Polyamide resin composition and polyamide molded article

Abstract

This polyamide resin composition includes a polyamide resin and a copper-based heat-resistant stabilizing agent. The copper content in the copper-based stabilizing agent is 0.001-0.050 parts by mass with respect to 100 parts by mass of the polyamide resin. The polyamide resin includes a dicarboxylic acid-derived component unit (a) and a diamine-derived component unit (b). The dicarboxylic acid-derived component unit (a) includes an aromatic dicarboxylic acid-derived component unit or an alicyclic dicarboxylic acid-derived component unit. The diamine-derived component unit (b) includes a diamine-derived component unit (b2) represented by formula (1) in an amount of 10 mol% or more but less than 50 mol% with respect to the total number of moles of the diamine-derived component unit (b).

Description

[Technical Field]

[0001] The present disclosure relates to a polyamide resin composition and a polyamide molded article. [Background technology]

[0002] Polyamide resin compositions have been widely used as materials for various parts for clothing, industrial materials, automobiles, electrical and electronic products, industrial applications, etc. because of their excellent moldability, mechanical properties, and chemical resistance.

[0003] Various additives are added to polyamide resin compositions used for these applications to achieve properties suited to each application. For example, it is known to add a copper-based heat stabilizer to improve the heat aging resistance of polyamide resin compositions. For example, Patent Document 1 describes that adding a copper-based heat stabilizer can extend the time until the tensile strength is reduced by half when heat-treated at 180°C to several hundred hours.

[0004] Furthermore, attempts have been made to change the physical properties of polyamide resins by changing the raw materials of the polyamide resin. For example, Patent Document 2 describes the use of bis-aminomethyl-norbornane as a diamine component used in the production of polyamides by polycondensing a diamine component and a dicarboxylic acid component. It also describes that polyamides using equimolar amounts of bis-aminomethyl-norbornane and 2-methylpentamethylene as diamine components are transparent and have a high freezing point. It also describes the selection of a diamine component to completely prevent crystallization during cooling in order to enhance the transparency of the polyamide.

[0005] Patent Document 3 describes that part of the hexamethylenediamine used as a diamine component is a mixture of equivalent amounts of 2,5-bis-aminomethyl-norbornane and 2,6-bis-aminomethyl-norbornane, and that the molar ratio of the mixture is 20 mol % or less, thereby producing a transparent polyamide having a high transition temperature.

[0006] Patent Document 4 describes that the blending ratio of bis-aminomethyl-norbornane as a diamine component is 17% by weight or more. Specifically, it describes that a polyamide obtained by blending hexamethylenediamine and bis-aminomethyl-norbornane in a weight ratio of hexamethylenediamine / bis-aminomethyl-norbornane of 30 / 70 (molar ratio of 36 / 64) has a high glass transition point. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 06-032979 [Patent Document 2] Japanese Patent Application Publication No. 48-60193 [Patent Document 3] Japanese Patent Application Publication No. 53-125497 [Patent Document 4] Japanese Patent Application Publication No. 63-154739 Summary of the Invention [Problem to be solved by the invention]

[0008] As described in Patent Document 1, it is known that the use of a copper-based heat stabilizer can improve the heat aging resistance of a polyamide resin composition. However, the present inventors' new findings have revealed that the addition of a copper-based heat stabilizer reduces the inherent tensile strength of the polyamide resin composition. The problem of reduced tensile strength is particularly pronounced when a molded article of the polyamide resin composition is used in a high-temperature environment. In addition, in recent years, there has been an increasing demand for further improving the long-term heat resistance of polyamide resin compositions, and there is a need for the development of polyamide resin compositions that can maintain a predetermined tensile strength for a longer period of time in a high-temperature environment.

[0009] In view of these circumstances, an object of the present disclosure is to provide a polyamide resin composition that can suppress a decrease in tensile strength at high temperatures due to the addition of a copper-based heat stabilizer and can maintain a predetermined tensile strength for a longer period of time in a high-temperature environment, and a polyamide molded article containing the polyamide resin composition. [Means for solving the problem]

[0010] [1] A polyamide resin composition comprising a polyamide resin and a copper-based heat stabilizer, wherein the copper content of the copper-based heat stabilizer is 0.001 parts by mass or more and 0.050 parts by mass or less per 100 parts by mass of the polyamide resin, and the polyamide resin comprises component units (a) derived from a dicarboxylic acid and component units (b) derived from a diamine, wherein the dicarboxylic acid-derived component units (a) comprise component units derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and the diamine-derived component units (b) comprise component units (b1) derived from an alkylene diamine having from 4 to 18 carbon atoms, which account for more than 50 mol % and not more than 90 mol % of the total number of moles of the diamine-derived component units (b), and component units (b2) derived from a diamine represented by the following formula (1), which account for from 10 mol % to less than 50 mol % of the total number of moles of the diamine-derived component units (b): [ka] (In formula (1), m and n each independently represent 0 or 1; -X- is a single bond or a divalent group selected from the group consisting of -O-, -S-, -SO2-, -CO- and -CH2-. [2] The polyamide resin composition according to [1], wherein the polyamide resin contains 15 mol% or more and less than 45 mol% of component units (b2) derived from the diamine represented by formula (1) relative to the total number of moles of component units (b) derived from the diamine. [3] The polyamide resin composition according to [1] or [2], wherein the component unit (b1) derived from an alkylenediamine having from 4 to 18 carbon atoms includes a component unit derived from a linear alkylenediamine or a branched alkylenediamine. [4] The polyamide resin composition according to [3], wherein the linear alkylenediamine or branched alkylenediamine is a diamine selected from the group consisting of 1,4-diaminobutane, 1,6-diaminohexane, 1,9-nonanediamine, 1,10-decanediamine, 2-methyl-1,5-pentanediamine, and 2-methyl-1,8-octanediamine. [5] The polyamide resin composition according to any one of [1] to [4], wherein the aromatic dicarboxylic acid or alicyclic dicarboxylic acid is terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid. [6] The polyamide resin composition according to any one of [1] to [5], wherein the polyamide resin has a melting point (Tm) of 280° C. or higher. [7] The polyamide resin composition according to any one of [1] to [6], wherein the polyamide resin is a crystalline polyamide resin. [8] The polyamide resin composition according to any one of [1] to [7], wherein the polyamide resin has a heat of fusion (ΔH) of 10 mJ / mg or more. [9] The polyamide resin composition according to any one of [1] to [8], which is a resin composition for an in-vehicle member.

[0011]

[10] A polyamide molded article comprising the polyamide resin composition according to any one of [1] to [9].

[11] The polyamide molded article according to

[10] , which is an in-vehicle component. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a polyamide resin composition that can suppress a decrease in tensile strength due to the addition of a copper-based heat resistance stabilizer and can maintain a predetermined tensile strength for a longer period of time in a high-temperature environment, and a polyamide molded product containing the polyamide resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1. Polyamide resin composition The polyamide resin composition of the present disclosure is a resin composition in which the main component of the resin components is a polyamide resin. Main component means that the proportion of the polyamide resin in the resin components is 50% by mass or more. The proportion of the polyamide resin in the resin components is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The upper limit of the proportion of the polyamide resin in the resin components is not particularly limited, but may be 100% by mass or less, or may be 90% by mass or less, or may be 80% by mass or less.

[0014] The proportion of the polyamide resin contained in the polyamide resin composition is preferably 20% by mass or more and 80% by mass or less based on the total mass of the polyamide resin composition.

[0015] 1-1. Polyamide resin The polyamide resin may contain component units (a) derived from a dicarboxylic acid and component units (b) derived from a diamine. In this case, in order to appropriately increase the melting point (Tm) and glass transition temperature (Tg) of the polyamide resin, the component units (a) derived from a dicarboxylic acid preferably contain component units derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and the component units (b) derived from a diamine preferably contain component units (b1) derived from an alkylene diamine having from 4 to 18 carbon atoms, which account for more than 50 mol% and not more than 90 mol% of the total number of moles of the component units (b) derived from the diamine, and component units (b2) derived from a diamine represented by the following formula (1), which account for from 10 mol% to less than 50 mol% of the total number of moles of the component units (b) derived from the diamine: [ka] (In formula (1), m and n each independently represent 0 or 1; -X- is a single bond or a divalent group selected from the group consisting of -O-, -S-, -SO2-, -CO- and -CH2-.

[0016] [Component unit (a) derived from dicarboxylic acid] When the polyamide resin contains a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid as the component unit (a) derived from a dicarboxylic acid, the melting point (Tm) and crystallinity can be sufficiently increased.

[0017] Examples of aromatic dicarboxylic acids include terephthalic acid, naphthalenedicarboxylic acid and their esters. Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid and its esters.

[0018] In the present disclosure, the dicarboxylic acid-derived component units (a) preferably include component units (a1) derived from terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid. These component units (a1), unlike, for example, isophthalic acid, can enhance the crystallinity of polyamides. To ensure the crystallinity of the polyamide resin, the content of these component units (a1) is set to more than 20 mol% and not more than 100 mol% relative to the total moles of the dicarboxylic acid-derived component units (a). To further enhance the crystallinity of the polyamide resin, the content of these component units (a1) is preferably 45 mol% or more, more preferably 50 mol% or more, even more preferably more than 80 mol%, and particularly preferably more than 90 mol% relative to the total moles of the dicarboxylic acid-derived component units (a). The upper limit of the content of component units (a1) may be 100 mol% or not more than 99 mol% relative to the total moles of the dicarboxylic acid-derived component units (a). Among these, from the viewpoint of obtaining a polyamide resin having high crystallinity and high heat resistance, the component unit (a1) is more preferably a component unit derived from terephthalic acid.

[0019] The dicarboxylic acid-derived component unit (a) may further include a component unit (a2) derived from an aromatic dicarboxylic acid other than the above-mentioned component unit (a1), a component unit (a3) ​​derived from an aliphatic dicarboxylic acid having from 4 to 18 carbon atoms, or a component unit (a4) derived from a tribasic or higher polycarboxylic acid, within the scope of the present disclosure.

[0020] Examples of the component units (a2) derived from aromatic dicarboxylic acids other than terephthalic acid include component units derived from isophthalic acid and 2-methylterephthalic acid, preferably component units derived from isophthalic acid. From the viewpoint of easily ensuring the crystallinity of the polyamide resin, the content of these component units (a2) is preferably 1 mol % to 50 mol %, more preferably 1 mol % to 20 mol %, even more preferably 1 mol % to 10 mol %, and particularly preferably 1 mol % to 5 mol %, based on the total number of moles of the component units (a) derived from dicarboxylic acids.

[0021] The component unit (a3) ​​derived from an aliphatic dicarboxylic acid having from 4 to 18 carbon atoms is a component unit derived from an aliphatic dicarboxylic acid having an alkylene group having from 4 to 18 carbon atoms, and is preferably a component unit derived from an aliphatic dicarboxylic acid having an alkylene group having from 6 to 12 carbon atoms. Examples of aliphatic dicarboxylic acids include component units derived from malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, and suberic acid, with component units derived from adipic acid and sebacic acid being preferred. From the viewpoint of ensuring the crystallinity of the polyamide resin, the content of these component units (a3) ​​is preferably 0 mol % or more and 40 mol % or less, more preferably 0 mol % or more and 20 mol % or less, even more preferably 1 mol % or more and 10 mol % or less, and particularly preferably 1 mol % or more and 5 mol % or less, relative to the total number of moles of component units (a) derived from dicarboxylic acid.

[0022] Examples of the unit (a4) derived from a tribasic or higher polycarboxylic acid include units derived from trimellitic acid, pyromellitic acid, and esters thereof. The content of such units derived from polycarboxylic acids can be from 0 mol % to 5 mol % relative to the total number of moles of the units (a) derived from dicarboxylic acids.

[0023] However, from the viewpoint of preventing the crystallinity of the resin from being impaired, the content of component units derived from isophthalic acid and component units derived from aliphatic dicarboxylic acids other than adipic acid having 4 to 18 carbon atoms is preferably small, and more preferably 20 mol % or less, and more preferably 10 mol % or less, of the total number of moles of component units (a) derived from dicarboxylic acids.

[0024] [Diamine-derived component unit (b)] When a polyamide resin contains, as diamine-derived component units (b), component units (b1) derived from an alkylenediamine having from 4 to 18 carbon atoms, and component units (b2) derived from an alkylenediamine having a specific cyclic structure (diamine represented by formula (1)), the glass transition temperature (Tg) can be sufficiently increased.

[0025] That is, the component unit (b2) derived from the diamine represented by formula (1) has a nonlinear structure, thereby reducing the mobility of the molecular chain of the polyamide resin. Therefore, the component unit (b2) derived from the diamine represented by formula (1) can increase the glass transition temperature (Tg) of a polyamide resin containing the component unit (b2) compared to a polyamide resin not containing the component unit (b2). As a result, it is believed that a polyamide resin containing the component unit (b2) has high mechanical strength even at high temperatures and can maintain this high mechanical strength for a long period of time.

[0026] Furthermore, the component unit (b2) derived from the diamine represented by formula (1) can appropriately lower the melting point (Tm) of a polyamide resin having the component unit (b2) compared to a polyamide resin not having the component unit (b2), thereby providing the polyamide resin with the component unit (b2) with high fluidity during injection molding and excellent moldability.

[0027] According to the findings of the present inventors, the copper-based heat stabilizer described below is resistant to decomposition at high temperatures and therefore enhances the heat aging resistance of polyamide resin compositions. However, because it is a foreign substance in the resin composition and a compound containing a metal with properties significantly different from those of the resin, it significantly reduces the crystallinity of the polyamide resin and tends to reduce the initial tensile strength of the polyamide resin composition from the initial stage of production. Furthermore, in high-temperature environments where the resin has high fluidity, the copper-based heat stabilizer, which is a foreign substance, tends to move more freely within the composition. This movement further inhibits the expansion / contraction and crystallization of the resin molecules, resulting in a more pronounced decrease in tensile strength. In contrast, the diamine-derived component unit (b2) represented by formula (1) increases the glass transition temperature of the polyamide resin, thereby limiting the movement of the copper-based heat stabilizer in high-temperature environments. This is thought to reduce the inhibition of expansion / contraction and crystallization of the resin molecules by the copper-based heat stabilizer, thereby suppressing the decrease in tensile strength of the polyamide resin composition in high-temperature environments.

[0028] Furthermore, the diamine-derived component (b2) of formula (1) has a cyclic structure, which makes it difficult for the molecular chain of the resin to be severable even when placed in a high-temperature environment for a long period of time, thereby enhancing the long-term heat resistance of the polyamide resin itself. Therefore, the diamine-derived component (b2) of formula (1) is thought to facilitate the maintenance of the tensile strength of a molded article of the polyamide resin composition for a long period of time even in a high-temperature environment.

[0029] In addition, the polyamide resin has crystallinity due to the component unit (b1) derived from alkylenediamine having from 4 to 18 carbon atoms, and therefore (the polyamide resin itself) has high fluidity and mechanical strength during injection molding. Furthermore, since the polyamide resin has a high glass transition temperature (Tg), it has high mechanical strength even at high temperatures and is thought to easily maintain this high mechanical strength.

[0030] The alkylenediamine having 4 to 18 carbon atoms, which is the raw material for the component unit (b1), more preferably has 4 to 10 carbon atoms, from the viewpoint of preventing a decrease in the Tg of the resin.

[0031] The alkylenediamine having 4 to 18 carbon atoms may include a linear alkylenediamine or a branched alkylenediamine. From the viewpoint of enhancing the crystallinity of the resin, the alkylenediamine having 4 to 18 carbon atoms preferably includes a linear alkylenediamine. That is, the component units derived from the alkylenediamine having 4 to 18 carbon atoms preferably include component units derived from a linear alkylenediamine.

[0032] Examples of alkylenediamines having 4 to 18 carbon atoms include linear alkylenediamines such as 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine, and branched alkylenediamines such as 2-methyl-1,5-pentanediamine and 2-methyl-1,8-octanediamine. Among these, 1,4-diaminobutane, 1,6-diaminohexane, 1,9-nonanediamine, 1,10-decanediamine, 2-methyl-1,5-pentanediamine, and 2-methyl-1,8-octanediamine are preferred, and 1,6-diaminohexane and 1,10-decanediamine are more preferred. These alkylenediamines may be used alone or in combination.

[0033] The content of the component units (b1) derived from alkylenediamine having from 4 to 18 carbon atoms is preferably more than 50 mol% and not more than 90 mol% of the total number of moles of the component units (b) derived from diamine. When this content is more than 50 mol%, the crystallinity of the polyamide resin is sufficiently increased, thereby further improving the flowability and mechanical strength of the polyamide resin itself during injection molding. When this content is not more than 90 mol%, the content of the component units (b2) derived from the diamine represented by formula (1) can be increased. This increases the glass transition temperature (Tg) of the polyamide resin, improving mechanical strength at high temperatures, and appropriately lowers the Tm of the polyamide resin, improving moldability.

[0034] From the same viewpoint, the content of the component units (b1) derived from alkylenediamine having from 4 to 18 carbon atoms is more preferably from 55 mol % to 85 mol % and even more preferably from 60 mol % to 80 mol % of the total number of moles of the component units (b) derived from diamine.

[0035] On the other hand, the content of the diamine-derived component (b2) represented by formula (1) is preferably 10 mol% or more and less than 50 mol% of the total number of moles of the diamine-derived component (b). A content of 10 mol% or more increases the glass transition temperature (Tg) of the polyamide resin, thereby increasing its mechanical strength at high temperatures, and moderately decreases the Tm of the polyamide resin, thereby improving its moldability. A content of less than 50 mol% increases the content of the component (b1) derived from an alkylenediamine having 4 to 18 carbon atoms. This not only sufficiently increases the crystallinity of the polyamide resin and further increases the mechanical strength of the molded article, but also prevents the component (b2) derived from the diamine represented by formula (1) from reducing the fluidity of the polyamide resin itself.

[0036] From the same viewpoint, the content of the component units (b2) derived from the diamine represented by formula (1) is more preferably 15 mol% or more and less than 45 mol%, even more preferably 20 mol% or more and 40 mol% or less, still more preferably 20 mol% or more and 38 mol% or less, and particularly preferably 22 mol% or more and 35 mol% or less, relative to the total number of moles of the component units (b) derived from the diamine.

[0037] Furthermore, the inventors have found that adding glass fibers treated with a sizing agent having a carboxyl group to a polyamide resin composition can reduce the fluidity of the polyamide resin composition. This reduction in fluidity was also observed when glass fibers treated with other sizing agents or surface treatment agents having acidic groups were added to the polyamide resin composition. The reduction in fluidity when glass fibers treated with a sizing agent or surface treatment agent having acidic groups were added to the polyamide resin composition is thought to be caused by the acidic groups of the sizing agent or surface treatment agent reacting with the amino terminals of the polyamide resin when the polyamide resin composition is melted. In other words, this reaction bonds the polyamide resin and the glass fibers via the sizing agent or surface treatment agent, increasing the apparent molecular weight of the polyamide resin. This increase in apparent molecular weight is thought to reduce the fluidity of the polyamide resin composition. In contrast, the component unit (b2) derived from the diamine represented by formula (1) bends the molecular chain of the polyamide resin, causing moderate steric hindrance, which can further inhibit the reaction between the acidic group of the sizing agent or surface treatment agent and the amino terminal of the polyamide resin, which is thought to suppress an increase in the apparent molecular weight of the polyamide resin and thus provide the further effect of suppressing a decrease in the fluidity of the polyamide resin composition when a sizing agent or surface treatment agent having an acidic group is used.

[0038] The diamine-derived unit (b) may further contain a diamine-derived unit (b3) derived from another diamine, provided that the effect of the present disclosure is not impaired. Examples of the diamine include aromatic diamines and alicyclic diamines. The content of the diamine-derived unit (b3) may be 50 mol % or less based on the total number of moles of the diamine-derived unit (b).

[0039] In order to improve the thermal stability during compounding or molding and to further increase the mechanical strength of the polyamide resin, at least some of the molecular terminal groups may be capped with a terminal capping agent. For example, when the molecular terminal is a carboxy group, the terminal capping agent is preferably a monoamine, and when the molecular terminal is an amino group, the terminal capping agent is preferably a monocarboxylic acid.

[0040] Examples of monoamines include aliphatic monoamines such as methylamine, ethylamine, propylamine, and butylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; and aromatic monoamines such as aniline and toluidine. Examples of monocarboxylic acids include aliphatic monocarboxylic acids having 2 to 30 carbon atoms such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid. The aromatic monocarboxylic acid and alicyclic monocarboxylic acid may have a substituent on the ring structure portion.

[0041] [Physical Properties] The polyamide resin may have a melting point (Tm) of 280°C or higher and 330°C or lower, as measured by a differential scanning calorimeter (DSC), and a glass transition temperature (Tg) of 135°C or higher and 180°C or lower, as measured by DSC.

[0042] When the melting point (Tm) of the polyamide resin is 280°C or higher, the mechanical strength and heat resistance of the polyamide resin composition and molded article at high temperatures are less likely to be impaired, and when it is 330°C or lower, the molding temperature does not need to be excessively high, which tends to improve the molding processability of the polyamide resin composition. From the above viewpoints, the melting point (Tm) of the polyamide resin is more preferably 290°C or higher and 330°C or lower, and even more preferably 300°C or higher and 330°C or lower.

[0043] When the glass transition temperature (Tg) of the polyamide resin is 135°C or higher, the heat resistance of the polyamide resin composition and molded article is less likely to be impaired, and at the same time, the mechanical strength at high temperatures can be further increased. When the glass transition temperature (Tg) of the polyamide resin is 180°C or lower, the molding processability of the polyamide resin composition is likely to be good. From the above viewpoint, the glass transition temperature (Tg) of the polyamide resin is more preferably 140°C or higher and 170°C or lower.

[0044] The heat of fusion (ΔH) of the polyamide resin is preferably 10 mJ / mg or more. When the heat of fusion (ΔH) of the polyamide resin is 10 mJ / mg or more, the polyamide resin has crystallinity, which makes it easy to improve the fluidity and mechanical strength during injection molding. From the same viewpoint, the heat of fusion (ΔH) of the polyamide resin is more preferably 15 mJ / mg or more, and even more preferably 20 mJ / mg or more. The upper limit of the heat of fusion (ΔH) of the polyamide resin is not particularly limited, but can be 90 mJ / mg from the viewpoint of not impairing moldability.

[0045] The heat of fusion (ΔH), melting point (Tm) and glass transition temperature (Tg) of the polyamide resin can be measured using a differential scanning calorimeter (DSC220C model, manufactured by Seiko Instruments Inc.).

[0046] Specifically, approximately 5 mg of polyamide resin is sealed in a measuring aluminum pan and heated from room temperature to 350°C at 10°C / min. To completely melt the resin, it is held at 350°C for 3 minutes and then cooled to 30°C at 10°C / min. After leaving it at 30°C for 5 minutes, it is heated a second time to 350°C at 10°C / min. The temperature (°C) of the endothermic peak during this second heating is taken as the melting point (Tm) of the polyamide resin, and the inflection point corresponding to the glass transition is taken as the glass transition temperature (Tg). The heat of fusion (ΔH) is calculated from the area of ​​the endothermic peak during the second heating process in accordance with JIS K7122.

[0047] The melting point (Tm), glass transition temperature (Tg) and heat of fusion (ΔH) of the polyamide resin can be adjusted by the structure of the component unit (a) derived from dicarboxylic acid, the content of the component unit (b2) derived from the diamine represented by formula (1), the content ratio of the component unit (b1) derived from an alkylenediamine having from 4 to 18 carbon atoms to the component unit (b2) derived from the diamine represented by formula (1), and the number of carbon atoms of the alkylenediamine having from 4 to 18 carbon atoms.

[0048] Furthermore, when increasing the heat of fusion (ΔH) of the polyamide resin, it is preferable to reduce the content or content ratio of the component unit (b2) (the ratio of the component unit (b2) to the total number of moles of the component unit (b) derived from the diamine).On the other hand, when increasing the glass transition temperature (Tg) and lowering the melting point (Tm) of the polyamide resin, it is preferable to increase the content or content ratio of the component unit (b2) (the ratio of the component unit (b2) to the total number of moles of the component unit (b) derived from the diamine).

[0049] The polyamide resin preferably has an intrinsic viscosity [η] of 0.6 dL / g or more and 1.5 dL / g or less, as measured in 96.5% sulfuric acid at 25°C. When the polyamide resin has an intrinsic viscosity [η] of 0.6 dL / g or more, the mechanical strength (toughness, etc.) of the molded product is easily increased, and when the intrinsic viscosity [η] is 1.5 dL / g or less, the fluidity of the polyamide resin composition during molding is less likely to be impaired. From the same viewpoint, the polyamide resin more preferably has an intrinsic viscosity [η] of 0.8 dL / g or more and 1.2 dL / g or less. The intrinsic viscosity [η] can be adjusted by, for example, the amount of end-capping of the polyamide resin.

[0050] The intrinsic viscosity of the polyamide resin can be measured in accordance with JIS K6810-1977. Specifically, 0.5 g of polyamide resin is dissolved in 50 ml of 96.5% sulfuric acid solution to prepare a sample solution. The flow time of this sample solution is measured using an Ubbelohde viscometer at 25±0.05°C, and the obtained value can be used to calculate the viscosity using the following formula: [η]=ηSP / [C(1+0.205ηSP)]

[0051] In the above formula, each algebra or variable represents the following: [η]: Intrinsic viscosity (dl / g) ηSP: Specific viscosity C: Sample concentration (g / dl)

[0052] ηSP is calculated by the following formula: ηSP=(t-t0) / t0 t: Number of seconds for sample solution to flow down (seconds) t0: Number of seconds for blank sulfuric acid to flow (seconds)

[0053] [Manufacturing method] The polyamide resin can be produced, for example, by polycondensing the aforementioned dicarboxylic acid and the aforementioned diamine in a homogeneous solution. Specifically, the polyamide resin can be produced by heating the dicarboxylic acid and the diamine in the presence of a catalyst to obtain a low-order condensate, as described in WO 03 / 085029, and then applying shear stress to a melt of the low-order condensate to polycondense it.

[0054] The aforementioned terminal blocking agent may be added to the reaction system from the viewpoint of adjusting the intrinsic viscosity of the polyamide resin. The intrinsic viscosity [η] (or molecular weight) of the polyamide resin can be adjusted by adjusting the amount of terminal blocking agent added.

[0055] The end-capping agent is added to the reaction system of the dicarboxylic acid and the diamine in an amount of preferably 0.07 mol or less, more preferably 0.05 mol or less, per mol of the total amount of the dicarboxylic acid.

[0056] 1-2.Heat stabilizer The copper-based heat stabilizer can improve the fluidity of the polyamide resin composition during molding, and also improves the heat aging resistance of the polyamide resin composition.

[0057] The copper-based heat resistance stabilizer contains (i) a salt of a halogen and a metal element of Group 1 or 2 of the periodic table (halogen metal salt), and (ii) a copper compound, and may further contain (iii) a metal salt of a higher fatty acid, as needed.

[0058] (i) Examples of halogen metal salts include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. Among these, potassium iodide and potassium bromide are preferred. Only one type of halogen metal salt may be contained, or two or more types may be contained.

[0059] (ii) Examples of copper compounds include copper halides, copper salts (such as sulfate, acetate, propionate, benzoate, adipate, terephthalate, salicylate, nicotinate, and stearate), and copper chelate compounds (compounds of copper with ethylenediamine or ethylenediaminetetraacetic acid). Among these, copper iodide, copper (I) bromide, copper (II) bromide, copper (I) chloride, and copper acetate are preferred. Only one type of copper compound may be contained, or two or more types may be contained.

[0060] The mass ratio of (i) the halogen metal salt to (ii) the copper compound can be adjusted so that the molar ratio of halogen to copper is 0.1 / 1 to 200 / 1, preferably 0.5 / 1 to 100 / 1, and more preferably 2 / 1 to 40 / 1, from the viewpoint of facilitating improvement in the heat resistance of the molded body and the corrosion resistance during production.

[0061] (iii) Examples of metal salts of higher fatty acids include metal salts of higher saturated fatty acids and metal salts of higher unsaturated fatty acids.

[0062] The metal salt of a higher saturated fatty acid is preferably a metal salt of a saturated fatty acid having 6 to 22 carbon atoms and a metal element (M1) such as an element of Groups 1, 2, or 3 of the Periodic Table, zinc, or aluminum. Such a metal salt of a higher saturated fatty acid is represented by the following formula (2): CH3(CH2) n COO(M1)...(2) (In formula (2), the metal element (M1) is an element of Groups 1, 2, or 3 of the periodic table, zinc, or aluminum, and n can be 8 to 30.)

[0063] Examples of metal salts of higher saturated fatty acids include lithium salts, sodium salts, magnesium salts, calcium salts, zinc salts and aluminum salts of capric acid, uradecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, melissic acid and lacteric acid.

[0064] The higher unsaturated fatty acid metal salt is preferably a metal salt of an unsaturated fatty acid having 6 to 22 carbon atoms and a metal element (M1) such as an element of Groups 1, 2, or 3 of the periodic table, zinc, or aluminum.

[0065] Examples of metal salts of higher unsaturated fatty acids include lithium salts, sodium salts, magnesium salts, calcium salts, zinc salts and aluminum salts of undecylenic acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassidic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, stearic acid, 2-hexadecenoic acid, 7-hexadecenoic acid, 9-hexadecenoic acid, gadoleic acid, gadoelaidic acid and 11-eicosenoic acid.

[0066] Examples of copper-based heat stabilizers include a mixture of 10% by mass of copper(I) iodide and 90% by mass of potassium iodide, and a mixture of 14.3% by mass of copper(I) iodide and 85.7% by mass of potassium iodide / calcium distearate (98:2 mass ratio).

[0067] The copper content of the copper-based heat stabilizer in the polyamide resin composition is from 0.001 to 0.050 parts by mass, preferably from 0.002 to 0.030 parts by mass, more preferably from 0.003 to 0.020 parts by mass, and even more preferably from 0.005 to 0.010 parts by mass, per 100 parts by mass of polyamide resin. When the amount of copper contained in the copper-based heat stabilizer is 0.001 part by mass or more per 100 parts by mass of polyamide resin, the fluidity and heat aging resistance of the resin composition can be further improved, and when it is 0.050 parts by mass or less, the mechanical strength of the molded product is less likely to be impaired.

[0068] The content of the copper-based heat stabilizer in the polyamide resin composition may be set so that the content of copper derived from the copper-based heat stabilizer falls within the above range. For example, the content of the copper-based heat stabilizer in the polyamide resin composition may be 0.01% by mass or more to 3% by mass or less, preferably 0.1% by mass or more to 3% by mass or less, more preferably 0.1% by mass or more to 0.5% by mass, based on the total mass of the resin composition. When the amount of the copper-based heat stabilizer is 0.01% by mass or more based on the total mass of the resin composition, the fluidity and heat aging resistance of the resin composition can be further improved, and when it is 3% by mass or less, the mechanical strength of the molded product is less likely to be impaired.

[0069] 1-3.Other ingredients The polyamide resin composition may contain other known components.

[0070] Examples of other components include reinforcing materials, nucleating agents, lubricants, flame retardants, corrosion resistance improvers, anti-drip agents, ion scavengers, elastomers (rubbers), antistatic agents, mold release agents, antioxidants (phenols, amines, sulfur compounds, phosphorus compounds, etc.), heat stabilizers (lactone compounds, vitamin E compounds, hydroquinones, copper halides, iodine compounds, etc.), light stabilizers (benzotriazoles, triazines, benzophenones, benzoates, hindered amines, oxanilides, etc.), other polymers (polyolefins, olefin copolymers such as ethylene-propylene copolymers and ethylene-1-butene copolymers, olefin copolymers such as propylene-1-butene copolymers, polystyrene, polyamides, polycarbonates, polyacetals, polysulfones, polyphenylene oxides, fluororesins, silicone resins, and LCPs). Among these, polyamide resin compositions preferably further contain a reinforcing material to enhance the mechanical strength of molded articles.

[0071] The reinforcing material can impart high mechanical strength to the polyamide resin composition. Examples of the reinforcing material include fibrous reinforcing materials such as glass fiber, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, zinc oxide whiskers, milled fiber, and cut fiber, as well as granular reinforcing materials. One of these may be used alone, or two or more may be used in combination. Among these, wollastonite, glass fiber, and potassium titanate whiskers are preferred, with wollastonite or glass fiber being more preferred, and glass fiber being even more preferred, because they can easily increase the mechanical strength of the molded article.

[0072] The type of glass fiber is not particularly limited as long as it is used to reinforce resin, and may be chopped strands or shorter milled fibers, etc. The cross-sectional shape of the glass fiber may be circular or non-circular, such as elliptical or oval.

[0073] The average fiber length of the glass fiber may be, for example, from 1 μm to 20 mm, preferably from 5 μm to 10 mm, from the viewpoint of improving the moldability of the resin composition and improving the mechanical strength and heat resistance of the resulting molded article. The aspect ratio of the glass fiber may be, for example, from 5 to 2,000, preferably from 30 to 600.

[0074] The average fiber length and average fiber diameter of the glass fibers can be measured by the following method. 1) The resin composition is dissolved in a hexafluoroisopropanol / chloroform solution (0.1 / 0.9% by volume), and then filtered to obtain a filtrate. 2) The filtered material obtained in 1) is dispersed in water, and the fiber length (Li) and fiber diameter (di) of each of 300 randomly selected fibers are measured using an optical microscope (magnification: 50x). The number of fibers with a fiber length of Li is defined as qi, and the weight-average length (Lw) is calculated based on the following formula, which is the average fiber length of the glass fibers. Weight average length (Lw) = (Σqi × Li 2 ) / (Σqi×Li) Similarly, the number of fibers having a fiber diameter Di is defined as ri, and the weight average diameter (Dw) is calculated based on the following formula, which is the average fiber diameter of the glass fibers. Weight average diameter (Dw)=(Σri×Di 2 ) / (Σri×Di)

[0075] The content of the glass fiber is not particularly limited, but can be, for example, 15% by mass or more and 70% by mass or less, preferably 15% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 50% by mass or less, relative to the total mass of the polyamide resin composition.

[0076] The content of the glass fiber is not particularly limited, but can be 0.001 parts by mass or more and 0.050 parts by mass or less, preferably 0.002 parts by mass or more and 0.040 parts by mass or less, and more preferably 0.005 parts by mass or more and 0.030 parts by mass or less, per 100 parts by mass of the polyamide resin.

[0077] The glass fibers include a surface treatment or sizing agent.

[0078] The surface treatment agent or sizing agent may be any known surface treatment agent or sizing agent used for glass fibers blended into a polyamide resin composition. However, the surface treatment agent or sizing agent has an acidic group. Examples of the acidic group include a carboxy group, an acid anhydride group, an ester group, and a sulfonic acid group. Of these, the carboxy group, the acid anhydride group, and the ester group are preferred, and the carboxy group and the acid anhydride group are more preferred. The ester group may be a functional group derived from a carboxylic acid ester.

[0079] Examples of surface treatment agents having an acidic group include silane coupling agents containing an acid anhydride group such as 3-trimethoxysilylpropylsuccinic anhydride.

[0080] Examples of sizing agents having an acidic group include sizing agents containing a homopolymer or copolymer of an unsaturated carboxylic acid, or a copolymer of an unsaturated carboxylic acid or an anhydride thereof with an unsaturated monomer.

[0081] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, mesaconic acid, citraconic acid, and maleic acid. Examples of anhydrides of unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, and dodecenylsuccinic anhydride. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred.

[0082] Examples of the unsaturated monomer include styrene, butadiene, acrylonitrile, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, methylstyrene, ethylene, propylene, butylene, isobutylene, and vinyl ether, etc. Among these, methyl acrylate and methyl methacrylate are preferred, and it is more preferred to include both methyl acrylate and methyl methacrylate.

[0083] When the sizing agent contains a copolymer of the unsaturated carboxylic acid or its anhydride with an unsaturated monomer, the proportion of the unsaturated carboxylic acid or its anhydride relative to the total mass of the copolymer is preferably 20% by mass or more and 60% by mass or less. When this proportion is 20% by mass or more, the acidic groups (carboxy groups) enhance the chemical interaction with the polyamide resin, thereby significantly improving the mechanical strength of the polyamide resin composition. When this proportion is 60% by mass or less, the molecular weight (chain length) of the copolymer is increased, thereby enhancing the physical interaction with the polyamide resin, thereby significantly improving the mechanical strength of the polyamide resin composition.

[0084] The above homopolymers or copolymers may be used in combination with other resins such as urethane resins and epoxy resins.

[0085] Glass fibers containing a surface treatment agent or a sizing agent can be obtained, for example, during the glass fiber manufacturing process, by applying (applying) the surface treatment agent or the sizing agent to a fiber strand using a known method such as a roller-type applicator, and then drying and allowing it to react.

[0086] The amount of the surface treatment agent or sizing agent attached is preferably 0.2 to 3 parts by mass, more preferably 0.2 to 2 parts by mass, and even more preferably 0.3 to 2 parts by mass, in terms of solid content per 100 parts by mass of glass fiber. When the amount is 0.2 parts by mass or more, the bundling ability of the glass fiber is further improved. Furthermore, when the amount is 2 parts by mass or less, the thermal stability of the resin composition is further improved.

[0087] The content of the reinforcing material such as glass fiber is not particularly limited, but can be, for example, 15% by mass or more and 70% by mass or less relative to the total mass of the polyamide resin composition.

[0088] The crystal nucleating agent can increase the crystallinity of the molded body. Examples of the crystal nucleating agent include metal salt compounds such as sodium 2,2-methylenebis(4,6-di-t-butylphenyl)phosphate, aluminum tris(pt-butylbenzoate), and stearates; sorbitol compounds such as bis(p-methylbenzylidene)sorbitol and bis(4-ethylbenzylidene)sorbitol; and inorganic substances such as talc, calcium carbonate, and hydrotalcite. Among these, talc is preferred from the viewpoint of further increasing the crystallinity of the molded body. These crystal nucleating agents may be used alone or in combination of two or more.

[0089] The content of the nucleating agent is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, relative to the total mass of the polyamide resin composition. When the content of the nucleating agent is within the above range, the crystallinity of the molded product is easily increased sufficiently, and sufficient mechanical strength is easily obtained.

[0090] The lubricant improves the injection flowability of the polyamide resin composition and improves the appearance of the resulting molded article. The lubricant can be a metal salt of a fatty acid such as a metal salt of an oxycarboxylic acid or a metal salt of a higher fatty acid.

[0091] The hydroxycarboxylic acid constituting the hydroxycarboxylic acid metal salt may be an aliphatic hydroxycarboxylic acid or an aromatic hydroxycarboxylic acid. Examples of aliphatic hydroxycarboxylic acids include aliphatic hydroxycarboxylic acids having 10 to 30 carbon atoms, such as α-hydroxymyristic acid, α-hydroxypalmitic acid, α-hydroxystearic acid, α-hydroxyeicosanoic acid, α-hydroxydocosanoic acid, α-hydroxytetraeicosanoic acid, α-hydroxyhexaeicosanoic acid, α-hydroxyoctaeicosanoic acid, α-hydroxytriacontanoic acid, β-hydroxymyristic acid, 10-hydroxydecanoic acid, 15-hydroxypentadecanoic acid, 16-hydroxyhexadecanoic acid, 12-hydroxystearic acid, and ricinoleic acid. Examples of aromatic hydroxycarboxylic acids include salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, gallic acid, mandelic acid, and trovic acid.

[0092] Examples of the metal constituting the metal oxycarboxylic acid salt include alkali metals such as lithium, and alkaline earth metals such as magnesium, calcium, and barium.

[0093] Of these, the metal oxycarboxylic acid salt is preferably a metal salt of 12-hydroxystearic acid, and more preferably magnesium 12-hydroxystearate and calcium 12-hydroxystearate.

[0094] Examples of higher fatty acids that constitute higher fatty acid metal salts include higher fatty acids having 15 to 30 carbon atoms, such as stearic acid, oleic acid, behenic acid, behenic acid, and montanic acid.

[0095] Examples of metals constituting the higher fatty acid metal salts include calcium, magnesium, barium, lithium, aluminum, zinc, sodium, and potassium.

[0096] Of these, preferred higher fatty acid metal salts are calcium stearate, magnesium stearate, barium stearate, calcium behenate, sodium montanate, calcium montanate, and the like.

[0097] The content of the lubricant is preferably 0.01% by mass or more and 1.3% by mass or less relative to the total mass of the polyamide resin composition. When the content of the lubricant is 0.01% by mass or more, the fluidity during molding tends to be improved, and the appearance of the obtained molded product tends to be improved. When the content of the lubricant is 1.3% by mass or less, gas due to decomposition of the lubricant is unlikely to be generated during molding, and the appearance of the product tends to be good.

[0098] 1-4. Manufacturing method The polyamide resin composition can be produced by a known resin kneading method, for example, by mixing the above-mentioned polyamide resin and, if necessary, other components in a Henschel mixer, V blender, ribbon blender, or tumbler blender, or by mixing and then melt-kneading the resulting mixture in a single-screw extruder, multi-screw extruder, kneader, or Banbury mixer, followed by granulation or pulverization.

[0099] 2. Uses of polyamide resin compositions The polyamide resin composition of the present disclosure can be molded by a known molding method such as compression molding, injection molding, or extrusion molding to be used as various polyamide molded articles.

[0100] Molded articles of the polyamide resin composition of the present disclosure can be used in various applications. Examples of such applications include automotive exterior parts such as radiator grilles, rear spoilers, wheel covers, hubcaps, cowl vent grilles, air outlet louvers, air scoops, hood bulges, sunroofs, sunroof rails, fenders, and tailgates; automotive engine compartment parts such as cylinder head covers, engine mounts, air intake manifolds, throttle bodies, air intake pipes, radiator tanks, radiator supports, water pumps, water pump inlets, water pump outlets, thermostat housings, cooling fans, fan shrouds, oil pans, oil filter housings, oil filler caps, oil level gauges, oil pumps, timing belts, timing belt covers, and engine covers; fuel caps, fuel filler tubes, automotive fuel tanks, fuel sender modules, fuel cut-off valves, quick connectors, canisters, and fuel delivery systems. automotive fuel system parts such as pipes and fuel filler necks; automotive drive system parts such as shift lever housings and propeller shafts; automotive chassis parts such as stabilizer bars, linkage rods, and engine mount brackets; automotive functional parts such as window regulators, door locks, door handles, outside door mirror stays, wipers and their parts; accelerator pedals, pedal modules, joints, plastic screws, nuts, bushings, seal rings, bearings, bearing retainers, gears, and actuators; automotive electronics parts such as wire harnesses and connectors, relay blocks, sensor housings, fuse parts, encapsulations, ignition coils, and distributor caps; general-purpose equipment fuel system parts such as fuel tanks for general-purpose equipment (brush cutters, lawn mowers, and chainsaws); electrical and electronic parts such as connectors and LED reflectors; building materials; industrial equipment parts; and various housings or exterior parts such as small housings (including housings for personal computers and mobile phones) and exterior molded products.

[0101] In particular, the polyamide resin composition of the present disclosure exhibits little decrease in mechanical strength even in high-temperature and high-humidity environments, and is therefore suitable for use in high-temperature and high-humidity environments such as in-vehicle components, particularly tubes through which antifreeze flows. Additionally, the polyamide resin composition of the present disclosure can be suitably used for automotive electronics components, electric and electronic components, industrial equipment components, and electrical equipment components such as housings or exterior parts for electrical equipment. [Example]

[0102] The present disclosure will be described below with reference to examples, which should not be construed as limiting the scope of the present disclosure.

[0103] In the following experiments, the melting point (Tm) and glass transition temperature (Tg) of the polyamide resin were measured by the following methods.

[0104] (Melting point (Tm), glass transition temperature (Tg), heat of fusion (ΔH)) The heat of fusion (ΔH), melting point (Tm) and glass transition temperature (Tg) of the polyamide resin were measured using a differential scanning calorimeter (DSC220C, manufactured by Seiko Instruments Inc.).

[0105] Specifically, approximately 5 mg of polyamide resin was sealed in a measurement aluminum pan and heated from room temperature to 350°C at 10°C / min. To completely melt the resin, it was held at 350°C for 3 minutes and then cooled to 30°C at 10°C / min. After leaving it at 30°C for 5 minutes, it was heated a second time to 350°C at 10°C / min. The temperature (°C) of the endothermic peak during this second heating was taken as the melting point (Tm) of the polyamide resin, and the inflection point corresponding to the glass transition was taken as the glass transition temperature (Tg). The heat of fusion (ΔH) was calculated from the area of ​​the endothermic peak during the second heating process in accordance with JIS K7122.

[0106] (Intrinsic viscosity [η]) The intrinsic viscosity [η] of the polyamide resin was calculated by dissolving 0.5 g of the polyamide resin in 50 ml of a 96.5% sulfuric acid solution, measuring the flow time of the resulting solution at 25°C ± 0.05°C using an Ubbelohde viscometer, and then calculating the intrinsic viscosity [η] based on the formula: [η] = ηSP / (C(1 + 0.205ηSP)). [η]: Intrinsic viscosity (dl / g) ηSP: Specific viscosity C: Sample concentration (g / dl) t: Number of seconds for sample solution to flow down (seconds) t0: Number of seconds for blank sulfuric acid to flow (seconds) ηSP=(t-t0) / t0

[0107] 1. Synthesis / preparation of materials 1-1. Synthesis of polyamide resin (Synthesis Example 1) 259.5 g (1,561.7 mmol) of terephthalic acid, 118.9 g (1,023.1 mmol) of 1,6-diaminohexane, 85.0 g (551.1 mmol) of norbornanediamine, 0.37 g of sodium hypophosphite monohydrate, and 81.8 g of distilled water were placed in a 1 L autoclave and purged with nitrogen. Stirring was initiated at 190 °C, and the internal temperature was raised to 250 °C over 3 hours. At this time, the internal pressure of the autoclave was increased to 3.0 MPa. After the reaction was continued for 1 hour, the autoclave was vented to the atmosphere through a spray nozzle installed at the bottom, and the low-order condensation product was extracted. The low-order condensation product was then cooled to room temperature, pulverized in a pulverizer to a particle size of 1.5 mm or less, and dried at 110 °C for 24 hours.

[0108] Next, this low-order condensate was placed in a tray-type solid-state polymerization reactor, and after replacing with nitrogen, the temperature was raised to 215°C over about 1 hour and 30 minutes, followed by reaction for 1 hour and 30 minutes, and then the temperature was lowered to room temperature.

[0109] The obtained prepolymer was then melt-polymerized in a twin-screw extruder with a screw diameter of 30 mm and L / D=36 at a barrel set temperature of 330°C, a screw rotation speed of 200 rpm, and a resin feed rate of 6 kg / h to obtain polyamide resin 1.

[0110] The resulting polyamide resin 1 had an intrinsic viscosity [η] of 0.97 dl / g, a melting point (Tm) of 312°C, a glass transition temperature (Tg) of 167°C, and a heat of fusion (ΔH) of 44 mJ / mg.

[0111] (Synthesis Example 2) Polyamide resin 2 was obtained in the same manner as in Synthesis Example 1, except that the amounts of 1,6-hexanediamine, terephthalic acid, and isophthalic acid placed in the autoclave were 280 g (2410 mmol), 277.4 g (1670 mmol), 119.6 g (720 mmol), 3.66 g (30 mmol) of benzoic acid, 5.7 g of sodium hypophosphite monohydrate, and 545 g of distilled water.

[0112] The resulting polyamide resin 2 had an intrinsic viscosity of 1.0 dl / g, a melting point (Tm) of 330°C, a glass transition temperature (Tg) of 125°C, and a heat of fusion (ΔH) of 50 J / g.

[0113] 1-2.Heat stabilizer Copper-based heat stabilizer A mixture of 10% by mass of copper (I) iodide and 90% by mass of potassium iodide was used as a copper-based heat stabilizer. Phenolic heat stabilizer Pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate] (BASF, Irganox 1010) was used as a phenolic heat stabilizer. Phosphorus-based heat stabilizer 3,9-Bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (ADEKA Corporation, Adekastab PEP-36) was used as a phosphorus-based heat stabilizer. Sulfur-based heat stabilizer 2,2-bis[[3-(dodecylthio)propionic acid] 1-oxopropyloxy] methyl] -1,3-propanediyl (SEENOX412S, manufactured by Shipro Chemical Co., Ltd.) was used as a sulfur-based heat stabilizer.

[0114] 1-3. Lubricants Sodium montanate (manufactured by Clariant, LICOMONT NAV101, "LICOMONT" is a registered trademark of the company)

[0115] 1-4. Nucleating Agents Talc (fine particle talc)

[0116] 1-5. Reinforcement material Glass fiber containing a sizing agent with a carboxyl group (FT756D, manufactured by Owens Corning)

[0117] 2. Preparation of polyamide resin composition The above materials were mixed in a tumbler blender in the composition ratios (units: parts by mass) shown in Table 1, and melt-kneaded using a 30 mmφ vented twin-screw extruder at a cylinder temperature of 300 to 335°C. The kneaded mixture was then extruded into strands and cooled in a water bath. The strands were then taken up in a pelletizer and cut to obtain a pelletized polyamide resin composition.

[0118] 3. Evaluation The resulting polyamide resin compositions were evaluated according to the following criteria.

[0119] 3-1. Tensile strength (at high temperatures) Each polyamide resin composition was injection molded under the following conditions to prepare a 3.2 mm thick ASTM-1 (dumbbell) test piece. Molding machine: SE50DU, manufactured by Sumitomo Heavy Industries, Ltd. Molding machine cylinder temperature: Polyamide resin melting point + 10°C Mold temperature: Glass transition temperature of polyamide resin + 20°C The prepared test piece was left to stand for 24 hours in a nitrogen atmosphere at a temperature of 23°C in accordance with ASTM D638. Then, a tensile test was carried out in an atmosphere at a temperature of 140°C in accordance with ASTM D638 to measure the tensile strength.

[0120] 3-2. Tensile strength retention rate before and after adding copper-based heat stabilizer The tensile strength at high temperatures of a polyamide resin composition containing a copper-based heat stabilizer was compared with the tensile strength at high temperatures of a polyamide resin composition containing the same amount of additives but not containing the copper-based stabilizer, and the retention rate of tensile strength at high temperatures before and after the addition of the copper-based heat stabilizer was calculated.

[0121] 3-3. Tensile strength (initial) The test piece thus prepared was left to stand for 24 hours in a nitrogen atmosphere at 23°C in accordance with ASTM D638. Then, a tensile test was carried out in accordance with ASTM D638 in an atmosphere at 23°C and a relative humidity of 50% to measure the tensile strength.

[0122] 3-4. Tensile strength (after high-temperature treatment) The prepared test piece was left at a temperature of 220° C. for 1000 hours. Thereafter, the test piece was allowed to cool to 23° C., and a tensile test was performed in accordance with ASTM D638 in an atmosphere at a temperature of 23° C. and a relative humidity of 50%, to measure the tensile strength.

[0123] 3-5. Tensile strength retention rate The initial tensile strength and the tensile strength after the high-temperature treatment were compared to calculate the ratio (retention rate) of the tensile strength after the high-temperature treatment to the initial tensile strength.

[0124] 3-6. Flow length Each polyamide resin composition was injected into a bar flow mold having a width of 10 mm and a thickness of 0.5 mm under the following conditions, and the flow length (mm) of the polyamide resin composition in the mold was measured. Note that a longer flow length indicates better injection flowability. Molding machine: Toshiba Machine Co., Ltd., EC75N-2A Injection pressure setting: 2000 kg / cm 2 Molding machine cylinder temperature: 335℃ Mold temperature: 160℃

[0125] Table 1 shows the composition, fluidity, tensile strength (at high temperature), tensile strength retention rate (at high temperature) before and after the addition of a copper-based heat stabilizer, tensile strength (initial), tensile strength (after high-temperature treatment), and tensile strength retention rate of the prepared polyamide resin composition.

[0126] [Table 1]

[0127] As is clear from Table 1, the polyamide resin having the component unit (b2) derived from the diamine represented by formula (1) can suppress the decrease in tensile strength at high temperatures caused by the addition of a copper-based heat resistance stabilizer (comparison between Example 1 and Comparative Example 2). Furthermore, the polyamide resin having the component unit (b2) derived from the diamine represented by formula (1) can suppress the decrease in mechanical strength in high-temperature and high-humidity environments.

[0128] A resin composition similar to that of Example 1 was also prepared, except that the polyamide resin was PA6T (diamine: HDMA 100 mol %). However, it did not melt under the above conditions and could not be injection molded, so evaluation was not possible.

[0129] It was also newly confirmed that even when a heat stabilizer other than a copper-based heat stabilizer was added, a decrease in tensile strength and a decrease in fluidity occurred after high-temperature treatment. In these cases, it was found that the decrease in tensile strength and a decrease in fluidity after high-temperature treatment could not be sufficiently suppressed even when the above-mentioned polyamide resin was used in combination (comparison between Example 1 and Reference Examples 5 to 10). From these findings, it was found that by combining a polyamide resin having component unit (b2) derived from a diamine represented by formula (1) with a copper-based heat stabilizer, it is possible to suppress a decrease in fluidity and a decrease in mechanical strength in a high-temperature and high-humidity environment.

[0130] This application claims priority from Japanese Patent Application No. 2022-003317, filed January 12, 2022, the entire contents of which are incorporated herein by reference. [Industrial Applicability]

[0131] The polyamide resin composition of the present disclosure can achieve both improved mechanical strength by adding a copper-based heat stabilizer and suppressed reduction in tensile strength after high-temperature treatment. Therefore, the present disclosure is expected to broaden the applicability of polyamide resins to various applications and contribute to the further popularization of polyamide resins.

Claims

1. A polyamide resin composition comprising a polyamide resin and a copper-based heat stabilizer, the copper content of the copper-based heat resistance stabilizer is 0.001 parts by mass or more and 0.050 parts by mass or less relative to 100 parts by mass of the polyamide resin; The polyamide resin is Contains a component unit (a) derived from a dicarboxylic acid and a component unit (b) derived from a diamine, The component unit (a) derived from the dicarboxylic acid is The component units (a1) derived from terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid account for more than 80 mol% of the total moles of the component units (a) derived from the dicarboxylic acid, The diamine-derived component unit (b) is component units (b1) derived from alkylenediamine having from 4 to 18 carbon atoms, in an amount of from 50 mol % to 90 mol % based on the total number of moles of component units (b) derived from the diamine; a component unit (b2) derived from a diamine represented by the following formula (1) in an amount of 10 mol % or more and less than 50 mol % relative to the total number of moles of the component unit (b) derived from the diamine; Including, Polyamide resin composition. 【Chemical 1】 (In formula (1), m and n each independently represent 0 or 1; -X- is a single bond, or -O-, -S-, or -SO ２ -, -CO- and -CH ２ - is a divalent group selected from the group consisting of

2. The polyamide resin contains 15 mol % or more and less than 45 mol % of the component units (b2) derived from the diamine represented by formula (1) relative to the total number of moles of the component units (b) derived from the diamine. The polyamide resin composition according to claim 1.

3. The component unit (b1) derived from an alkylenediamine having from 4 to 18 carbon atoms includes a component unit derived from a linear alkylenediamine or a branched alkylenediamine. The polyamide resin composition according to claim 1.

4. The linear alkylenediamine or branched alkylenediamine is a diamine selected from the group consisting of 1,4-diaminobutane, 1,6-diaminohexane, 1,9-nonanediamine, 1,10-decanediamine, 2-methyl-1,5-pentanediamine, and 2-methyl-1,8-octanediamine. The polyamide resin composition according to claim 3.

5. The melting point (Tm) of the polyamide resin is 280°C or higher. The polyamide resin composition according to claim 1.

6. The polyamide resin is a crystalline polyamide resin. The polyamide resin composition according to claim 1.

7. The heat of fusion (ΔH) of the polyamide resin is 10 mJ / mg or more. The polyamide resin composition according to claim 1.

8. A resin composition for automotive components, The polyamide resin composition according to any one of claims 1 to 7.

9. A polyamide resin composition comprising the polyamide resin composition according to any one of claims 1 to 7. Polyamide molding.

10. Automotive components, The polyamide molded article according to claim 9.

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