Methods for manufacturing semi-aromatic polyamide resins, polyamide resin compositions, and semi-aromatic polyamide resins

Abstract

A semi-aromatic polyamide resin comprising diamine units and dicarboxylic acid units, wherein the diamine units comprise 60-100 mol% aliphatic diamine units having 7-13 carbon atoms per 100 mol% of the diamine units, and the dicarboxylic acid units comprise 60-100 mol% aromatic dicarboxylic acid units per 100 mol% of the carboxylic acid units. The specific logarithmic viscosity η, measured in concentrated sulfuric acid at 30°C, is... inh The content of terminal amino group [NH2] is 1.6 to 3.0 dl / g, the content of terminal amino group [NH2] is 10 to 70 μequivalents / g, the content of terminal carboxyl group [COOH] is 10 to 90 μequivalents / g, and the ratio of the above-mentioned terminal amino group [NH2] to the above-mentioned terminal carboxyl group [COOH], i.e., [NH2] / [COOH] is 0.1 or more and less than 1.0.

Description

Technical Field

[0001] This invention relates to semi-aromatic polyamide resins, polyamide resin compositions, and methods for manufacturing semi-aromatic polyamide resins. More specifically, it relates to semi-aromatic polyamide resins exhibiting excellent fatigue resistance and retention stability during melt processing, and polyamide resin compositions containing the semi-aromatic polyamide resin. Furthermore, it relates to methods for manufacturing the semi-aromatic polyamide resin. Background Technology

[0002] Resin materials such as polyamide resins are widely used in components used in automobiles and industrial machinery. Resin products are also widely used in sliding components such as gears. In recent years, there has been a trend towards developing products aimed at miniaturization and high output of sliding components, especially gears. To achieve this, it is necessary to increase the torque and speed applied to the sliding components, specifically gears. Therefore, sliding components, specifically gears, are required to operate under high-load environments compared to the past, thus increasing the demand for resin materials with high fatigue resistance capable of withstanding high loads. Furthermore, for such resin materials, lower water absorption is required to prevent failures caused by meshing defects due to dimensional changes based on water absorption.

[0003] Semi-aromatic polyamide resins, derived from long-chain aliphatic diamines such as poly(nonadiamine terephthalamide) (hereinafter also known as PA9T) and poly(decyl terephthalamide) (hereinafter also known as PA10T), possess excellent 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. On the other hand, the fatigue resistance of semi-aromatic polyamide resins is inferior to that of aliphatic polyamide resins; therefore, improvements in the fatigue resistance of semi-aromatic polyamide resins are desired.

[0004] Furthermore, resin materials used in sliding components, specifically gears, require stability during melting and molding processes, i.e., retention stability. Resin materials with low retention stability experience molecular chain breakage due to the heat generated during melting and molding, resulting in a decrease in resin viscosity. This not only reduces mechanical properties such as fatigue resistance but also leads to undesirable appearance due to the formation of ablation, voids, and impact marks.

[0005] Generally, increasing the molecular weight of a semi-aromatic polyamide resin is known as a method to improve its fatigue resistance. For example, Patent Document 1 discloses a polyamide resin with a specific viscosity number where the difference between the concentration of amino-terminal groups and the concentration of carboxyl-terminal groups is within a specified range. Patent Document 2 discloses a semi-aromatic polyamide resin in which the relationship between the concentration of amino-terminal groups, the concentration of carboxyl-terminal groups, and the concentration of amino-terminal groups capped with carboxylic acid is controlled within a specified range. Patent Document 3 discloses a semi-aromatic polyamide resin in which compatibility is improved by maintaining the ratio of amino-terminal group concentration to carboxylic acid-terminal group concentration within a specified range in a semi-aromatic polyamide mainly composed of terephthalic acid and 1,10-decanediamine.

[0006] In addition, semi-aromatic polyamide resins with improved retention stability were also studied. Patent document 4 discloses that by setting the amount of terminal amino groups in the semi-aromatic polyamide resin to a specific range, and further making the value obtained by dividing the amount of terminal amino groups by the amount of terminal carboxyl groups above a predetermined value, a polyamide resin with excellent retention stability can be obtained.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2015-199873

[0010] Patent Document 2: International Publication No. 2021 / 065205

[0011] Patent Document 3: Japanese Patent Application Publication No. 2016-94508

[0012] Patent Document 4: International Publication No. 2006 / 098434 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] However, in any of Patent Documents 1 to 3, the fatigue resistance and retention stability of high molecular weight semi-aromatic polyamide resins are not clearly defined. Although Patent Document 4 describes a semi-aromatic polyamide resin with excellent retention stability, the examples are limited to semi-aromatic polyamide resins with an intrinsic viscosity [η] of about 1.2 dl / g, and there is no description of semi-aromatic polyamide resins with higher intrinsic viscosities than this, i.e., high molecular weight semi-aromatic polyamide resins with excellent retention stability.

[0015] Recent research on increasing the molecular weight of semi-aromatic polyamide resins has revealed issues such as reduced retention stability and decreased fatigue resistance during melt processing. In particular, due to the high melting point of semi-aromatic polyamide resins, the high temperatures required for melt processing lead to their easy decomposition.

[0016] Therefore, the objective of this invention is to provide a semi-aromatic polyamide resin with excellent fatigue resistance and retention stability during melt processing, and with a high molecular weight.

[0017] Methods for solving problems

[0018] In order to solve the above-mentioned problems, in-depth research was conducted, and as a result, the inventors came up with the following invention and found that it can solve the problems.

[0019] That is, the present invention is as follows.

[0020] [1] A semi-aromatic polyamide resin comprising diamine units and dicarboxylic acid units,

[0021] The aforementioned diamine unit comprises, per 100 mol%, 60 to 100 mol% of an aliphatic diamine unit having 7 to 13 carbon atoms.

[0022] The dicarboxylic acid unit mentioned above comprises 60 to 100 mol% of aromatic dicarboxylic acid units per 100 mol% of the carboxylic acid unit mentioned above.

[0023] The specific logarithmic viscosity η measured in concentrated sulfuric acid at 30°C inh The concentration ranges from 1.6 to 3.0 dl / g.

[0024] The terminal amino group [NH2] content is 10–70 μequivalents / g.

[0025] The amount of terminal carboxyl group [COOH] is 10–90 μequivalents / g.

[0026] The ratio of the amount of terminal amino group [NH2] to the amount of terminal carboxyl group [COOH], i.e., [NH2] / [COOH], is 0.1 or more and less than 1.0.

[0027] [2] According to the semi-aromatic polyamide resin described in [1], the aliphatic diamine unit with 7 to 13 carbon atoms is selected from at least one of 1,10-decanediamine unit, 1,9-nonanediamine unit and 2-methyl-1,8-octanediamine unit.

[0028] [3] According to the semi-aromatic polyamide resin described in [1] or [2], wherein the above-mentioned specific logarithmic viscosity η inh It ranges from 1.7 to 2.5 dl / g.

[0029] [4] According to any of [1] to [3], the semi-aromatic polyamide resin, wherein the above-mentioned specific logarithmic viscosity η inh It ranges from 1.8 to 2.5 dl / g.

[0030] [5] The semi-aromatic polyamide resin described in any of [1] to [4], wherein the amount of terminal amino group [NH2] is 20 to 60 μ equivalents / g.

[0031] [6] The semi-aromatic polyamide resin described in any of [1] to [5], wherein the amount of terminal amino group [NH2] is 30 to 60 μ equivalents / g.

[0032] [7] The semi-aromatic polyamide resin described in any of [1] to [6], wherein the amount of terminal carboxyl group [COOH] is 30 to 80 μ equivalents / g.

[0033] [8] The semi-aromatic polyamide resin described in any of [1] to [7], wherein the [NH2] / [COOH] ratio is 0.2 to 0.9.

[0034] [9] A polyamide resin composition comprising a semi-aromatic polyamide resin as described in any of [1] to [6] and a crystallizing nucleating agent.

[0035]

[10] The polyamide resin composition according to [9] contains 0.01 to 10 parts by weight of the above-mentioned crystallizing nucleating agent relative to 100 parts by weight of the above-mentioned semi-aromatic polyamide resin.

[0036]

[11] A polyamide resin composition comprising a semi-aromatic polyamide resin as described in any of [1] to

[10] and an antioxidant.

[0037]

[12] The polyamide resin composition described in

[11] contains 0.01 to 5 parts by weight of the antioxidant described above relative to 100 parts by weight of the semi-aromatic polyamide resin described above.

[0038]

[13] A polyamide resin composition comprising a semi-aromatic polyamide resin, the semi-aromatic polyamide resin comprising a diamine unit and a dicarboxylic acid unit.

[0039] The aforementioned diamine unit comprises, per 100 mol%, 60 to 100 mol% of an aliphatic diamine unit having 7 to 13 carbon atoms.

[0040] The dicarboxylic acid unit mentioned above comprises 60 to 100 mol% of aromatic dicarboxylic acid units per 100 mol% of the carboxylic acid unit mentioned above.

[0041] The weight-average molecular weight (Mw) of the aforementioned semi-aromatic polyamide resin, calculated from polymethyl methacrylate by gel permeation chromatography (GPC), is 40,000–90,000.

[0042] The terminal amino group [NH2] content is 10–70 μequivalents / g.

[0043] The amount of terminal carboxyl group [COOH] is 10–90 μequivalents / g.

[0044] The ratio of the amount of terminal amino group [NH2] to the amount of terminal carboxyl group [COOH], i.e., [NH2] / [COOH], is 0.1 or more and less than 1.0.

[0045]

[14] The polyamide resin composition according to

[13] comprises at least one selected from crystal nucleating agents, antioxidants, lubrication modifiers and lubricants.

[0046]

[15] The polyamide resin composition according to

[14] contains, relative to 100 parts by weight of the above-mentioned semi-aromatic polyamide resin, 0.01 to 10 parts by weight of at least one of the above-mentioned nucleating agent, antioxidant, lubrication modifier and lubricant.

[0047]

[16] A molded article comprising the polyamide resin composition described in any of [9] to

[15] .

[0048]

[17] According to the molded article described in

[16] , it is a sliding component.

[0049]

[18] According to the molded product described in

[17] , it is a gear.

[0050]

[19] A method for manufacturing a semi-aromatic polyamide resin, comprising a diamine unit and a dicarboxylic acid unit, the method comprising:

[0051] The first reaction step involves subjecting a raw material containing an aliphatic diamine, an aromatic dicarboxylic acid, and a capping agent to a polycondensation reaction to obtain a primary polycondensation product; and

[0052] The second reaction step involves solid-state polymerization of the aforementioned primary condensation reactants to obtain the aforementioned semi-aromatic polyamide resin.

[0053] The ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the above raw materials, x / y, is greater than 1.01 and less than 1.03.

[0054] The amount of capping agent contained in the above raw materials is 0.1 to 1.5 mol% relative to 100 mol% of diamine contained in the raw materials.

[0055] Invention Effects

[0056] According to the present invention, a semi-aromatic polyamide resin with excellent fatigue resistance and retention stability during melt processing and a high molecular weight, and a polyamide resin composition containing the semi-aromatic polyamide resin, are provided. Detailed Implementation

[0057] The following description is based on an example of an embodiment of the present invention (hereinafter sometimes referred to as "this embodiment"). However, the embodiments shown below are illustrative examples used to embody the technical concept of the present invention, and the present invention is not limited to the following description.

[0058] Furthermore, while preferred embodiments are shown in this specification, combinations of two or more preferred embodiments are also preferred. Regarding the numerical ranges, when several numerical ranges exist, their lower and upper limits can be selectively combined to form preferred embodiments.

[0059] In this specification, when a numerical range of "XX~YY" is specified, it means "above XX and below YY".

[0060] In addition, in this specification, "~ unit" (here, "~" means monomer) means "structural unit derived from ~", for example, "dicarboxylic acid unit" means "structural unit derived from dicarboxylic acid", and "diamine unit" means "structural unit derived from diamine".

[0061] [Semi-aromatic polyamide resin]

[0062] The semi-aromatic polyamide resin of this embodiment comprises diamine units and dicarboxylic acid units. In this embodiment, the diamine units comprise 60 to 100 mol% of aliphatic diamines having 7 to 13 carbon atoms per 100 mol% of the diamine units, and the dicarboxylic acid units comprise 60 to 100 mol% of aromatic dicarboxylic acid units per 100 mol% of the dicarboxylic acid units.

[0063] (Diamine unit)

[0064] The aforementioned diamine unit comprises, per 100 mol%, 60 to 100 mol% of an aliphatic diamine unit having 7 to 13 carbon atoms. The aforementioned aliphatic diamine unit having 7 to 13 carbon atoms can be a linear diamine unit and / or a branched diamine unit. That is, the aforementioned aliphatic diamine unit having 7 to 13 carbon atoms can be at least one selected from linear diamine units and branched diamine units. The aforementioned aliphatic diamine unit having 7 to 13 carbon atoms can contain only one of linear diamine units or branched diamine units, or it can contain both linear diamine units and branched diamine units.

[0065] Examples of linear diamine units include those derived from at least one diamine unit selected from 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and 1,13-tetanediamine.

[0066] Examples of branched diamine units derived from 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, 4 A diamine unit selected from at least one of 5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 5-methyl-1,9-nonanediamine, 2-ethyl-1,7-heptanediamine, 2-ethyl-1,8-octanediamine, 2-propyl-1,6-hexanediamine, 2-propyl-1,7-heptanediamine, and 2,4-diethyl-1,6-hexanediamine.

[0067] From the viewpoints of low water absorption and heat resistance, the aliphatic diamine unit with 7 to 13 carbon atoms is preferably derived from at least one selected from 1,9-nonanediamine, 1,10-decanediamine, and 2-methyl-1,8-octanediamine, more preferably from a diamine unit derived from 1,9-nonanediamine and / or from a diamine unit derived from 2-methyl-1,8-octanediamine. That is, the aliphatic diamine unit with 7 to 13 carbon atoms is more preferably derived from at least one selected from 1,9-nonanediamine and 2-methyl-1,8-octanediamine. From the viewpoints of low water absorption and heat resistance, the aliphatic diamine unit with 7 to 13 carbon atoms is preferably derived from a diamine unit derived from 1,9-nonanediamine and a diamine unit derived from 2-methyl-1,8-octanediamine. When both the diamine unit derived from 1,9-nonanediamine and the diamine unit derived from 2-methyl-1,8-octanediamine are aliphatic diamine units with 7 to 13 carbon atoms, their molar ratio is preferably in the range of 95 / 5 to 40 / 60, more preferably in the range of 90 / 10 to 50 / 50.

[0068] The aforementioned diamine unit comprises, per 100 mol%, 60 to 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms. From the viewpoints of mechanical properties and heat resistance, it is preferable to include 70 to 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms, more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol%. The aforementioned diamine unit may comprise 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms.

[0069] The diamine unit described above may include diamine units derived from other diamines besides aliphatic diamine units, without impairing the effects of the present invention. Examples of diamine units derived from such other diamines include diamine units derived from at least one of alicyclic diamines and aromatic diamines.

[0070] Examples of diamine units derived from alicyclic diamines include diamine units derived from at least one of cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornenedimethylamine, and tricyclodecanedimethyldiamine.

[0071] Examples of diamine units derived from aromatic diamines include diamine units derived from at least one of p-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenyl ether.

[0072] The aforementioned diamine unit may contain only one type of diamine unit derived from these other diamines, or it may contain two or more types.

[0073] The content of the diamine unit derived from the other diamines in the diamine unit is less than 40 mol% relative to 100 mol% of the diamine unit, preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less.

[0074] The content of diamine units derived from the other diamines in the aforementioned diamine unit is preferably 0 mol% or more and less than 40 mol% relative to 100 mol% of the diamine unit, more preferably 0 mol% or more and less than 30 mol%, further preferably 0 mol% or more and less than 20 mol%, and even more preferably 0 mol% or more and less than 10 mol%. The content of diamine units derived from the other diamines in the aforementioned diamine unit may be 0 mol%.

[0075] (Dicarboxylic acid unit)

[0076] The dicarboxylic acid unit mentioned above contains 60 to 100 mol% of aromatic dicarboxylic acid units per 100 mol% of dicarboxylic acid unit.

[0077] Examples of aromatic dicarboxylic acid units include those derived from at least one of terephthalic acid, isophthalic acid, biphenylic acid, 4,4'-biphenyl dicarboxylic 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.

[0078] These structural units derived from aromatic dicarboxylic acid units may contain only one type or more than two types.

[0079] From the perspectives of mechanical properties, heat resistance, and reactivity with diamines, aromatic dicarboxylic acid units derived from terephthalic acid are preferred as the aforementioned aromatic dicarboxylic acid units.

[0080] Regarding the proportion of the aromatic dicarboxylic acid units contained in the aforementioned dicarboxylic acid unit, it comprises 60 mol% or more of the aromatic dicarboxylic acid units relative to 100 mol% of the aforementioned dicarboxylic acid unit. From the viewpoint 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 aforementioned dicarboxylic acid unit may be 100 mol%.

[0081] The dicarboxylic acid unit comprises, more preferably, 70 to 100 mol% of aromatic dicarboxylic acid units relative to 100 mol% of the dicarboxylic acid unit, more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol%.

[0082] The aforementioned dicarboxylic acid unit may include dicarboxylic acid units derived from dicarboxylic acids other than aromatic dicarboxylic acids, without impairing the effects of the present invention. Examples of such other dicarboxylic acids include aliphatic dicarboxylic acids and alicyclic dicarboxylic acids.

[0083] Examples of dicarboxylic acid units derived from aliphatic dicarboxylic acids include: dicarboxylic acid units derived from at least one of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic 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.

[0084] Examples of dicarboxylic acid units derived from alicyclic dicarboxylic acids include: dicarboxylic acid units derived from at least one of 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid.

[0085] The aforementioned dicarboxylic acid unit may contain only one dicarboxylic acid unit derived from these other dicarboxylic acids, or it may contain two or more.

[0086] The content of dicarboxylic acid units derived from the other dicarboxylic acids contained in the above-mentioned dicarboxylic acid units is less than 40 mol% relative to 100 mol% of the above-mentioned dicarboxylic acid units, preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less.

[0087] The content of dicarboxylic acid units derived from the other dicarboxylic acids in the above-mentioned dicarboxylic acid units is preferably 0 mol% or more and less than 40 mol% relative to 100 mol% of the above-mentioned dicarboxylic acid units, more preferably 0 mol% or more and less than 30 mol%, further preferably 0 mol% or more and less than 20 mol%, and even more preferably 0 mol% or more and less than 10 mol%. The content of diamine units derived from the other dicarboxylic acids in the above-mentioned dicarboxylic acid units may be 0 mol%.

[0088] In this embodiment, the ratio of the diamine units and dicarboxylic acid units in 100 mol% of the semi-aromatic polyamide resin (the ratio of the total moles of dicarboxylic acid units and diamine units to the total moles of all structural units constituting the polyamide resin) is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, can be 95 mol% or more, and can even be 100 mol%. By keeping the total ratio of diamine units and dicarboxylic acid units within the above range, it is possible to produce a semi-aromatic polyamide resin with superior mechanical properties and heat resistance.

[0089] The ratio of the diamine units and dicarboxylic acid units in 100 mol% of the semi-aromatic polyamide resin in this embodiment (the ratio of the total number of moles of dicarboxylic acid units and diamine units to the total 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 can be 95 mol% or more and 100 mol% or less, and even more preferably 100 mol%.

[0090] (Aminocarboxylic acid unit)

[0091] In addition to the diamine unit and the dicarboxylic acid unit described above, the semi-aromatic polyamide resin of this embodiment may further contain an aminocarboxylic acid unit.

[0092] Examples of aminocarboxylic acid units include: lactams such as acetamide and lauryl lactam; and at least one aminocarboxylic acid unit derived from 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 unit and the dicarboxylic acid unit in the above-mentioned semi-aromatic polyamide resin.

[0093] Relative to the total of 100 mol% of the diamine unit and the dicarboxylic acid unit in the semi-aromatic polyamide resin, the content of the aminocarboxylic acid unit in the semi-aromatic polyamide resin is preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 20 mol% or less, further preferably 0 mol% or more and 10 mol% or less, and even more preferably 0 mol% or more and 5 mol% or less.

[0094] (Polycarboxylic acid unit)

[0095] Without impairing the effects of the present invention, the semi-aromatic polyamide resin of this embodiment may also contain structural units derived from polycarboxylic acids of 3 or more, such as trimellitic acid, pyromellitic acid, and pyromellitic tetracarboxylic acid, within the range where melt molding is possible.

[0096] (End-of-terminal rate)

[0097] From the viewpoint of melt stability and hydrolysis resistance, the semi-aromatic polyamide resin of this embodiment preferably has its terminal groups on the molecular chain capped. The capping of the terminal groups can be performed using a capping agent. Details of the capping agent will be described below. Furthermore, the proportion of all terminal groups on the molecular chain of the aforementioned semi-aromatic polyamide resin that are capped is called the capping rate. This capping rate is preferably 5 mol% or more, more preferably 10 mol% or more. Furthermore, from the viewpoint of obtaining a semi-aromatic polyamide resin with a higher molecular weight, the capping rate is preferably 40 mol% or less, more preferably 30 mol% or less. The above-mentioned capping rate is preferably 5 to 40 mol%, more preferably 10 to 30 mol%, and even more preferably 10 to 20 mol%.

[0098] The end-capping rate of the aforementioned semi-aromatic polyamide resin can be determined by measuring the amount of terminal carboxyl groups, terminal amino groups, and the amount of terminal groups capped by the end-capping agent in the semi-aromatic polyamide resin, and then by using the following formula (1). It should be noted that in formula (1), A represents the total amount of terminal groups (which is 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.

[0099] End capping rate (%) = [(AB) / A] × 100 Equation (1)

[0100] In this specification, the amounts of the aforementioned terminal groups in the semi-aromatic polyamide resin of this embodiment refer to the amounts of the semi-aromatic polyamide resin dissolved in deuterated 1,1,1,3,3,3-hexafluoroisopropanol under conditions of 600 MHz and 50°C. 1 The value is calculated based on the integral of the characteristic signals of each terminal group using ¹H-NMR analysis. More specifically, it can be obtained using the method described in the examples.

[0101] (Specific viscosity logarithmic viscosity of semi-aromatic polyamide resin)

[0102] The specific viscosity logarithmic viscosity η of the semi-aromatic polyamide resin in this embodiment is... inh The specific viscosity is 1.6–3.0 dl / g. The above specific logarithmic viscosity η... inh Preferably, it is 1.7 dl / g or more, more preferably 1.8 dl / g or more, and even more preferably 1.9 dl / g or more. This is achieved by adjusting the above-mentioned specific viscosity logarithmic viscosity η. inh Within the aforementioned range, it is possible to produce semi-aromatic polyamide resins with superior fatigue resistance. Furthermore, the aforementioned specific logarithmic viscosity η... inh Preferably, it is 2.7 dl / g or less, more preferably 2.5 dl / g or less, and even more preferably 2.3 dl / g or less. This is achieved by adjusting the specific viscosity logarithmic viscosity η. inh Within the above range, semi-aromatic polyamide resins with excellent formability and retention stability can be produced. The above-mentioned specific logarithmic viscosity η... inh Preferably, it is 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.

[0103] The above specific logarithmic viscosity η inh The time it takes for a solution using concentrated sulfuric acid (0.2 g / dL) at 30°C as a solvent to flow down can be determined. More specifically, it can be determined using the method described in the examples.

[0104] (Amount of terminal amino groups)

[0105] The semi-aromatic polyamide resin of this embodiment has a terminal amino group content [NH2] of 10 to 70 μequivalents / g. The terminal amino group content [NH2] is preferably 15 μequivalents / g or more, more preferably 20 μequivalents / g or more, further preferably 30 μequivalents / g or more, and even more preferably 40 μequivalents / g or more. By keeping the terminal amino group content [NH2] within the above range, the specific logarithmic viscosity η, representing the molecular weight of the semi-aromatic polyamide resin, is obtained.inh The desired range is achieved, resulting in superior fatigue resistance. Furthermore, the amount of terminal amino groups [NH2] is preferably 60 μe / g or less, more preferably 50 μe / g or less, and even more preferably 45 μe / g or less. By keeping the amount of terminal amino groups [NH2] within the above range, cross-linking between the terminal amino groups during melt processing is suppressed, enabling the production of a polyamide resin with excellent retention stability. The amount of terminal amino groups [NH2] is preferably 10–60 μe / g, more preferably 10–50 μe / g, even more preferably 15–50 μe / g, and even more preferably 15–45 μe / g.

[0106] (Amount of terminal carboxyl groups)

[0107] The semi-aromatic polyamide resin of this embodiment has a terminal carboxyl group content [COOH] of 10 to 90 μequivalents / g. The terminal carboxyl group content [COOH] is preferably 20 μequivalents / g or more, more preferably 30 μequivalents / g or more, further preferably 40 μequivalents / g or more, and even more preferably 55 μequivalents / g or more. By keeping the terminal carboxyl group content [COOH] within the above range, the specific logarithmic viscosity η, representing the molecular weight of the semi-aromatic polyamide resin, is obtained. inh The desired range is achieved, resulting in superior fatigue resistance. Furthermore, the terminal carboxyl group content [COOH] is preferably 85 μe / g or less, more preferably 80 μe / g or less. By keeping the terminal carboxyl group content [COOH] within the above range, hydrolysis during melt processing is suppressed, enabling the production of a semi-aromatic polyamide resin with excellent retention stability. The terminal carboxyl group content [COOH] is preferably 20–85 μe / g, more preferably 30–80 μe / g, further preferably 40–80 μe / g, and even more preferably 55–80 μe / g.

[0108] In this embodiment, the aforementioned amount of terminal amino groups [NH2] refers to the amount of terminal amino groups contained in 1g of semi-aromatic polyamide resin (unit: μ equivalent / g). Furthermore, the aforementioned amount of terminal carboxyl groups [COOH] refers to the amount of terminal carboxyl groups contained in 1g of semi-aromatic polyamide resin (unit: μ equivalent / g).

[0109] In this specification, the aforementioned amount of terminal amino groups [NH2] and terminal carboxyl groups [COOH] in the semi-aromatic polyamide resin of this embodiment refer to: the amount of terminal amino groups [NH2] and terminal carboxyl groups [COOH] in the semi-aromatic polyamide resin dissolved in deuterated 1,1,1,3,3,3-hexafluoroisopropanol under conditions of 600 MHz and 50°C. 1 The value is calculated based on the integral of the characteristic signals of each terminal group using ¹H-NMR analysis. More specifically, it can be obtained using the method described in the examples.

[0110] In this embodiment, the ratio of the amount of terminal amino groups [NH2] to the amount of terminal carboxyl groups [COOH], i.e., [NH2] / [COOH], is 0.1 or more and less than 1.0. The [NH2] / [COOH] ratio 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. By setting the [NH2] / [COOH] ratio within the above range, the specific viscosity η, representing the molecular weight of the semi-aromatic polyamide resin, is obtained. inh This results in a range that meets expectations, thus exhibiting superior fatigue resistance. Furthermore, it enables the production of semi-aromatic polyamide resins with suppressed crosslinking and hydrolysis between terminal amino groups during melt processing, and excellent retention stability.

[0111] (weight-average molecular weight)

[0112] From the viewpoint of fatigue resistance, the weight-average molecular weight of the semi-aromatic polyamide resin in this embodiment is preferably 40,000 or more, more preferably 45,000 or more, and even more preferably 50,000 or more. Furthermore, from the viewpoint of formability, the weight-average molecular weight of the above-mentioned 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 above-mentioned 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.

[0113] (Rate of decrease in weight-average molecular weight)

[0114] The reduction rate of the weight-average molecular weight (hereinafter also referred to as Mw) of the semi-aromatic polyamide resin before and after melt blending in this embodiment is preferably 20% or less. This improves retention stability. Regarding melt blending, the semi-aromatic polyamide resin can be melt blended alone, or it can be melt blended with other components to form a composition. The aforementioned reduction rate of weight-average molecular weight is calculated using the following formula (2). In this formula (2), Mw0 is the weight-average molecular weight before melt blending, and Mw1 is the weight-average molecular weight after melt blending using a twin-screw extruder at a barrel temperature of 320–325°C.

[0115] The rate of decrease in weight-average molecular weight = (Mw0 - Mw1) × 100 / Mw 0　 Equation (2)

[0116] From the viewpoint of the mechanical properties of the melt-mixed product and the appearance of the molded product, the reduction rate of the weight-average molecular weight is more preferably 18% or less, and even more preferably 15% or less. Here, the melt mixing is performed using a twin-screw extruder "BTN-32-S2-30-L" manufactured by Research Laboratory of Plastics Technology Co., Ltd., with a barrel temperature of 320 to 325°C and a residence time of 1 to 5 minutes. More specifically, it can be carried out by the method described in the examples.

[0117] Furthermore, in this specification, the weight-average molecular weight of the semi-aromatic polyamide resin is a value obtained using gel permeation chromatography (GPC) in the form of a molecular weight converted from standard polymethyl methacrylate. More specifically, it can be obtained using the methods described in the examples.

[0118] (Melting point)

[0119] The melting point of the semi-aromatic polyamide resin in this embodiment is preferably 250°C or higher, more preferably 280°C or higher, and even more preferably 290°C or higher. By keeping the melting point within the above range, a semi-aromatic polyamide resin with excellent heat resistance can be produced. There is no particular limitation on the upper limit of the melting point of the above-mentioned semi-aromatic polyamide resin; however, considering factors such as formability, 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 above-mentioned semi-aromatic polyamide resin is preferably 250–330°C, more preferably 280–320°C, even more preferably 290–320°C, and even more preferably 290–310°C.

[0120] In this specification, the melting point of the aforementioned semi-aromatic polyamide resin is a value determined as the peak temperature of the endothermic peak that appears when the temperature is increased at a rate of 10°C / min using a differential scanning calorimetry (DSC) apparatus. More specifically, it can be determined by the method described in the examples.

[0121] (Heat of fusion)

[0122] The heat of dissolution ΔHm of the semi-aromatic polyamide resin in this embodiment is preferably 20 mJ / mg or more, more preferably 30 mJ / mg or more, and even more preferably 40 mJ / mg or more. By keeping the heat of dissolution ΔHm within the above range, the crystallinity of the semi-aromatic polyamide resin is increased, and a semi-aromatic polyamide resin with excellent rigidity and wear resistance can be produced. The higher the heat of dissolution ΔHm of the semi-aromatic polyamide resin, the more preferred it is. From the viewpoint of formability, 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 dissolution ΔHm is preferably 20 to 80 mJ / mg, more preferably 30 to 70 mJ / mg, even more preferably 30 to 60 mJ / mg, and even more preferably 40 to 60 mJ / mg, and even more preferably 40 to 50 mJ / mg.

[0123] In this specification, the heat of fusion ΔHm of the aforementioned semi-aromatic polyamide resin is a value obtained using differential scanning calorimetry (DSC) as the peak area of ​​the endothermic peak that appears when the temperature is increased at a rate of 10°C / min. More specifically, it can be obtained using the method described in the examples.

[0124] (Manufacturing method of semi-aromatic polyamide resin)

[0125] Preferably, the method for manufacturing the semi-aromatic polyamide resin of this embodiment includes: a first reaction step, wherein a raw material containing an aliphatic diamine, an aromatic dicarboxylic acid and a capping agent is subjected to a polycondensation reaction to obtain a primary polycondensation product; and a second reaction step, wherein the primary polycondensation product is subjected to solid-state polymerization to obtain a semi-aromatic polyamide resin, wherein the ratio (x / y) of the number of moles of amino groups to the number of moles of carboxyl groups contained in the raw material is greater than 1.010 and less than 1.030, and the amount of the capping agent contained in the raw material is 0.1 to 1.5 moles relative to 100 mol% of the diamine contained in the raw material.

[0126] (raw material)

[0127] In the first reaction step, a raw material comprising an aliphatic diamine, an aromatic dicarboxylic acid, and a capping agent is melt-polymerized to induce a polycondensation reaction. It should be noted that a raw material preparation step can be performed before the first reaction step. The raw material preferably comprises an aliphatic diamine, an aromatic dicarboxylic acid, and a capping agent. Furthermore, the raw material preferably includes a catalyst and other components as needed. At this time, the ratio (x / y) of the molar number of amino groups to the molar number of carboxyl groups in the above-mentioned raw material is greater than 1.01 and less than 1.03, preferably 1.015 to 1.025, more preferably 1.02 to 1.03. By keeping the above ratio (x / y) within the above range, the disruption of the molar balance of the raw material caused by the volatilization of at least one of the aliphatic diamine and the aromatic dicarboxylic acid can be suppressed, and the specific logarithmic viscosity η... inh The manufacture of semi-aromatic polyamide resins with the amount of each terminal group within the desired range becomes easier.

[0128] It should be noted that the above molar number of amino groups (x) is the total molar number of each amino group derived from aliphatic diamines, amino-containing capping agents, and other components. Similarly, the above molar number of carboxyl groups (y) is the total molar number of each carboxyl group derived from aromatic carboxylic acids, carboxyl-containing capping agents, and other components.

[0129] (End-capping agent)

[0130] When manufacturing the semi-aromatic polyamide resin of this embodiment, it is preferable to include a capping agent in the raw materials.

[0131] The amount of the capping agent contained in the raw material 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 the diamine units contained in the raw material. Furthermore, it is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, and even more preferably 0.7 mol% or more. By keeping the content of the capping agent within the above range, it is possible to produce a high molecular weight polyamide resin with superior mechanical properties. The amount of the capping agent is preferably 0.1 to 5.0 mol% relative to 100 mol% of the diamine units contained in the raw material, more preferably 0.5 to 3.0 mol%, and even more preferably 0.7 to 1.5 mol%.

[0132] As capping agents, monofunctional compounds that react with the amino or carboxyl groups at the ends of the molecular chains of semi-aromatic polyamide resins can be used. Specifically, examples include monocarboxylic acids, acid anhydrides, monoisocyanates, monoacyl halides, monoesters, monoalcohols, and monoamines. From the viewpoints of reactivity and capping stability, monocarboxylic acids are preferred as capping agents targeting amino groups. Furthermore, monoamines are preferred as capping agents targeting carboxyl groups. From the viewpoint of ease of operation, monocarboxylic acids are more preferred as capping agents.

[0133] As a monocarboxylic acid used as a capping agent, there are no particular limitations as long as it is reactive with an amino group. Examples include: aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, tervaric acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclopentanecarboxylic acid and cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthoic acid, β-naphthoic acid, methylnaphthoic acid, and phenylacetic acid; and any mixture thereof. Among these, from the perspectives of reactivity, stability of the capping end, and price, it is preferred to select at least one from acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid.

[0134] The monoamine used as a capping agent is not particularly limited as long as it is reactive with a carboxyl group. Examples 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 mixture thereof. Among these, at least one selected from butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline is preferred from the perspectives of reactivity, high boiling point, stability of the capping end, and price.

[0135] (catalyst)

[0136] A catalyst may be added when manufacturing the semi-aromatic polyamide resin of this embodiment.

[0137] The amount of catalyst used relative to the total mass of the raw materials 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. If the amount of catalyst used is at or above the lower limit, polymerization proceeds well. If it is below the upper limit, impurities originating from the catalyst are less likely to be generated; for example, when extruding a polyamide resin composition containing the semi-aromatic polyamide resin of the present invention, adverse conditions caused by the aforementioned impurities can be prevented. The amount of catalyst used relative to the total mass of the raw materials is preferably 0.01 to 1.0% by mass, more preferably 0.05 to 0.5% by mass.

[0138] As a catalyst, phosphoric acid, phosphorous acid, hypophosphorous acid, their salts or esters can be used. Examples of salts or esters include: salts of phosphoric acid, phosphorous acid, or hypophosphorous acid with metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony; ammonium salts of phosphoric acid, phosphorous acid, or hypophosphorous acid; and ethyl, isopropyl, butyl, hexyl, isodecyl, octadecyl, decyl, stearyl, and phenyl esters of phosphoric acid, phosphorous acid, or hypophosphorous acid.

[0139] (First reaction process)

[0140] In the first reaction step described above, a primary condensation product is obtained. Specifically, a primary condensation product is obtained by melt polymerization of a raw material containing an aliphatic diamine, an aromatic dicarboxylic acid, and a capping agent. The raw material only needs to contain the aliphatic diamine, the aromatic dicarboxylic acid, and the capping agent; they can be mixed all at once or added separately later. Heating polymerization is preferred during the condensation reaction. The polymerization temperature is preferably 200–270°C, more preferably 240–260°C. By keeping the polymerization temperature within this range, the degree of polymerization of the primary condensation product increases, which can suppress the melting or agglomeration of the condensation product in subsequent solid-state polymerization processes, and prevent the disruption of the molar balance between the dicarboxylic acid and diamine components.

[0141] (Second reaction process)

[0142] In the second reaction step described above, a semi-aromatic polyamide resin is obtained. Specifically, the semi-aromatic polyamide resin is obtained by solid-state polymerization of the primary condensation reactant. As a method for solid-state polymerization, it is preferable to perform solid-state polymerization of the primary condensation reactant 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, more preferably 215°C or higher, and even more preferably 230°C or higher. The solid-state polymerization method is preferably a heating and stirring method where heating and stirring are performed simultaneously. As a heating and stirring method, any method that can uniformly heat and stir is acceptable; for example, a horizontal heating and stirring apparatus can be used.

[0143] If the solid-state polymerization temperature is below 200℃, the desired molecular weight (specific viscosity η) will be achieved. inh This process requires a long time and reduces productivity. On the other hand, if the solid-state polymerization temperature is above the melting point of the primary condensation reactant, it can easily cause the primary condensation reactant to fuse, agglomerate, adhere to the vessel wall, become discolored, or have its molar balance disrupted due to the volatilization of the dicarboxylic acid and diamine components that form the primary condensation reactant. Therefore, it is preferable to carry out the solid-state polymerization of the primary condensation reactant at a temperature range of 100°C to 40°C lower than the melting point of the primary condensation reactant.

[0144] Furthermore, from the viewpoint of suppressing the deterioration of semi-aromatic polyamide resins caused by oxygen at high temperatures and obtaining high-molecular-weight semi-aromatic polyamide resins with excellent quality, specifically with suppressed yellowing of the resin itself and narrow molecular weight distribution, it is preferable to carry out solid-phase polymerization of the condensation reaction product under reduced pressure or under inactive gas flow.

[0145] [Polyamide resin composition]

[0146] As one embodiment of this invention, the aforementioned semi-aromatic polyamide resin can be used to prepare a polyamide resin composition. The polyamide resin composition is prepared by at least combining the aforementioned semi-aromatic polyamide resin.

[0147] The above-mentioned polyamide resin composition preferably contains 50% by mass and less than 100% by mass of the above-mentioned 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 keeping the content of the above-mentioned semi-aromatic polyamide resin within the above range, a polyamide resin composition with excellent retention stability and heat aging resistance during molding can be produced.

[0148] (Crystallization nucleating agent)

[0149] The polyamide resin composition of this embodiment preferably comprises the above-mentioned semi-aromatic polyamide resin and a crystallizing nucleating agent.

[0150] The above-mentioned polyamide resin composition preferably contains 0.01 to 10 parts by weight of a crystallizing nucleating agent relative to 100 parts by weight of the above-mentioned semi-aromatic polyamide resin, more preferably 0.1 to 5 parts by weight, even more preferably 1 to 5 parts by weight, and even more preferably 1 to 3 parts by weight. By keeping the content of the crystallizing nucleating agent within the above range, a polyamide resin composition with excellent mechanical strength and wear resistance can be produced.

[0151] Examples of nucleating agents for crystallization include: metal oxides such as zinc oxide, magnesium oxide, iron oxide, antimony oxide, titanium oxide, aluminum oxide, and silicon dioxide; 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 acidic 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 elements such as zinc powder, aluminum powder, graphite powder, and carbon black; aluminum p-tert-butylbenzoate, sodium bis(4-tert-butylphenyl) phosphate, sodium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate, and aluminum di(tert-tert-butylbenzoic acid) hydroxide. These nucleating agents can be used individually or in combination of two or more.

[0152] From the perspective of superior mechanical strength and wear resistance, talc is the preferred choice.

[0153] The average particle size of the above-mentioned nucleating agent is preferably 0.01 to 20 μm or less, more preferably 0.5 to 15 μm or less, and even more preferably 1 to 10 μm or less. By ensuring that the average particle size of the above-mentioned nucleating agent is within the above-mentioned range, the formation of crystal nuclei in the above-mentioned semi-aromatic polyamide resin is promoted, thereby enabling the production of a polyamide resin composition with excellent mechanical strength and wear resistance.

[0154] The average particle size of the aforementioned nucleating agents can be obtained by the following method: A molded article containing a polyamide resin composition with nucleating agents is dissolved in a solvent such as formic acid, which dissolves polyamide. The insoluble components obtained are observed using an optical microscope, scanning electron microscope, etc. The average particle size can be obtained by averaging the maximum Feretta diameters of more than 100 nucleating agents. It should be noted that the Feretta diameter refers to the distance between two parallel straight lines when the nucleating agent is sandwiched between them.

[0155] The aforementioned nucleating agents can be treated with silane coupling agents, titanium coupling agents, etc., as needed. There are no particular limitations on the silane coupling agents used; examples include: aminosilane-based coupling agents such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; mercaptosilane-based coupling agents such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; epoxysilane-based coupling agents; and vinylsilane-based coupling agents. These silane coupling agents can be used alone or in combination of two or more.

[0156] (Antioxidants)

[0157] The polyamide resin composition of this embodiment preferably includes the above-mentioned semi-aromatic polyamide resin and an antioxidant.

[0158] The above-mentioned polyamide resin composition preferably contains 0.01 to 5 parts by weight of antioxidant relative to 100 parts by weight of the above-mentioned semi-aromatic polyamide resin, more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 2 parts by weight. By keeping the content of the antioxidant within the above range, a polyamide resin composition with excellent retention stability and heat aging resistance during molding can be produced.

[0159] Examples of antioxidants mentioned above include organic antioxidants such as phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and amine antioxidants, as well as inorganic antioxidants such as copper compounds and halides.

[0160] The antioxidants described above can be used alone or in combination of two or more. From the viewpoint of excellent heat aging resistance, at least one of the antioxidants is preferred, selected from phenolic antioxidants, amine antioxidants, and combinations of copper compounds and halides.

[0161] Examples of phenolic antioxidants include: 2,2-thio-diethylidene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, hexamethylenebis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, and hexamethylenebis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Tris(3,5-di-tert-butyl-4-hydroxy-5-methylphenyl)propionate, 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, etc.

[0162] From the viewpoint of the heat resistance of the obtained polyamide resin composition, the phenolic antioxidant is preferably selected from at least one of N,N'-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide and 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionoxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0163] Examples of phosphorus-based antioxidants include: monosodium phosphate, disodium phosphate, trisodium phosphate, sodium phosphite, calcium phosphite, magnesium phosphite, manganese phosphite, pentaerythritol-type phosphite compounds, trioctyl phosphite, trilauryl phosphite, octyl diphenyl phosphite, triisodecyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isoodecyl phosphite, diphenyl (tridecyl) phosphite, triphenyl phosphite, tri(octadecyl) phosphite, tridecyl phosphite, tri(nonylphenyl) phosphite, tri(2,4-di-tert-butylphenyl) phosphite, and tri(2,4-di-tert-butyl-5-methylphenyl) phosphite. Tris(butoxyethyl) phosphite, 4,4'-butylene-bis(3-methyl-6-tert-butylphenyl-tetra(tetrazyl)) diphosphite, tetra(C12-C15 mixed alkyl)-4,4'-isopropylene diphenyl diphosphite, 4,4'-isopropylene bis(2-tert-butylphenyl)·di(nonylphenyl) phosphite, tris(biphenyl) phosphite, tetra(tetrazyl)-1,1,3-tris(2-methyl-5-tert-butyl-4-hydroxyphenyl)butane diphosphite, tetra(tetrazyl)-4,4'-butylene bis(3-methyl-6-tert-butylphenyl) diphosphite, tetra(C1-C15 mixed alkyl)-4,4'-isopropylene diphenyl Diphosphite, tris(mono- and di-mixed nonylphenyl) phosphite, 4,4'-isopropylidene bis(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'-isopropylidene diphenyl polyphosphite, bis(octylphenyl)·bis(4,4'-butylidene bis(3-methyl-6-tert-butylphenyl))·1,6-hexanol diphosphite, hexa(tetranyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl) diphosphite, tris(4,4'-isopropylidene bis(2-tert-butylphenyl) Phosphite, tris(1,3-stearoyloxyisopropyl) phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, 2,2-methylenebis(3-methyl-4,6-di-tert-butylphenyl)-2-ethylhexyl phosphite, tetra(2,4-di-tert-butyl-5-methylphenyl)-4,4'-biphenyl diphosphite, tetra(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphite, 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]-diphosphaheptan (Japanese: オキサホスフェピン), etc.

[0164] Examples of sulfur-based antioxidants include: distearate 3,3'-thiodipropionate, pentaerythritol tetra(3-lauryl thiopropionate), 2-mercaptobenzimidazole, di(dodecyl) 3,3'-thiodipropionate, di(tetrazyl) 3,4'-thiodipropionate, and 2,2-bis[[3-(dodecylthio)-1-oxopropoxy]methyl]-1,3-propanediol ester.

[0165] Examples of amine-based antioxidants include: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (NOCRAC CD manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., and Naugard445 manufactured by Addivant Japan Co., Ltd.), N,N'-di-2-naphthyl-p-phenylenediamine (NOCRAC White manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), N,N'-diphenyl-p-phenylenediamine (NOCRAC DP manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), N-phenyl-1-naphthylamine (NOCRAC PA manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), N-phenyl-N'-isopropyl-p-phenylenediamine (NOCRAC 810-NA manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (NOCRAC 810-NA manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.). 6C” etc.), N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine (NOCRAC G-1 etc. manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.), 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(phenylacetoxy)-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine Methylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-(ethylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(cyclohexylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(phenylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, bis(2,2,6,6) 1,2-Tetramethyl-4-piperidinyl) carbonate, bis(2,2,6,6-tetramethyl-4-piperidinyl) oxalate, bis(2,2,6,6-tetramethyl-4-piperidinyl) malonate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) adipate, bis(2,2,6,6-tetramethyl-4-piperidinyl) terephthalate, 1,2-bis(2,2,6,6-tetramethyl-4-piperidinyl) terephthalate Methyl-4-piperidinoxy)ethane, α,α'-bis(2,2,6,6-tetramethyl-4-piperidinoxy)-p-xylene, bis(2,2,6,6-tetramethyl-4-piperidinyl)methylphenylene-2,4-dicarbamate, bis(2,2,6,6-tetramethyl-4-piperidinyl)hexamethylene-1,6-dicarbamate, tris(2,2,6,6-tetramethyl-4-piperidinyl)benzene-1,3,5-tricarbamate, tris(2,2,Condensates of 6,6-tetramethyl-4-piperidinyl)benzene-1,3,4-tricarboxylate, 1-[2-{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy}butyl]-4-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]2,2,6,6-tetramethylpiperidine, condensates of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol with β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]undecane]diethanol, etc.

[0166] From the viewpoint of the heat resistance of the obtained polyamide resin composition, the above-mentioned amine antioxidant is preferably 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0167] Examples of the aforementioned copper compounds include: copper halides, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, and copper complex salts coordinated with chelating agents such as ethylenediamine and ethylenediaminetetraacetic acid. Examples of the aforementioned copper halides include: copper iodide; copper bromide such as cuprous bromide and copper bromide; and copper chloride such as cuprous chloride. From the viewpoint of excellent heat aging resistance and ability to suppress metal corrosion of the screw or barrel during extrusion, it is preferable that at least one of copper halides and copper acetate is selected, more preferably that at least one of copper iodide, copper bromide, copper chloride, and copper acetate is selected, and even more preferably that at least one of copper iodide, copper bromide, and copper acetate is selected.

[0168] As the aforementioned halide, a halide not belonging to the aforementioned copper compounds can be used, preferably a salt of a metal element from Group 1 or Group 2 of the periodic table and a halogen. Examples include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. Among these, from the viewpoint that the obtained polyamide resin composition has excellent high-temperature heat resistance, such as heat aging resistance, and can inhibit metal corrosion, it is preferable to select at least one of potassium iodide and potassium bromide, and more preferably potassium iodide.

[0169] From the viewpoint that the obtained polyamide resin composition has excellent high-temperature heat resistance, such as heat aging resistance, it is preferable to use the above-mentioned copper compound and the above-mentioned halide together.

[0170] The polyamide resin composition of this embodiment may contain a semi-aromatic polyamide resin and at least one selected from crystal nucleating agents and antioxidants.

[0171] (Slip modifier)

[0172] The polyamide resin composition of this embodiment preferably includes a lubrication modifier. The polyamide resin composition preferably contains 0.01 to 10 parts by weight of the lubrication modifier per 100 parts by weight of the semi-aromatic polyamide resin, more preferably 0.05 to 7 parts by weight, even more preferably 0.1 to 5 parts by weight, and even more preferably 1 to 4 parts by weight. This improves the lubrication of the molded article containing the polyamide resin composition.

[0173] Examples of sliding modifiers include: polytetrafluoroethylene (PTFE), PTFE-perfluoroalkoxyethylene copolymer, PTFE-polyhexafluoropropylene copolymer, and other fluororesins; (high molecular weight) polyethylene; oxidized polyethylene; acid-modified (ultra-high molecular weight) polyethylene; polypropylene; acid-modified polypropylene; copolymer polyolefins; acid-modified copolymer polyolefins, and other polyolefins; polydimethylsiloxane; polymethylphenylsiloxane; amino-modified polydimethylsiloxane; epoxy-modified polydimethylsiloxane; alcohol-modified polydimethylsiloxane; and carboxyl-modified polydimethylsiloxane. The lubrication modifiers include organosilicones such as fluorinated polydimethylsiloxane, layered inorganic compounds such as graphite and molybdenum disulfide, inorganic fibers such as glass fiber, potassium titanate whiskers, zinc oxide whiskers, and borate whiskers, organic fibers such as LCP fiber, aramid fiber, and carbon fiber, inorganic particles such as alumina, talc, and silica, phosphates such as metaphosphate, pyrophosphate, calcium phosphate, dicalcium phosphate, barium phosphate, lithium phosphate, calcium metaphosphate, and zinc pyrophosphate, mineral oils such as spindle oil, turbine oil, engine oil, and generator oil, and lignite salts such as calcium lignite. These lubrication modifiers can be used individually or in combination of two or more.

[0174] Among the above-mentioned lubrication modifiers, from the viewpoint of having a greater effect on reducing wear and friction coefficient, fluoropolymers, oxidized polyethylene, acid-modified (ultra-high molecular weight) polyethylene, acid-modified copolymer polyolefins, molybdenum disulfide, and aromatic polyamide fibers are preferred.

[0175] Furthermore, the polyamide resin composition of this embodiment preferably comprises a semi-aromatic polyamide resin and at least one selected from a crystallizing nucleating agent, an antioxidant, and a lubrication modifier. In this case, it may also be contained in the preferred amounts described above.

[0176] (Other additives)

[0177] The polyamide resin composition of this embodiment may include other additives as needed. Examples of other additives include: lubricants, inorganic fillers, impact modifiers, mold release agents, colorants, plasticizers, ultraviolet absorbers, light stabilizers, oxygen absorbers, hydrogen sulfide adsorbents, flame retardants, flame retardant additives, antistatic agents, crystallization delay agents, organic fibrous fillers, etc.

[0178] The content of the other additives mentioned above is not particularly limited within the range that does not impair the effect of the present invention. It is preferably 0.01 to 200 parts by weight relative to 100 parts by weight of the semi-aromatic polyamide resin, and more preferably 0.02 to 100 parts by weight.

[0179] The content of the aforementioned lubricant relative to 100 parts by weight of the aforementioned semi-aromatic polyamide resin is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight. This improves the flowability of the polyamide resin composition and the appearance and release properties of the molded article containing the polyamide resin composition.

[0180] Examples of such lubricants include, for instance, higher fatty acids with 8 or more carbon atoms such as stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, and limonite; higher fatty acid metal salts such as calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, calcium limonite, sodium limonite, aluminum limonite, zinc limonite, magnesium limonite, 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 stearamide, oleamide, erucamide, ethylene bis-stearamide, ethylene bis-oleamide, N-stearyl stearamide, and N-stearyl erucamide; and polyolefins such as polyethylene, oxidized polyethylene, acid-modified polyethylene, polypropylene, and acid-modified polypropylene. These lubricants can be used alone or in combination of two or more.

[0181] Among the above-mentioned lubricants, from the viewpoint of excellent heat resistance and formability, metal stearate salts, metal lignite salts, ethylene bis-stearamides, and polyolefins are preferred.

[0182] Examples of inorganic fillers mentioned above include: fibrous fillers such as glass fiber, carbon fiber, calcium silicate fiber, potassium titanate fiber, aluminum borate fiber, and wollastonite; and fibrous fillers such as glass flakes, silicon nitride, hydrotalcite zeolite, boehmite, aluminum hydroxide, calcium silicate, sodium aluminosilicate, carbon nanotubes, graphene, brass, copper, silver, nickel, iron, calcium fluoride, montmorillonite, swelling fluoromica, and apatite. These inorganic fillers can be used individually or in combination of two or more.

[0183] From the viewpoint of excellent formability and mechanical strength, at least one of the inorganic fillers mentioned above is preferably selected from fibrous fillers.

[0184] Further, as another mode, the polyamide resin composition of the present embodiment contains a semi-aromatic polyamide resin, the semi-aromatic polyamide resin containing diamine units and dicarboxylic acid units, the diamine units containing 60 to 100 mol% of aliphatic diamine units having 7 to 13 carbon atoms with respect to 100 mol% of the diamine units, and the dicarboxylic acid units containing 60 to 100 mol% of aromatic dicarboxylic acid units with respect to 100 mol% of the carboxylic acid units. Further, the weight-average molecular weight Mw in terms of polymethyl methacrylate measured by gel permeation chromatography (GPC) of the semi-aromatic polyamide resin is 40,000 to 90,000, the terminal amino group amount [NH2] is 10 to 70 μeq / g, the terminal carboxyl group amount [COOH] is 10 to 90 μeq / g, and the ratio of the terminal amino group amount [NH2] to the terminal carboxyl group amount [COOH], i.e., [NH2] / [COOH], is 0.1 or more and less than 1.0.

[0185] The preferred mode of the semi-aromatic polyamide resin contained in the polyamide resin composition of the present embodiment as another mode is the same as the preferred mode described in the above [Semi-aromatic polyamide resin].

[0186] However, the terminal amino group amount [NH2] and the terminal carboxyl group amount [COOH] in the semi-aromatic polyamide resin contained in the polyamide resin composition of the present embodiment as another mode are values calculated by a titration method. More specifically, the terminal amino group amount [NH2] is a value calculated by titration using an aqueous HCl solution having a 0.01 or 0.1 normal concentration (Japanese: 規定) with thymol blue as an indicator, and the terminal carboxyl group amount [COOH] is a value calculated by titration using a potassium hydroxide / ethanol solution having a 0.01 or 0.1 normal concentration with a potentiometric titration apparatus. Even more specifically, it can be obtained by the method described in the examples.

[0187] In another embodiment, the polyamide resin composition preferably contains at least one selected from a nucleating agent, an antioxidant, a lubrication modifier, and a lubricant. Furthermore, in another embodiment, the polyamide resin composition preferably contains 0.01 to 10 parts by weight of at least one selected from the nucleating agent, antioxidant, lubrication modifier, and lubricant relative to 100 parts by weight of the semi-aromatic polyamide resin, more preferably 0.1 to 10 parts by weight, and even more preferably 0.1 to 8 parts by weight. In another embodiment, the polyamide resin composition preferably contains a total of 0.01 to 10 parts by weight of the nucleating agent, antioxidant, lubrication modifier, and lubricant relative to 100 parts by weight of the semi-aromatic polyamide resin, more preferably 0.1 to 10 parts by weight, even more preferably 0.1 to 8 parts by weight, and even more preferably 0.2 to 8 parts by weight. This improves the lubricity of the molded article containing the polyamide resin composition.

[0188] As another embodiment, the preferred manner in which the crystallizing nucleating agent, antioxidant, lubrication modifier, lubricant, and other additives contained in the polyamide resin composition are the same as those in the polyamide resin composition of this embodiment described above.

[0189] (Fatigue resistance)

[0190] The polyamide resin composition of this embodiment exhibits excellent fatigue resistance due to its inclusion of the aforementioned semi-aromatic polyamide resin. The fatigue resistance of the polyamide resin composition can be evaluated by the number of repetitions until fatigue failure obtained in a planar bending fatigue test. The number of repetitions until fatigue failure of the polyamide resin composition of this embodiment can be determined by the following method. Specifically, the composition is injection molded to produce a No. I test piece I-20 as described in JIS K7119 (1972). Using this test piece, a planar bending fatigue test is performed according to JIS K7119 (1972). The planar bending fatigue test conditions are set as follows: chuck distance 30 mm, ambient temperature 23°C, load 40 MPa, load repetition rate 1800 times per minute, and stress mode set to alternating planar bending. The number of repetitions until fatigue failure is then obtained. The preferred number of repetitions until fatigue failure of the polyamide resin composition of this embodiment is 5.0 × 10⁻⁶. 5 For cycles of one or more, 1.0 × 10 is more preferred. 6 This number of repetitions can be determined more specifically by the method described in the examples.

[0191] (Water absorption)

[0192] The polyamide resin composition of this embodiment has low water absorption by including the above-mentioned semi-aromatic polyamide resin. Water absorption can be evaluated by the water absorption rate of the above-mentioned polyamide resin composition. The water absorption rate can be calculated by injection molding the above-mentioned polyamide resin composition to produce a No. I test piece I-20 (3 mm thick) as described in JIS K7119 (1972), and by immersing it 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. This water absorption rate can be determined by the following method: injection molding the polyamide resin composition using an 80-ton injection molding machine manufactured by Nissei Resin Kogyo Co., Ltd. at a barrel temperature of 320°C and a mold temperature of 140°C, and using the test piece obtained therefrom, more specifically, the method described in the examples.

[0193] (Slippery)

[0194] The polyamide resin composition of this embodiment comprises the above-mentioned semi-aromatic polyamide resin, and further comprises at least one selected from the above-mentioned crystallizing nucleating agent and the above-mentioned lubrication modifier, thereby exhibiting excellent lubrication properties. The lubrication properties of the polyamide resin composition can be evaluated by the wear amount (mg) and the coefficient of dynamic friction obtained in a sliding wear test. The wear amount and coefficient of dynamic friction of the polyamide resin composition of this embodiment can be determined by the following method. A square plate test piece with a thickness of 3 mm is prepared by injection molding of the composition. Using the test piece, a sliding wear test is performed according to JIS K7218 (1986) A method. The conditions for the sliding wear test are set at 23°C and a surface pressure of 10 kg / cm². 2 The sliding speed was 50 cm / sec, and the material was S45C. The wear amount and coefficient of dynamic friction were thus obtained. Lower wear amount is preferred for the polyamide resin composition of this embodiment, preferably 250 mg or less, more preferably 200 mg or less, and even more preferably 150 mg or less. Furthermore, the coefficient of dynamic friction of the polyamide resin composition of this embodiment is preferably 0.5 or less, more preferably 0.45 or less. The test piece was obtained by injection molding the polyamide resin composition at a barrel temperature of 320°C and a mold temperature of 140°C using an 80-ton injection molding machine manufactured by Nissei Resin Kogyo Co., Ltd. The wear amount and coefficient of dynamic friction can be more specifically determined by the method described in the examples.

[0195] (Method for manufacturing polyamide resin composition)

[0196] There are no particular limitations on the method for manufacturing the above-mentioned polyamide resin composition. A method capable of uniformly mixing the above-mentioned semi-aromatic polyamide resin, a nucleating agent and / or antioxidant as needed, and other additives as needed is preferred. Specifically, the preferred method for manufacturing the above-mentioned polyamide resin composition is a method that uniformly mixes the above-mentioned semi-aromatic polyamide resin, at least one selected from nucleating agents and antioxidants, and other additives as needed. Mixing is generally preferably performed using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or the like for melt mixing. The melt mixing conditions are not particularly limited; for example, a method of melt mixing for about 1 to 30 minutes at a temperature range approximately 10 to 60°C higher than the melting point of the above-mentioned polyamide resin to obtain a granulated polyamide resin composition can be described.

[0197] [Molded product]

[0198] (Forming method)

[0199] The molded article of this embodiment can be a molded article containing the aforementioned semi-aromatic polyamide resin. Alternatively, the molded article can also be a molded article containing a polyamide resin composition. The molded article described above is manufactured using a semi-aromatic polyamide resin or a polyamide resin composition by a known molding method. Specifically, it can be obtained by molding using various molding methods such as injection molding, blow molding, extrusion molding, compression molding, stretch molding, vacuum forming, foaming molding, rotational molding, impregnation, laser sintering, and hot melt lamination. Furthermore, the semi-aromatic polyamide resin or polyamide resin composition of this embodiment can also be compounded with other polymers, compositions containing other polymers and metals, etc., to obtain the molded article. For example, by extruding a metal sheet and the semi-aromatic polyamide resin composition of this embodiment, a molded article can be obtained in which a layer containing the semi-aromatic polyamide resin composition of this embodiment is present on the surface of the metal sheet.

[0200] (use)

[0201] The molded product of this embodiment has excellent fatigue resistance and sliding properties, so it can be used in sliding components of automobiles, electric bicycles (especially e-bikes), industrial machinery, household appliances, etc. Examples of sliding components include various gears, bearings, bushings, chain tensioners, door hinges, end face materials of mechanical seals, valve seats, V-rings, push rod seals, piston rings, rotating shafts and sleeves of compressors, pistons, impellers, blades, rotors, etc.

[0202] The molded article of this embodiment exhibits particularly excellent low water absorption, making it suitable for use in gears requiring high dimensional accuracy in the aforementioned sliding components. Examples of gears include: spur gears, bevel gears, helical gears, spiral gears, herringbone gears, internal gears, worm gears, rack and pinion gears, and Maltese gears. From the viewpoints of fatigue resistance, sliding properties, and low water absorption, the molded article of this embodiment is particularly preferred for: spur gears and helical gears in drive units for e-bikes, and worm gears in electric power steering systems for automobiles. The molded article of this embodiment exhibits particularly excellent low water absorption, resulting in high dimensional stability of the gears. Therefore, when used in the various gears described above in e-bikes, noise caused by the meshing of gears can be suppressed, resulting in excellent quietness.

[0203] Example

[0204] The present invention will now be described in more detail by way of examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[0205] [Evaluation Method]

[0206] The semi-aromatic polyamide resins and polyamide resin compositions obtained in the examples and comparative examples were evaluated according to the methods shown below.

[0207] 1. Evaluation methods for semi-aromatic polyamide resins

[0208] (Specific viscosity logarithmic viscosity)

[0209] Concentrated sulfuric acid was used as a solvent to dissolve the semi-aromatic polyamide resins obtained in the examples and comparative examples at a concentration of 0.2 g / dl, thus preparing a sample solution. Next, the flow time of the solvent (concentrated sulfuric acid) at 30°C and the flow time of the sample solution were measured, and the specific logarithmic viscosity η was calculated using the following equation (3). inh The results are shown in Table 2.

[0210] η inh (dl / g) = [ln(t1 / t0)] / c Equation (3)

[0211] In the above formula, t0 represents the flow time (seconds) of the solvent (concentrated sulfuric acid), t1 represents the flow time (seconds) of the sample solution, and c represents the concentration (g / dl) of the sample (semi-aromatic polyamide) in the sample solution.

[0212] (Amount of terminal amino groups, amount of terminal carboxyl groups, and capping ratio)

[0213] The nuclear magnetic resonance imaging (NMR) was performed using the high-resolution NMR spectrometer "ECZ-600" manufactured by NEC Corporation, at a resolution of 600 MHz, a solvent of deuterated 1,1,1,3,3,3-hexafluoroisopropanol, and a temperature of 50°C. 1 ¹H-NMR analysis was performed. The amount of terminal amino groups, terminal carboxyl groups, and terminal groups capped by the capping agent were calculated based on the integrated values ​​of the characteristic signals of each terminal group. The chemical shift values ​​of representative signals used in the determination are shown in Table 1. The determination results of the amount of terminal amino groups and terminal carboxyl groups are shown in Table 2.

[0214] [Table 1]

[0215]

[0216] In addition, the end-capping ratio of the semi-aromatic polyamide resin is calculated using the following formula (1). It should be noted that in formula (1), A represents the total amount of terminal groups, and B represents the sum of the amount of terminal carboxyl groups and terminal amino groups.

[0217] End capping rate (%) = [(AB) / A] × 100 Equation (1)

[0218] The results are shown in Table 2.

[0219] (weight-average molecular weight)

[0220] The weight-average molecular weight (Mw0) of the semi-aromatic polyamide resin was determined using gel permeation chromatography (GPC) in the form of a molecular weight equivalent to 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 0.4 μm membrane filter to prepare the test sample. The test sample was then measured using the same method described in "Retention Stability" of "2. Evaluation Methods for Polyamide Resin Compositions".

[0221] The results are shown in Table 2.

[0222] (Melting point and heat of fusion)

[0223] The melting point and heat of fusion ΔHm of each of the semi-aromatic polyamide resins obtained in the examples and comparative examples were determined using a differential scanning calorimetry (DSC7020) device manufactured by Hitachi High-Tech Science Co., Ltd.

[0224] Melting point and heat of fusion ΔHm were determined according to ISO 11357-3 (2nd edition, 2011). Specifically, under a nitrogen atmosphere, the semi-aromatic polyamide resins used as samples were heated from 30°C to 340°C at a rate of 10°C / min. Then, after being held at 340°C for 5 minutes to allow complete melting, the samples were cooled to 50°C at a rate of 10°C / min and held at 50°C for 5 minutes. The peak temperature of the melting peak that appeared when the temperature was raised back to 340°C at a rate of 10°C / min was taken as the melting point (°C), and the peak area was taken as the heat of fusion ΔHm (J / g).

[0225] The results are shown in Table 2.

[0226] 2. Evaluation methods for polyamide resin compositions

[0227] Production of test pieces

[0228] For each polyamide resin composition obtained in the examples and comparative examples, dumbbell test pieces (I-20, No. I test piece as described in JIS K7119 (1972)) for fatigue resistance evaluation and water absorption evaluation and square plate test pieces (55mm long × 55mm wide × 3mm thick) for sliding evaluation were prepared using an 80-ton injection molding machine manufactured by Nissei Resin Kogyo Co., Ltd., under the conditions of barrel temperature of 320°C and mold temperature of 140°C.

[0229] (Amount of terminal amino groups)

[0230] 1 g of each polyamide resin composition obtained in the examples and comparative examples was dissolved in 30 ml of phenol and then mixed with 3 ml of methanol to prepare a sample solution. Using thymol blue as an indicator, titration was performed with an aqueous HCl solution of 0.01 or 0.1 equivalent concentration to determine the amount of terminal amino groups ([NH2], unit: μ equivalent / g) of the semi-aromatic polyamide resin contained in the above polyamide resin compositions.

[0231] (Amount of terminal carboxyl groups)

[0232] 0.5 g of each polyamide resin composition obtained in the examples and comparative examples was dissolved in 40 ml of o-cresol to prepare a sample solution. The amount of terminal carboxyl groups ([COOH], unit: μ equivalent / g) of the semi-aromatic polyamide resin contained in the above polyamide resin compositions was determined by titration with a potassium hydroxide / ethanol solution of 0.01 or 0.1 equivalent concentration using a potentiometric titration apparatus.

[0233] (Measurement conditions)

[0234] • Measuring device: AT-710 (manufactured by Kyoto Electronics Industry Co., Ltd.)

[0235] • Main control unit: MCU-710 (manufactured by Kyoto Electronics Industry Co., Ltd.)

[0236] (Stay-at-home stability)

[0237] For retention stability, the reduction rate of the weight-average molecular weight (Mw) of the semi-aromatic polyamide resin contained in the polyamide resin composition before and after melt mixing was evaluated. Specifically, retention stability was evaluated according to the following criteria based on the reduction rate of the weight-average molecular weight of the semi-aromatic polyamide resin contained in the polyamide resin composition shown in Equation (4) below. The results are shown in Table 3.

[0238] The rate of decrease in weight-average molecular weight (%) = (Mw0 - Mw1) × 100 / Mw0 Equation (4)

[0239] In formula (4), Mw0 refers to the weight-average molecular weight of the semi-aromatic polyamide resin before melt mixing, and Mw1 refers to the weight-average molecular weight of the semi-aromatic polyamide resin contained in the polyamide resin composition after melt mixing. Melt mixing was carried out using a twin-screw extruder "BTN-32-S2-30-L" manufactured by Research Laboratory of Plastics Technology Co., Ltd., with a barrel temperature of 320-325°C and a residence time of 1-5 minutes.

[0240] Evaluation Criteria

[0241] A: The reduction rate of weight-average molecular weight is less than 20%.

[0242] B: The weight-average molecular weight decreased by more than 20%.

[0243] The weight-average molecular weight (Mw0) of the semi-aromatic polyamide resin before melt mixing was obtained by gel permeation chromatography (GPC) converted to 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 0.4 μm membrane filter to prepare the test sample. The test sample was then measured under the conditions shown below.

[0244] Furthermore, the weight-average molecular weight (Mw1) of the semi-aromatic polyamide resin contained in the melt-blended polyamide resin composition is obtained by gel permeation chromatography (GPC) converted to standard polymethyl methacrylate. Specifically, the weight-average molecular weight is determined by the following method.

[0245] The polyamide resin composition was measured to a mass of 1.5 mg of the semi-aromatic polyamide resin contained in the polyamide resin composition and dissolved in hexafluoroisopropanol (HFIP). The solution was then filtered using a membrane filter with a pore size of 0.4 μm, thereby preparing a sample for determination containing the organic components of the semi-aromatic polyamide resin. The sample was then measured under the conditions shown below.

[0246] <Measurement Conditions>

[0247] ·Device: HLC-8320GPC (manufactured by Tosoh Corporation)

[0248] • Column: Two TSKgel SuperHM-N (manufactured by Tosoh Corporation) are connected in series.

[0249] • Eluent: 0.085% sodium trifluoroacetate / HFIP solution

[0250] • Flow rate: 0.5 mL / min (reference column: 0.25 mL / min)

[0251] • Sample injection volume: 10 μL

[0252] Column temperature: 40℃

[0253] • Standard polymethyl methacrylate: Shodex Standard M-75 (manufactured by RESONAC Corporation), Polymethyl methacrylate (Agilent Technologies Corporation), molecular weight 1010.

[0254] • Detector: UV (254nm) detector

[0255] (Fatigue resistance)

[0256] Using the obtained dumbbell test pieces, planar bending fatigue tests were conducted according to JIS K7119 (1972). The testing machine used was a vibration fatigue testing machine "B-70-TL" manufactured by Toyo Seiki Co., Ltd. The number of repetitions (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: alternating planar bending. This number was used as the fatigue resistance test result.

[0257] The results are shown in Table 3.

[0258] (Water absorption)

[0259] Weigh the obtained dumbbell test piece and calculate the weight W0 of the test piece before water absorption. Next, immerse the test piece in water and perform an immersion treatment at 23°C for 168 hours. Weigh it again to calculate the weight W1 of the test piece after water absorption. Calculate the water absorption rate using the following formula (5) to evaluate the water absorption. The results are shown in Table 3.

[0260] Water absorption rate (%) = (W1 - W0) × 100 / W0 Equation (5)

[0261] (Slippery)

[0262] Using the obtained square plate test piece, a sliding wear test was performed according to JIS K7218 (1986) A method. The testing machine used was an EFM-3-G friction and wear testing machine manufactured by A&D Corporation. The temperature was 23°C and the surface pressure was 10 kg / cm². 2 Under the condition of a sliding speed of 50 cm / sec, using S45C steel as the material, the wear amount (mg) and the coefficient of dynamic friction were measured to evaluate the sliding performance. The results are shown in Table 3.

[0263] [Example 1]

[0264] (Manufacturing of semi-aromatic polyamide resin PA9T-1)

[0265] A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [molar ratio = 85 / 15], 6134.9 g (38.76 mol), 6297.2 g (37.91 mol) of terephthalic acid, 23.2 g (0.19 mol, 0.5 mol% relative to 100 mol% of diamine), 12.5 g of sodium hypophosphite monohydrate (0.1 wt% relative to the total mass of raw materials), and 4.8 liters of distilled water [the ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw materials (x / y) is 1.02] were added to a 40-liter autoclave for nitrogen replacement. 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 point, the pressure inside the autoclave reached 2 MPa. Under these conditions, heating was continued for 5 hours while maintaining a pressure of 2 MPa, and water vapor was slowly released to facilitate the reaction. Next, the pressure was reduced to 1.3 MPa over 30 minutes, and the reaction was allowed to continue for 1 hour to obtain the prepolymer. The obtained prepolymer was dried at 120°C under reduced pressure for 12 hours and pulverized to a particle size of less than 2 mm. It was then subjected to solid-state polymerization at 230°C and 13 Pa (0.1 mmHg) for 10 hours to obtain a white semi-aromatic polyamide resin, PA9T-1.

[0266] [Example 2]

[0267] (Manufacturing of semi-aromatic polyamide resin PA9T-2)

[0268] A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [molar ratio = 85 / 15] 7787.4 g (49.20 mol), 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 wt% relative to the total mass of raw materials), and 7.6 liters of distilled water [the ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw materials (x / y) is 1.02] were added to a 40-liter autoclave, and then a white semi-aromatic polyamide resin PA9T-2 was obtained by the same method as in Example 1.

[0269] [Example 3]

[0270] (Manufacturing of semi-aromatic polyamide resin PA9T-3)

[0271] A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [molar ratio = 85 / 15] of 6603.0 g (41.72 mol), 6794.3 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 (0.1 wt% relative to the total mass of raw materials) of sodium hypophosphite monohydrate, and 4.5 liters of distilled water [the ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw materials (x / y) is 1.02] were added to a 40-liter autoclave, and then a white semi-aromatic polyamide resin PA9T-3 was obtained by the same method as in Example 1.

[0272] [Comparative Example 1]

[0273] (Manufacturing of semi-aromatic polyamide resin PA9T-4)

[0274] A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [molar ratio = 85 / 15] of 6074.8 g (38.38 mol), 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 wt% relative to the total mass of raw materials), and 4.8 liters of distilled water [the ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw materials (x / y) is 1.01] were added to a 40-liter autoclave, and then a white semi-aromatic polyamide resin PA9T-4 was obtained by the same method as in Example 1.

[0275] [Comparative Example 2]

[0276] (Manufacturing of semi-aromatic polyamide resin PA9T-5)

[0277] A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [molar ratio = 85 / 15] of 6652.8 g (41.40 mol), 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 (0.1 wt% relative to the total mass of raw materials) of sodium hypophosphite monohydrate, and 5.1 liters of distilled water [the ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw materials (x / y) is 1.04] were added to a 40-liter autoclave, and then a white semi-aromatic polyamide resin PA9T-5 was obtained by the same method as in Example 1.

[0278] [Comparative Example 3]

[0279] (Manufacturing of semi-aromatic polyamide resin PA9T-6)

[0280] A mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [molar ratio = 80 / 20] 7891.0 g (49.85 mol), 8076.0 g (48.61 mol) of terephthalic acid, 103.0 g (0.84 mol, 1.7 mol% relative to 100 mol% of diamine), 16.0 g of sodium hypophosphite monohydrate (0.1 wt% relative to the total mass of raw materials), and 7.7 liters of distilled water [the ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw materials (x / y) is 1.02] were added to a 40-liter autoclave, and then a white semi-aromatic polyamide resin PA9T-6 was obtained by the same method as in Example 1.

[0281] [Table 2]

[0282]

[0283] (Preparation of polyamide resin composition)

[0284] Each half of the aromatic polyamide resin and the crystallizing nucleating agent, antioxidant, and other additives (lubricants) shown below were premixed in the proportions shown in Table 3. The mixture was then fed into the upstream feed port of a twin-screw extruder "BTN-32-S2-30-L" manufactured by Research Laboratory of Plastics Technology Co., Ltd. The mixture was melt-mixed and extruded at a barrel temperature of 320–325°C, cooled, and cut to produce granular polyamide resin compositions.

[0285] It should be noted that the components shown in Table 3 are described below.

[0286] • Crystallization nucleating agent

[0287] "MICRON WHITE #5000S", manufactured by Hayashi Kasei Co., Ltd.

[0288] Antioxidants

[0289] "SUMILIZER GA-80", manufactured by Sumitomo Chemical Co., Ltd.

[0290] • Slip modifier

[0291] "Licowax PED191", manufactured by Clariant Chemicals Co., Ltd.

[0292] Other additives (lubricants)

[0293] "LICOWAX OP", manufactured by Clariant Chemicals Co., Ltd.

[0294] [Table 3]

[0295]

[0296] According to Table 2, the specific logarithmic viscosity η of the semi-aromatic polyamide resins in Examples 1-3, measured in concentrated sulfuric acid at 30°C, is... inh The concentration is 1.6–3.0 dl / g, the amount of terminal amino group is 10–70 μequivalents / g, the amount of terminal carboxyl group is 10–90 μequivalents / g, and the ratio of the amount of terminal amino group [NH2] (μequivalents / g) to the amount of terminal carboxyl group [COOH] (μequivalents / g), i.e., [NH2] / [COOH], is greater than 0.1 and less than 1.0.

[0297] As shown in Table 3, Examples 4 to 7 contain the semi-aromatic polyamide resins of Examples 1 to 3, which have high retention stability and fatigue resistance.

[0298] Therefore, according to Tables 2 and 3, the semi-aromatic polyamide resin and polyamide resin composition of the examples maintain excellent fatigue resistance while improving retention stability during melt processing, and both fatigue resistance and retention stability are excellent.

Claims

1. A semi-aromatic polyamide resin comprising diamine units and dicarboxylic acid units, the diamine units contain 60 to 100 mole% of aliphatic diamine units having 7 to 13 carbon atoms, relative to 100 mole% of the diamine units, the dicarboxylic acid units contain 60 to 100 mole% of aromatic dicarboxylic acid units, relative to 100 mole% of the carboxylic acid units, Specific viscosity ηsp measured in concentrated sulfuric acid at 30°C inh is 1.6 dl / g to 3.0 dl / g, the amount of terminal amino groups [NH2] is 10 to 70 μeq / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μeq / g, the ratio of the amount of terminal amino groups [NH2] to the amount of terminal carboxyl groups [COOH], i.e., [NH2] / [COOH], is 0.1 or greater and less than 1.

0.

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

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

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

5. The semi-aromatic polyamide resin according to any one of claims 1 to 4, wherein, the amount of terminal amino groups [NH2] is 20 to 60 μeq / g.

6. The semi-aromatic polyamide resin according to any one of claims 1 to 4, wherein, the amount of terminal amino groups [NH2] is 30 to 60 μeq / 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 μeq / g.

8. The semi-aromatic polyamide resin according to any one of claims 1 to 7, wherein, the [NH2] / [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 crystallization nucleating agent.

10. The polyamide resin composition according to claim 9, which contains 0.01 to 10 parts by mass of the crystallization nucleating agent, relative to 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, which contains 0.01 to 5 parts by mass of the antioxidant, relative to 100 parts by mass of the semi-aromatic polyamide resin.

13. A polyamide resin composition comprising a semi-aromatic polyamide resin, the semi-aromatic polyamide resin comprising diamine units and dicarboxylic acid units, the diamine units contain 60 to 100 mole% of aliphatic diamine units having 7 to 13 carbon atoms, relative to 00 mole% of the diamine units, the dicarboxylic acid units contain 60 mole% to 100 mole% of aromatic dicarboxylic acid units, relative to 100 moie% of the carboxylic acid units, the semi-aromatic polyamide resin has a weight average molecular weight Mw measured by gel permeation chromatography (GPC) in terms of polymethyl methacrylate of 40,000 to 90,000, the amount of terminal amino groups [NH2] is 10 to 70 μeq / g, the amount of terminal carboxyl groups [COOH] is 10 to 90 μηq / g, the ratio of the amount of terminal amino groups [NH2] to the amount of the terminal carboxyl groups [COOH], i.e., [NH2] / [COOH] is 0.1 or greater and less than 1.

0.

14. The polyamide resin composition according to claim 13, comprising at least one selected from the group consisting of a nucleating agent, an antioxidant, a lubrication modifier, and a lubricant.

15. The polyamide resin composition according to claim 14, wherein 0.01 to 10 parts by weight of at least one selected from a crystallizing nucleating agent, an antioxidant, a lubrication modifier, and a lubricant are included relative to 100 parts by weight of the semi-aromatic polyamide resin.

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

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

18. The molded article according to claim 17, wherein it is a gear.

19. A method for manufacturing a semi-aromatic polyamide resin, comprising a diamine unit and a dicarboxylic acid unit, the method comprising: The first reaction step involves subjecting the raw materials containing aliphatic diamine, aromatic dicarboxylic acid, and end-capping agent to a polycondensation reaction to obtain a primary polycondensation product. as well as The second reaction step involves solid-state polymerization of the primary condensation reactants to obtain the semi-aromatic polyamide resin. The ratio of the number of moles of amino groups (x) to the number of moles of carboxyl groups (y) in the raw material is greater than 1.01 and less than 1.

03. The amount of capping agent contained in the raw material is 0.1 mol% to 1.5 mol% relative to 100 mol% of diamine contained in the raw material.

Images