Molded body and method of using the molded body

Abstract

To provide a molded body that can have excellent mechanical strength even when used in contact with low-viscosity lubricating oil, and to provide a method of using a molded body.SOLUTION: Provided is a molded body, which is a molded body that is made of a polyamide resin-containing resin composition, and the polyamide resin has an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more, and the molded body is used in contact with a lubricating-oil having a kinematic viscosity of 30 mm2 / s or less at 40°C. Also provided is a method of using a molded body.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a molded article to be used in contact with a low-viscosity lubricating oil, and a method for using the molded article. [Background technology]

[0002] Polyamide resins are excellent in mechanical strength, heat resistance, chemical resistance, etc. Therefore, it is known that polyamide resins can be used for resin parts that come into contact with lubricating oils used in automatic transmissions, manual transmissions, internal combustion engines, etc. (for example, Patent Documents 1 to 6). On the other hand, there is a demand for lubricating oils with reduced viscosity to improve power transmission capacity (for example, Patent Documents 7 and 8). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-286044 [Patent Document 2] JP 2002-323046 A [Patent Document 3] Japanese Patent Application Publication No. 11-343408 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-285176 [Patent Document 5] International Publication No. 2006 / 019121 [Patent Document 6] Japanese Patent Application Laid-Open No. 2006-176597 [Patent Document 7] Japanese Patent Application Laid-Open No. 2010-180278 [Patent Document 8] International Publication No. 2016 / 152229 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when polyamide resins are used in contact with low-viscosity lubricating oils, there is a problem in that the physical properties of the polyamide resins, such as mechanical strength, are significantly reduced compared to lubricating oils that are not low-viscosity. This is thought to be because, for example, when used in automatic transmission fluid (hereinafter abbreviated as ATF), the ATF is oxidized at high temperatures, accelerating the hydrolysis of the polyamide resins.

[0005] The present invention provides a molded article that can have excellent mechanical strength even when used in contact with a low-viscosity lubricating oil, and a method for using the molded article. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that the above problems can be solved by using a specific polyamide resin, and after further research, have completed the present invention. That is, the present invention is as follows.

[0007] [1] A molded article made of a resin composition containing a polyamide resin, The polyamide resin has an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more, Kinematic viscosity at 40°C is 30mm 2 A molded body used in contact with a lubricating oil having a viscosity of 1000 ppm or less. [2] The molded article according to [1], wherein the polyamide resin is at least one selected from the group consisting of semi-aromatic polyamides and aliphatic polyamides. [3] The molded article according to [2], wherein the semi-aromatic polyamide contains diamine units derived from an aliphatic diamine and dicarboxylic acid units derived from an aromatic dicarboxylic acid. [4] The molded article according to [2] or [3], wherein the semi-aromatic polyamide contains diamine units derived from an aliphatic diamine having 4 to 18 carbon atoms and dicarboxylic acid units derived from at least one selected from the group consisting of terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. [5] The molded article according to any one of [1] to [4], wherein the polyamide resin comprises at least one selected from the group consisting of polyhexamethylene terephthalamide, polynonamethylene terephthalamide / poly(2-methyloctamethylene) terephthalamide copolymer, polynonamethylene terephthalamide, polydecamethylene terephthalamide, polyundecaneamide, polydodecanamide, polymetaxylylene adipamide, and polymetaxylylene sebacamide. [6] The molded article according to any one of [1] to [5], wherein the resin composition further contains a polyolefin. [7] The molded article according to any one of [1] to [6], wherein the resin composition further contains an inorganic filler. [8] A molded article made of a resin composition containing a polyamide resin having an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more, Kinematic viscosity at 40°C is 30mm 2 A method of using a molded body by contacting the molded body with a lubricating oil having a viscosity of 1 / s or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a molded article that has excellent mechanical strength even when used in contact with a low-viscosity lubricating oil, and a method for using the molded article. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below based on an example of an embodiment, but the embodiment shown below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. In addition, although preferred embodiments are shown in this specification, a combination of two or more of the individual preferred embodiments is also a preferred embodiment. When there are several numerical ranges for matters shown as numerical ranges, the lower limit and upper limit can be selectively combined to form a preferred embodiment. In this specification, when a numerical range such as "XX to YY" is stated, it means "XX or more and YY or less." Furthermore, "~ unit" (where "~" indicates a monomer) means "a structural unit derived from ~." For example, "dicarboxylic acid unit" means "a structural unit derived from dicarboxylic acid." Furthermore, "low viscosity lubricating oil" means "a lubricating oil having a kinematic viscosity of 30 mm at 40°C." 2 / s or less lubricating oil.

[0010] <Resin composition> The molded article of this embodiment is made of a resin composition containing a polyamide resin, and is characterized in that the polyamide resin has an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more. Low-viscosity lubricating oils are prone to generating acidic components at high temperatures. Therefore, when a molded article made of a resin composition containing a polyamide resin is used in a low-viscosity lubricating oil, the acidic components in the lubricating oil are thought to promote hydrolysis of amide groups, resulting in a deterioration in physical properties. After extensive investigations, the inventors focused on the proportion of amide groups in the repeating units that are likely to be hydrolyzed and the amount of terminal amino groups that act to neutralize acidic components. After further investigations, the inventors found that the above characteristics are effective in suppressing hydrolysis of amide groups and preventing a deterioration in the physical properties of molded articles when used in a low-viscosity lubricating oil. Based on these findings, the inventors arrived at the present invention. Each component contained in the resin composition will be described below.

[0011] [Polyamide resin] Polyamide resins are mainly made from lactams, aminocarboxylic acids, or a combination of diamines and dicarboxylic acids, and may be made from homopolymers or copolymers obtained by polymerizing these raw materials, either singly or in combination.

[0012] Examples of lactams include ε-caprolactam, enantholactam, undecane lactam, dodecane lactam, α-pyrrolidone, α-piperidone, etc. These may be used alone or in combination of two or more. Examples of aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, etc. These may be used alone or in combination of two or more.

[0013] The diamine may be, for example, an aliphatic diamine, an aromatic diamine, or an alicyclic diamine. Aliphatic diamines include ethylenediamine, 1,3-propylenediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanediamine, 1,16-hexadecanediamine, 1,17-heptadecanediamine, 1,18-octadecanediamine, and the like. Linear aliphatic diamines such as kutadecanediamine, 1,19-nonadecanediamine, and 1,20-eicosanediamine; 1,2-propanediamine, 1-butyl-1,2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1,4-butanediamine, 1,4-dimethyl-1,4-butanediamine, 2-methyl-1,3-propanediamine, 2-methyl-1,4-butanediamine, and 2,3-dimethyl-1,4-butane Diamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3,3-dimethyl-1,6-hexanediamine, 2,2-dimethyl-1,6-hexanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine branched aliphatic diamines such as nonanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-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, and 5-methyl-1,9-nonanediamine; etc. These may be used alone or in combination of two or more.

[0014] Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, etc. These may be used alone or in combination of two or more. Examples of the alicyclic diamine include cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornanedimethylamine, tricyclodecanedimethyldiamine, etc. These may be used alone or in combination of two or more.

[0015] The dicarboxylic acid may be, for example, an aliphatic dicarboxylic acid or an aromatic carboxylic acid. Examples of alicyclic dicarboxylic acids include 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, cyclodecanedicarboxylic acid, etc. These may be used alone or in combination of two or more. Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, etc. These may be used alone or in combination of two or more.

[0016] As a raw material for the polyamide resin, a polycarboxylic acid such as trimellitic acid, trimesic acid, pyromellitic acid, etc. may be used. The polyamide resin may contain units derived from the polycarboxylic acid within a range that allows melt molding.

[0017] In this embodiment, from the viewpoint of better maintaining the mechanical strength of the molded body against low-viscosity lubricating oil, the polyamide resin is preferably at least one selected from the group consisting of semi-aromatic polyamides and aliphatic polyamides. <Semi-aromatic polyamide> The semi-aromatic polyamide refers to a polyamide containing dicarboxylic acid units mainly composed of aromatic dicarboxylic acid units and diamine units mainly composed of aliphatic diamine units, or a polyamide resin containing dicarboxylic acid units mainly composed of aliphatic dicarboxylic acid units and diamine units mainly composed of aromatic diamine units. Here, "mainly composed" means that the polyamide contains 50 to 100 mol %, preferably 60 to 100 mol %, of all units. In this embodiment, the semi-aromatic polyamide preferably contains diamine units derived from an aliphatic diamine and dicarboxylic acid units derived from an aromatic dicarboxylic acid, from the viewpoint of better maintaining the mechanical strength of a molded body against low-viscosity lubricating oils. Furthermore, from the viewpoint of better maintaining the mechanical strength of a molded body against low-viscosity lubricating oils, the semi-aromatic polyamide more preferably contains diamine units derived from an aliphatic diamine having 4 to 18 carbon atoms and dicarboxylic acid units derived from at least one selected from the group consisting of terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, and further preferably contains diamine units derived from 1,9-nonanediamine and 2-methyl-1,8-octanediamine and dicarboxylic acid units derived from terephthalic acid.

[0018] As the aliphatic diamine having 4 to 18 carbon atoms, it is preferable to use at least one of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, and more preferably to use both in combination. The content of 1,9-nonanediamine units and / or 2-methyl-1,8-octanediamine units in the total amount of diamine units constituting the semi-aromatic polyamide is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, even more preferably 75 to 100 mol%, and even more preferably 90 to 100 mol%. When the content of 1,9-nonanediamine units and / or 2-methyl-1,8-octanediamine units in the total amount of diamine units constituting the semi-aromatic polyamide is within the above range, the mechanical strength of the molded body can be further improved with respect to low-viscosity lubricating oils, and heat resistance and chemical resistance can also be expected.

[0019] When 1,9-nonanediamine and 2-methyl-1,8-octanediamine are used in combination, the molar ratio of 1,9-nonanediamine:2-methyl-1,8-octanediamine is preferably 99:1 to 1:99, more preferably 95:5 to 30:70, and even more preferably 90:10 to 40:60. When the molar ratio of 1,9-nonanediamine to 2-methyl-1,8-octanediamine is within the above range, the mechanical strength of the molded body can be further improved when used with low-viscosity lubricating oils, and low water absorption can also be expected.

[0020] The aromatic dicarboxylic acid units constituting the semi-aromatic polyamide are preferably terephthalic acid units and / or naphthalenedicarboxylic acid units, more preferably terephthalic acid units. The content of terephthalic acid units and / or naphthalenedicarboxylic acid units in the total amount of dicarboxylic acid units constituting the semi-aromatic polyamide is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, even more preferably 75 to 100 mol%, and even more preferably 90 to 100 mol%. When the content of terephthalic acid units and / or naphthalenedicarboxylic acid units in the total amount of dicarboxylic acid units constituting the semi-aromatic polyamide is within the above range, the mechanical strength of the molded body is further improved when used with low-viscosity lubricating oils.

[0021] Furthermore, the content of the aliphatic diamine having 4 to 18 carbon atoms in the total amount of monomers constituting the semi-aromatic polyamide is preferably 30 to 55 mol%, more preferably 40 to 55 mol%. The content of the aromatic dicarboxylic acid in the total amount of monomers constituting the semi-aromatic polyamide is preferably 30 to 55 mol%, more preferably 40 to 55 mol%. The total content of the aliphatic diamine having 4 to 18 carbon atoms and aromatic dicarboxylic acid in the total amount of monomers constituting the semi-aromatic polyamide is preferably 80 to 100 mol%, more preferably 90 to 100 mol%.

[0022] Representative semi-aromatic polyamides containing diamine units mainly composed of aliphatic diamine units and dicarboxylic acid units mainly composed of aromatic dicarboxylic acid units include polytetramethylene terephthalamide (polyamide 4T), polypentamethylene terephthalamide (polyamide 5T), polyhexamethylene terephthalamide (polyamide 6T), polynonamethylene terephthalamide (polyamide 9T), poly(2-methyloctamethylene) terephthalamide (polyamide M8T), polynonamethylene terephthalamide / poly(2-methyloctamethylene) terephthalamide copolymer (polyamide 9T / M8T), polynonamethylene naphthalenedicarboxamide (polyamide 9N), and polynonamethylene naphthalenedicarboxamide. Examples include poly(2-methyloctamethylene)naphthalene dicarboxamide copolymer (polyamide 9N / M8N), polydecamethylene terephthalamide (polyamide 10T), polyhexamethylene isophthalamide (polyamide 6I), a copolymer of polyamide 6I and polyamide 6T (polyamide 6I / 6T), a copolymer of polyamide 66, polyamide 6I and polyamide 6T (polyamide 66 / polyamide 6I / 6T), a copolymer of polyamide 6T and polyundecane amide (polyamide 11) (polyamide 6T / 11), a copolymer of polyamide 6T and polyamide 10T (polyamide 6T / 10T), and a copolymer of polyamide 10T and polyundecane amide (polyamide 11) (polyamide 10T / 11).

[0023] Representative semi-aromatic polyamides containing diamine units primarily composed of aromatic diamine units and dicarboxylic acid units primarily composed of aliphatic dicarboxylic acid units include polyamide MXD6 (polymetaxylylene adipamide) and polyamide MXD10 (polymetaxylylene sebacamide).

[0024] <Aliphatic polyamide> Aliphatic polyamides include polycaproamide (polyamide 6), polyundecaneamide (polyamide 11), polydodecanamide (polyamide 12), polyethylene adipamide (polyamide 26), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene azelamide (polyamide 69), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene undecamide (polyamide 611), polyhexamethylene dodecamide (polyamide 612), polynonameethylene adipamide (polyamide 96), and polynonameethylene azelamide (polyamide 99). ), polynonamethylene sebacamide (polyamide 910), polynonamethylene undecamide (polyamide 911), polynonamethylene dodecamide (polyamide 912), polydecamethylene adipamide (polyamide 106), polydecamethylene azelamide (polyamide 109), polydecamethylene sebacamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene adipamide (polyamide 126), polydodecamethylene azelamide (polyamide 129), polydodecamethylene sebacamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1212), and the like.

[0025] In this embodiment, among the above polyamide resins, from the viewpoint of better maintaining the mechanical strength of the molded article against low-viscosity lubricating oils, at least one selected from the group consisting of polyhexamethylene terephthalamide, polynonamemethylene terephthalamide / poly(2-methyloctamethylene)terephthalamide copolymer, polynonamemethylene terephthalamide, polydecamethylene terephthalamide, polyundecane amide, polydodecanamide, polymetaxylylene adipamide, and polymetaxylylene sebacamide is preferred. Furthermore, from the viewpoint of further improving the maintenance of the mechanical strength of the molded article against low-viscosity lubricating oils and being expected to have good heat resistance, low water absorption, and chemical resistance, polynonamemethylene terephthalamide is more preferred.

[0026] <Amide group concentration> The amide group concentration in the polyamide resin is 8.5 mmol / g or less. If the amide group concentration is greater than 8.5 mmol / g, it becomes difficult to avoid hydrolysis of the amide groups in a low-viscosity lubricating oil, and the molded article cannot maintain excellent mechanical strength. From the viewpoint of further improving the maintenance of mechanical strength of the molded article in a low-viscosity lubricating oil, the amide group concentration is preferably 8.0 mmol / g or less, more preferably 7.5 mmol / g or less. Furthermore, from the viewpoints of further improving the maintenance of the mechanical strength of the molded body against low-viscosity lubricating oils and also being able to expect heat resistance, low water absorption, and chemical resistance, the content is preferably 4 mmol / g or more, more preferably 5 mmol / g or more, and even more preferably 5.5 mmol / g or more. In the present invention, the amide group concentration refers to the number of amide groups derived from a monomer and contained per structural unit of a polyamide resin. The amide group concentration (mmol / g) can be calculated by [number of amide groups per structural unit (units)] ÷ [molecular weight of structural unit (g / mol)] × 1000. When there are a plurality of monomers per structural unit, the molecular weight is calculated taking into account the proportion of each monomer for each diamine unit or dicarboxylic acid unit, for example.

[0027] <End-capping agent unit> The polyamide resin may contain structural units derived from an end-capping agent (end-capping agent units). The content of the terminal blocking agent units is preferably 1.0 mol% or more relative to 100 mol% of the diamine units. When the content of the terminal blocking agent units is within the above range, the resulting resin composition has superior mechanical properties and flowability. The content of the terminal blocking agent units can be adjusted to fall within the above desired range by appropriately adjusting the amount of terminal blocking agent when charging the polymerization raw materials. Note that, taking into consideration the volatilization of the monomer components during polymerization, it is desirable to finely adjust the amount of terminal blocking agent charged so that the desired amount of terminal blocking agent units is introduced into the resulting polyamide resin. As a method for determining the content of the terminal blocking agent unit in the polyamide resin, for example, as disclosed in Japanese Patent Laid-Open No. 7-228690, a method is used in which the viscosity of the solution is measured, the total amount of terminal groups is calculated from the relational expression between the viscosity and the number average molecular weight, and the amount of amino groups and the amount of carboxyl groups determined by titration are subtracted from the total amount of terminal groups, or 1 Examples of such a method include determining the value based on the integral values ​​of the signals corresponding to the diamine unit and the end-capping agent unit using H-NMR, with the latter being preferred.

[0028] As the terminal blocking agent, a monofunctional compound reactive with a terminal amino group or a terminal carboxyl group can be used. Specific examples include monocarboxylic acids, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, and monoamines. From the viewpoints of reactivity and the stability of the blocked terminals, monocarboxylic acids are preferred as terminal blocking agents for terminal amino groups, and monoamines are preferred as terminal blocking agents for terminal carboxyl groups. From the viewpoints of ease of handling, monocarboxylic acids are more preferred as terminal blocking agents.

[0029] The monocarboxylic acid used as the end-capping agent is not particularly limited as long as it is reactive with an amino group, and examples thereof include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclopentanecarboxylic acid and cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and any mixtures thereof. Among these, at least one selected from acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid is preferred from the standpoints of reactivity, stability of the blocked end, and cost.

[0030] The monoamine used as the terminal blocking agent is not particularly limited as long as it is reactive with a carboxyl group. Examples of the monoamine include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine; and any mixtures thereof. Among these, at least one selected from butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline is preferred in terms of reactivity, high boiling point, stability of the blocked terminal, and cost.

[0031] <Melting point> The polyamide resin preferably has a melting point of 250°C or higher, and may be 280°C or higher. A melting point within the above range allows the polyamide resin to have excellent mechanical strength and heat resistance. There is no particular upper limit to the melting point of the polyamide resin, but in consideration of moldability, it is preferably 330°C or lower. The melting point of the polyamide resin can be determined as the peak temperature of an endothermic peak that appears when the temperature is increased at a rate of 10°C / min using a differential scanning calorimetry (DSC) analyzer. More specifically, it can be determined by the method described in the Examples.

[0032] <Intrinsic viscosity> The polyamide resin has an intrinsic viscosity [η inh ] is preferably 0.1 dl / g or more, more preferably 0.5 dl / g or more, and even more preferably 0.8 dl / g or more. inh The intrinsic viscosity [η] of the polyamide resin is preferably 3.0 dl / g or less, more preferably 2.0 dl / g or less, and even more preferably 1.5 dl / g or less. inh If the value of [R] is within the above range, the composition will have excellent physical properties such as moldability. The intrinsic viscosity [η inh ] is calculated from the solvent (concentrated sulfuric acid) flow time t0 (seconds), the sample solution flow time t1 (seconds), and the sample concentration c (g / dl) in the sample solution (i.e., 0.2 g / dl), inh =[ln(t1 / t0)] / c. More specifically, it can be determined by the method described in the Examples.

[0033] <Amount of terminal amino groups> The polyamide resin has a terminal amino group amount ([NH2]) of 20 μmol / g or more. If the terminal amino group amount is less than 20 μmol / g, the mechanical strength of the molded article tends to decrease when used in contact with a low-viscosity lubricating oil. From the viewpoint of further improving the maintenance of the mechanical strength of the molded article against a low-viscosity lubricating oil, the terminal amino group amount is preferably 25 μmol / g or more, more preferably 30 μmol / g or more. Furthermore, the terminal amino group amount is preferably 100 μmol / g or less, more preferably 70 μmol / g or less. In the present invention, the amount of terminal amino groups refers to the amount of terminal amino groups (unit: μmol) contained in 1 g of the polyamide resin. The amount of terminal amino groups can be determined by neutralization titration using an indicator. More specifically, it can be determined by the method described in the Examples. The amount of terminal amino groups in the polyamide resin can be adjusted by adjusting the amounts of diamine and dicarboxylic acid monomers charged and the degree of polymerization completion.

[0034] <Method of manufacturing polyamide resin> When the polyamide resin of this embodiment is a semi-aromatic polyamide containing dicarboxylic acid units and diamine units, the semi-aromatic polyamide can be produced, for example, from dicarboxylic acid and diamine as raw materials by a method such as melt polymerization, solid-state polymerization, melt extrusion polymerization, etc. Specifically, the semi-aromatic polyamide can be produced as follows. First, a dicarboxylic acid, a diamine, and optionally an aminocarboxylic acid, a lactam, a catalyst, an end-capping agent, etc. are mixed to produce a nylon salt. Next, the produced nylon salt is heated to a temperature of 200 to 250°C and thermally polymerized to form a prepolymer. The prepolymer can then be subjected to solid-state polymerization or to a high polymerization degree using a melt extruder to obtain a semi-aromatic polyamide. When the high polymerization degree stage is carried out by solid-state polymerization, it is preferably carried out under reduced pressure or in an inert gas flow, and a polymerization temperature within the range of 200 to 280°C results in a high polymerization rate, excellent productivity, and effective suppression of coloration and gelation. Furthermore, when the high polymerization degree stage is carried out using a melt extruder, the polymerization temperature is preferably 370°C or lower, and polymerization under such conditions results in a semi-aromatic polyamide with almost no decomposition and minimal deterioration.

[0035] Examples of catalysts that can be used in producing semi-aromatic polyamides include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts or esters thereof. Examples of the salts or esters include salts of phosphoric acid, phosphorous acid, or hypophosphorous acid with metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony; ammonium salts of phosphoric acid, phosphorous acid, or hypophosphorous acid; and ethyl esters, isopropyl esters, butyl esters, hexyl esters, isodecyl esters, octadecyl esters, decyl esters, stearyl esters, and phenyl esters of phosphoric acid, phosphorous acid, or hypophosphorous acid. The amount of catalyst used is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, based on 100% by mass of the total mass of the raw materials for the semi-aromatic polyamide. The amount of catalyst used is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. If the amount of catalyst used is equal to or greater than the lower limit, polymerization proceeds more smoothly.

[0036] [Polyolefin] In this embodiment, the resin composition preferably further contains a polyolefin from the viewpoint of improving mechanical strength, heat resistance, and chemical resistance. The polyolefin is not particularly limited as long as it can suitably achieve the effects of the present invention, but is preferably at least one selected from the group consisting of the following (1) to (5). (1) α-olefin copolymer (2) A copolymer of at least one selected from the group consisting of ethylene, propylene, and α-olefins having 4 or more carbon atoms with at least one selected from the group consisting of α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid esters, and α,β-unsaturated carboxylic acid anhydrides. (3) Ionomer of (2) above (4) Copolymer of aromatic vinyl compound and conjugated diene compound (5) A polymer obtained by modifying at least one selected from the group consisting of (1) to (4) above with an unsaturated compound having at least one selected from the group consisting of a carboxyl group and an acid anhydride group.

[0037] (1) α-olefin copolymer (1) Examples of the α-olefin copolymer include a copolymer of ethylene and an α-olefin having 3 or more carbon atoms, and a copolymer of propylene and an α-olefin having 4 or more carbon atoms. Examples of α-olefins having 3 or more carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. These α-olefins may be used alone or in combination of two or more.

[0038] In addition, (1) α-olefin copolymers include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 4,8-dimethyl-1,4,8-decatriene (DMDT), dicyclopentadiene, It may also be a copolymer of a non-conjugated polyene such as cyclohexadiene, cyclooctadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, or 2-propenyl-2,5-norbornadiene. These non-conjugated polyenes may be used alone or in combination of two or more.

[0039] (2) Copolymer (2) The copolymer is a copolymer of at least one selected from the group consisting of ethylene, propylene, and α-olefins having 4 or more carbon atoms and at least one selected from the group consisting of α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid esters, and α,β-unsaturated carboxylic acid anhydrides. The α-olefin may be any of those described in the description of (1) α-olefin copolymer, which has 4 or more carbon atoms. These α-olefins having 4 or more carbon atoms may be used alone or in combination of two or more. Examples of the α,β-unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. These α,β-unsaturated carboxylic acids may be used alone or in combination of two or more. Examples of the α,β-unsaturated carboxylic acid ester include methyl esters, ethyl esters, propyl esters, butyl esters, pentyl esters, hexyl esters, heptyl esters, octyl esters, nonyl esters, and decyl esters of the above-mentioned α,β-unsaturated carboxylic acids. These α,β-unsaturated carboxylic acid esters may be used alone or in combination of two or more. Examples of the α,β-unsaturated carboxylic acid anhydride include maleic anhydride and itaconic anhydride. These α,β-unsaturated carboxylic acid anhydrides may be used alone or in combination of two or more. The at least one selected from the group consisting of α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid esters, and α,β-unsaturated carboxylic acid anhydrides is preferably an α,β-unsaturated carboxylic acid anhydride, more preferably maleic anhydride.

[0040] (3) Ionomer (3) Ionomers include copolymers (2) in which at least a portion of the carboxyl groups are ionized by neutralization with metal ions. Examples of metal ions include alkali metals and alkaline earth metals such as Li, Na, K, Mg, Ca, Sr, and Ba, as well as Al, Sn, Sb, Ti, Mn, Fe, Ni, Cu, Zn, and Cd. These metal ions may be used alone or in combination.

[0041] (4) Copolymer (4) The copolymer is a copolymer of an aromatic vinyl compound and a conjugated diene compound, preferably a block copolymer. Examples of the block copolymer include block copolymers composed of an aromatic vinyl compound polymer block and a conjugated diene compound polymer block (aromatic vinyl compound / conjugated diene compound block copolymers), and block copolymers having at least one aromatic vinyl compound polymer block and at least one conjugated diene compound polymer block are preferred. Furthermore, in the block copolymer, some or all of the unsaturated bonds in the conjugated diene compound polymer block may be hydrogenated.

[0042] The aromatic vinyl compound polymer block is a polymer block mainly composed of structural units derived from an aromatic vinyl compound. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, vinylnaphthalene, vinylanthracene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, and 4-(phenylbutyl)styrene. These may be used alone or in combination of two or more. Furthermore, the aromatic vinyl compound polymer block may optionally contain a small amount of structural units derived from other unsaturated monomers. The conjugated diene compound polymer block is a polymer block mainly composed of structural units derived from a conjugated diene compound. Examples of the conjugated diene compound include 1,3-butadiene, chloroprene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 4-methyl-1,3-pentadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more. In a hydrogenated aromatic vinyl compound / conjugated diene compound block copolymer, typically, some or all of the unsaturated bonds in the conjugated diene compound polymer block are converted to single bonds by hydrogenation.

[0043] The molecular structure of the aromatic vinyl compound / conjugated diene compound block copolymer (which may be a hydrogenated product) may be linear, branched, radial, or any combination thereof. Among these, the aromatic vinyl compound / conjugated diene compound block copolymer (which may be a hydrogenated product) is preferably one or more of a diblock copolymer in which one aromatic vinyl compound polymer block and one conjugated diene compound polymer block are linearly bonded, or a triblock copolymer in which three polymer blocks are linearly bonded in the following order: aromatic vinyl compound polymer block-conjugated diene compound polymer block-aromatic vinyl compound polymer block (all of which may be hydrogenated). Examples of aromatic vinyl compound / conjugated diene compound block copolymers (which may be hydrogenated products) include unhydrogenated or hydrogenated styrene / butadiene block copolymers, unhydrogenated or hydrogenated styrene / isoprene block copolymers, unhydrogenated or hydrogenated styrene / isoprene / styrene block copolymers, unhydrogenated or hydrogenated styrene / butadiene / styrene block copolymers, and unhydrogenated or hydrogenated styrene / (isoprene and butadiene) / styrene block copolymers.

[0044] (5) Modified polymer (5) The modified polymer is a polymer obtained by modifying at least one selected from the group consisting of (1) to (4) above with an unsaturated compound having at least one selected from the group consisting of a carboxyl group and an acid anhydride group.

[0045] Examples of the unsaturated compound having a carboxyl group include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid. Examples of the unsaturated compound having an acid anhydride group include dicarboxylic acid anhydrides having an α,β-unsaturated bond such as maleic anhydride and itaconic anhydride. The unsaturated compound having at least one group selected from the group consisting of a carboxyl group and an acid anhydride group is preferably a dicarboxylic acid anhydride having an α,β-unsaturated bond, more preferably maleic anhydride.

[0046] The total content of carboxyl groups and acid anhydride groups in the modified polymer (5) is preferably in the range of 25 to 200 μmol / g, more preferably in the range of 50 to 100 μmol / g. If the content is 25 μmol / g or more, the effect of improving mechanical properties is sufficient, while if it is 200 μmol / g or less, the moldability of the resin composition is improved.

[0047] Examples of the modification method using an unsaturated compound include a method in which at least one selected from the group consisting of (1) to (4) above (hereinafter also referred to as "base resin") is copolymerized with the unsaturated compound when produced by addition polymerization, and a method in which the unsaturated compound is grafted onto the base resin, with the latter being preferred.

[0048] The polyolefin may be used alone or in combination of two or more. From the viewpoint of obtaining the effects of the present invention, the polyolefin is preferably (5) a modified polymer, more preferably a polymer obtained by modifying an α-olefin copolymer with an unsaturated compound having at least one selected from the group consisting of a carboxyl group and an acid anhydride group, and even more preferably a maleic anhydride modified product of an ethylene-propylene copolymer. When a (5) modified polymer is used as the polyolefin, the terminal amino groups of the polyamide resin react with the carboxyl groups and / or acid anhydride groups of the (5) modified polymer, thereby strengthening the affinity at the interface between the polyamide resin phase and the polyolefin phase, thereby further improving mechanical properties such as impact resistance and elongation characteristics. (5) As the modified polymer, commercially available products can be used, such as "TAFMER (registered trademark)" manufactured by Mitsui Chemicals, Inc.

[0049] The resin composition preferably contains 1 to 80 parts by mass of polyolefin per 100 parts by mass of polyamide resin. The polyolefin content is more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of polyamide resin. The polyolefin content is more preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, and can be 20 parts by mass or less, per 100 parts by mass of polyamide resin. When the polyolefin content is 1 part by mass or more, the resin composition is more likely to exhibit superior mechanical strength and heat resistance, and molded articles obtained by molding the resin composition are less likely to suffer from defects such as cracks. When the polyolefin content is 100 parts by mass or less, the resin composition can have superior mechanical strength, heat resistance, and chemical resistance.

[0050] [Inorganic filler] In this embodiment, the resin composition preferably further contains an inorganic filler from the viewpoint of improving mechanical strength. Examples of inorganic fillers include fibrous fillers such as glass fiber, carbon fiber, calcium silicate fiber, potassium titanate fiber, and aluminum borate fiber; glass flakes, talc, kaolin, mica, silicon nitride, hydrotalcite, calcium carbonate, zinc carbonate, titanium oxide, calcium hydrogen phosphate, wollastonite, silica, zeolite, alumina, boehmite, aluminum hydroxide, calcium silicate, sodium aluminosilicate, magnesium silicate, ketjen black, acetylene black, furnace black, carbon nanotubes, graphite, graphene, brass, copper, silver, aluminum, nickel, iron, calcium fluoride, montmorillonite, swellable fluoromica, and apatite. Among these, fibrous fillers are preferred, and glass fiber is more preferred. These inorganic fillers may be used alone or in combination.

[0051] The resin composition preferably contains 1 part by mass or more and 200 parts by mass or less of an inorganic filler relative to 100 parts by mass of the polyamide resin. The content of the inorganic filler is more preferably 10 parts by mass or more and even more preferably 20 parts by mass or more relative to 100 parts by mass of the polyamide resin. The content of the inorganic filler is more preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and can be 60 parts by mass or less relative to 100 parts by mass of the polyamide resin. When the content of the inorganic filler is 1 part by mass or more, the resin composition is more likely to exhibit superior mechanical strength and heat resistance, and molded articles obtained by molding the resin composition are less likely to have defects such as cracks. Furthermore, when the content of the inorganic filler is 200 parts by mass or less, the resin composition can have superior mechanical strength and moldability.

[0052] [others] In this embodiment, the resin composition may contain other additives as needed in addition to the polyamide resin, polyolefin, and inorganic filler. Examples of additives include stabilizers such as copper compounds; antioxidants such as hindered phenol antioxidants, hindered amine antioxidants, phosphorus antioxidants, and thio antioxidants; lubricants such as PTFE; flame retardants such as brominated polymers, antimony oxide, metal hydroxides, and phosphinates; flame retardant assistants; colorants; ultraviolet absorbers; light stabilizers; antistatic agents; crystal nucleating agents; plasticizers; lubricants; dispersants; oxygen absorbers; hydrogen sulfide adsorbents; crystallization retarders; and organic fibrous fillers such as wholly aromatic polyamide fibers. These additives may be used alone or in combination of two or more. The resin composition may contain additives in an amount not impairing the effects of the present invention, for example, 0.01 to 20 parts by mass per 100 parts by mass of polyamide resin.

[0053] [Method of producing resin composition] The method for producing the resin composition is not particularly limited, and any method capable of uniformly mixing the polyamide resin, the polyolefin used as needed, the inorganic filler, and the above-mentioned additives can be preferably used. The mixing is usually preferably performed by melt-kneading using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or the like. In one embodiment of the present invention, the resin composition may be composed solely of a polyamide resin, provided that the effects of the present invention are not impaired. From the viewpoint of improving mechanical strength and achieving superior physical properties such as heat resistance, chemical resistance, and moldability, the resin composition preferably contains a polyamide resin and a polyolefin, more preferably a polyamide resin and an inorganic filler, and more preferably a polyamide resin, a polyolefin, and an inorganic filler. Preferred embodiments of these resin compositions may further contain additives.

[0054] <Molded body> A molded article made of a resin composition can be obtained by molding the resin composition using various molding methods, such as injection molding, blow molding, extrusion molding, compression molding, stretch molding, vacuum molding, foam molding, rotational molding, impregnation, laser sintering, and fused deposition modeling. Furthermore, a molded article can also be obtained by composite molding of the resin composition and other polymers. Applications of the molded articles include, for example, bearings, bearing retainers, gears, bushings, spacers, rollers, cams, end face materials for mechanical seals, valve seats, V-rings, rod packing, piston rings, rotating shafts and rotating sleeves for compressors, pistons, seal rings, impellers, vanes, rotors, guide rails, thrust washers, ball joints, motor housings, bus bars, resolvers, and piping for transporting fluids.

[0055] <Lubricating oil> The molded product of this embodiment has a kinematic viscosity of 30 mm at 40°C. 2 The molded article of this embodiment has excellent mechanical strength even when used in contact with a lubricating oil having a kinematic viscosity of 30 mm / s or less at 40°C.2 Even when used in contact with lubricating oils exceeding 1mm / s, excellent mechanical strength can be expected. 2 / s or more. As mentioned above, it is believed that the acid component in the lubricating oil contributes to the deterioration of the physical properties of the molded article made of the resin composition containing the polyamide resin. 2 Lubricating oils having an acid value of 0.5 to 10 mgKOH / g or less tend to have a relatively high acid value when used in a high-temperature environment, which can easily cause a deterioration in the physical properties of the molded article. On the other hand, the molded article of this embodiment can suppress a decrease in the mechanical strength of the molded article even if the acid value of the lubricating oil is 0.5 to 10 mgKOH / g. In this specification, the acid value is measured in accordance with "7. Potentiometric titration method (acid value)" of JIS K2501:2003 "Petroleum products and lubricants - Testing method for neutralization number."

[0056] <How to use> In this embodiment, a molded article made of a resin composition containing a polyamide resin having an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more is molded into a molded article having a kinematic viscosity of 30 mm at 40° C. 2 The present invention also provides a method for using the molded article by contacting the molded article with a lubricating oil having a viscosity of 1 / s or less. [Example]

[0057] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0058] [Measurement and Evaluation] Measurements and evaluations in the Production Examples, Examples, and Comparative Examples were carried out according to the methods shown below. (Calculation method for amide group concentration) For polyamide resins, the amide group concentration (mmol / g) was calculated from [number of amide groups per structural unit]÷[molecular weight of structural unit]×1000. For example, in Production Example 1, the monomers used were terephthalic acid as the dicarboxylic acid and a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine as the diamine. Specifically, when the above formula is applied to Production Example 1, the amide group concentration is as follows: [Number of amide groups per structural unit] ÷ [Molecular weight of structural unit] × 1000 =[2(pieces)]÷[288(g / mol)]×1000 =6.9 (mmol / g)

[0059] (Melting Point) The melting points of the polyamide resins (samples) obtained in the Production Examples were measured using a differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Corporation. The melting point was measured in accordance with ISO 11357-3 (2011, 2nd edition). Specifically, in a nitrogen atmosphere, a sample was heated from 30°C to 340°C at a rate of 10°C / min, held at 340°C for 5 minutes to completely melt the sample, then 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 sample was again heated to 340°C at a rate of 10°C / min was taken as the melting point (°C). If there were multiple melting peaks, the peak temperature of the highest melting peak was taken as the melting point (°C).

[0060] (Amount of terminal amino groups) 1 g of the polyamide resin obtained in the Production Example was dissolved in 35 ml of phenol and mixed with 2 ml of methanol to prepare a sample solution. Using thymol blue as an indicator, titration was carried out using a 0.01 N HCl aqueous solution to measure the amount of terminal amino groups (μmol / g).

[0061] (Intrinsic viscosity of polyamide resin) A sample solution was prepared by dissolving the polyamide resin obtained in the Production Example in concentrated sulfuric acid as a solvent to a concentration of 0.2 g / dL. The flow time of the solvent (concentrated sulfuric acid) and the flow time of the sample solution were then measured at a temperature of 30°C, and the intrinsic viscosity was calculated using the following formula. η inh =[ln(t1 / t0)] / c In the above relational expression, 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 polyamide resin in the sample solution.

[0062] (oil resistance) (1) Preparation of ISO multipurpose test specimen A1 type dumbbell Using the pellets obtained in the Examples, Comparative Examples, and Reference Examples, an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., clamping force: 100 tons, screw diameter: 32 mm) was used to produce ISO multipurpose test specimens, type A1 dumbbell (4 mm thick, total length 170 mm, parallel portion length 80 mm, parallel portion width 10 mm), using a T-runner mold under conditions of a cylinder temperature of 300°C or 320°C, a mold temperature of 140°C, and a cycle time of 40 seconds or less. (2) Oil resistance test The above-mentioned ISO multipurpose test specimen, type A dumbbell (test specimen), was immersed in oil in a pressure vessel at 150°C for 1000 hours. The tensile properties of the test pieces before and after the immersion treatment were measured in accordance with ISO 527-1 (2012, 2nd edition) using a universal testing machine 5969 (manufactured by Instron Corporation) to measure the tensile breaking strength (MPa) at 23°C. The ratio (%) of the "tensile breaking strength of the test piece after the immersion treatment" to the "tensile breaking strength of the test piece before the immersion treatment" was then calculated and used as an index of oil resistance (%). The oils used for the above immersion are as follows: <Oil type 1> Kinematic viscosity at 40°C is 22mm 2 / s (measured according to ASTM D445) transmission oil, acid value (based on JIS K2501:2003) 0.6 mg KOH / g <Oil Type 2>: Dynamic viscosity at 40°C is 15mm 2 / s (measured according to ASTM D445) transmission oil, acid value (based on JIS K2501:2003) 1.0 mgKOH / g <Oil type 3> Dynamic viscosity at 40°C is 35mm 2 / s (measured according to ASTM D445) transmission oil, acid value (based on JIS K2501:2003) 0.4 mg KOH / g

[0063] [Each ingredient] The components used to prepare the resin compositions in the examples and comparative examples are shown below. <Polyamide resin> Manufacturing Example 1 (Production of Polyamide Resin (A-1)) 4539.3g (27.3 mol) of terephthalic acid, 4478.8g (28.3 mol) of a 50 / 50 mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, 101.6g (0.83 mol) of benzoic acid, 9.12g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 2.5L of distilled water were placed in a 40L autoclave, and the internal temperature was raised to 220°C over 3 hours. The autoclave was then pressurized to 2MPa. The reaction was continued for 4 hours while gradually releasing water vapor to maintain the pressure at 2MPa. The pressure was then reduced to 1.2MPa over 30 minutes, yielding a prepolymer. The prepolymer was pulverized and dried at 120°C under reduced pressure for 12 hours. This was polymerized at 200°C and 13.3 Pa for 2 hours, followed by solid-state polymerization at 235°C and 13.3 Pa to obtain a white polyamide with a melting point of 263°C, a terminal amino group content of 60 μmol / g, and an intrinsic viscosity of 1.25 dL / g.

[0064] Manufacturing Example 2 (Production of Polyamide Resin (A-2)) 4601.0 g (27.7 mol) of terephthalic acid, 4432.1 g (28.0 mol) of a 50 / 50 mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, 101.6 g (0.83 mol) of benzoic acid, 9.12 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 2.5 L of distilled water were placed in a 40 L autoclave, and the internal temperature was raised to 220°C over 3 hours. The autoclave was then pressurized to 2 MPa. The reaction was continued for 4 hours while gradually releasing water vapor to maintain the pressure at 2 MPa. The pressure was then reduced to 1.2 MPa over 30 minutes, yielding a prepolymer. The prepolymer was pulverized and dried at 120°C under reduced pressure for 12 hours. This was polymerized at 200°C and 13.3 Pa for 2 hours, followed by solid-state polymerization at 235°C and 13.3 Pa to obtain a white polyamide with a melting point of 263°C, a terminal amino group content of 8 μmol / g, and an intrinsic viscosity of 1.25 dL / g.

[0065] Manufacturing Example 3 (Production of Polyamide Resin (A-3)) 4539.3g (27.3 mol) of terephthalic acid, 4478.8g (28.3 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [80 / 20 (molar ratio)], 101.6g (0.83 mol) of benzoic acid, 9.12g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 2.5L of distilled water were placed in a 40L autoclave, and the internal temperature was raised to 220°C over 3 hours. The autoclave was then pressurized to 2MPa. The reaction was continued for 4 hours while gradually releasing water vapor to maintain the pressure at 2MPa. The pressure was then reduced to 1.2MPa over 30 minutes, yielding a prepolymer. The prepolymer was pulverized and dried at 120°C under reduced pressure for 12 hours. This was polymerized at 200°C and 13.3 Pa for 2 hours, followed by solid-state polymerization at 235°C and 13.3 Pa to obtain a white polyamide with a melting point of 300°C, a terminal amino group content of 60 μmol / g, and an intrinsic viscosity of 1.20 dL / g.

[0066] Manufacturing Example 4 (Production of Polyamide Resin (A-4)) 4547.4 g (27.4 mol) of terephthalic acid, 4400.4 g (28.1 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [80 / 20 (molar ratio)], 119.1 g (0.97 mol) of benzoic acid, 9.06 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 2.5 L of distilled water were placed in a 40 L autoclave, and the internal temperature was raised to 220°C over 3 hours. The autoclave was then pressurized to 2 MPa. The reaction was continued for 4 hours while gradually releasing water vapor to maintain the pressure at 2 MPa. The pressure was then reduced to 1.2 MPa over 30 minutes, yielding a prepolymer. This prepolymer was pulverized and dried at 120°C under reduced pressure for 12 hours. This was polymerized at 200°C and 13.3 Pa for 2 hours, followed by solid-state polymerization at 235°C and 13.3 Pa to obtain a white polyamide with a melting point of 300°C, a terminal amino group content of 30 μmol / g, and an intrinsic viscosity of 1.23 dL / g.

[0067] Production Example 5 (Production of Polyamide Resin (A-5)) 4601.0 g (27.7 mol) of terephthalic acid, 4432.1 g (28.0 mol) of a mixture of 1,9-nonanediamine and 2-methyl-1,8-octanediamine [80 / 20 (molar ratio)], 101.6 g (0.83 mol) of benzoic acid, 9.12 g of sodium hypophosphite monohydrate (0.1% by mass relative to the total mass of the raw materials), and 2.5 L of distilled water were placed in a 40 L autoclave, and the internal temperature was raised to 220°C over 3 hours. The autoclave was then pressurized to 2 MPa. The reaction was continued for 4 hours while gradually releasing water vapor to maintain the pressure at 2 MPa. The pressure was then reduced to 1.2 MPa over 30 minutes, yielding a prepolymer. This prepolymer was pulverized and dried at 120°C under reduced pressure for 12 hours. This was polymerized at 200°C and 13.3 Pa for 2 hours, followed by solid-state polymerization at 235°C and 13.3 Pa to obtain a white polyamide with a melting point of 300°C, a terminal amino group content of 8 μmol / g, and an intrinsic viscosity of 1.20 dL / g.

[0068] PA46: "Stanyl (registered trademark) TW241F6" manufactured by DSM Co., Ltd., polyamide 46, containing 30% by mass of glass fiber PA66: "Amira (registered trademark) CM3006G-30" manufactured by Toray Industries, Inc., polyamide 66, containing 30% glass fiber by mass

[0069] <Inorganic fillers> Glass fiber: "CS03JA-FT2A", manufactured by Owens Corning Japan LLC <Polyolefin> Elastomer: "Tafmer MH7010", manufactured by Mitsui Chemicals, Inc. <Other> PTFE: "KTL-620", manufactured by Kitamura Co., Ltd.

[0070] [Example 1] 95 parts by mass of the polyamide resin (A-1) obtained in Production Example 1 and 5 parts by mass of the elastomer were dry blended and then fed from the upstream hopper of a twin-screw extruder "TEM-26SS" (manufactured by Toshiba Machine Co., Ltd.). The mixture was melt-kneaded and extruded under the condition of a cylinder temperature of 300°C, followed by cooling and cutting to produce polyamide resin composition pellets. Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 300°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0071] [Examples 2 and 3] The evaluation was carried out in the same manner as in Example 1, except that the blending amount of the elastomer in Example 1 was changed.

[0072] [Example 4] 100 parts by mass of the polyamide resin (A-3) obtained in Production Example 3 was fed from the upstream hopper of a twin-screw extruder "TEM-26SS" (manufactured by Toshiba Machine Co., Ltd.). The mixture was melt-kneaded and extruded under conditions of a cylinder temperature of 320°C, cooled, and cut to produce polyamide resin composition pellets. Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 320°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0073] [Example 5] 65 parts by mass of the polyamide resin (A-3) obtained in Production Example 3 was fed from the upstream hopper of a twin-screw extruder "TEM-26SS" (manufactured by Toshiba Machine Co., Ltd.), and 35 parts by mass of glass fiber was fed from the side feed port of the barrel on the downstream side of the extruder. The mixture was melt-kneaded and extruded at a cylinder temperature of 320°C, followed by cooling and cutting to produce polyamide resin composition pellets. Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 320°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0074] [Example 6] 65 parts by mass of the polyamide resin (A-4) obtained in Production Example 4 and 5 parts by mass of elastomer were dry-blended and then fed from the upstream hopper of a twin-screw extruder "TEM-26SS" (manufactured by Toshiba Machine Co., Ltd.), and 30 parts by mass of glass fiber was fed from the side feed port of the barrel on the downstream side of the extruder. The mixture was melt-kneaded and extruded under conditions of a cylinder temperature of 320°C, followed by cooling and cutting to produce polyamide resin composition pellets. Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 320°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0075] [Example 7] 65 parts by mass of the polyamide resin (A-4) obtained in Production Example 4 and 5 parts by mass of PTFE were dry-blended and then fed into the upstream hopper of a twin-screw extruder "TEM-26SS" (manufactured by Toshiba Machine Co., Ltd.), and 30 parts by mass of glass fiber was fed into the barrel on the downstream side of the extruder through a side feed port. The mixture was melt-kneaded and extruded under conditions of a cylinder temperature of 320°C, followed by cooling and cutting to produce polyamide resin composition pellets. Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 320°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0076] [Comparative Example 1] Polyamide resin composition pellets were obtained in the same manner as in Example 2, except that the polyamide resin (A-1) was changed to the polyamide resin (A-2). Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 300°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0077] Comparative Example 2 70 parts by mass of the polyamide resin (A-5) obtained in Production Example 5 was fed from the upstream hopper of a twin-screw extruder "TEM-26SS" (manufactured by Toshiba Machine Co., Ltd.), and 30 parts by mass of glass fiber was fed from the side feed port of the barrel on the downstream side of the extruder. The mixture was melt-kneaded and extruded at a cylinder temperature of 320°C, followed by cooling and cutting to produce polyamide resin composition pellets. Using the polyamide resin pellets, ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties were prepared by the method described above at a cylinder temperature of 320°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0078] [Reference example] Using the ISO multipurpose A1 type dumbbell test piece (test piece) for measuring physical properties prepared in Comparative Example 2, oil resistance was evaluated using oil type 3. The results are shown in Table 1.

[0079] Comparative Example 3 PA46 (Stanyl (registered trademark) TW241F6) pellets were used to prepare ISO multipurpose test specimens A1 type dumbbells (test specimens) for measuring physical properties at a cylinder temperature of 300°C and a mold temperature of 100°C, and the oil resistance was evaluated. The results are shown in Table 1.

[0080] Comparative Example 4 PA66 (Amilan (registered trademark) CM3006G-30) pellets were prepared into ISO multipurpose A1 type dumbbell test specimens for measuring physical properties at a cylinder temperature of 290°C and a mold temperature of 80°C, and oil resistance was evaluated. The results are shown in Table 1.

[0081] [Table 1]

[0082] The meanings of the notations in Table 1 are as follows: *1: PA46 contains 30% by mass of glass fiber. *2: PA66 contains 30% glass fiber by mass. (Parts by mass): Parts by mass relative to 100 parts by mass of polyamide resin.

[0083] As can be seen from Table 1, the molded articles of the Examples exhibited excellent tensile strength retention even after immersion in low-viscosity oil at 150°C. On the other hand, the molded articles of the Comparative Examples exhibited poor tensile strength retention after immersion in low-viscosity oil at 150°C. For reference, the kinematic viscosity at 40°C is 30mm 2 Therefore, from the results of Reference Example and Comparative Example 2, it can be seen that even if a molded article does not satisfy the requirements of the present invention, even if the kinematic viscosity is 30 mm / s, the tensile strength retention rate is excellent. 2It can be understood that even if the molded article of the present embodiment can maintain mechanical strength such as tensile strength in oil with a viscosity of more than 1 / s, the mechanical strength decreases when the molded article is used in contact with a low-viscosity oil. Therefore, it can be said that the molded article of the present embodiment, which can maintain excellent mechanical strength even when used in contact with a low-viscosity lubricating oil, has extremely excellent effects. [Industrial Applicability]

[0084] The molded article of the present invention can suppress deterioration in physical properties even when used in contact with low-viscosity lubricating oil, and is therefore useful particularly as a part for use in an oil-related application.

Claims

1. A molded article made of a resin composition containing a polyamide resin, the polyamide resin has an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more; Kinematic viscosity at 40°C is 30 mm ２ / s or less and is used in contact with a lubricating oil having an acid value of 0.5 to 10 mgKOH / g.

2. The molded article according to claim 1, wherein the polyamide resin is at least one selected from the group consisting of semi-aromatic polyamides and aliphatic polyamides.

3. The molded article according to claim 2 , wherein the semi-aromatic polyamide contains diamine units derived from an aliphatic diamine and dicarboxylic acid units derived from an aromatic dicarboxylic acid.

4. The molded article according to claim 2 or 3, wherein the semi-aromatic polyamide contains diamine units derived from an aliphatic diamine having 4 to 18 carbon atoms and dicarboxylic acid units derived from at least one selected from the group consisting of terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

5. 3. The molded article according to claim 1, wherein the polyamide resin comprises at least one selected from the group consisting of polyhexamethylene terephthalamide, polynonamemethylene terephthalamide / poly(2-methyloctamethylene) terephthalamide copolymer, polynonamemethylene terephthalamide, polydecamethylene terephthalamide, polyundecaneamide, polydodecanamide, polymetaxylylene adipamide, and polymetaxylylene sebacamide.

6. The molded article according to any one of claims 1 to 5, wherein the resin composition further contains a polyolefin.

7. The molded article according to any one of claims 1 to 6, wherein the resin composition further contains an inorganic filler.

8. A molded article made of a resin composition containing a polyamide resin having an amide group concentration of 8.5 mmol / g or less and a terminal amino group amount of 20 μmol / g or more, Kinematic viscosity at 40°C is 30 mm ２ / s or less and an acid value of 0.5 to 10 mgKOH / g.

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