Polyamide resin composition and polyamide molded body

Abstract

This invention provides a polyamide resin composition that can suppress the decrease in tensile strength caused by the addition of a copper-based heat stabilizer at high temperatures and can maintain a predetermined tensile strength for a longer period of time at high temperatures. The polyamide resin composition comprises a polyamide resin and a copper-based heat stabilizer. The polyamide resin comprises: a dicarboxylic acid component (a) derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and a component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane, comprising 10 mol% or more and less than 50 mol% of the total molar amount of the diamine-derived component unit (b). The copper content of the copper stabilizer is 0.001 parts by mass or less and 0.050 parts by mass relative to 100 parts by mass of the polyamide resin.

Description

Technical Field

[0001] This invention relates to polyamide resin compositions and polyamide molded articles. Background Technology

[0002] Polyamide resin compositions have long been widely used as materials for various components in clothing, industrial materials, automobiles, electrical / electronics, and other industrial applications due to their excellent molding processability, mechanical properties, and chemical resistance.

[0003] To exhibit properties appropriate for various applications, various additives are added to polyamide resin compositions intended for those applications. For example, it is known to add copper-based heat stabilizers to improve the heat aging resistance of polyamide resin compositions. For instance, Patent Document 1 describes how, by adding a copper-based heat stabilizer, the time until the tensile strength is halved during heat treatment at 180°C is extended to several hundred hours.

[0004] Furthermore, attempts have been made to change the raw materials of the polyamide resin to alter its physical properties. For example, Patent Documents 2 and 3 describe a polyamide resin that uses 1,3-bis(aminomethyl)cyclohexane as the diamine component for manufacturing polyamide by polycondensation of a diamine component with a dicarboxylic acid component. Patent Document 2 describes a polyamide resin with high transparency, while Patent Document 3 describes a polyamide resin with a high glass transition point and improved crystallinity.

[0005] Furthermore, it is known to incorporate reinforcing materials such as glass fibers to improve the impact resistance and rigidity of polyamide resin compositions. For purposes such as improving dispersibility in polyamide resins, the aforementioned glass fibers are sometimes treated with sizing agents or surface treatment agents. For example, Patent Document 1 discloses a glass fiber bundler containing: 20-60% by mass of a copolymer compound formed by copolymerizing unsaturated dicarboxylic acid or carboxylic anhydride, 20-75% by mass of methyl acrylate, and 5-20% by mass of methyl methacrylate; an aminosilane; and a polyurethane resin, wherein the weight-average molecular weight of the glass fiber bundler is 10,000-60,000. Patent Document 1 discloses that the aforementioned bundler can improve the mechanical strength (particularly tensile strength) of polyamide resins containing glass fibers.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 06-032979

[0009] Patent Document 2: Japanese Patent Application Publication No. 49-55796

[0010] Patent Document 3: Japanese Patent Application Publication No. 2017-75303

[0011] Patent Document 4: Japanese Patent Application Publication No. 2014-231452 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] As described in Patent Document 1, it is known that copper-based heat stabilizers can improve the heat aging resistance of polyamide resin compositions. However, according to the present inventors' new understanding, there is a problem that the addition of copper-based heat stabilizers leads to a decrease in the tensile strength of the polyamide resin composition itself. This problem of decreased tensile strength is particularly pronounced when molded articles of polyamide resin compositions are used at high temperatures. Furthermore, in recent years, there has been an increasing demand for further improvements in the long-term heat resistance of polyamide resin compositions, requiring the development of polyamide resin compositions that can maintain a predetermined tensile strength for a longer period of time at high temperatures.

[0014] In view of these circumstances, the object of the present invention is to provide a polyamide resin composition capable of suppressing the decrease in tensile strength caused by the addition of copper-based heat stabilizers at high temperatures and capable of maintaining a predetermined tensile strength for a longer period of time in high-temperature environments, and a polyamide molded article comprising the polyamide resin composition.

[0015] Methods for solving problems

[0016] [1] A polyamide resin composition comprising: a polyamide resin and a copper-based heat stabilizer.

[0017] The aforementioned polyamide resin is a polyamide resin comprising a component unit (a) derived from dicarboxylic acid and a component unit (b) derived from diamine.

[0018] The aforementioned dicarboxylic acid-derived component unit (a) includes component units derived from aromatic dicarboxylic acids or alicyclic dicarboxylic acids.

[0019] The above-mentioned component unit (b) derived from diamine includes:

[0020] The component unit (b1) derived from alkylene diamines with 4 to 18 carbon atoms, having a total molar percentage greater than 50 mol% and less than 90 mol% relative to the total molar percentage of the component unit (b) derived from diamines, and

[0021] The component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane has a total molar percentage of 10 mol% or more but less than 50 mol% relative to the total molar percentage of the component unit (b) derived from diamine.

[0022] The copper content in the aforementioned copper-based heat stabilizer is between 0.001 and 0.050 parts by weight relative to the polyamide resin content in the polyamide resin composition per 100 parts by weight.

[0023] [2] The polyamide resin composition according to [1] comprises glass fiber of 1 to 300 parts by mass relative to the content of polyamide resin contained in the above polyamide resin composition, wherein the glass fiber comprises a surface treatment agent having acidic groups or a sizing agent having acidic groups.

[0024] [3] In the polyamide resin composition according to [2], the above-mentioned acidic group is a carboxyl group, an anhydride group or an ester group.

[0025] [4] The polyamide resin composition according to any one of [1] to [3], wherein the polyamide resin comprises a component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane in a total molar number of 15 mol% or more and less than 45 mol% relative to the total molar number of the component unit (b) derived from the diamine.

[0026] [5] In any one of the polyamide resin compositions according to [1] to [4], the component unit (b1) derived from alkylene diamines having 4 to 18 carbon atoms comprises a component unit derived from linear alkylene diamines or branched alkylene diamines.

[0027] [6] In the polyamide resin composition according to [5], the linear or branched alkylene diamine 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.

[0028] [7] In any one of [1] to [6], the aromatic dicarboxylic acid or alicyclic dicarboxylic acid is terephthalic acid, naphthalic acid or cyclohexanedicarboxylic acid.

[0029] [8] The polyamide resin composition according to any one of [1] to [7] is a resin composition for vehicle components.

[0030] [9] A polyamide molded article comprising any one of the polyamide resin compositions described in [1] to [8].

[0031]

[10] The polyamide molded body according to [9] is a vehicle component.

[0032] The effects of the invention

[0033] According to this disclosure, a polyamide resin composition capable of suppressing the decrease in tensile strength caused by the addition of a copper-based heat stabilizer and maintaining a predetermined tensile strength for a longer period of time at high temperatures, and a polyamide molded article comprising the polyamide resin composition, are provided. Detailed Implementation

[0034] In this disclosure, the numerical range represented by “~” refers to the range in which the values ​​recorded before and after “~” are respectively the minimum and maximum values.

[0035] In the numerical ranges described in this disclosure, the upper or lower limit value recorded in a certain numerical range can be replaced by the upper or lower limit value of other numerical ranges described in different stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value recorded in a certain numerical range can be replaced by the value shown in the embodiments.

[0036] 1. First Implementation Method

[0037] The first embodiment of this disclosure relates to a polyamide resin composition.

[0038] The above-described polyamide resin composition is a resin composition in which polyamide resin is the main component. The term "main component" refers to a resin composition in which polyamide resin accounts for 50% or more by mass. Preferably, the proportion of polyamide resin in the resin composition is 60% or more by mass, more preferably 70% or more by mass, further preferably 80% or more by mass, and particularly preferably 90% or more by mass. The upper limit of the proportion of polyamide resin in the resin composition is not particularly limited; it can be 100% or less by mass, 90% or less by mass, or 80% or less by mass.

[0039] The proportion of polyamide resin contained in the above polyamide resin composition is preferably 20% by mass or more and 80% by mass or less relative to the total mass of the above polyamide resin composition.

[0040] 1-1. Polyamide resin

[0041] The aforementioned polyamide resin can be a polyamide resin comprising a component unit (a) derived from a dicarboxylic acid and a component unit (b) derived from a diamine. In this case, to ensure that the melting point (Tm) and glass transition temperature (Tg) of the polyamide resin are within the aforementioned ranges, the component unit (a) derived from the dicarboxylic acid preferably comprises a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and the component unit (b) derived from the diamine preferably comprises a component unit (b1) derived from an alkylene diamine having 4 to 18 carbon atoms, comprising a component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane, comprising a component unit (b2) ...

[0042] [Component unit (a) derived from dicarboxylic acid]

[0043] If the polyamide resin contains a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid as a component unit derived from a dicarboxylic acid (a), the melting point (Tm) and crystallinity can be significantly improved.

[0044] Examples of aromatic dicarboxylic acids include terephthalic acid, naphthalic acid, and their esters. Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid and its esters. From the viewpoint of obtaining polyamide resins with high crystallinity and high heat resistance, the component unit (a) derived from dicarboxylic acids preferably includes a component unit derived from aromatic dicarboxylic acids, and more preferably includes a component unit derived from terephthalic acid.

[0045] The content of the component units derived from aromatic dicarboxylic acids or alicyclic dicarboxylic acids (preferably component units derived from aromatic dicarboxylic acids, more preferably component units derived from terephthalic acid) is not particularly limited, but is preferably 50 mol% to 100 mol% relative to the total moles of component units (a) derived from dicarboxylic acids. If the content of the above-mentioned component units is 50 mol% or more, the crystallinity of the polyamide resin is easily improved. From the same point of view, the content of the above-mentioned component units is more preferably 70 mol% to 100 mol%.

[0046] In this embodiment, the component unit (a) derived from dicarboxylic acid preferably includes component units (a1) derived from terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid. These component units (a1), unlike isophthalic acid, can improve the crystallinity of the polyamide. From the viewpoint of ensuring the crystallinity of the polyamide resin, the content of these component units (a1) relative to the total moles of component units (a) derived from dicarboxylic acid is greater than 20 mol% and less than 100 mol%. From the viewpoint of further improving the crystallinity of the polyamide resin, the content of these component units (a1) relative to the total moles of component units (a) derived from dicarboxylic acid is preferably more than 45 mol% and less than 100 mol%, more preferably more than 50 mol% and less than 99 mol%, more preferably greater than 80 mol% and less than 99 mol%, and particularly preferably greater than 90 mol% and less than 99 mol%.

[0047] To the extent that it does not impair the effects disclosed in this specification, the component unit (a) derived from dicarboxylic acids may include aromatic dicarboxylic acid component units (a2) other than the aforementioned component unit (a1) or aliphatic dicarboxylic acid component units (a3) ​​with 4 to 20 carbon atoms. From the viewpoint of not impairing the crystallinity of the resin, it is preferable to have a low content of component units derived from isophthalic acid and aliphatic dicarboxylic acids with 4 to 18 carbon atoms other than adipic acid. Specifically, relative to the total molar number of component units (a) derived from dicarboxylic acids, it is preferably 20 mol% or less, more preferably 10 mol% or less.

[0048] Examples of aromatic dicarboxylic acid component units (a2) other than terephthalic acid include component units derived from isophthalic acid and 2-methylterephthalic acid. Among these, component units derived from isophthalic acid are preferred. From the viewpoint of ensuring the crystallinity of the polyamide resin, the content of these component units (a2) relative to the total moles of component units (a) derived from dicarboxylic acids is preferably 1 mol% to 50 mol%, more preferably 1 mol% to 20 mol%, further preferably 1 mol% to 10 mol%, and particularly preferably 1 mol% to 5 mol%.

[0049] The component unit (a3) ​​derived from aliphatic dicarboxylic acids is a component unit derived from aliphatic dicarboxylic acids having 4 to 20 carbon atoms, preferably a component unit derived from aliphatic dicarboxylic acids having 6 to 12 carbon atoms. Examples of the aforementioned aliphatic dicarboxylic acids include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyl adipic acid, trimethyl adipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, octanoic acid, etc. Among these, adipic acid and sebacic acid are preferred. From the viewpoint of ensuring the crystallinity of the polyamide resin, the content of these component units (a3) ​​relative to the total molar number of component units (a) derived from dicarboxylic acids is preferably 0 mol% to 40 mol% or less, more preferably 0 mol% to 20 mol% or less, further preferably 1 mol% to 10 mol% or less, and particularly preferably 1 mol% to 5 mol% or less.

[0050] In addition to the aforementioned component units (a1), (a2), and (a-3), the semi-aromatic polyamide resin (A) may further contain small amounts of tri- or higher polycarboxylic acid component units such as trimellitic acid or pyromellitic acid. The content of such polycarboxylic acid component units relative to the total moles of component units (a) derived from dicarboxylic acids may be between 0 mol% and 5 mol%.

[0051] [Component unit derived from diamine (b)]

[0052] If the polyamide resin contains, in addition to the component unit (b1) derived from alkylene diamines with 4 to 18 carbon atoms, a component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane as a component unit (b) derived from diamines, the glass transition temperature (Tg) can be sufficiently increased.

[0053] That is, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane, due to its nonlinear structure, reduces the molecular chain mobility of the polyamide resin. Therefore, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane can result in a higher glass transition temperature (Tg) for polyamide resins containing this component unit (b2) compared to those without. Furthermore, it is believed that polyamide resins containing this component unit (b2) exhibit high mechanical strength even under high temperature / high humidity conditions and can maintain this high mechanical strength for extended periods.

[0054] Furthermore, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane can appropriately lower the melting point (Tm) of the polyamide resin containing this component unit (b2) compared to the polyamide resin without this component unit (b2). Therefore, the polyamide resin containing this component unit (b2) exhibits high flowability and high processability during injection molding.

[0055] Furthermore, according to the present inventors' understanding, the copper-based heat stabilizer described below is more effective than organic-based heat stabilizers in improving the stability of polyamide resin compositions at high temperatures (e.g., above 150°C), thus more effectively improving the heat aging resistance of the polyamide resin composition. However, the copper-based heat stabilizer itself is a foreign substance in the resin composition and is a compound containing a metal with properties very different from the resin, thus easily and significantly reducing the crystallinity of the polyamide resin and decreasing the tensile strength of the polyamide resin composition itself from the initial manufacturing stage. Moreover, in high-temperature environments where the resin has high fluidity, the copper-based heat stabilizer, as a foreign substance, tends to move more freely in the composition. Through this movement, the stretching / shrinkage and crystallization of resin molecules are easily hindered, thus more significantly manifesting the aforementioned reduction in tensile strength. In contrast, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane limits the movement of the aforementioned copper-based heat stabilizer at high-temperature environments by increasing the glass transition temperature of the polyamide resin. Therefore, it is believed that the resistance to stretching / shrinkage and crystallization of resin molecules caused by copper-based heat stabilizers is not easily generated, which can suppress the decrease in tensile strength of polyamide resin compositions under high temperature conditions.

[0056] Furthermore, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane, due to its cyclic structure, is less prone to molecular chain cleavage even after prolonged exposure to high temperatures, thus improving the long-term heat resistance of the polyamide resin itself. Therefore, it is believed that the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane more easily maintains the tensile strength of the molded polyamide resin composition for a longer period of time, even under high-temperature conditions.

[0057] Furthermore, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane bends the molecular chains of the polyamide resin, inhibiting the penetration of moisture into the interior of the polyamide resin composition. Therefore, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane is less likely to hydrolyze the polyamide resin. This is believed to suppress the decrease in mechanical strength (especially tensile strength) of the molded polyamide resin composition, particularly under high temperature / high humidity conditions.

[0058] Furthermore, the aforementioned polyamide resin exhibits high flowability and mechanical strength during injection molding due to the crystallinity derived from alkylene diamines with 4 to 18 carbon atoms (b1). It is further believed that the aforementioned polyamide resin possesses high mechanical strength even in high-temperature regions due to its high glass transition temperature (Tg), and this high mechanical strength is easily maintained.

[0059] From the viewpoint that it is not easy to reduce the Tg of the resin, the carbon number of the alkylene diamine, which is the raw material of the component unit (b1), is more preferably 4 or more and 10 or less.

[0060] Alkylene diamines with 4 to 18 carbon atoms can include either linear or branched alkylene diamines. From the viewpoint of improving the crystallinity of the resin, it is preferable that the alkylene diamines with 4 to 18 carbon atoms include linear alkylene diamines. That is, the component units derived from alkylene diamines with 4 to 18 carbon atoms preferably include component units derived from linear alkylene diamines.

[0061] Examples of alkylene diamines having 4 to 18 carbon atoms include: linear alkylene diamines comprising 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine; and branched alkylene diamines comprising 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, with 1,6-diaminohexane and 1,10-decanediamine being particularly desirable. These alkylene diamines may be one or more types.

[0062] The content of the component unit (b1) derived from alkylene diamines with 4 to 18 carbon atoms is preferably greater than 50 mol% and less than 90 mol% relative to the total moles of component units (b) derived from diamines. If the content is greater than 50 mol%, the crystallinity of the polyamide resin can be sufficiently improved, further enhancing the resin's flowability and mechanical strength during injection molding. If the content is less than 90 mol%, the content of the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane can be increased. This increases the glass transition temperature (Tg) of the polyamide resin, improves its mechanical strength in high-temperature regions, and moderately reduces the glass transition temperature (Tm) of the polyamide resin, thereby improving its processability.

[0063] On the other hand, the content of the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane relative to the total moles of the component unit (b) derived from diamine is preferably 10 mol% or more and less than 50 mol%. If the above content is 10 mol% or less, the glass transition temperature (Tg) of the polyamide resin can be increased, the mechanical strength in the high-temperature region can be improved, and the temperature (Tm) of the polyamide resin can be moderately reduced, thereby improving the molding processability. If the above content is less than 50 mol%, the content of the component unit (b1) derived from alkylene diamines with 4 to 18 carbon atoms can be increased. As a result, in addition to sufficiently improving the crystallinity of the polyamide resin and further improving the mechanical strength of the molded article, the decrease in the flowability of the polyamide resin itself caused by the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane can also be suppressed.

[0064] From the above perspective, the content of the component unit (b1) derived from alkylene diamines with 4 to 18 carbon atoms is preferably greater than 50 mol% and less than 90 mol% relative to the total number of moles of component units (b) derived from diamines, more preferably 55 mol% to 85 mol%, and even more preferably 60 mol% to 80 mol%.

[0065] Furthermore, from the above perspective, the content of the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane relative to the total number of moles of the component unit (b) derived from the diamine is preferably 10 mol% or more and less than 50 mol%, more preferably 15 mol% or more and less than 45 mol%, even more preferably 20 mol% or more and less than 40 mol%, even more preferably 20 mol% or more and less than 38 mol%, and particularly preferably 20 mol% or more and less than 33 mol%.

[0066] The diamine-derived component unit (b) may further comprise, to the extent that it does not impair the effects disclosed herein, component units (b3) derived from other diamines. Examples of other diamines include aromatic diamines and alicyclic diamines. The content of component units (b3) derived from other diamines relative to the total molar percentage of component units (b) derived from diamines may be 50 mol% or less.

[0067] From the viewpoint of improving the thermal stability of the composite during molding, or further improving mechanical strength, polyamide resins can have at least a portion of their molecular end groups sealed by a capping agent. The capping agent is preferably a monoamine when the molecular end is a carboxyl group, and preferably a monocarboxylic acid when the molecular end is an amino group.

[0068] 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 with 2 to 30 carbon atoms such as acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, lauric acid, tridecyl acid, myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid; aromatic monocarboxylic acids such as benzoic acid, phenylacetic acid, naphtholic acid, methylnaphtholic acid, and phenylacetic acid; and alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid. Aromatic and alicyclic monocarboxylic acids may have substituents in the cyclic portion.

[0069] [physical properties]

[0070] The above-mentioned polyamide resin can achieve a melting point (Tm) of 280°C or higher and 330°C or lower as measured by differential scanning calorimetry (DSC), and can achieve a glass transition temperature (Tg) of 135°C or higher and 180°C or lower as measured by DSC.

[0071] If the melting point (Tm) of the polyamide resin is above 280°C, it is less likely to damage the mechanical strength and heat resistance of the polyamide resin composition and the molded article in high-temperature regions. If it is below 330°C, it is not necessary to excessively increase the molding temperature, thus the molding processability of the polyamide resin composition becomes easier to achieve. From the above perspective, the melting point (Tm) of the polyamide resin is more preferably above 290°C and below 330°C, and even more preferably above 300°C and below 330°C.

[0072] If the glass transition temperature (Tg) of the aforementioned polyamide resin is 135°C or higher, the heat resistance of the polyamide resin composition and the molded article is less likely to be damaged, and the mechanical strength in high-temperature regions can be further improved. If the glass transition temperature (Tg) of the aforementioned polyamide resin is 180°C or lower, the molding processability of the polyamide resin composition becomes easier to achieve. From the above perspective, the glass transition temperature (Tg) of the aforementioned polyamide resin is more preferably 140°C or higher and 170°C or lower.

[0073] If the glass transition temperature (Tg) of the aforementioned polyamide resin is 135°C or higher, and the difference between the melting point (Tm) and the glass transition temperature (Tg) of the aforementioned polyamide resin is 170°C or lower, then in addition to possessing both the high mechanical strength of the polyamide resin composition in the high-temperature region and the high thermosetting properties resulting from the inhibition of decomposition of copper-based heat stabilizers, it is also possible to suppress the decrease in fluidity during injection molding caused by the addition of glass fibers treated with sizing agents or surface treatment agents having acidic groups. From the above perspective, a glass transition temperature (Tg) of 140°C or higher is more preferred, and the difference between the melting point (Tm) and the glass transition temperature (Tg) of the aforementioned polyamide resin is 120°C or higher and 170°C or lower; more preferably, a glass transition temperature (Tg) of 150°C or higher is preferred, and the difference between the melting point (Tm) and the glass transition temperature (Tg) of the aforementioned polyamide resin is 130°C or higher and 165°C or lower.

[0074] The heat of fusion (ΔH) of the crystalline polyamide resin is preferably 10 mJ / mg or higher. If the heat of fusion (ΔH) of the crystalline polyamide resin is 10 mJ / mg or higher, it exhibits crystallinity, thus easily improving its flowability and mechanical strength during injection molding. From the same viewpoint, the heat of fusion (ΔH) of the crystalline polyamide resin is more preferably 15 mJ / mg or higher, and even more preferably 20 mJ / mg or higher. Furthermore, there is no particular upper limit to the heat of fusion (ΔH) of the crystalline polyamide resin; from the viewpoint of not impairing molding processability, it can be as low as 90 mJ / mg.

[0075] In addition, the heat of fusion (ΔH), melting point (Tm), and glass transition temperature (Tg) of polyamide resin can be measured using a differential scanning calorimeter (DSC220C type, manufactured by Seiko Instruments).

[0076] Specifically, approximately 5 mg of polyamide resin was sealed in an aluminum dish for testing and heated from room temperature to 350°C at a rate of 10°C / min. To ensure complete melting of the resin, it was held at 360°C for 3 minutes, and then cooled to 30°C at a rate of 10°C / min. After standing at 30°C for 5 minutes, a second heating was performed at a rate of 10°C / min until reaching 360°C. The temperature (°C) of the endothermic peak during this second heating was designated as the melting point (Tm) of the crystalline polyamide resin, and the inflection point corresponding to the glass transition was designated as the glass transition temperature (Tg). The heat of fusion (ΔH) was calculated according to JIS K7122 from the area of ​​the endothermic peak during the first heating process.

[0077] The melting point (Tm), glass transition temperature (Tg), and heat of fusion (ΔH) of crystalline 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 shown in formula (1), the ratio of the component unit (b1) derived from alkylene diamine with 4 to 18 carbon atoms to the component unit (b2) derived from the diamine shown in formula (1), and the number of carbon atoms in the alkylene diamine with 4 to 18 carbon atoms.

[0078] Furthermore, when increasing the heat of fusion (ΔH) of the crystalline polyamide resin, it is preferable to reduce the content and content ratio (the ratio of the total number of moles of component unit (b2) to component unit (b) derived from diamine). On the other hand, when increasing the glass transition temperature (Tg) and decreasing the melting point (Tm) of the crystalline polyamide resin, it is preferable to increase, for example, the content and content ratio (the ratio of the total number of moles of component unit (b2) to component unit (b) derived from diamine).

[0079] The intrinsic viscosity [η] of the crystalline polyamide resin, measured at 25°C in 96.5% sulfuric acid, is preferably 0.6 dl / g or higher and 1.5 dl / g or lower. If the intrinsic viscosity [η] of the crystalline polyamide resin is 0.6 dl / g or higher, the mechanical strength (toughness, etc.) of the molded article can be easily and sufficiently improved; if it is 1.5 dl / g or lower, the flowability of the resin composition during molding is less likely to be impaired. From the same point of view, the intrinsic viscosity [η] of the crystalline polyamide resin is more preferably 0.8 dl / g or higher and 1.2 dl / g or lower. The intrinsic viscosity [η] can be adjusted by the amount of end-capping of the crystalline polyamide resin, etc.

[0080] The intrinsic viscosity of crystalline polyamide resins can be determined according to JIS K6810-1977.

[0081] Specifically, 0.5 g of crystalline polyamide resin is dissolved in 50 ml of 96.5% sulfuric acid solution to prepare a sample solution. The flow rate of the sample solution can be measured using an Uberloud viscometer at 25 ± 0.05 °C, and the obtained value is substituted into the following formula to calculate the flow rate.

[0082] [η] = ηSP / [C(1+0.205ηSP)]

[0083] In the above formula, the following shows each algebraic number or variable.

[0084] [η]: Intrinsic viscosity (dl / g)

[0085] ηSP: Specific viscosity

[0086] C: Sample concentration (g / dl)

[0087] ηSP is obtained by the following formula.

[0088] ηSP=(t-t0) / t0

[0089] t: Number of seconds (seconds) it takes for the sample solution to flow down.

[0090] t0: Number of seconds for blank sulfuric acid to flow (seconds)

[0091] [Manufacturing Method]

[0092] Polyamide resins can be manufactured, for example, by polycondensation of the aforementioned dicarboxylic acid and diamine in a homogeneous solution. Specifically, it can be manufactured as follows: the dicarboxylic acid and diamine are heated in the presence of a catalyst as described in International Publication No. 03 / 085029 to obtain a low-valent condensate, and then shear stress is applied to the melt of the low-valent condensate to cause it to polycondense.

[0093] From the perspective of adjusting the intrinsic viscosity of polyamide resin, the aforementioned end-capping agent can be added to the reaction system. The intrinsic viscosity [η] (or molecular weight) of the polyamide resin can be adjusted by the amount of end-capping agent added.

[0094] The capping agent is added to the reaction system of dicarboxylic acid and diamine. The amount added is preferably 0.07 mol or less, more preferably 0.05 mol or less, relative to the total mole of dicarboxylic acid of 1 mol.

[0095] 1-2. Heat stabilizers

[0096] By including a copper-based heat stabilizer along with component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane, the flowability of the polyamide resin composition during molding can be improved. This improvement in flowability is believed to be due to the suppression of molecular chain entanglement by the component unit derived from 1,3-bis(aminomethyl)cyclohexane, thus more significantly leveraging the viscosity reduction effect of the added copper-based heat stabilizer. Furthermore, the copper-based heat stabilizer improves the heat aging resistance of the resin composition.

[0097] Copper-based heat stabilizers preferably comprise: (i) halogens and salts of metals in Group 1 or Group 2 of the periodic table, i.e., halogen metal salts; and (ii) copper compounds. Further, if desired, they preferably comprise (iii) higher fatty acid metal salts.

[0098] (i) Examples of halogen metal salts include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. Potassium iodide and potassium bromide are preferred. The halogen metal salt may contain only one type or more types.

[0099] (ii) Examples of copper compounds include copper halides, copper salts (sulfates, acetates, propionates, benzoates, adipates, terephthalates, salicylates, nicotinates, and stearates, etc.), and copper chelates (compounds of copper with ethylenediamine or ethylenediaminetetraacetic acid, etc.). Preferably, copper iodide, cuprous bromide, copper bromide, cuprous chloride, and copper acetate are used. The copper compound may contain only one type or two or more types.

[0100] From the viewpoint of easily improving the heat resistance and corrosion resistance of the molded article during manufacturing, the mass ratio of (i) halogen metal salt to (ii) 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.

[0101] (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.

[0102] The preferred metal salts of higher saturated fatty acids are saturated fatty acids with 6 to 22 carbon atoms and metal salts of elements in groups 1, 2, and 3 of the periodic table, as well as metals such as zinc and aluminum (M1). Such higher saturated fatty acid metal salts are represented by the following formula (1).

[0103] CH3(CH2) n COO(M1)...(1)

[0104] (In formula (1), the metallic element (M1) is an element in Group 1, 2, or 3 of the periodic table, zinc, or aluminum, and n can be 8 to 30.)

[0105] Examples of higher saturated fatty acid metal salts include lithium, sodium, magnesium, calcium, zinc, and aluminum salts of decanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanic acid, stearic acid, nonadecanic acid, arachidic acid, behenic acid, ceric acid, heptadecanic acid, linalic acid, beeswax acid, and shellac ceric acid.

[0106] The preferred metal salts of high-grade unsaturated fatty acids are unsaturated fatty acids with 6 to 22 carbon atoms and metal salts of elements in groups 1, 2, and 3 of the periodic table, as well as metal elements such as zinc and aluminum (M1).

[0107] Examples of metal salts of higher unsaturated fatty acids include lithium, sodium, magnesium, calcium, zinc, and aluminum salts of undecenoic acid, oleic acid, transoleic acid, cetearic acid, erucic acid, brassinolic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, stearyleneic acid, 2-hexadecenoic acid, 7-hexadecenoic acid, 9-hexadecenoic acid, cis-9-eicosenoic acid, trans-9-eicosenoic acid, and 11-eicosenoic acid.

[0108] Examples of copper-based heat stabilizers include: a mixture of 10% by mass copper iodide (I) and 90% by mass potassium iodide, a mixture of 14.3% by mass copper iodide (I) and 85.7% by mass potassium iodide / calcium distearate (98:2 mass ratio), etc.

[0109] The content of the copper-based heat stabilizer in the resin composition can be 0.01% by mass or more and 3% by mass or less relative to the total mass of the resin composition, preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.1% by mass or more and 0.5% by mass or less. If the amount of the copper-based heat stabilizer is 0.01% by mass or more relative to the total mass of the resin composition, the flowability and heat aging resistance of the resin composition can be further improved. In addition, if it is 3% by mass or less, the mechanical strength of the molded article is less likely to be compromised.

[0110] Furthermore, when the total content of all polyamide resin contained in the polyamide resin composition is set to 100 parts by mass, the copper content of the copper-based heat stabilizer in the resin composition is 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, more preferably 0.003 parts by mass or more and 0.030 parts by mass or less, and even more preferably 0.005 parts by mass or more and 0.025 parts by mass or less. If the copper content of the copper-based heat stabilizer is 0.001% by mass or more relative to 100 parts by mass of polyamide resin, the flowability and heat aging resistance of the resin composition can be further improved. In addition, if it is 0.050% by mass or less, the mechanical strength of the molded article is less likely to be damaged.

[0111] 1-3. Glass fiber

[0112] The aforementioned polyamide fibers may include glass fibers.

[0113] It is known to incorporate reinforcing materials such as glass fibers to improve the impact resistance and rigidity of polyamide resin compositions. For purposes such as improving dispersibility in polyamide resins, these glass fibers are sometimes treated with sizing agents or surface treatment agents (Patent Document 4, etc.). However, according to the present inventors' new understanding, if glass fibers treated with sizing agents having acidic groups such as carboxyl, anhydride, and ester groups are added to a polyamide resin composition, the flowability of the polyamide resin composition may sometimes decrease. This decrease in flowability has also been observed when glass fibers treated with other sizing agents or surface treatment agents having acidic groups are added to a polyamide resin composition.

[0114] According to the present inventors, the reason for the reduced flowability of the polyamide resin composition when glass fibers treated with an acidic sizing agent or surface treatment agent are added is that, during the melting of the polyamide resin composition, the acidic groups of the aforementioned sizing agent or surface treatment agent react with the amino termini of the polyamide resin. That is, this reaction causes the polyamide resin to bond with the glass fibers via the aforementioned sizing agent or surface treatment agent, increasing the apparent molecular weight of the polyamide resin. Furthermore, it is believed that the increased apparent molecular weight reduces the flowability of the polyamide resin composition. In contrast, the component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane causes the molecular chains of the polyamide resin to bend, moderately creating steric hindrance and hindering the reaction between the acidic groups of the aforementioned sizing agent or surface treatment agent and the amino termini of the polyamide resin. Therefore, it is believed that the increase in the apparent molecular weight of the polyamide resin can be suppressed, thus suppressing the decrease in flowability of the polyamide resin composition when using an acidic sizing agent or surface treatment agent.

[0115] The type of glass fiber described above is not particularly limited if it is used for resin reinforcement; it can be chopped filaments or ground fibers with even shorter fiber lengths. Furthermore, the cross-sectional shape of the glass fiber can be circular, or it can be elliptical, oblong, or other non-circular shapes.

[0116] From the viewpoint of improving the moldability of the resin composition and the mechanical strength and heat resistance of the obtained molded article, the average fiber length of the glass fiber can be set to, for example, 1 μm or more and 20 mm or less, preferably 5 μm or more and 10 mm or less. Furthermore, the aspect ratio of the glass fiber can be set to, for example, 5 or more and 2000 or less, preferably 30 or more and 600 or less.

[0117] The average fiber length and average fiber diameter of glass fibers can be determined by the following methods.

[0118] 1) After dissolving the resin composition in a hexafluoroisopropanol / chloroform solution (0.1 / 0.9 vol%), filter the solution and collect the resulting filtrate.

[0119] 2) Disperse the filter material obtained in 1) in water, and measure the length (Li) and diameter (di) of any 300 individual fibers using an optical microscope (magnification: 50x). Let the number of fibers with a length of Li be qi, and calculate the weight-average length (Lw) based on the following formula, and set it as the average fiber length of the glass fiber.

[0120] Weight-average length (Lw) = (Σqi × Li) 2 ) / (Σqi×Li)

[0121] Similarly, let ri be the number of fibers with a fiber diameter of Di, calculate the weight-average diameter (Dw) based on the following formula, and set it as the average fiber diameter of the glass fiber.

[0122] Weight average diameter (Dw)=(Σri×Di 2 ) / (Σri×Di)

[0123] The content of the glass fiber is not particularly limited, and relative to the total mass of the polyamide resin composition, it can be, for example, more than 15% by mass and less than 70% by mass, preferably more than 15% by mass and less than 50% by mass, and more preferably more than 20% by mass and less than 50% by mass.

[0124] Furthermore, there is no particular limitation on the content of the aforementioned glass fiber. When the total content of all polyamide resin contained in the polyamide resin composition is set to 100 parts by mass, it is 1 part by mass or more and 300 parts by mass or less, preferably 10 parts by mass or more and 270 parts by mass or less, more preferably 20 parts by mass or more and 250 parts by mass or less, and even more preferably 30 parts by mass or more and 100 parts by mass or less.

[0125] The aforementioned glass fibers contain surface treatment agents or sizing agents.

[0126] The aforementioned surface treatment agent or sizing agent may be any known surface treatment agent or sizing agent used with glass fibers incorporated in a polyamide resin composition. The aforementioned surface treatment agent or sizing agent has acidic groups. Examples of such acidic groups include carboxyl groups, anhydride groups, ester groups, and sulfonic acid groups. Among these, carboxyl groups, anhydride groups, and ester groups are preferred, and carboxyl groups and anhydride groups are more preferred. The aforementioned ester group may be a functional group derived from a carboxylic acid ester.

[0127] Examples of surface treatment agents with acidic groups include silane coupling agents containing anhydride groups, such as 3-trimethoxysilylpropyl succinic anhydride.

[0128] Examples of sizing agents with acidic groups include sizing agents containing homopolymers or copolymers of unsaturated carboxylic acids, or copolymers of unsaturated carboxylic acids or their anhydrides with unsaturated monomers.

[0129] Examples of the aforementioned unsaturated carboxylic acids include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, citric acid, and maleic acid. Examples of the aforementioned anhydrides of unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, and dodecenylsuccinic anhydride. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred.

[0130] Examples of the aforementioned unsaturated monomers include styrene, butadiene, acrylonitrile, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, methylstyrene, ethylene, propylene, butene, isobutylene, and vinyl ethers. Among these, methyl acrylate and methyl methacrylate are preferred, and it is more preferable to include both methyl acrylate and methyl methacrylate.

[0131] When the sizing agent comprises a copolymer of the aforementioned unsaturated carboxylic acid or its anhydride and 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. If the proportion is 20% by mass or more, the mechanical strength of the polyamide resin composition is significantly improved by enhancing the chemical interaction between the acidic groups (carboxyl groups) and the polyamide resin. If the proportion is 60% by mass or less, the mechanical strength of the polyamide resin composition is significantly improved by increasing the molecular weight (chain length) of the copolymer to enhance its physical interaction with the polyamide resin.

[0132] The above homopolymers or copolymers can be used in combination with other resins such as urethane resins and epoxy resins.

[0133] (Manufacturing method)

[0134] Glass fibers containing the aforementioned surface treatment agent or sizing agent can be obtained, for example, by applying the aforementioned surface treatment agent or sizing agent to the fiber bundle using a known method such as a roller applicator during the glass fiber manufacturing process, followed by drying and reaction.

[0135] Relative to 100 parts by weight of glass fiber, the amount of the surface treatment agent or sizing agent adhered to is preferably 0.2 parts by weight or more and 3 parts by weight or less, more preferably 0.2 parts by weight or more and 2 parts by weight or less, and even more preferably 0.3 parts by weight or more and 2 parts by weight or less. If the amount of adhesion is 0.2 parts by weight or more, the bundled properties of the glass fiber are further improved. Furthermore, if the amount of adhesion is 2 parts by weight or less, the thermal stability of the resin composition is further improved.

[0136] 1-4. Other ingredients

[0137] The above-described polyamide resin composition may contain other known components.

[0138] Examples of other components include: reinforcing materials, nucleating agents, lubricants, flame retardants, corrosion resistance modifiers, anti-dripping agents, ion trapping agents, elastomers (rubber), antistatic agents, release agents, antioxidants (phenols, amines, sulfur compounds, and phosphorus compounds, etc.), heat stabilizers (lactone compounds, vitamin E compounds, hydroquinone compounds, copper halides, and iodine compounds, etc.), light stabilizers (benzotriazoles, triazines, benzophenones, benzoate esters, hindered amines, and oxanilides, etc.), and other polymers (polyolefins, ethylene-propylene copolymers, ethylene-1-butene copolymers, propylene-1-butene copolymers, polystyrene, polyamides, polycarbonates, polyacetals, polysulfones, polyphenylene ethers, fluoropolymers, silicone resins, and LCPs), etc. From the viewpoint of improving the mechanical strength of the molded article, the resin composition of this disclosure preferably further includes reinforcing materials.

[0139] Reinforcing materials can impart high mechanical strength to resin compositions. Examples of reinforcing materials include fibrous reinforcing materials such as glass fibers, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, zinc oxide whiskers, ground fibers, and cut fibers; as well as granular reinforcing materials. One of these can be used alone, or two or more can be used in combination. Among these, wollastonite, glass fibers, and potassium titanate whiskers are preferred, and wollastonite or glass fibers are more preferred, considering the ease with which the mechanical strength of the molded article can be improved.

[0140] From the viewpoint of the moldability of the resin composition and the mechanical strength and heat resistance of the obtained molded article, the average fiber length of the fibrous reinforcing material can be, for example, 1 μm or more and 20 mm or less, preferably 5 μm or more and 10 mm or less. Furthermore, the aspect ratio of the fibrous reinforcing material can be, for example, 5 or more and 2000 or less, preferably 30 or more and 600 or less.

[0141] The average fiber length and average fiber diameter of fibrous reinforced materials can be determined by the following methods.

[0142] 1) After dissolving the resin composition in a hexafluoroisopropanol / chloroform solution (0.1 / 0.9 vol%), filter the solution and collect the resulting filtrate.

[0143] 2) Disperse the filter material obtained in 1) in water, and measure the length (Li) and diameter (di) of any 300 individual fibers using an optical microscope (magnification: 50x). Let the number of fibers with a length of Li be qi, and calculate the weight-average length (Lw) based on the following formula, and set it as the average fiber length of the fibrous reinforcement material.

[0144] Weight-average length (Lw) = (Σqi × Li) 2 ) / (Σqi×Li)

[0145] Similarly, let ri be the number of fibers with a fiber diameter of Di, and calculate the weight-average diameter (Dw) based on the following formula, and set it as the average fiber diameter of the fibrous reinforcement material.

[0146] Weight average diameter (Dw)=(Σri×Di 2 ) / (Σri×Di)

[0147] There is no particular limitation on the content of fibrous reinforcing material, which can be, for example, more than 15% by mass and less than 70% by mass relative to the total mass of the resin composition.

[0148] Crystallization nucleating agents can improve the crystallinity of the molded article. Examples of crystallization nucleating agents include: metal salt compounds containing sodium 2,2-methylenebis(4,6-di-tert-butylphenyl)phosphate, aluminum tris(p-tert-butylbenzoate), and stearate; sorbitol compounds containing bis(p-methylbenzyl)sorbitol and bis(4-ethylbenzyl)sorbitol; and inorganic substances containing talc, calcium carbonate, and hydrotalcite. Among these, talc is preferred from the viewpoint of further improving the crystallinity of the molded article. These crystallization nucleating agents can be used alone or in combination of two or more.

[0149] The content of the nucleating agent relative to the total mass of the polyamide resin composition is preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.1 parts by mass or more and 3 parts by mass or less. If the content of the nucleating agent is within the above range, it is easy to sufficiently improve the crystallinity of the molded article and easily obtain sufficient mechanical strength.

[0150] Lubricants improve the injection flowability of polyamide resin compositions and enhance the appearance of the resulting molded articles. Lubricants can be fatty acid metal salts such as hydroxycarboxylic acid metal salts and higher fatty acid metal salts.

[0151] The hydroxycarboxylic acids constituting the aforementioned metal salts of hydroxycarboxylic acids can be either aliphatic or aromatic. Examples of aliphatic hydroxycarboxylic acids include: α-hydroxymyristic acid, α-hydroxypalmitic acid, α-hydroxystearic acid, α-hydroxyeicosanoic acid, α-docosalic acid, α-hydroxytetracosanoic acid, α-hydroxyhexacosanoic acid, α-hydroxyoctacosanoic acid, α-hydroxytriacosanoic acid, β-hydroxymyristic acid, 10-hydroxydecanoic acid, 15-hydroxypentadecanoic acid, 16-hydroxyhexadecanoic acid, 12-hydroxystearic acid, and ricinoleic acid, which are aliphatic hydroxycarboxylic acids with 10 to 30 carbon atoms. Examples of aromatic hydroxycarboxylic acids include: salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, gallic acid, mandelic acid, and tropic acid.

[0152] Examples of metals that constitute the above-mentioned hydroxycarboxylic acid metal salts include alkali metals such as lithium, and alkaline earth metals such as magnesium, calcium and barium.

[0153] Among these, the metal salt of the aforementioned hydroxycarboxylic acid is preferably a metal salt of 12-hydroxystearic acid, and more preferably magnesium 12-hydroxystearate and calcium 12-hydroxystearate.

[0154] Examples of higher fatty acids that constitute the aforementioned higher fatty acid metal salts include: stearic acid, oleic acid, docosanoic acid, behenic acid, and linalic acid, which are higher fatty acids with 15 to 30 carbon atoms.

[0155] Examples of metals that constitute the aforementioned higher fatty acid metal salts include calcium, magnesium, barium, lithium, aluminum, zinc, sodium, and potassium.

[0156] Among these, the aforementioned higher fatty acid metal salts are preferably calcium stearate, magnesium stearate, barium stearate, calcium behenate, sodium lignite, and calcium lignite.

[0157] The lubricant content 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. If the lubricant content is 0.01% by mass or more, the fluidity during molding is easily improved, and the appearance of the resulting molded article is easily improved. If the lubricant content is 1.3% by mass or less, gas is less likely to be generated from the decomposition of the lubricant during molding, and the appearance of the article is easily improved.

[0158] 1-5. Manufacturing Method

[0159] The above-mentioned polyamide resin composition can be manufactured by mixing the above-mentioned polyamide resin and other components as needed using a known resin mixing method, such as mixing using a Henschel mixer, V-type agitator, belt mixer, or drum mixer, or by further melt mixing using a single-screw extruder, multi-screw extruder, kneader, or Banbury mixer, followed by granulation or pulverization.

[0160] 2. Uses of the resin composition

[0161] The resin composition disclosed herein can be used in various polyamide molded forms by molding using known molding methods such as compression molding, injection molding, and extrusion molding.

[0162] The molded articles of the resin compositions disclosed herein can be used for a variety of applications. Examples of such applications include: automotive exterior parts such as radiator grilles, rear spoilers, wheel covers, wheel hubcaps, front vent grilles, louvered air vents, air intakes, hood bulges, sunroofs, sunroof rails, mudguards, and rear doors; water pump housings such as cylinder head covers, engine mounts, intake manifolds, throttle bodies, intake pipes, radiator tanks, radiator brackets, water pumps, water pump inlets, and water pump outlets; thermostat housings such as water jacket gaskets and thermostat housings; automotive engine interior parts such as cooling fans, fan shrouds, oil pans, oil filter housings, filler caps, fuel gauges, fuel pumps, timing belts, timing belt covers, and engine covers; fuel caps, filler hoses, automotive fuel tanks, and fuel level sensor modules. Automotive fuel system components such as fuel cut-off valves, quick connectors, canisters, fuel delivery pipes, and fuel dispenser necks; automotive drive system components such as gearshift lever housings and drive shafts; automotive chassis components such as stabilizer bar connecting rods and engine mounting brackets; automotive functional components such as window adjusters, door locks, door handles, exterior door mirror stays, wipers and their components, accelerator pedals, pedal modules, connectors, resin screws, nuts, bushings, seals, bearings, bearing cages, gears, and actuators; wiring harness connectors and relay blocks. Automotive electronic components such as blocks, sensor housings, fuse components, encapsulation, ignition coils, and distributor caps; fuel system components for general equipment such as fuel canisters for brush cutters, lawnmowers, and chainsaws; electrical and electronic components such as connectors and LED reflectors; building material components, industrial equipment components, and various housings or exterior parts such as small housings (including housings for personal computers, mobile phones, etc.) and exterior molded products.

[0163] The resin composition disclosed herein exhibits minimal reduction in mechanical strength even under high temperature / high humidity conditions, making it suitable for automotive components, particularly for use in pipes supplying antifreeze in high temperature and high humidity environments. It is suitable for thermostat housings, water pump housings, water jacket gaskets, etc. Furthermore, it is suitable for automotive components where the ambient temperature is above 100°C, particularly turbine-related components and high-voltage automotive electrical components. In addition, the resin composition disclosed herein is suitable for components of automotive electronic components, electrical and electronic components, industrial equipment components, and housings or exterior parts of electrical equipment.

[0164] Example

[0165] The following detailed description refers to embodiments. The scope of this specification is not intended to be limited to the embodiments.

[0166] In addition, in the following experiments, the melting point (Tm) and glass transition temperature (Tg) of polyamide resin were determined by the following methods.

[0167] (Melting point (Tm), Glass transition temperature (Tg))

[0168] 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).

[0169] Specifically, approximately 5 mg of polyamide resin was sealed in an aluminum dish for testing and heated from room temperature to 350°C at a rate of 10°C / min. To ensure complete melting of the resin, it was held at 360°C for 3 minutes, and then cooled to 30°C at a rate of 10°C / min. After standing at 30°C for 5 minutes, a second heating was performed at a rate of 10°C / min until reaching 360°C. The temperature (°C) of the endothermic peak during this second heating was designated as the melting point (Tm) of the crystalline polyamide resin, and the inflection point corresponding to the glass transition was designated as the glass transition temperature (Tg). The heat of fusion (ΔH) was calculated according to JIS K7122 from the area of ​​the endothermic peak during the first heating process.

[0170] (Intrinsic viscosity [η])

[0171] Regarding the intrinsic viscosity [η] of polyamide resin, 0.5g of polyamide resin was dissolved in 50ml of 96.5% sulfuric acid solution, and the number of seconds it took for the solution to flow down at 25℃±0.05℃ was measured using an Uberloud viscometer. The viscosity was calculated based on the mathematical formula: [η]=ηSP / (C(1+0.205ηSP))

[0172] [η]: Intrinsic viscosity (dl / g)

[0173] ηSP: Specific viscosity

[0174] C: Sample concentration (g / dl)

[0175] t: Number of seconds (seconds) it takes for the sample solution to flow down.

[0176] t0: Number of seconds for blank sulfuric acid to flow (seconds)

[0177] ηSP=(t-t0) / t0

[0178] (Heat of fusion (ΔH))

[0179] The heat of fusion (ΔH) of polyamide resin is calculated from the area of ​​the exothermic peak of crystallization during the first heating process, according to JIS K 7122 (2012).

[0180] 1. Material synthesis / preparation

[0181] 1-1. Synthesis of Polyamide Resins

[0182] (Synthesis example 1)

[0183] 259.5 g (1561.7 mmol) of terephthalic acid, 128.1 g (1102.0 mmol) of 1,6-diaminohexane, 67.2 g (472.3 mmol) of 1,3-bis(aminomethyl)cyclohexane, 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 started at 190 °C, and the internal temperature was raised to 250 °C over 3 hours. At this point, the internal pressure of the autoclave was increased to 3.0 MPa. After reacting under these conditions for 1 hour, the mixture was released to the atmosphere through a nozzle located at the bottom of the autoclave, and the low-valent condensate was removed. The low-valent condensate was then cooled to room temperature and pulverized to a particle size of less than 1.5 mm using a pulverizer, and dried at 110 °C for 24 hours.

[0184] Next, the low-valent condensate was placed in a tray-type solid-phase polymerization apparatus, purged with nitrogen, and heated to 215°C for approximately 1 hour and 30 minutes. Then, the reaction was carried out for 1 hour and 30 minutes, followed by cooling to room temperature.

[0185] Then, using a twin-screw extruder with a screw diameter of 30 mm and L / D = 36, the barrel temperature was set to 330°C, and the obtained prepolymer was melt-polymerized at a screw speed of 200 rpm and a resin supply rate of 6 kg / h to obtain polyamide resin 1.

[0186] The obtained polyamide resin 1 has an intrinsic viscosity [η] of 0.9 dl / g, a melting point (Tm) of 323℃, a glass transition temperature (Tg) of 154℃, and a heat of fusion (ΔH) of 51 mJ / mg.

[0187] (Synthesis example 2)

[0188] The amount of 1,6-diaminohexane added to the autoclave was 118.9 g (1023.1 mmol), and the amount of 1,3-bis(aminomethyl)cyclohexane was 78.4 g (551.1 mmol). Otherwise, the procedure was the same as in Synthesis Example 1, and polyamide resin 2 was obtained. Polyamide resin 2 has an intrinsic viscosity [η] of 0.9 dl / g, a melting point (Tm) of 320 °C, a glass transition temperature (Tg) of 156 °C, and a heat of fusion (ΔH) of 48 mJ / mg.

[0189] (Synthesis example 3)

[0190] The amount of 1,6-diaminohexane added to the autoclave was 109.9 g (944.5 mmol), and the amount of 1,3-bis(aminomethyl)cyclohexane was 89.5 g (629.7 mmol). Otherwise, the procedure was the same as in Synthesis Example 1, and polyamide resin 3 was obtained. Polyamide resin 3 has an intrinsic viscosity [η] of 0.9 dl / g, a melting point (Tm) of 305 °C, a glass transition temperature (Tg) of 166 °C, and a heat of fusion (ΔH) of 35 mJ / mg.

[0191] (Synthesis Example 4)

[0192] The amount of 1,6-hexanediamine added to the autoclave was 280 g (2410 mmol), terephthalic acid was 277.4 g (1670 mmol), isophthalic acid was 119.6 g (720 mmol), benzoic acid was 3.66 g (30 mmol), sodium hypophosphite monohydrate was 5.7 g, and distilled water was 545 g. Otherwise, the procedure was the same as in Synthesis Example 1, to obtain polyamide resin 4. Polyamide resin 4 has 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.

[0193] 1-2. Copper-based heat stabilizers

[0194] A mixture of 10% by mass copper iodide (I) and 90% by mass potassium iodide was used as a copper-based heat stabilizer.

[0195] 1-3. Lubricant

[0196] Sodium lignite (manufactured by Clariant, LICOMONT NAV101, "LICOMONT" is a registered trademark of the company)

[0197] 1-4. Crystallizing nucleating agent

[0198] ·talc

[0199] 1-5. Reinforcing Materials

[0200] • Glass fiber (manufactured by Owens Corning: FT-2A) (glass fiber with surface modification through acid modification)

[0201] 2. Preparation of polyamide resin composition

[0202] The above materials were mixed using a rotary drum mixer according to the composition ratios shown in Tables 1 to 3 (in parts by mass), and melt-blended using a 30 mm φ vented twin-screw extruder at a barrel temperature of 300–335 °C. The mixture was then extruded into linear form and cooled in a water bath. The linear form was then drawn and cut using a granulator to obtain granular polyamide resin composition.

[0203] 3. Evaluation

[0204] The obtained polyamide resin composition was evaluated according to the following criteria.

[0205] 3-1. Tensile strength (at high temperature)

[0206] Various polyamide resin compositions were injection molded under the following conditions to produce ASTM-1 (dumbbell plate) test pieces with a thickness of 3.2 mm.

[0207] Molding machine: SE50DU manufactured by Sumitomo Heavy Industries, Ltd.

[0208] Molding machine barrel temperature: melting point of polyamide resin + 10℃

[0209] Mold temperature: glass transition temperature of polyamide resin +20℃

[0210] The prepared test specimens were placed in a nitrogen atmosphere at 23°C for 24 hours according to ASTM D638. Then, a tensile test was performed at 140°C according to ASTM D638 to determine the tensile strength.

[0211] 3-2. Tensile strength retention rate before and after the addition of copper-based stabilizers

[0212] The tensile strength at high temperature of the polyamide resin composition containing a copper stabilizer is compared with the tensile strength at high temperature of the polyamide resin composition containing the same amount of additives other than the copper stabilizer, and the retention rate of tensile strength before and after the addition of the copper stabilizer is calculated.

[0213] 3-3. Tensile Strength (Initial)

[0214] The test pieces were placed in a nitrogen atmosphere at 23°C for 24 hours according to ASTM D638. Then, a tensile test was performed at 23°C and 50% relative humidity according to ASTM D638 to determine the tensile strength.

[0215] 3-4. Tensile strength (after high-temperature treatment)

[0216] The test pieces were placed at 180°C for 2000 hours. Then, the test pieces were cooled to 23°C and tensile tests were performed according to ASTM D638 at 23°C and 50% relative humidity to determine the tensile strength.

[0217] 3-5. Tensile strength retention rate (after high-temperature treatment)

[0218] The initial tensile strength is compared with the tensile strength after high-temperature treatment, and the ratio of the tensile strength after high-temperature treatment to the initial tensile strength (retention rate) is calculated.

[0219] 3-6. Tensile strength (after high temperature and high humidity treatment)

[0220] The test pieces were placed at 23°C and 50% relative humidity for 48 hours. Then, the test pieces were cooled to 23°C and tensile tests were performed according to ASTM D638 at 23°C and 50% relative humidity to determine the tensile strength.

[0221] 3-7. Tensile strength retention rate (after high temperature and high humidity treatment)

[0222] The initial tensile strength is compared with the tensile strength after high temperature and high humidity treatment, and the ratio of the tensile strength after high temperature treatment to the initial tensile strength (retention rate) is calculated.

[0223] 3-8. Flow length

[0224] Using a bar casting mold with a width of 10 mm and a thickness of 0.5 mm, each polyamide resin composition was injected under the following conditions, and the flow length (mm) of the polyamide resin composition in the mold was measured. A longer flow length indicates better injection flowability.

[0225] Molding machine: Toshiba Machine Co., Ltd., EC75N-2A

[0226] Injection pressure setting: 2000 kg / cm 2

[0227] Molding machine barrel temperature: 335℃

[0228] Mold temperature: 160℃

[0229] 3-9. Flow length retention rate before and after glass fiber integration

[0230] The flow length of the polyamide resin composition containing a copper-based stabilizer and glass fiber, or the polyamide resin composition containing glass fiber, is compared with the flow length of a polyamide resin composition containing the same amount of additives other than glass fiber, and the flow length retention rate before and after glass fiber addition is calculated.

[0231] The composition, tensile strength (at high temperature), flow length retention rate, initial tensile strength, tensile strength (after high temperature treatment), and tensile strength retention rate of the prepared polyamide resin composition are shown in Tables 1 to 3. In Tables 1 to 3, the unit for 100 parts by mass of copper / polyamide resin in the copper-based stabilizer is parts by mass.

[0232] [Table 1]

[0233]

[0234] [Table 2]

[0235]

[0236] [Table 3]

[0237]

[0238] Tables 1-3 clearly show that polyamide resins containing component units (b2) derived from 1,3-bis(aminomethyl)cyclohexane can suppress the decrease in tensile strength at high temperatures caused by the addition of copper-based heat stabilizers. Furthermore, polyamide resins containing component units (b2) derived from 1,3-bis(aminomethyl)cyclohexane can suppress the decrease in mechanical strength under high temperature / high humidity conditions.

[0239] Tables 1 to 3 show that polyamide resins containing component units (b2) derived from 1,3-bis(aminomethyl)cyclohexane can suppress the decrease in flowability caused by the combination of glass fibers containing surface treatment agents or sizing agents with acidic groups.

[0240] This application claims priority based on Japanese Application No. 2021-044984, filed on March 18, 2021, the contents of which are incorporated herein by reference.

[0241] Industrial availability

[0242] The polyamide resin composition disclosed herein achieves a balance between increased mechanical strength resulting from the addition of copper-based heat stabilizers and suppression of decreased flowability. Therefore, this disclosure expands the application possibilities of polyamide resins in a variety of uses and is expected to 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 polyamide resin is a polyamide resin comprising a component unit (a) derived from dicarboxylic acid and a component unit (b) derived from diamine. The dicarboxylic acid-derived component unit (a) comprises component units derived from aromatic dicarboxylic acids or alicyclic dicarboxylic acids. The component unit (b) derived from diamine comprises: The component unit (b1) derived from an alkylene diamine having 4 to 18 carbon atoms, comprising more than 50 mol% and less than 90 mol% of the total molar number of the component unit (b) derived from the diamine, and The component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane comprises 10 mol% or more and less than 50 mol% of the total molar number of the component unit (b) derived from the diamine. The copper content in the copper-based heat stabilizer is between 0.001 and 0.050 parts by weight relative to the polyamide resin content in the polyamide resin composition per 100 parts by weight.

2. The polyamide resin composition according to claim 1, comprising glass fibers in an amount of 1 part by weight or more to 300 parts by weight relative to the polyamide resin contained in the polyamide resin composition, wherein the glass fibers comprise a surface treatment agent having acidic groups.

3. The polyamide resin composition according to claim 2, wherein the acidic group is a carboxyl group, an anhydride group, or an ester group.

4. The polyamide resin composition according to any one of claims 1 to 3, wherein the polyamide resin comprises a component unit (b2) derived from 1,3-bis(aminomethyl)cyclohexane in a total molar percentage of 15 mol% or more and less than 45 mol% relative to the total molar percentage of the component unit (b) derived from the diamine.

5. The polyamide resin composition according to any one of claims 1 to 3, wherein the component unit (b1) derived from an alkylene diamine having 4 to 18 carbon atoms comprises a component unit derived from a linear alkylene diamine or a branched alkylene diamine.

6. The polyamide resin composition according to claim 5, wherein the linear or branched alkylene diamine 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.

7. The polyamide resin composition according to any one of claims 1 to 3, wherein the aromatic dicarboxylic acid or alicyclic dicarboxylic acid is terephthalic acid, naphthalic acid or cyclohexanedicarboxylic acid.

8. The polyamide resin composition according to any one of claims 1 to 3, wherein it is a resin composition for vehicle components.

9. A polyamide molded article comprising the polyamide resin composition according to any one of claims 1 to 8.

10. The polyamide molded body according to claim 9, which is a vehicle-mounted component.

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