from the group consisting of lactams such as caprolactam and lauryllactam; and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. The content of the aminocarboxylic acid unit in the semi-aromatic polyamide resin is preferably 30 mol% or less, more preferably 20 mol% or less, relative to the total 100 mol% of the diamine units and dicarboxylic acid units in the semi-aromatic polyamide resin. The content of the aminocarboxylic acid unit in the semi-aromatic polyamide resin is preferably 0 mol% to 30 mol%, more preferably 0 mol% to 20 mol%, even more preferably 0 mol% to 10 mol%, and even more preferably 0 mol% to 5 mol%, relative to the total 100 mol% of the diamine units and dicarboxylic acid units in the semi-aromatic polyamide resin.

[0030] (Polycarboxylic Acid Unit) The semi-aromatic polyamide resin of this embodiment may also contain structural units derived from trivalent or higher polycarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid, to the extent that melt molding is possible, as long as the effects of the present invention are not impaired.

[0031] (Terminal Cap Rate) From the viewpoints of melt stability and hydrolysis resistance, it is preferable that the terminal groups of the molecular chain of the semi-aromatic polyamide resin of this embodiment are capped. A terminal capping agent can be used to cap the terminal groups. Details of this terminal capping agent will be described later. The terminal cap rate refers to the proportion of all terminal groups of the molecular chain of the semi-aromatic polyamide resin that are capped. This terminal cap rate is preferably 5 mol% or more, more preferably 10 mol% or more. From the viewpoint of obtaining a semi-aromatic polyamide resin with a higher molecular weight, the terminal cap rate is preferably 40 mol% or less, more preferably 30 mol% or less. The terminal cap rate is preferably 5 to 40 mol%, more preferably 10 to 30 mol%, and even more preferably 10 to 20 mol%. The terminal cap rate of the semi-aromatic polyamide resin can be calculated by measuring the amount of terminal carboxyl groups, the amount of terminal amino groups, and the amount of terminal groups capped with the terminal capping agent of the semi-aromatic polyamide resin, and then using the following formula (1): In formula (1), A represents the total amount of terminal groups (usually equal to twice the number of molecules of the semi-aromatic polyamide resin), and B represents the total amount of terminal carboxyl groups and terminal amino groups. End-capping rate (%) = [(A - B) / A] x 100 Formula (1) In this specification, the amount of each of the terminal groups of the semi-aromatic polyamide resin of this embodiment is determined by measuring the terminal capping rate (%) of the semi-aromatic polyamide resin dissolved in deuterated 1,1,1,3,3,3-hexafluoroisopropanol at 600 MHz and 50°C. １ It is a value calculated from the integrated value of the characteristic signal of each terminal group by H-NMR analysis. More specifically, it can be determined by the method described in the Examples.

[0032] (Inherent Viscosity of Semi-Aromatic Polyamide Resin) Inherent viscosity η of the semi-aromatic polyamide resin of this embodiment ｉｎｈ is 1.6 to 3.0 dl / g. ｉｎｈ is preferably 1.7 dl / g or more, more preferably 1.8 dl / g or more, and even more preferably 1.9 dl / g or more. ｉｎｈWhen the inherent viscosity η is in the above range, the semi-aromatic polyamide resin can have excellent fatigue resistance. ｉｎｈ is preferably 2.7 dl / g or less, more preferably 2.5 dl / g or less, and even more preferably 2.3 dl / g or less. ｉｎｈ When the inherent viscosity η is in the above range, the semi-aromatic polyamide resin can have excellent moldability and retention stability. ｉｎｈ is preferably 1.7 to 2.7 dl / g, more preferably 1.7 to 2.5 dl / g, even more preferably 1.8 to 2.5 dl / g, even more preferably 1.9 to 2.5 dl / g, and most preferably 1.9 to 2.3 dl / g. ｉｎｈ can be determined by measuring the flow time of a solution containing concentrated sulfuric acid as a solvent at a concentration of 0.2 g / dl and a temperature of 30° C. More specifically, it can be determined by the method described in the Examples.

[0033] (Amount of terminal amino groups) The amount of terminal amino groups [NH ２ The amount of terminal amino groups [NH ２ The amount of terminal amino groups [NH ２ ] is in the above range, the inherent viscosity η ｉｎｈ is in the desired range, the fatigue resistance is superior. ２ The amount of terminal amino groups [NH ２ When the amount of terminal amino groups [NH ２] is preferably 10 to 60 μequivalents / g, more preferably 10 to 50 μequivalents / g, even more preferably 15 to 50 μequivalents / g, and even more preferably 15 to 45 μequivalents / g.

[0034] (Terminal Carboxyl Group Amount) The terminal carboxyl group amount [COOH] of the semi-aromatic polyamide resin of this embodiment is 10 to 90 μequivalents / g. The terminal carboxyl group amount [COOH] is preferably 20 μequivalents / g or more, more preferably 30 μequivalents / g or more, even more preferably 40 μequivalents / g or more, and even more preferably 55 μequivalents / g or more. When the terminal carboxyl group amount [COOH] is in the above range, the inherent viscosity η, which indicates the molecular weight of the semi-aromatic polyamide resin, can be reduced. ｉｎｈ is within the desired range, resulting in superior fatigue resistance. Furthermore, the amount of terminal carboxyl groups [COOH] is preferably 85 μequivalents / g or less, and more preferably 80 μequivalents / g or less. Having the amount of terminal carboxyl groups [COOH] within the above range suppresses hydrolysis during melt processing, resulting in a semi-aromatic polyamide resin with excellent retention stability. The amount of terminal carboxyl groups [COOH] is preferably 20 to 85 μequivalents / g, more preferably 30 to 80 μequivalents / g, even more preferably 40 to 80 μequivalents / g, and even more preferably 55 to 80 μequivalents / g.

[0035] In this embodiment, the amount of terminal amino groups [NH ２ ] refers to the amount of terminal amino groups (unit: μ equivalents / g) contained in 1 g of the semi-aromatic polyamide resin. The amount of terminal carboxyl groups [COOH] refers to the amount of terminal carboxyl groups (unit: μ equivalents / g) contained in 1 g of the semi-aromatic polyamide resin. In this specification, the amount of terminal amino groups [NH ２ and the amount of terminal carboxyl groups [COOH] are determined by measuring the amount of terminal carboxyl groups in a semi-aromatic polyamide resin dissolved in deuterated 1,1,1,3,3,3-hexafluoroisopropanol at 600 MHz and 50° C. １It is a value calculated from the integrated value of the characteristic signal of each terminal group by H-NMR analysis. More specifically, it can be determined by the method described in the Examples.

[0036] The amount of terminal amino groups [NH ２ ] to the amount of terminal carboxyl groups [COOH], [NH ２ ] / [COOH] is 0.1 or more and less than 1.0. ２ ] / [COOH] is preferably 0.2 to 0.9, more preferably 0.2 to 0.8, even more preferably 0.2 to 0.7, and even more preferably 0.3 to 0.7. ２ ] / [COOH] is in the above range, the inherent viscosity η ｉｎｈ In addition, crosslinking between terminal amino groups and hydrolysis during melt processing are suppressed, resulting in a semi-aromatic polyamide resin with excellent retention stability.

[0037] (Weight-average molecular weight) From the viewpoint of fatigue resistance, the weight-average molecular weight of the semi-aromatic polyamide resin of this embodiment is preferably 40,000 or more, more preferably 45,000 or more, and even more preferably 50,000 or more. From the viewpoint of moldability, the weight-average molecular weight of the semi-aromatic polyamide resin is preferably 90,000 or less, more preferably 80,000 or less, and even more preferably 70,000 or less. The weight-average molecular weight of the semi-aromatic polyamide resin is preferably 40,000 to 90,000, more preferably 45,000 to 80,000, and even more preferably 50,000 to 70,000.

[0038] (Reduction rate of weight average molecular weight) The semi-aromatic polyamide resin of this embodiment preferably has a reduction rate of weight average molecular weight (hereinafter also referred to as Mw) before and after melt-kneading of 20% or less. This makes it possible to improve retention stability. The melt-kneading may be performed by melt-kneading only the semi-aromatic polyamide resin alone, or by melt-kneading it with other components as a composition. The reduction rate of the weight average molecular weight is calculated by the following formula (2). In this formula (2), Mw ０ is the weight average molecular weight before melt kneading, Mw １ is the weight average molecular weight after melt-kneading using a twin-screw extruder at a cylinder temperature of 320 to 325°C. ０ -Mw １ ) × 100 / Mw ０　 Formula (2) From the viewpoint of mechanical properties and molded product appearance after melt-kneading, the rate of decrease in the weight-average molecular weight is more preferably 18% or less, and even more preferably 15% or less. The melt-kneading is carried out using a twin-screw extruder "BTN-32-S2-30-L" manufactured by Plastics Engineering Research Institute Co., Ltd., at a cylinder temperature of 320 to 325°C and a residence time of 1 to 5 minutes, and more specifically, can be carried out by the method described in the Examples. Furthermore, in this specification, the weight-average molecular weight of the semi-aromatic polyamide resin is a value determined using gel permeation chromatography (GPC) as a standard polymethyl methacrylate-equivalent molecular weight. More specifically, it can be determined by the method described in the Examples.

[0039] (Melting Point) The semi-aromatic polyamide resin of this embodiment preferably has a melting point of 250°C or higher, more preferably 280°C or higher, and even more preferably 290°C or higher. Having a melting point within the above range allows for the semi-aromatic polyamide resin to have excellent heat resistance. There is no particular upper limit to the melting point of the semi-aromatic polyamide resin; however, taking into consideration moldability and other factors, it is preferably 330°C or lower, more preferably 320°C or lower, and even more preferably 310°C or lower. The melting point of the semi-aromatic polyamide resin is preferably 250 to 330°C, more preferably 280 to 320°C, even more preferably 290 to 320°C, and even more preferably 290 to 310°C. In this specification, the melting point of the semi-aromatic polyamide resin is determined using a differential scanning calorimetry (DSC) analyzer as the peak temperature of the endothermic peak that appears when the temperature is increased at a rate of 10°C / min. More specifically, it can be determined by the method described in the Examples.

[0040] (Heat of Fusion) The semi-aromatic polyamide resin of this embodiment preferably has a heat of fusion ΔHm of 20 mJ / mg or more, more preferably 30 mJ / mg or more, and even more preferably 40 mJ / mg or more. Having the heat of fusion ΔHm within the above range increases the crystallinity of the semi-aromatic polyamide resin, resulting in a semi-aromatic polyamide resin with excellent rigidity and abrasion resistance. While a higher heat of fusion ΔHm of the semi-aromatic polyamide resin is preferable, from the viewpoint of moldability, it is preferably 80 mJ / mg or less, more preferably 70 mJ / mg or less, and even more preferably 60 mJ / mg or less. The heat of fusion ΔHm is preferably 20 to 80 mJ / mg, more preferably 30 to 70 mJ / mg, even more preferably 30 to 60 mJ / mg, even more preferably 40 to 60 mJ / mg, and even more preferably 40 to 50 mJ / mg. In this specification, the heat of fusion ΔHm of the semi-aromatic polyamide resin is a value determined as the peak area of ​​an endothermic peak that appears when the temperature is increased at a rate of 10°C / min using a differential scanning calorimetry (DSC) analyzer. More specifically, it can be determined by the method described in the Examples.

[0041] (Method for producing semi-aromatic polyamide resin) The method for producing a semi-aromatic polyamide resin of this embodiment includes a first reaction step in which a raw material containing an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent is polycondensed to obtain a primary polycondensation reaction product, and a second reaction step in which the primary polycondensation reaction product is solid-state polymerized to obtain a semi-aromatic polyamide resin, wherein the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw material is preferably greater than 1.010 and not greater than 1.030, and the amount of the end-capping agent contained in the raw material is preferably 0.1 to 1.5 mol % relative to 100 mol % of the diamine contained in the raw material.

[0042] (Raw Materials) In the first reaction step, raw materials containing an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent are melt-polymerized and polycondensed. A preparation step for preparing the raw materials may be performed before the first reaction step. The raw materials preferably contain an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent. The raw materials preferably contain a catalyst and other components as needed. In this case, the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials is greater than 1.01 and not more than 1.03, preferably 1.015 to 1.025, and more preferably 1.02 to 1.03. By keeping the ratio (x / y) within the above range, it is possible to prevent the molar balance of the raw materials from being disrupted due to the volatilization of at least one of the aliphatic diamine and the aromatic dicarboxylic acid, and to reduce the inherent viscosity η ｉｎｈ This facilitates the production of semi-aromatic polyamide resins in which the amount of each end group falls within the desired range. The number of moles of amino groups (x) is the sum of the number of moles of amino groups derived from the aliphatic diamine, the end-capping agent having an amino group, and other components. The number of moles of carboxyl groups (y) is the sum of the number of moles of carboxyl groups derived from the aromatic carboxylic acid, the end-capping agent having a carboxyl group, and other components.

[0043] (End-capping agent) When producing the semi-aromatic polyamide resin of this embodiment, it is preferable to include an end-capping agent in the raw materials. The amount of end-capping agent contained in the raw materials is preferably 5.0 mol% or less, more preferably 3.0 mol% or less, and even more preferably 1.5 mol% or less, relative to 100 mol% of diamine units contained in the raw materials. It is also preferably 0.1 mol% or more, more preferably 0.5 mol% or more, and even more preferably 0.7 mol% or more. By having the content of the end-capping agent within the above range, a high-molecular-weight polyamide resin with superior mechanical properties can be obtained. The amount of the end-capping agent is preferably 0.1 to 5.0 mol%, more preferably 0.5 to 3.0 mol%, and even more preferably 0.7 to 1.5 mol%, relative to 100 mol% of diamine units contained in the raw materials.

[0044] As the terminal blocking agent, a monofunctional compound reactive with the amino group or carboxyl group at the molecular chain terminal of the semi-aromatic polyamide resin can be used. Specific examples include monocarboxylic acids, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, and monoamines. From the viewpoints of reactivity and terminal blocking stability, monocarboxylic acids are preferred as terminal blocking agents for amino groups. Furthermore, monoamines are preferred as terminal blocking agents for carboxyl groups. From the viewpoints of ease of handling, monocarboxylic acids are more preferred as terminal blocking agents.

[0045] The monocarboxylic acid used as the end-capping agent is not particularly limited as long as it is reactive 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-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and any mixtures thereof. Among these, at least one 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 preferred from the standpoints of reactivity, stability of the blocked end, cost, and the like.

[0046] The monoamine used as the terminal blocking agent is not particularly limited as long as it is reactive with a 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; and any 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 standpoints of reactivity, high boiling point, stability of blocked terminals, and cost.

[0047] (Catalyst) A catalyst can be added when producing the semi-aromatic polyamide resin of this embodiment. The amount of 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, relative to the total mass of the raw materials. If the amount of catalyst used is above the lower limit, polymerization proceeds smoothly. If the amount is below the upper limit, catalyst-derived impurities are less likely to be generated, and, for example, defects due to such impurities can be prevented when a polyamide resin composition containing the semi-aromatic polyamide resin of the present invention is extrusion molded. The amount of catalyst used is preferably 0.01 to 1.0% by mass, more preferably 0.05 to 0.5% by mass, relative to the total mass of the raw materials.

[0048] As the catalyst, phosphoric acid, phosphorous acid, hypophosphorous acid, salts or esters thereof, etc. can be used. Examples of the 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 esters, isopropyl esters, butyl esters, hexyl esters, isodecyl esters, octadecyl esters, decyl esters, stearyl esters and phenyl esters of phosphoric acid, phosphorous acid or hypophosphorous acid.

[0049] (First Reaction Step) In the first reaction step, a primary polycondensation reaction product is obtained. Specifically, raw materials containing an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent are polycondensed by melt polymerization to obtain a primary polycondensation reaction product. The raw materials may contain an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent, and may be mixed all at once or may be mixed by adding a portion separately later. Heat polymerization is preferably performed during the polycondensation reaction. The polymerization temperature is preferably 200 to 270°C, more preferably 240 to 260°C. By maintaining the polymerization temperature within the above range, the degree of polymerization of the primary polycondensation reaction product is increased, and fusion and aggregation of the polycondensation reaction product during the subsequent solid-state polymerization step, as well as disruption of the molar balance between the dicarboxylic acid component and the diamine component, can be suppressed.

[0050] (Second Reaction Step) In the second reaction step, a semi-aromatic polyamide resin is obtained. Specifically, the semi-aromatic polyamide resin is obtained by solid-state polymerizing the primary polycondensation reaction product. As a method for solid-state polymerization, it is preferable to carry out solid-state polymerization of the primary polycondensation reaction product at a temperature of 200°C or higher and lower than the melting point of the semi-aromatic polyamide resin. The solid-state polymerization temperature is the reaction temperature during solid-state polymerization, and is more preferably 215°C or higher, and even more preferably 230°C or higher. As a method for solid-state polymerization, heating and stirring in which the mixture is stirred while being heated is preferable. As a method for heating and stirring, any method that can uniformly heat and stir may be used, and for example, a horizontal heating and stirring device can be used. If the solid-state polymerization temperature is lower than 200°C, the desired molecular weight (inherent viscosity η ｉｎｈ ), resulting in reduced productivity. On the other hand, if the solid-state polymerization temperature is equal to or higher than the melting point of the primary polycondensation reactant, the primary polycondensation reactant is likely to undergo fusion, aggregation, adhesion to the vessel wall, and coloration during solid-state polymerization, or the molar balance is likely to be disrupted due to volatilization of the dicarboxylic acid component and diamine component constituting the primary polycondensation reactant. Therefore, it is preferable to carry out the solid-state polymerization of the primary polycondensation reactant at a temperature within a range of 100°C to 40°C lower than the melting point of the primary polycondensation reactant. Furthermore, from the viewpoint of suppressing deterioration of the semi-aromatic polyamide resin due to oxygen at high temperatures and obtaining a semi-aromatic polyamide resin of excellent quality, specifically, a high-molecular-weight semi-aromatic polyamide resin in which yellowing of the resin itself is suppressed and which has a narrow molecular weight distribution, it is preferable to carry out the solid-state polymerization of the primary polycondensation reactant under reduced pressure or in an inert gas flow.

[0051] [Polyamide Resin Composition] In one embodiment of the present invention, the semi-aromatic polyamide resin can be a polyamide resin composition. The polyamide resin composition contains at least the semi-aromatic polyamide resin. The polyamide resin composition preferably contains 50% by mass or more but less than 100% by mass of the semi-aromatic polyamide resin, more preferably 60 to 99.5% by mass, even more preferably 70 to 99% by mass, and even more preferably 80 to 99% by mass. By containing the semi-aromatic polyamide resin in the above range, the polyamide resin composition can have excellent retention stability during molding and heat aging resistance.

[0052] (Nucleating Agent) The polyamide resin composition of this embodiment preferably contains the semi-aromatic polyamide resin and a nucleating agent. The polyamide resin composition preferably contains 0.01 to 10 parts by mass of the nucleating agent per 100 parts by mass of the semi-aromatic polyamide resin, more preferably 0.1 to 5 parts by mass, even more preferably 1 to 5 parts by mass, and even more preferably 1 to 3 parts by mass. By having the content of the nucleating agent within the above range, the polyamide resin composition can be made to have excellent mechanical strength and abrasion resistance.

[0053] Examples of nucleating agents include metal oxides such as zinc oxide, magnesium oxide, iron oxide, antimony oxide, titanium oxide, alumina, and silica; inorganic salts such as sodium carbonate, potassium carbonate, calcium carbonate, zinc carbonate, magnesium carbonate, calcium silicate, lead silicate, magnesium silicate, calcium phosphate, lead phosphate, calcium sulfate, and barium sulfate; clays such as talc, kaolin, mica, and acid clay; organic acid salts such as calcium oxalate, calcium benzoate, magnesium stearate, and zinc salicylate; high-melting point polymers such as polyamide 6T and polyamide 46; powdered simple substances such as zinc powder, aluminum powder, graphite powder, and carbon black; aluminum p-t-butylbenzoate, bis(4-t-butylphenyl)sodium phosphate, 2,2'-methylenebis(4,6-di-t-butylphenyl)sodium phosphate, and di(p-t-butylbenzoate)hydroxyaluminum. These nucleating agents may be used alone or in combination of two or more. Among these, talc is preferred from the viewpoint of superior mechanical strength and abrasion resistance.

[0054] The average particle size of the nucleating agent is preferably 0.01 to 20 μm, more preferably 0.5 to 15 μm, and even more preferably 1 to 10 μm. Having the average particle size of the nucleating agent within this range promotes nucleation of crystals in the semi-aromatic polyamide resin, resulting in a polyamide resin composition with excellent mechanical strength and abrasion resistance. The average particle size of the nucleating agent can be obtained by the following method. A molded article made of a polyamide resin composition containing a nucleating agent is dissolved in a solvent such as formic acid in which polyamide is soluble. The resulting insoluble component is observed using an optical microscope or scanning electron microscope, and the average particle size can be determined as the average of the maximum Feret diameters of 100 or more nucleating agents. The Feret diameter refers to the distance between two parallel lines when the nucleating agent is sandwiched between the two lines.

[0055] The crystal nucleating agent may be treated with a silane coupling agent, a titanium coupling agent, or the like, as necessary. The silane coupling agent is not particularly limited, but examples thereof include aminosilane coupling agents such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; mercaptosilane coupling agents such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; epoxysilane coupling agents; and vinylsilane coupling agents. These silane coupling agents may be used alone or in combination of two or more.

[0056] (Antioxidant) The polyamide resin composition of this embodiment preferably contains the semi-aromatic polyamide resin and an antioxidant. The polyamide resin composition preferably contains 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and even more preferably 0.1 to 2 parts by mass of the antioxidant per 100 parts by mass of the semi-aromatic polyamide resin. By having the antioxidant content within the above range, the polyamide resin composition can be made to have excellent retention stability during molding and heat aging resistance.

[0057] Examples of the antioxidant include organic antioxidants such as phenolic antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and amine-based antioxidants, and inorganic antioxidants such as copper compounds and halides. One type of antioxidant may be used alone, or two or more types may be used in combination. Among the antioxidants, at least one selected from phenolic antioxidants, amine-based antioxidants, and combinations of copper compounds and halides is preferred from the viewpoint of excellent heat aging resistance.

[0058] Examples of the phenolic antioxidant include 2,2-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)], pentaerythrityl-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 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. From the viewpoint of the heat resistance of the resulting polyamide resin composition, the phenolic antioxidant is preferably at least one selected from N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide and 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0059] Examples of the phosphorus-based antioxidant 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, trisisodecyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl (tridecyl) phosphite, decyl) phosphite, triphenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, tri(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(2,4-di-tert-butyl-5-methylphenyl) phosphite, tris(butoxyethyl) phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenyl-tetratridecyl) diphosphite, tetra(C12-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphite phosphite, 4,4'-isopropylidenebis(2-tert-butylphenyl)di(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 diphosphite, tris(mono- and di-mixed nonylphenyl)phosphite sphite, 4,4'-isopropylidenebis(2-tert-butylphenyl)di(nonylphenyl)phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite, hydrogenated 4,4'-isopropylidenediphenyl polyphosphite, bis(octylphenyl)bis(4,4'-butylidenebis(3-methyl-6-tert-butylphenyl))1,6-hexanol diphosphite, hexatridecyl-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)octylphosphite, 2,2-methylenebis(3-methyl-4,6-di-tert-butylphenyl)-2-ethylhexyl 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]-dioxaphosphepine, and the like.

[0060] Examples of the sulfur-based antioxidant include distearyl 3,3′-thiodipropionate, pentaerythrityl 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.

[0061] Examples of the amine antioxidant include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (such as "Nocrac CD" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. and "Naugard 445" manufactured by Addiband Japan Co., Ltd.), N,N'-di-2-naphthyl-p-phenylenediamine (such as "Nocrac White" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N,N'-diphenyl-p-phenylenediamine (such as "Nocrac DP" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and N-phenyl-1-naphthylamine (such as "Nocrac DP" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.). PA"), N-phenyl-N'-isopropyl-p-phenylenediamine (such as "Nocrac 810-NA" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (such as "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine (such as "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-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy bis(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,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,α'-bis(2,2,6,6-tetramethyl-4-piperidyloxy)-p-xylene, bis(2,2,6,6-tetramethyl-4-piperidyl)tolylene-2,4-dicarbamate, bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylene-1,6-dicarbamate, tris(2,2,6,6-tetramethyl-4-piperidyl)benzene-1,3, Examples of suitable antioxidants include 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]undecane]diethanol, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, and the like. From the viewpoint of the heat resistance of the resulting polyamide resin composition, the amine antioxidant is preferably 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0062] Examples of the copper compound include copper halides, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, and copper complex salts coordinated with chelating agents such as ethylenediamine and ethylenediaminetetraacetic acid. Examples of the copper halides include copper iodide; copper bromides such as copper (I) bromide and copper (II) bromide; and copper chlorides such as copper (I) chloride. Among these copper compounds, at least one selected from the group consisting of copper halides and copper acetate is preferred, from the viewpoint of excellent heat aging resistance and suppressing metal corrosion of the screw and cylinder during extrusion. At least one selected from the group consisting of copper iodide, copper bromide, copper chloride, and copper acetate is more preferred, and at least one selected from the group consisting of copper iodide, copper bromide, and copper acetate is even more preferred. As the halide, halides other than those listed above can be used, and salts of metal elements from Group 1 or 2 of the Periodic Table with halogens are preferred. Examples include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. Among these, at least one selected from the group consisting of potassium iodide and potassium bromide is preferred, and potassium iodide is more preferred, from the viewpoint that the resulting polyamide resin composition has excellent high-temperature resistance, such as heat aging resistance, and can suppress metal corrosion. The copper compound and the halide are preferably used in combination, from the viewpoint that the resulting polyamide resin composition has excellent high-temperature resistance, such as heat aging resistance.

[0063] The polyamide resin composition of this embodiment may contain a semi-aromatic polyamide resin and at least one selected from the group consisting of a crystal nucleating agent and an antioxidant.

[0064] (Slidability Improver) The polyamide resin composition of this embodiment preferably contains a sliding property improver. The polyamide resin composition preferably contains 0.01 to 10 parts by mass, more preferably 0.05 to 7 parts by mass, even more preferably 0.1 to 5 parts by mass, and even more preferably 1 to 4 parts by mass of the sliding property improver per 100 parts by mass of the semi-aromatic polyamide resin. This can improve the sliding property of a molded article made from the polyamide resin composition.

[0065] Examples of the sliding property improver include fluororesins such as polytetrafluoroethylene, polytetrafluoroethylene-perfluoroalkoxyethylene copolymers, and polytetrafluoroethylene-polyhexafluoropropylene copolymers; polyolefins such as (high molecular weight) polyethylene, oxidized polyethylene, acid-modified (ultra-high molecular weight) polyethylene, polypropylene, acid-modified polypropylene, copolymerized polyolefins, and acid-modified copolymerized polyolefins; polydimethylsiloxane, polymethylphenylsiloxane, amino-modified polydimethylsiloxane, epoxy-modified polydimethylsiloxane, alcohol-modified polydimethylsiloxane, carboxymethylsiloxane, and the like. Examples of suitable sliding property improvers include silicones such as modified polydimethylsiloxane and fluorine-modified polydimethylsiloxane, layered inorganic compounds such as graphite and molybdenum disulfide, inorganic fibers such as glass fibers, potassium titanate whiskers, zinc oxide whiskers, and boronate whiskers, organic fibers such as LCP fibers, aramid fibers, and carbon fibers, inorganic particles such as alumina, talc, and silica, phosphates such as metaphosphate, pyrophosphate, calcium phosphate, calcium hydrogen phosphate, barium phosphate, lithium phosphate, calcium metaphosphate, and zinc pyrophosphate, mineral oils such as spindle oil, turbine oil, machine oil, and dynamo oil, and montanic acid salts such as calcium montanate. These sliding property improvers may be used alone or in combination of two or more.

[0066] Among the above-mentioned sliding property improvers, fluororesin, polyethylene oxide, acid-modified (ultra-high molecular weight) polyethylene, acid-modified copolymerized polyolefin, molybdenum disulfide, and aramid fiber are preferred from the viewpoint of their significant effect of reducing the amount of wear and the coefficient of friction.

[0067] The polyamide resin composition of this embodiment preferably contains a semi-aromatic polyamide resin and at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, and a sliding property improver. In this case, too, the polyamide resin composition can contain the above-mentioned preferred content.

[0068] (Other Additives) The polyamide resin composition of this embodiment may contain other additives as needed. Examples of other additives include lubricants, inorganic fillers, impact modifiers, release agents, colorants, plasticizers, UV absorbers, light stabilizers, oxygen absorbers, hydrogen sulfide adsorbents, flame retardants, flame retardant assistants, antistatic agents, crystallization retarders, and organic fibrous fillers. The content of the other additives is not particularly limited as long as it does not impair the effects of the present invention, but is preferably 0.01 to 200 parts by mass, and more preferably 0.02 to 100 parts by mass, per 100 parts by mass of the semi-aromatic polyamide resin.

[0069] The content of the lubricant is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the semi-aromatic polyamide resin, which can improve the flowability of the polyamide resin composition and the appearance and releasability of a molded article made of the polyamide resin composition.

[0070] Examples of the lubricant include higher fatty acids having 8 or more carbon atoms, such as stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, and montanic acid; higher fatty acid metal salts, such as calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, calcium montanate, sodium montanate, aluminum montanate, zinc montanate, magnesium montanate, calcium behenate, sodium behenate, zinc behenate, calcium laurate, zinc laurate, and calcium palmitate; higher fatty acid esters, such as stearyl alcohol, behenyl alcohol, and lauryl alcohol; higher fatty acid amides, such as stearic acid amide, oleic acid amide, erucic acid amide, ethylene bisstearylamide, ethylene bisoleylamide, N-stearylstearylamide, and N-stearylerucamide; and polyolefins, such as polyethylene, oxidized polyethylene, acid-modified polyethylene, polypropylene, and acid-modified polypropylene. These lubricants may be used alone or in combination of two or more.

[0071] Among the above lubricants, metal stearates, metal montanates, ethylene bisstearylamides, and polyolefins are preferred from the viewpoint of excellent heat resistance and moldability.

[0072] Examples of the inorganic filler include fibrous fillers such as glass fiber, carbon fiber, calcium silicate fiber, potassium titanate fiber, aluminum borate fiber, and wollastonite; glass flakes, silicon nitride, hydrotalcite zeolite, boehmite, aluminum hydroxide, calcium silicate, sodium aluminosilicate, carbon nanotubes, graphene, brass, copper, silver, nickel, iron, calcium fluoride, montmorillonite, swellable fluoromica, and apatite. These inorganic fillers may be used alone or in combination of two or more.

[0073] Among the inorganic fillers, at least one selected from fibrous fillers is preferred from the viewpoint of excellent moldability and mechanical strength.

[0074] In another aspect, the polyamide resin composition of this embodiment is a polyamide resin composition containing a semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the diamine units contain 60 to 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms relative to 100 mol% of the diamine units, and the dicarboxylic acid units contain 60 to 100 mol% of aromatic dicarboxylic acid units relative to 100 mol% of the carboxylic acid units. The semi-aromatic polyamide resin has a weight average molecular weight Mw of 40,000 to 90,000 in terms of polymethyl methacrylate as measured by gel permeation chromatography (GPC), and a terminal amino group content [NH ２ ] is 10 to 70 μ equivalents / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μ equivalents / g, and the amount of terminal amino groups [NH ２ ] to the amount of terminal carboxyl groups [COOH], [NH ２ ] / [COOH] is 0.1 or more and less than 1.0.

[0075] A preferred embodiment of the semi-aromatic polyamide resin contained in the polyamide resin composition of this embodiment, which is another embodiment, is the same as the preferred embodiment described above in [Semi-aromatic polyamide resin]. However, in the semi-aromatic polyamide resin contained in the polyamide resin composition of this embodiment, which is another embodiment, the amount of terminal amino groups [NH ２ ] and the amount of terminal carboxyl groups [COOH] are values ​​calculated by titration. More specifically, the amount of terminal amino groups [NH ２ The amount of terminal carboxyl groups [COOH] is a value calculated by titration using a 0.01 or 0.1 N potassium hydroxide / ethanol solution with a potentiometric titrator. More specifically, it can be determined by the method described in the Examples.

[0076] The polyamide resin composition of this embodiment, which is another aspect, preferably contains at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, a sliding property improver, and a lubricant. Furthermore, the polyamide resin composition of this embodiment, which is another aspect, preferably contains 0.01 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 8 parts by mass, of at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, a sliding property improver, and a lubricant, relative to 100 parts by mass of the semi-aromatic polyamide resin. Furthermore, the polyamide resin composition of this embodiment, which is another aspect, preferably contains 0.01 to 10 parts by mass in total of the crystal nucleating agent, antioxidant, sliding property improver, and lubricant, relative to 100 parts by mass of the semi-aromatic polyamide resin, more preferably 0.1 to 10 parts by mass, more preferably 0.1 to 8 parts by mass, and even more preferably 0.2 to 8 parts by mass. This can improve the sliding properties of a molded article made from the polyamide resin composition. Preferred embodiments of the crystal nucleating agent, antioxidant, sliding property improver, lubricant, and other additives contained in the polyamide resin composition of this embodiment, which is another embodiment, are the same as those of the polyamide resin composition of this embodiment described above.

[0077] (Fatigue Resistance) The polyamide resin composition of this embodiment has excellent fatigue resistance due to the inclusion of the semi-aromatic polyamide resin. The fatigue resistance of a polyamide resin composition can be evaluated by the number of repetitions until fatigue failure obtained in a plane bending fatigue test. The number of repetitions until fatigue failure of the polyamide resin composition of this embodiment can be measured by the following method. Specifically, the composition is injection molded to prepare a type I test piece I-20 described in JIS K7119 (1972). Using this test piece, a plane bending fatigue test is performed in accordance with JIS K7119 (1972). The plane bending fatigue test conditions are a chuck distance of 30 mm, an ambient temperature of 23°C, a load of 40 MPa, a load repetition rate of 1800 times per minute, and reverse plane bending as the stress mode. This allows the number of repetitions until fatigue failure to be obtained. The number of repetitions until fatigue failure of the polyamide resin composition of this embodiment is 5.0 x 10 ５ cycles or more, and 1.0 x 10 ６More specifically, the number of repetitions can be determined by the method described in the Examples.

[0078] (Water Absorption) The polyamide resin composition of this embodiment has low water absorption due to the inclusion of the semi-aromatic polyamide resin. The water absorption can be evaluated by the water absorption rate of the polyamide resin composition. The polyamide resin composition is injection molded to prepare a type I test piece I-20 (3 mm thick) as described in JIS K7119 (1972), and the water absorption rate can be calculated from the amount of water absorbed before and after immersion in water at 23°C for 168 hours. The water absorption rate is preferably 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The water absorption rate can be measured using a test piece obtained by injection molding the polyamide resin composition using an 80-ton injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd. under conditions of a cylinder temperature of 320°C and a mold temperature of 140°C, and more specifically, can be measured by the method described in the Examples.

[0079] (Slidability) The polyamide resin composition of this embodiment contains the semi-aromatic polyamide resin and further contains at least one selected from the group consisting of the crystal nucleating agent and the sliding property improver, thereby exhibiting excellent sliding properties. The sliding properties of the polyamide resin composition can be evaluated by the wear amount (mg) and dynamic friction coefficient obtained in a sliding wear test. The wear amount and dynamic friction coefficient of the polyamide resin composition of this embodiment can be measured by the following method. The composition is injection molded to prepare a square plate test piece with a thickness of 3 mm. Using this test piece, a sliding wear test is performed in accordance with JIS K7218 (1986) Method A. The sliding wear test conditions are 23°C and a surface pressure of 10 kg / cm. ２, sliding speed 50 cm / sec, mating material S45C. This allows the wear amount and dynamic friction coefficient to be obtained. The lower the wear amount of the polyamide resin composition of this embodiment, the more preferable, and it is preferably 250 mg or less, more preferably 200 mg or less, and even more preferably 150 mg or less. Furthermore, the dynamic friction coefficient of the polyamide resin composition of this embodiment is preferably 0.5 or less, more preferably 0.45 or less. The test piece used is a test piece obtained by injection molding the polyamide resin composition using an 80-ton injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd. under conditions of a cylinder temperature of 320°C and a mold temperature of 140°C. More specifically, the wear amount and dynamic friction coefficient can be determined by the methods described in the Examples.

[0080] (Method of Producing Polyamide Resin Composition) The method of producing the polyamide resin composition is not particularly limited, and a method capable of uniformly mixing the semi-aromatic polyamide resin, optionally a crystal nucleating agent and / or antioxidant, and optionally other additives, can be preferably employed. That is, the method of producing the polyamide resin composition is preferably a method capable of uniformly mixing the semi-aromatic polyamide resin, at least one selected from the group consisting of a crystal nucleating agent and an antioxidant, and optionally other additives. The mixing is typically preferably performed by melt-kneading using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, or the like. The melt-kneading conditions are not particularly limited, but an example includes a method of melt-kneading the polyamide resin at a temperature range approximately 10 to 60°C higher than the melting point of the polyamide resin for approximately 1 to 30 minutes to obtain a pelletized polyamide resin composition.

[0081] [Molded Article] (Molding Method) The molded article of this embodiment can be a molded article made from the semi-aromatic polyamide resin. The molded article can also be a molded article made from a polyamide resin composition. The molded article is produced by a known molding method using a semi-aromatic polyamide resin or a polyamide resin composition. Specifically, the molded article can be obtained by molding using various molding methods such as injection molding, blow molding, extrusion molding, compression molding, stretch molding, vacuum molding, foam molding, rotational molding, impregnation, laser sintering, and fused deposition modeling. Furthermore, a molded article can also be obtained by composite molding of the semi-aromatic polyamide resin or polyamide resin composition of this embodiment with other polymers or compositions containing other polymers and metals. For example, a molded article can be obtained by extrusion molding a metal plate and the semi-aromatic polyamide resin composition of this embodiment, comprising a layer of the semi-aromatic polyamide resin composition of this embodiment on the surface of the metal plate.

[0082] (Applications) The molded article of this embodiment has excellent fatigue resistance and sliding properties, and therefore can be used as sliding members for automobiles, electric bicycles (especially e-bikes), industrial machinery, household appliances, and the like. Examples of sliding members include various gears, bearings, bushings, chain tensioners, bearings, end face materials for mechanical seals, valve seats, V-rings, rod packings, piston rings, rotating shafts and rotating sleeves for compressors, pistons, impellers, vanes, and rotors. The molded article of this embodiment has particularly excellent low water absorption properties, and therefore can be suitably used for gears that require high dimensional accuracy, among the above sliding members. Examples of gears include sprue gears, bevel gears, helical gears, spiral gears, double helical gears, internal gears, worm gears, rack and pinion gears, and Geneva gears. From the viewpoints of fatigue resistance, sliding properties, and low water absorption, the molded article of this embodiment is particularly suitable for use in sprue gears and helical gears for e-bike drive units, and worm gears for automobile electric power steering. The molded article of this embodiment has particularly excellent low water absorption, resulting in high gear dimensional stability. Therefore, when used in the various gears of e-bikes mentioned above, noise caused by meshing between gears can be suppressed, resulting in excellent quietness.

[0083] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0084] [Evaluation Methods] The semi-aromatic polyamide resins and polyamide resin compositions obtained in the Examples and Comparative Examples were evaluated according to the methods shown below.

[0085] 1. Evaluation method for semi-aromatic polyamide resins (inherent viscosity) Each semi-aromatic polyamide resin obtained in the examples and comparative examples was dissolved in concentrated sulfuric acid as a solvent to a concentration of 0.2 g / dL to prepare a sample solution. Next, the flow time of the solvent (concentrated sulfuric acid) and the flow time of the sample solution at a temperature of 30°C were measured, and the inherent viscosity η was calculated using the following equation (3): ｉｎｈ The results are shown in Table 2. η ｉｎｈ (dl / g)=[ln(t １ / t ０)] / c Equation (3) In the above relational expression, t ０ represents the flow time (seconds) of the solvent (concentrated sulfuric acid), and t １ represents the flow time (seconds) of the sample solution, and c represents the concentration (g / dl) of the sample (semi-aromatic polyamide) in the sample solution.

[0086] (Amount of Terminal Amino Groups, Amount of Terminal Carboxyl Groups, and Terminal Capping Rate) A high-resolution nuclear magnetic resonance spectrometer "ECZ-600" manufactured by JEOL Ltd. was used under the conditions of resolution: 600 MHz, solvent: deuterated 1,1,1,3,3,3-hexafluoroisopropanol, and temperature: 50°C. １ H-NMR analysis was carried out. The amount of terminal amino groups, the amount of terminal carboxyl groups, and the amount of terminal groups blocked with the terminal blocking agent were calculated from the integrated values ​​of the characteristic signals of each terminal group. The chemical shift values ​​of representative signals used in the measurement are shown in Table 1. The measurement results of the amount of terminal amino groups and the amount of terminal carboxyl groups are shown in Table 2.

[0087] The terminal-capping rate of the semi-aromatic polyamide resin was calculated using the following formula (1): In formula (1), A represents the total amount of terminal groups, and B represents the total amount of terminal carboxyl groups and terminal amino groups. Terminal-capping rate (%) = [(A - B) / A] x 100 Formula (1) The results are shown in Table 2.

[0088] (Weight average molecular weight) Weight average molecular weight Mw of semi-aromatic polyamide resin ０ was determined using gel permeation chromatography (GPC) as a standard polymethyl methacrylate-equivalent molecular weight. Specifically, 1.5 mg of semi-aromatic polyamide resin was dissolved in 3 mL of eluent, and the solution was filtered through a membrane filter with a pore size of 0.4 μm to prepare a measurement sample. The measurement sample was measured in the same manner as described in "Retention Stability" in "2. Evaluation Methods for Polyamide Resin Compositions." The results are shown in Table 2.

[0089] (Melting Point and Heat of Fusion) The melting point and heat of fusion ΔHm of each semi-aromatic polyamide resin obtained in the examples and comparative examples were measured using a differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Corporation. The melting point and heat of fusion ΔHm were measured in accordance with ISO 11357-3 (2011, 2nd edition). Specifically, each semi-aromatic polyamide resin sample was heated from 30°C to 340°C at a rate of 10°C / min under a nitrogen atmosphere. The sample was then held at 340°C for 5 minutes to completely melt, then cooled to 50°C at a rate of 10°C / min and held at 50°C for 5 minutes. The sample was then heated again to 340°C at a rate of 10°C / min. The peak temperature of the melting peak that appeared was taken as the melting point (°C), and the peak area was taken as the heat of fusion ΔHm (J / g). The results are shown in Table 2.

[0090] 2. Evaluation method of polyamide resin composition Preparation of test pieces For each polyamide resin composition obtained in the examples and comparative examples, an 80-ton injection molding machine manufactured by Nissei Plastic Industrial Co., Ltd. was used to prepare dumbbell test pieces (type I test piece "I-20" described in JIS K7119 (1972)) for evaluating fatigue resistance and water absorption, and square plate test pieces (length 55 mm × width 55 mm × thickness 3 mm) for evaluating sliding properties, under conditions of a cylinder temperature of 320 ° C. and a mold temperature of 140 ° C.

[0091] (Amount of terminal amino groups) 1 g of each polyamide resin composition obtained in Examples and Comparative Examples was dissolved in 30 ml of phenol, and then 3 ml of methanol was added to prepare a sample solution. Titration was carried out using 0.01 or 0.1 N aqueous HCl solution with thymol blue as an indicator to determine the amount of terminal amino groups ([NH ２ ], unit: μequivalent / g) was measured.

[0092] (Amount of Terminal Carboxyl Groups) 0.5 g of each polyamide resin composition obtained in the Examples and Comparative Examples was dissolved in 40 ml of ortho-cresol to prepare a sample solution. Using a potentiometric titrator, titration was carried out using a 0.01 or 0.1 N potassium hydroxide / ethanol solution to measure the amount of terminal carboxyl groups ([COOH], unit: μequivalents / g) of the semi-aromatic polyamide resin contained in the polyamide resin composition. (Measurement Conditions) Measuring device: AT-710 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.) Main control unit: MCU-710 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.)

[0093] (Retention Stability) The retention stability was evaluated by evaluating the rate of decrease in the weight average molecular weight (Mw) of the semi-aromatic polyamide resin contained in the polyamide resin composition before and after melt-kneading. Specifically, the retention stability was evaluated according to the following criteria from the rate of decrease in the weight average molecular weight of the semi-aromatic polyamide resin contained in the polyamide resin composition, which is represented by the following formula (4). The results are shown in Table 3. Rate of decrease in weight average molecular weight (%) = (Mw ０ -Mw １ ) × 100 / Mw ０ Formula (4) In formula (4), Mw ０ indicates the weight average molecular weight of the semi-aromatic polyamide resin before melt-kneading, and Mw １ indicates the weight average molecular weight of the semi-aromatic polyamide resin contained in the polyamide resin composition after melt-kneading. The melt-kneading was carried out using a twin-screw extruder "BTN-32-S2-30-L" manufactured by Plastics Engineering Research Institute Co., Ltd., at a cylinder temperature of 320 to 325°C and a residence time of 1 to 5 minutes. <Evaluation criteria> A: The rate of decrease in weight average molecular weight is 20% or less. B: The rate of decrease in weight average molecular weight is more than 20%. The weight average molecular weight Mw of the semi-aromatic polyamide resin before melt-kneading ０The weight average molecular weight (Mw) of the semi-aromatic polyamide resin contained in the polyamide resin composition after melt-kneading was measured using gel permeation chromatography (GPC) and calculated as standard polymethyl methacrylate. Specifically, 1.5 mg of the semi-aromatic polyamide resin was dissolved in 3 mL of eluent, and the solution was filtered through a membrane filter with a pore size of 0.4 μm to prepare a measurement sample. The measurement sample was measured under the conditions shown below. In addition, the weight average molecular weight (Mw) of the semi-aromatic polyamide resin contained in the polyamide resin composition after melt-kneading was measured using the following conditions. １ The weight average molecular weight was determined by gel permeation chromatography (GPC) using a standard polymethyl methacrylate equivalent. Specifically, the weight average molecular weight was determined by the following method. A polyamide resin composition was weighed so that the mass of the semi-aromatic polyamide resin contained in the polyamide resin composition was 1.5 mg, and the polyamide resin composition was dissolved in hexafluoroisopropanol (HFIP). The solution was then filtered through a membrane filter with a pore size of 0.4 μm to prepare a measurement sample from which organic components containing the semi-aromatic polyamide resin were separated. The measurement sample was measured under the following conditions. <Measurement Conditions> Apparatus: HLC-8320GPC (manufactured by Tosoh Corporation) Column: Two TSKgel Super HM-N (manufactured by Tosoh Corporation) columns were connected in series. Eluent: 0.085% sodium trifluoroacetate / HFIP solution Flow rate: 0.5 mL / min (reference column: 0.25 mL / min) Sample injection volume: 10 μL Column temperature: 40° C. Standard polymethyl methacrylate: Shodex Standard M-75 (manufactured by Resonaq Co., Ltd.), Polymethylmethacrylate (Agilent Technologies, Inc.) molecular weight 1010 Polymethyl methacrylate Detector: UV (254 nm) detector

[0094] (Fatigue Resistance) Using the obtained dumbbell test pieces, a plane bending fatigue test was carried out in accordance with JIS K7119 (1972). The vibration fatigue tester "B-70-TL" manufactured by Toyo Seiki Seisakusho, Ltd. was used as the testing machine. The number of repetitions (number of cycles) until fatigue failure was measured under the following conditions: chuck distance: 30 mm, ambient temperature: 23°C, load: 40 MPa, load repetition rate: 1800 times per minute, stress mode: reverse plane bending, and this was taken as fatigue resistance. The results are shown in Table 3.

[0095] (Water Absorption) The obtained dumbbell test piece was weighed, and the weight of the test piece before water absorption W ０ Next, the test piece was immersed in water and immersed for 168 hours at 23°C, and then weighed again to determine the weight of the test piece after water absorption, W １ The water absorption was calculated using the following formula (5) to evaluate the water absorption. The results are shown in Table 3. Water absorption (%) = (W １ -W ０ ) x 100 / W ０ Formula (5)

[0096] (Sliding Properties) Using the obtained square plate test pieces, a sliding wear test was carried out in accordance with JIS K7218 (1986) Method A. The tester used was a friction wear tester "EFM-3-G" manufactured by A&D Co., Ltd. Temperature: 23°C, surface pressure: 10 kg / cm ２ The sliding speed was 50 cm / sec, and the wear amount (mg) and the coefficient of dynamic friction were measured with S45C steel as the mating material to evaluate the sliding properties. The results are shown in Table 3.

[0097] Example 1 (Production of Semi-Aromatic Polyamide Resin PA9T-1) 6,134.9 g (38.76 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 85 / 15 (molar ratio)], 6,297.2 g (37.91 mol) of terephthalic acid, 23.2 g (0.19 mol) of benzoic acid (0.5 mol% relative to 100 mol% diamine), 12.5 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 4.8 L of distilled water (the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials was 1.02) were placed in a 40 L autoclave and purged with nitrogen. The mixture was stirred at 100°C for 30 minutes, and the temperature inside the autoclave was raised to 220°C over 2 hours. At this time, the pressure inside the autoclave rose to 2 MPa. Heating was continued for 5 hours while maintaining the pressure at 2 MPa, and the water vapor was gradually released to allow the reaction. Next, the pressure was reduced to 1.3 MPa over 30 minutes, and the reaction was allowed to continue for another hour, yielding a prepolymer. The obtained prepolymer was dried at 120°C under reduced pressure for 12 hours and pulverized to a particle size of 2 mm or less. This was subjected to solid-state polymerization at 230°C and 13 Pa (0.1 mmHg) for 10 hours, yielding a white semi-aromatic polyamide resin PA9T-1.

[0098] [Example 2] (Production of semi-aromatic polyamide resin PA9T-2) 7787.4 g (49.20 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 85 / 15 (molar ratio)], 7967.6 g (47.96 mol) of terephthalic acid, 38.1 g (0.31 mol, 0.6 mol% relative to 100 mol% of diamine), 15.6 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 7.6 L of distilled water [the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials was 1.02] were placed in a 40-liter autoclave, and the subsequent procedures were carried out in the same manner as in Example 1 to obtain a white semi-aromatic polyamide resin PA9T-2.

[0099] [Example 3] (Production of semi-aromatic polyamide resin PA9T-3) A mixture of 6,603.0 g (41.72 mol) of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 85 / 15 (molar ratio)], 6,794.3 g (40.90 mol) of terephthalic acid, 25.0 g (0.21 mol, 0.5 mol% relative to 100 mol% of diamine), 13.4 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 4.5 L of distilled water [the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials was 1.02] was placed in a 40-liter autoclave, and the subsequent procedures were carried out in the same manner as in Example 1 to obtain a white semi-aromatic polyamide resin PA9T-3.

[0100] [Comparative Example 1] (Production of semi-aromatic polyamide resin PA9T-4) 6074.8 g (38.38 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 85 / 15 (molar ratio)], 6297.2 g (37.91 mol) of terephthalic acid, 23.2 g (0.19 mol, 0.5 mol% relative to 100 mol% of diamine), 12.4 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 4.8 L of distilled water [the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials was 1.01] were placed in a 40-liter autoclave, and the subsequent procedures were carried out in the same manner as in Example 1 to obtain a white semi-aromatic polyamide resin PA9T-4.

[0101] [Comparative Example 2] (Production of semi-aromatic polyamide resin PA9T-5) 6652.8 g (41.40 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 85 / 15 (molar ratio)], 6628.6 g (39.90 mol) of terephthalic acid, 24.4 g (0.20 mol, 0.5 mol% relative to 100 mol% of diamine), 13.2 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 5.1 L of distilled water [the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials was 1.04] were placed in a 40-liter autoclave, and the subsequent procedures were carried out in the same manner as in Example 1 to obtain a white semi-aromatic polyamide resin PA9T-5.

[0102] [Comparative Example 3] (Production of semi-aromatic polyamide resin PA9T-6) A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [former / latter = 80 / 20 (molar ratio)] 7891.0 g (49.85 mol), terephthalic acid 8076.0 g (48.61 mol), benzoic acid 103.0 g (0.84 mol, 1.7 mol% relative to 100 mol% diamine), sodium hypophosphite monohydrate 16.0 g (0.1% by mass relative to the total mass of the raw materials) and distilled water 7.7 L [the ratio (x / y) of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw materials was 1.02] was placed in an autoclave with an internal volume of 40 L, and thereafter, a white semi-aromatic polyamide resin PA9T-6 was obtained in the same manner as in Example 1.

[0103]

[0104] (Production of Polyamide Resin Compositions) Each semi-aromatic polyamide resin was pre-mixed with the crystal nucleating agent, antioxidant, and other additives (lubricants) shown below in the proportions shown in Table 3. This mixture was charged all at once into the upstream feed port of a twin-screw extruder "BTN-32-S2-30-L" manufactured by Plastics Technology Research Institute Co., Ltd. The mixture was melt-kneaded and extruded under conditions of a cylinder temperature of 320 to 325°C, and then cooled and cut to produce each polyamide resin composition in pellet form.

[0105] The components shown in Table 3 are as follows: Nucleating agent "MICRON WHITE #5000S", manufactured by Hayashi Kasei Co., Ltd. Antioxidant "SUMILIZER GA-80", manufactured by Sumitomo Chemical Co., Ltd. Sliding property improver "Licowax PED191", manufactured by Clariant Chemicals Co., Ltd. Other additives (lubricants) "LICOWAX OP", manufactured by Clariant Chemicals Co., Ltd.

[0106]

[0107] From Table 2, it can be seen that the semi-aromatic polyamide resins of Examples 1 to 3 have an inherent viscosity η measured in concentrated sulfuric acid at 30°C. ｉｎｈ is 1.6 to 3.0 dl / g, the amount of terminal amino groups is 10 to 70 μequivalents / g, the amount of terminal carboxyl groups is 10 to 90 μequivalents / g, and the amount of terminal amino groups [NH ２ ] (μ equivalents / g) to the amount of terminal carboxyl groups [COOH] (μ equivalents / g), [NH ２ ] / [COOH] is 0.1 or more and less than 1.0. Table 3 shows that Examples 4 to 7 contain the semi-aromatic polyamide resins of Examples 1 to 3 and have high retention stability and fatigue resistance. Therefore, Tables 2 and 3 show that the semi-aromatic polyamide resins and polyamide resin compositions of the Examples have improved retention stability during melt processing while maintaining excellent fatigue resistance, and are excellent in both fatigue resistance and retention stability.

Claims

1. A semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the diamine units contain 60 to 100 mol % of aliphatic diamine units having 7 to 13 carbon atoms relative to 100 mol % of the diamine units, and the dicarboxylic acid units contain 60 to 100 mol % of aromatic dicarboxylic acid units relative to 100 mol % of the carboxylic acid units, and the inherent viscosity η measured in concentrated sulfuric acid at 30°C ｉｎｈ is 1.6 to 3.0 dl / g, and the amount of terminal amino groups [NH ２ ] is 10 to 70 μ equivalents / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μ equivalents / g, and the amount of terminal amino groups [NH ２ ] to the amount of terminal carboxyl groups [COOH], [NH ２ ] / [COOH] is 0.1 or more and less than 1.

0.

2. The semi-aromatic polyamide resin according to claim 1, wherein the aliphatic diamine unit having 7 to 13 carbon atoms is at least one selected from the group consisting of 1,10-decanediamine units, 1,9-nonanediamine units and 2-methyl-1,8-octanediamine units.

3. The inherent viscosity η ｉｎｈ The semi-aromatic polyamide resin according to claim 1 or 2, wherein the viscosity is 1.7 to 2.5 dl / g.

4. The inherent viscosity η ｉｎｈ The semi-aromatic polyamide resin according to claim 1 or 2, wherein the viscosity is 1.8 to 2.5 dl / g.

5. The amount of terminal amino groups [NH ２ 5. The semi-aromatic polyamide resin according to claim 1, wherein the molecular weight of the polyamide is 20 to 60 μequivalents / g.

6. The amount of terminal amino groups [NH ２ 5. The semi-aromatic polyamide resin according to claim 1, wherein the molecular weight of the polyamide is 30 to 60 μequivalents / g.

7. The semi-aromatic polyamide resin according to any one of claims 1 to 6, wherein the amount of terminal carboxyl groups [COOH] is 30 to 80 μequivalents / g.

8. Said [NH ２ 8. The semi-aromatic polyamide resin according to claim 1, wherein the ratio of [COOH] / [COOH] is 0.2 to 0.

9.

9. A polyamide resin composition comprising the semi-aromatic polyamide resin according to any one of claims 1 to 8 and a crystal nucleating agent.

10. The polyamide resin composition according to claim 9, comprising 0.01 to 10 parts by mass of the crystal nucleating agent per 100 parts by mass of the semi-aromatic polyamide resin.

11. A polyamide resin composition comprising the semi-aromatic polyamide resin according to any one of claims 1 to 10 and an antioxidant.

12. The polyamide resin composition according to claim 11, comprising 0.01 to 5 parts by mass of the antioxidant per 100 parts by mass of the semi-aromatic polyamide resin.

13. A polyamide resin composition containing a semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the diamine units contain 60 to 100 mol % of aliphatic diamine units having 7 to 13 carbon atoms relative to 100 mol % of the diamine units, and the dicarboxylic acid units contain 60 to 100 mol % of aromatic dicarboxylic acid units relative to 100 mol % of the carboxylic acid units, and the semi-aromatic polyamide resin has a weight average molecular weight Mw of 40,000 to 90,000 in terms of polymethyl methacrylate as measured by gel permeation chromatography (GPC), and a terminal amino group amount [NH ２ ] is 10 to 70 μ equivalents / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μ equivalents / g, and the amount of terminal amino groups [NH ２ ] to the amount of terminal carboxyl groups [COOH], [NH ２ ] / [COOH] is 0.1 or more and less than 1.

0.

14. The polyamide resin composition according to claim 13, which contains at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, a sliding property improver and a lubricant.

15. The polyamide resin composition according to claim 14, which contains 0.01 to 10 parts by mass of at least one selected from the group consisting of a crystal nucleating agent, an antioxidant, a sliding property improver, and a lubricant, per 100 parts by mass of the semi-aromatic polyamide resin.

16. A molded article made of the polyamide resin composition according to any one of claims 9 to 15.

17. The molded article according to claim 16, which is a sliding member.

18. The molded article of claim 17 which is a gear.

19. A method for producing a semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, comprising: a first reaction step of polycondensing a raw material containing an aliphatic diamine, an aromatic dicarboxylic acid, and an end-capping agent to obtain a primary polycondensation reaction product; and a second reaction step of solid-state polymerizing the primary polycondensation reaction product to obtain the semi-aromatic polyamide resin, wherein the ratio x / y of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) contained in the raw material is greater than 1.01 and is 1.03 or less, and the amount of the end-capping agent contained in the raw material is 0.1 to 1.5 mol % relative to 100 mol % of the diamine contained in the raw material.

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