Polyamide resin composition and polyamide molded article

Abstract

A polyamide resin composition comprising a polyamide resin and glass fibers containing a surface treatment agent or a convergence agent. The surface treatment agent or convergence agent contains an acidic group. The polyamide resin contains a dicarboxylic acid-derived component unit (a) and a diamine-derived component unit (b), wherein: the dicarboxylic acid-derived component unit (a) contains a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid; and the diamine-derived component unit (b) contains a component unit (b2) derived from a diamine represented by formula (1) in an amount of 10 mol% or more and less than 50 mol% relative to the total mole number 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 Art

[0002] Conventionally, polyamide resin compositions have been widely used as materials for various parts such as clothing, industrial materials, automobiles, electric and electronic devices, and industrial uses because they are excellent in moldability, mechanical properties, and chemical resistance.

[0003] In order for the polyamide resin compositions used in these applications to exhibit characteristics suitable for each application, various additives are added. For example, it is known to blend a reinforcing material such as glass fiber to enhance the impact resistance and rigidity of the polyamide resin composition.

[0004] The above glass fiber may be treated with a sizing agent or a surface treatment agent for the purpose of enhancing its dispersibility in the polyamide resin. For example, Patent Document 1 describes a glass fiber sizing agent containing a copolymer compound obtained by copolymerizing 20 to 60% by mass of an unsaturated dicarboxylic acid or carboxylic anhydride, 20 to 75% by mass of methyl acrylate, and 5 to 20% by mass of methyl methacrylate, an aminosilane, and a polyurethane resin, and having a weight average molecular weight of 10,000 to 60,000. Patent Document 1 describes that the above sizing agent can enhance the mechanical strength (particularly tensile strength) of a polyamide resin to which glass fiber is added.

[0005] In addition, attempts have been made to change the physical properties of polyamide resins by changing the raw materials of polyamide resins. 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. And it is described that a polyamide using equimolar bis-aminomethyl-norbornane and 2-methylpentamethylene as the diamine component is transparent and has a high freezing point. Further, in order to enhance the transparency of polyamides, it is described that crystallization is not performed at all during cooling by selecting the diamine component.

[0006] Patent Document 3 describes that a part of hexamethylenediamine is used as an equivalent mixture of 2,5-bis-aminomethyl-norbornane and 2,6-bis-aminomethyl-norbornane as the diamine component, and the molar ratio of the mixture is set to 20 mol% or less. Thereby, it is described that a transparent polyamide having a high transition temperature can be obtained.

[0007] Patent Document 4 describes that the blending ratio of bis-aminomethyl-norbornane as the diamine component is 17% by weight or more. Specifically, it is described that a polyamide obtained by blending hexamethylenediamine and bis-aminomethyl-norbornane so that hexamethylenediamine / bis-aminomethyl-norbornane is 30 / 70 by weight ratio (36 / 64 by molar ratio) has a high glass transition point.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] The sizing agent described in Citation Document 1 has a carboxy group derived from an unsaturated dicarboxylic acid or a carboxylic anhydride. And according to the new findings of the present inventors, when glass fiber treated with the sizing agent having the above carboxy group is added to a polyamide resin composition, the fluidity of the polyamide resin composition may decrease. The above decrease in fluidity was also observed when glass fiber treated with a sizing agent or a surface treatment agent having other acidic groups was added to a polyamide resin composition.

[0010] In view of these circumstances, an object of the present disclosure is to provide a polyamide resin composition capable of suppressing a decrease in fluidity when glass fiber treated with a sizing agent or a surface treatment agent having an acidic group is added, and a polyamide molded article containing the polyamide resin composition.

Means for Solving the Problems

[0011] [1] A polyamide resin composition comprising 20% by mass or more and 85% by mass or less of a polyamide resin based on the total mass of the polyamide resin composition, and 15% by mass or more and 70% by mass or less of glass fiber containing a surface treatment agent or a sizing agent based on the total mass of the polyamide resin composition, wherein the surface treatment agent or the sizing agent has an acidic group, the polyamide resin 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 contains a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and the component unit (b) derived from the diamine contains a component unit (b1) derived from an alkylenediamine having 4 or more and 18 or less carbon atoms, which is more than 50 mol% and 90 mol% or less based on the total number of moles of the component unit (b) derived from the diamine, and a component unit (b2) derived from a diamine represented by the following formula (1), which is 10 mol% or more and less than 50 mol% based on the total number of moles of the component unit (b) derived from the diamine. [Chemical formula] (In formula (1), m and n are each independently 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 acidic group of the surface treatment agent or the sizing agent is a carboxy group, an acid anhydride group, or a carboxylic acid ester group. [3] The polyamide resin composition according to [1] or [2], wherein the polyamide resin contains a component unit (b2) derived from the diamine represented by the formula (1) in an amount of 10 mol% or more and less than 45 mol% based on the total number of moles of the component unit (b) derived from the diamine. [4] The polyamide resin composition according to any one of [1] to [3], wherein the component unit (b1) derived from the alkylenediamine having 4 to 18 carbon atoms contains a component unit derived from a linear alkylenediamine or a branched alkylenediamine. [5] The polyamide resin composition according to [4], wherein the linear alkylenediamine or the 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. [6] The polyamide resin composition according to any one of [1] to [5], wherein the aromatic dicarboxylic acid or the alicyclic dicarboxylic acid is terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid. [7] The polyamide resin composition according to any one of [1] to [6], wherein the melting point (Tm) of the polyamide resin is 280°C or higher. [8] The polyamide resin composition according to any one of [1] to [7], wherein the polyamide resin is a crystalline polyamide resin. [9] The polyamide resin composition according to any one of [1] to [8], wherein the heat of fusion (ΔH) of the polyamide resin is 10 mJ / mg or more.

[10] The polyamide resin composition according to any one of [1] to [9], which is a resin composition for in-vehicle members.

[0012]

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

[10] .

[12] The polyamide molded article according to

[11] , which is an in-vehicle member. [Advantages of the Invention]

[0013] According to the present disclosure, it is possible to provide a polyamide resin composition capable of suppressing a decrease in fluidity when adding glass fibers treated with a sizing agent or a surface treatment agent having an acidic group, and a polyamide molded article including the polyamide resin composition. [Embodiments for Carrying Out the Invention]

[0014] 1. Polyamide Resin Composition A polyamide resin composition is a resin composition in which the main component of the resin component is a polyamide resin. The main component means that the proportion of the polyamide resin in the resin component is 50% by mass or more. The proportion of the polyamide resin in the resin component is preferably 60% by mass or more, more preferably 70% by mass or more, still 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 component is not particularly limited, but can be 100% by mass or less, and may be 90% by mass or less, or 80% by mass or less.

[0015] The proportion of the polyamide resin contained in the polyamide resin composition is preferably 20% by mass or more and 85% by mass or less based on the total mass of the polyamide resin composition.

[0016] 1-1. Polyamide Resin The polyamide resin contains a component unit (a) derived from a dicarboxylic acid and a component unit (b) derived from a diamine. At this time, in order to make the melting point (Tm) and glass transition temperature (Tg) of the polyamide resin within the above ranges, the component unit (a) derived from a dicarboxylic acid preferably contains a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and the component unit (b) derived from a diamine contains, based on the total number of moles of the component unit (b) derived from a diamine, more than 50 mol% and 90 mol% or less of a component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms, and, based on the total number of moles of the component unit (b) derived from the above diamine, 10 mol% or more and less than 50 mol% of a component unit (b2) derived from a diamine represented by the following formula (1). [Chemical formula] (In formula (1), m and n are each independently 0 or 1, -X- is a single bond or a divalent group selected from the group consisting of -O-, -S-, -SO2-, -CO- and -CH2-)

[0017] [Component unit (a) derived from a 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.

[0018] Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid and their esters. Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid and its esters.

[0019] In the present disclosure, the component unit (a) derived from a dicarboxylic acid preferably contains a component unit (a1) derived from terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid. These component units (a1) can enhance the crystallinity of the polyamide, unlike, for example, isophthalic acid. From the viewpoint of ensuring the crystallinity of the polyamide resin, the content of these component units (a1) is more than 20 mol% and 100 mol% or less with respect to the total number of moles of the component units (a) derived from the dicarboxylic acid. From the viewpoint of further enhancing 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, still more preferably more than 80 mol%, and particularly preferably more than 90 mol% with respect to the total number of moles of the component units (a) derived from the dicarboxylic acid. The upper limit of the content of the component units (a1) is not particularly limited, and may be 100 mol% or 99 mol% or less with respect to the total number of moles of the component units (a) derived from the dicarboxylic acid. Among them, from the viewpoint of obtaining a polyamide resin with high crystallinity and high heat resistance, the above component units (a1) are more preferably component units derived from terephthalic acid.

[0020] The component unit (a) derived from the dicarboxylic acid may contain, within a range that does not impair the effects of the present disclosure, a component unit (a2) derived from an aromatic dicarboxylic acid other than the above component unit (a1), a component unit (a3) derived from an aliphatic dicarboxylic acid having 4 to 18 carbon atoms, or a component unit (a4) derived from a polybasic carboxylic acid having tribasic or higher functionality.

[0021] Examples of the component unit (a2) derived from an aromatic dicarboxylic acid other than terephthalic acid include component units derived from isophthalic acid and 2-methylterephthalic acid, and preferably include component units derived from isophthalic acid. From the viewpoint of facilitating the securing of the crystallinity of the polyamide resin, the content of these component units (a2) is preferably 1 mol% or more and 50 mol% or less, more preferably 1 mol% or more and 20 mol% or less, still more preferably 1 mol% or more and 10 mol% or less, and particularly preferably 1 mol% or more and 5 mol% or less based on the total number of moles of the component units (a) derived from dicarboxylic acids.

[0022] The component unit (a3) derived from an aliphatic dicarboxylic acid is a component unit derived from an aliphatic dicarboxylic acid having an alkylene group with 4 to 18 carbon atoms, and preferably is a constitutional unit derived from an aliphatic dicarboxylic acid having an alkylene group with 6 to 12 carbon atoms. Examples of the aliphatic dicarboxylic acid include 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 component units, and preferably include component units derived from adipic acid and sebacic acid. From the viewpoint of securing 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, still more preferably 1 mol% or more and 10 mol% or less, and particularly preferably 1 mol% or more and 5 mol% or less based on the total number of moles of the component units (a) derived from dicarboxylic acids.

[0023] Examples of the component unit (a4) derived from a polybasic carboxylic acid having three or more basic groups include component units derived from trimellitic acid, pyromellitic acid, and esters thereof. The content of the component unit derived from such a polybasic carboxylic acid can be 0 mol% or more and 5 mol% or less based on the total number of moles of the component units (a) derived from dicarboxylic acids.

[0024] However, from the viewpoint of making it difficult to impair the crystallinity of the resin, the content of the component unit derived from isophthalic acid and the component unit derived from an aliphatic dicarboxylic acid having 4 to 18 carbon atoms other than adipic acid is small. Specifically, it is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total number of moles of the component unit (a) derived from the dicarboxylic acid.

[0025] [Component unit (b) derived from diamine] When the polyamide resin contains, as the component unit (b) derived from diamine, in addition to the component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms, the component unit (b2) derived from an alkylenediamine having a specific cyclic structure (the diamine represented by formula (1)), the glass transition temperature (Tg) can be sufficiently increased.

[0026] That is, since the component unit (b2) derived from the diamine represented by formula (1) has a non-linear structure, the mobility of the molecular chain of the polyamide resin is reduced. Therefore, the component unit (b2) derived from the diamine represented by formula (1) can increase the glass transition temperature (Tg) of the polyamide resin having the component unit (b2) compared to the polyamide resin not having the component unit (b2). Further, thereby, the polyamide resin having the component unit (b2) is considered to have high mechanical strength even in a high temperature range and to be able to maintain this high mechanical strength over a long period of time.

[0027] Furthermore, the component unit (b2) derived from the diamine represented by formula (1) can moderately lower the melting point (Tm) of the polyamide resin having the component unit (b2) compared to the polyamide resin not having the component unit (b2). Thereby, the polyamide resin having the component unit (b2) has high fluidity during injection molding and high moldability.

[0028] Incidentally, according to the findings of the present inventors, the decrease in fluidity when glass fibers treated with a sizing agent or a surface treatment agent having an acidic group are added is considered to be caused by the reaction of the acidic group of the sizing agent or the surface treatment agent with the amino terminal of the polyamide resin during the melting of the polyamide resin composition. That is, the above reaction binds the polyamide resin and the glass fibers via a sizing agent or a surface treatment agent, increasing the apparent molecular weight of the polyamide resin alone. And it is considered that the fluidity of the polyamide resin composition decreases due to the increase in the apparent molecular weight. On the other hand, the component unit (b2) derived from the diamine represented by the formula (1) bends the molecular chain of the polyamide resin to cause appropriate steric hindrance, inhibiting the reaction between the acidic group of the sizing agent or the surface treatment agent and the amino terminal of the polyamide resin. Thereby, it is considered that the increase in the apparent molecular weight of the polyamide resin is suppressed, and the decrease in the fluidity of the polyamide resin composition when a sizing agent or a surface treatment agent having an acidic group is used is suppressed.

[0029] Further, the component unit (b2) derived from the diamine represented by the formula (1) bends the molecular chain of the polyamide resin, suppressing the intrusion of moisture into the polyamide resin composition. Thereby, the component unit (b2) derived from the diamine represented by the formula (1) makes the polyamide resin less likely to be hydrolyzed. Thereby, it is considered that the decrease in the mechanical strength (especially the tensile strength) of the molded article of the polyamide resin composition, particularly in a high-temperature and high-humidity environment, is suppressed.

[0030] In addition, since the polyamide resin has crystallinity due to the component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms, the fluidity and mechanical strength during injection molding (of the polyamide resin itself) are high. Furthermore, since the polyamide resin has a high glass transition temperature (Tg), it is considered to have high mechanical strength even in a high-temperature range and to easily maintain these high mechanical strengths.

[0031] From the perspective of making it difficult to lower the Tg of the resin, the number of carbon atoms of the alkylenediamine having 4 to 18 carbon atoms, which is the raw material of the component unit (b1), is more preferably 4 to 10.

[0032] The alkylenediamine having 4 to 18 carbon atoms may contain a linear alkylenediamine or a branched-chain alkylenediamine. From the perspective of enhancing the crystallinity of the resin, the alkylenediamine having 4 to 18 carbon atoms preferably contains a linear alkylenediamine. That is, the component unit derived from the alkylenediamine having 4 to 18 carbon atoms preferably contains a component unit derived from a linear alkylenediamine.

[0033] Examples of the alkylenediamine 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-chain 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 of two or more.

[0034] The content of the component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms is preferably more than 50 mol% and not more than 90 mol% based on the total number of moles of the component unit (b) derived from diamine. When the above content is more than 50 mol%, the crystallinity of the polyamide resin can be sufficiently increased, and the fluidity and mechanical strength during injection molding of the polyamide resin itself can be further enhanced. When the above content is not more than 90 mol%, the content of the component unit (b2) derived from the diamine represented by the formula (1) can be increased. Thereby, the glass transition temperature (Tg) of the polyamide resin can be increased, the mechanical strength in the high temperature range can be increased, and the (Tm) of the polyamide resin can be appropriately decreased to enhance the molding processability.

[0035] From the same perspective, the content of the component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms is more preferably 55 mol% or more and 85 mol% or less, and even more preferably 60 mol% or more and 80 mol% or less based on the total number of moles of the component unit (b) derived from diamine.

[0036] On the other hand, the content of the component unit (b2) derived from the diamine represented by the formula (1) is preferably 10 mol% or more and less than 50 mol% based on the total number of moles of the component unit (b) derived from diamine. When the above content is 10 mol% or more, the glass transition temperature (Tg) of the polyamide resin can be increased, the mechanical strength in the high temperature range can be increased, and the (Tm) of the polyamide resin can be appropriately decreased to enhance the molding processability. When the above content is less than 50 mol%, the content of the component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms can be increased. Thereby, the crystallinity of the polyamide resin can be sufficiently increased to further enhance the mechanical strength of the molded body, and the decrease in the fluidity of the polyamide resin itself due to the component unit (b2) derived from the diamine represented by the formula (1) can be suppressed.

[0037] From the same perspective, the content of the component unit (b2) derived from the diamine represented by formula (1) is more preferably 10 mol% or more and less than 45 mol% based on the total number of moles of the component unit (b) derived from the diamine, 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 36 mol% or less.

[0038] The component unit (b) derived from the diamine may further contain a component unit (b3) derived from another diamine as long as the effects of the present disclosure are not impaired. Examples of other diamines include aromatic diamines and alicyclic diamines. The content of the component unit (b3) derived from another diamine can be 50 mol% or less based on the total number of moles of the component unit (b) derived from the diamine.

[0039] From the perspective of enhancing the heat stability during compounding and molding or further enhancing the mechanical strength, at least some of the terminal groups of the polyamide resin molecules may be blocked with a terminal blocking agent. When the molecular terminal is a carboxy group, the terminal blocking agent is preferably a monoamine, and when the molecular terminal is an amino group, the terminal blocking agent is preferably a monocarboxylic acid.

[0040] Examples of the monoamine 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 the monocarboxylic acid 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 the alicyclic monocarboxylic acid may have a substituent in the cyclic structure portion.

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

[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 in the high temperature range are less likely to be impaired. When it is 330°C or lower, it is not necessary to raise the molding temperature excessively, so the molding processability of the polyamide resin composition tends to be good. 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 in the high temperature range can be made higher. When the glass transition temperature (Tg) of the polyamide resin is 180°C or lower, the molding processability of the polyamide resin composition tends to be good. From the above viewpoints, 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, since it has crystallinity, it is easy to enhance the fluidity and mechanical strength during injection molding. From the same viewpoints, 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 value of the heat of fusion (ΔH) of the polyamide resin is not particularly limited, but from the viewpoint of not impairing the molding processability, it can be 90 mJ / mg.

[0045] Incidentally, 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 type, manufactured by Seiko Instruments Inc.).

[0046] Specifically, about 5 mg of the polyamide resin is sealed in a measurement 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, the second heating is performed from 30 °C to 350 °C at 10 °C / min. The temperature (°C) of the endothermic peak in this second heating is defined as the melting point (Tm) of the polyamide resin, and the inflection point corresponding to the glass transition is defined as the glass transition temperature (Tg). The heat of fusion (ΔH) is determined from the area of the endothermic peak in 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 the dicarboxylic acid, the content of the component unit (b2) derived from the diamine represented by the formula (1), the content ratio of the component unit (b1) derived from an alkylenediamine having 4 or more and 18 or less carbon atoms to the component unit (b2) derived from the diamine represented by the formula (1), and the number of carbon atoms of the alkylenediamine having 4 or more and 18 or less carbon atoms.

[0048] Also, when increasing the heat of fusion (ΔH) of the polyamide resin, it is preferable to lower the content and content ratio (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) of the above polyamide resin and lowering the melting point (Tm), for example, it is preferable to increase the content and content ratio (the ratio of the component unit (b2) to the total number of moles of the component unit (b) derived from the diamine).

[0049] The intrinsic viscosity [η] of the polyamide resin, measured in 96.5% sulfuric acid at 25°C, is preferably 0.6 dl / g or more and 1.5 dl / g or less. When the intrinsic viscosity [η] of the polyamide resin is 0.6 dl / g or more, it is easy to sufficiently increase the mechanical strength (toughness, etc.) of the molded body. When it is 1.5 dl / g or less, the fluidity during molding of the polyamide resin composition is less likely to be impaired. From the same perspective, the intrinsic viscosity [η] of the polyamide resin is more preferably 0.8 dl / g or more and 1.2 dl / g or less. The intrinsic viscosity [η] can be adjusted by the amount of end capping of the polyamide resin, etc.

[0050] The intrinsic viscosity of the polyamide resin can be measured in accordance with JIS K6810 - 1977. Specifically, 0.5 g of the polyamide resin is dissolved in 50 ml of a 96.5% sulfuric acid solution to obtain a sample solution. The flow-down seconds of this sample solution are measured under the condition of 25 ± 0.05°C using an Ubbelohde viscometer, and the obtained value can be calculated by applying it to the following formula. [η]=ηSP / [C(1 + 0.205ηSP)]

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

[0052] ηSP is obtained by the following formula. ηSP=(t - t0) / t0 t: Flow-down seconds of the sample solution (seconds) t0: Flow-down seconds of the blank sulfuric acid (seconds)

[0053] The amount of terminal amino groups in the polyamide resin is preferably 10 mmol / kg or more and 150 mmol / kg or less, more preferably 15 mmol / kg or more and 130 mmol / kg or less, and even more preferably 20 mmol / kg or more and 100 mmol / kg or less. When the amount of terminal amino groups in the polyamide resin is 150 mmol / kg or more, a decrease in fluidity is likely to occur when glass fibers treated with a surface treatment agent or a sizing agent having an acidic group are added. Therefore, the effect of suppressing the decrease in fluidity by using the polyamide resin is remarkable. When the amount of terminal amino groups in the polyamide resin is 150 mmol / kg or less, the fluidity of the polyamide resin composition can be sufficiently ensured.

[0054] The amount of terminal amino groups is the value measured by the following method. Dissolve 1 g of the polyamide resin in 35 mL of phenol, mix with 2 mL of methanol to obtain a sample solution. Then, using thymol blue as an indicator, perform titration on the sample solution with 0.01 N HCl aqueous solution to specify the amount of terminal amino groups ([NH2], unit: mmol / kg).

[0055] [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 dicarboxylic acid and the diamine are heated in the presence of a catalyst as described in WO 03 / 085029 to obtain a lower condensate, and then the melt of this lower condensate is subjected to shear stress for polycondensation to produce it.

[0056] From the viewpoint of adjusting the intrinsic viscosity of the polyamide resin, etc., the aforementioned end-capping agent may be added to the reaction system. The intrinsic viscosity [η] (or molecular weight) of the polyamide resin can be adjusted by the addition amount of the end-capping agent.

[0057] The end-capping agent is added to the reaction system of the dicarboxylic acid and the diamine. The addition amount is preferably 0.07 mol or less, more preferably 0.05 mol or less, per 1 mol of the total amount of the dicarboxylic acid.

[0058] 1-2. Glass fiber The polyamide resin composition contains glass fiber.

[0059] The type of glass fiber is not particularly limited as long as it is used for reinforcing the resin, and it may be chopped strand or milled fiber with a shorter fiber length. Also, the cross-sectional shape of the glass fiber may be circular or non-circular such as elliptical or oblong.

[0060] From the viewpoint of enhancing the moldability of the polyamide resin composition and the mechanical strength and heat resistance of the resulting molded article, the average fiber length of the glass fiber can be, for example, 1 μm or more and 20 mm or less, preferably 5 μm or more and 10 mm or less. Also, the aspect ratio of the glass fiber can be, for example, 5 or more and 2000 or less, preferably 30 or more and 600 or less.

[0061] The average fiber length and average fiber diameter of the glass fiber can be measured by the following method. 1) After dissolving the polyamide resin composition in a hexafluoroisopropanol / chloroform solution (0.1 / 0.9 volume %), the filtrate obtained by filtration is collected. 2) The filtrate obtained in 1) is dispersed in water, and the fiber length (Li) and fiber diameter (di) of any 300 fibers each are measured with an optical microscope (magnification: 50 times). Let the number of fibers with fiber length Li be qi, and the weight average length (Lw) is calculated based on the following formula, and this is taken as the average fiber length of the glass fiber. Weight average length (Lw) = (Σqi × Li 2 ) / (Σqi × Li) Similarly, let the number of fibers with fiber diameter Di be ri, and the weight average diameter (Dw) is calculated based on the following formula, and this is taken as the average fiber diameter of the glass fiber. Weight average diameter (Dw) = (Σri × Di 2 ) / (Σri × Di)

[0062] The content of the glass fiber is not particularly limited, but it 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, based on the total mass of the polyamide resin composition.

[0063] The glass fiber contains a surface treatment agent or a sizing agent.

[0064] The surface treatment agent or the sizing agent may be a known surface treatment agent or sizing agent used for the glass fiber compounded in the polyamide resin composition. However, the surface treatment agent or the sizing agent has an acidic group. Examples of the acidic group include a carboxy group, an acid anhydride group, a carboxylic acid ester group, and a sulfonic acid group. Among these, a carboxy group, an acid anhydride group, and a carboxylic acid ester group are preferable, and a carboxy group and an acid anhydride group are more preferable. The carboxylic acid ester group may be a functional group derived from a carboxylic acid ester.

[0065] Examples of the surface treatment agent having an acidic group include silane coupling agents containing an acid anhydride group such as 3 - trimethoxysilylpropyl succinic anhydride.

[0066] Examples of the sizing agent 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 its anhydride and an unsaturated monomer.

[0067] Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, mesaconic acid, citraconic acid, and maleic acid. Examples of the anhydride of the unsaturated carboxylic acid include maleic anhydride, itaconic anhydride, and dodecenyl succinic anhydride. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable.

[0068] Examples of unsaturated monomers include styrene, butadiene, acrylonitrile, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, methyl styrene, ethylene, propylene, butylene, isobutylene, and vinyl ether. Among these, methyl acrylate and methyl methacrylate are preferred, and it is more preferred to include both methyl acrylate and methyl methacrylate.

[0069] When the convergence agent contains a copolymer of an unsaturated carboxylic acid or its anhydride and an unsaturated monomer, the ratio of the unsaturated carboxylic acid or its anhydride to the total mass of the copolymer is preferably 20% by mass or more and 60% by mass or less. When the ratio is 20% by mass or more, the effect of improving the mechanical strength of the polyamide resin composition by enhancing the chemical interaction with the polyamide resin due to the acidic group (carboxy group) is remarkable. When the ratio is 60% by mass or less, the effect of improving the mechanical strength of the polyamide resin composition by increasing the molecular weight (chain length) of the copolymer and enhancing the physical interaction with the polyamide resin is remarkable.

[0070] The weight average molecular weight (Mw) of the homopolymer or copolymer is preferably 3000 or more and 60000 or less. When the weight average molecular weight of the homopolymer or copolymer is 3000 or more, the effect of improving the mechanical strength of the polyamide resin composition by enhancing the physical interaction with the polyamide resin is further enhanced. On the other hand, by setting the weight average molecular weight of the copolymer to 60000 or less, the dispersibility of the glass fiber in the polyamide resin can be further improved. From the above viewpoints, the weight average molecular weight of the homopolymer or copolymer is preferably 10000 or more and 50000 or less, and more preferably 20000 or more and 50000 or less. The weight average molecular weight of the copolymer is a value measured by gel permeation chromatography (GPC) and calculated using polystyrene as a standard substance.

[0071] The homopolymer or copolymer may be used in combination with other resins such as urethane resin and epoxy resin.

[0072] Examples of urethane resins include urethane resins synthesized from isocyanates such as m-xylylene diisocyanate (XDI), 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI), and isophorone diisocyanate (IPDI), and polyester-based or polyether-based diols.

[0073] (Manufacturing method) Glass fibers containing a surface treatment agent or a sizing agent can be obtained, for example, by applying (imparting) the surface treatment agent or the sizing agent to the fiber strands using a known method such as a roller-type applicator during the manufacturing process of the glass fibers, and drying and reacting them.

[0074] The adhesion amount of the surface treatment agent or the sizing agent is preferably 0.2 parts by mass or more and 3 parts by mass or less, more preferably 0.2 parts by mass or more and 2 parts by mass or less, and even more preferably 0.3 parts by mass or more and 2 parts by mass or less in terms of solid content based on 100 parts by mass of the glass fibers. When the adhesion amount is 0.2 parts by mass or more, the bundling property of the glass fibers is further improved. Also, when the adhesion amount is 2 parts by mass or less, the thermal stability of the polyamide resin composition is further improved.

[0075] 1-3. Other components The polyamide resin composition may contain other known components. The content of the other components is preferably 0% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less based on the total mass of the polyamide resin composition.

[0076] Examples of other components include reinforcing materials other than glass fibers, crystal nucleating agents, lubricants, flame retardants, corrosion resistance improvers, drip inhibitors, ion scavengers, elastomers (rubbers), antistatic agents, mold release agents, antioxidants (such as phenols, amines, sulfurs, and phosphors), heat stabilizers (such as lactone compounds, vitamin E compounds, hydroquinones, copper halides, and iodine compounds), light stabilizers (such as benzotriazoles, triazines, benzophenones, benzoates, hindered amines, and oxanilides), and other polymers (such as olefin copolymers such as polyolefins, ethylene-propylene copolymers, and ethylene-1-butene copolymers, olefin copolymers such as propylene-1-butene copolymers, polystyrene, polyamide, polycarbonate, polyacetal, polysulfone, polyphenylene oxide, fluororesins, silicone resins, and LCP). Among these, from the viewpoint of enhancing the mechanical strength of the molded article, it is preferable that the polyamide resin composition of the present disclosure further contains a reinforcing material.

[0077] Examples of reinforcing materials other than glass fibers include fibrous reinforcing materials such as wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, zinc oxide whiskers, milled fibers, and cut fibers, and particulate reinforcing materials.

[0078] The crystal nucleating agent can increase the crystallinity of the molded article. Examples of the crystal nucleating agent include metal salt-based compounds containing, for example, 2,2 - methylenebis(4,6 - di - t - butylphenyl) sodium phosphate, tris(p - t - butylbenzoic acid) aluminum, and stearates; sorbitol-based compounds containing, for example, bis(p - methylbenzylidene) sorbitol and bis(4 - ethylbenzylidene) sorbitol; and inorganic substances containing, for example, talc, calcium carbonate, and hydrotalcite. Among these, from the viewpoint of further increasing the crystallinity of the molded article, talc is preferable. These crystal nucleating agents may be used alone or in combination of two or more.

[0079] The content of the crystal nucleating agent is preferably 0.1 part by mass or more and 5 parts by mass or less, more preferably 0.1 part by mass or more and 3 parts by mass or less, based on the total mass of the polyamide resin composition. When the content of the crystal nucleating agent is within the above range, it is easy to sufficiently increase the crystallinity of the molded body, and it is easy to obtain sufficient mechanical strength.

[0080] The lubricant enhances the injection fluidity of the polyamide resin composition and improves the appearance of the resulting molded body. The lubricant can be a fatty acid metal salt such as a metal salt of an oxycarboxylic acid and a metal salt of a higher fatty acid.

[0081] The oxycarboxylic acid constituting the metal salt of oxycarboxylic acid may be an aliphatic oxycarboxylic acid or an aromatic oxycarboxylic acid. Examples of the aliphatic oxycarboxylic acid include aliphatic oxycarboxylic 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 the aromatic oxycarboxylic acid include salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, gallic acid, mandelic acid, and tropic acid.

[0082] Examples of the metal constituting the metal salt of oxycarboxylic acid include alkali metals such as lithium, and alkaline earth metals such as magnesium, calcium, and barium.

[0083] Among these, the metal salt of oxycarboxylic acid is preferably a metal salt of 12-hydroxystearic acid, more preferably magnesium 12-hydroxystearate and calcium 12-hydroxystearate.

[0084] Examples of the higher fatty acids constituting the metal salts of higher fatty acids include higher fatty acids having 15 to 30 carbon atoms such as stearic acid, oleic acid, behenic acid, docosanoic acid, and montanic acid.

[0085] Examples of the metals constituting the metal salts of higher fatty acids include calcium, magnesium, barium, lithium, aluminum, zinc, sodium, and potassium.

[0086] Among these, the metal salts of higher fatty acids are preferably calcium stearate, magnesium stearate, barium stearate, calcium behenate, sodium montanate, calcium montanate, and the like.

[0087] The content of the lubricant is preferably 0.01% by mass or more and 1.3% by mass or less based on 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 is likely to increase, and the appearance of the obtained molded product is likely to improve. When the content of the lubricant is 1.3% by mass or less, gas generated by the decomposition of the lubricant is less likely to be generated during molding, and the appearance of the product is likely to be good.

[0088] 1-4. Manufacturing method The polyamide resin composition can be produced by mixing the above polyamide resin and, if necessary, other components by a known resin kneading method, for example, a method of mixing with a Henschel mixer, a V blender, a ribbon blender, or a tumbler blender, or after mixing, further melt-kneading with a single-screw extruder, a multi-screw extruder, a kneader, or a Banbury mixer, and then granulating or pulverizing.

[0089] 2. Use of the polyamide resin composition The polyamide resin composition of the present disclosure is used as various polyamide molded articles by molding by a known molding method such as a compression molding method, an injection molding method, or an extrusion molding method.

[0090] The molded body of the polyamide resin composition of the present disclosure can be used for various applications. Examples of such applications include automotive exterior parts such as radiator grilles, rear spoilers, wheel covers, wheel caps, cowl vent grilles, air outlet louvers, air scoops, hood bulges, sunroofs, sunroof rails, fenders, and back doors; automotive engine room interior 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; automotive fuel system parts such as fuel caps, fuel filler tubes, automotive fuel tanks, fuel sender modules, fuel cut-off valves, quick connectors, canisters, fuel delivery pipes, and fuel filler necks; automotive drive system parts such as shift lever housings and propeller shafts; automotive chassis parts such as stabilizer bar link 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, resin screws, nuts, bushings, seal rings, bearings, bearing retainers, gears, and actuators; automotive electronics parts such as wire harness connectors, relay blocks, sensor housings, fuse parts, encapsulations, ignition coils, and distributor caps; fuel system parts for general-purpose equipment (lawn mowers, lawn trimmers, and chain saws) such as fuel tanks; electrical and electronic parts such as connectors and LED reflectors; building materials parts; industrial equipment parts; and various housings or exterior parts such as small housings (including housings of personal computers, mobile phones, etc.) and exterior molded products are included.

[0091] Among them, the polyamide resin composition of the present disclosure has little decrease in mechanical strength even in a high-temperature and high-humidity environment, so it is suitable for use in in-vehicle members, particularly in a high-temperature and high-humidity environment such as a tube through which antifreeze flows. In addition, the polyamide resin composition of the present disclosure can be suitably used for parts of electric devices such as automotive electronics parts, electric and electronic parts, industrial equipment parts, and the housing or exterior parts of electric devices.

Examples

[0092] Hereinafter, the present disclosure will be described with reference to examples. The scope of the present disclosure is not construed as being limited by the examples.

[0093] In the following experiments, the melting point (Tm), glass transition temperature (Tg), intrinsic viscosity, heat of fusion, and amount of terminal amino groups of the polyamide resin were measured by the following methods.

[0094] (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 type, manufactured by Seiko Instruments Inc.).

[0095] Specifically, about 5 mg of the 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, the second heating was carried out from 30 °C to 350 °C at 10 °C / min. The temperature (°C) of the endothermic peak in 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 determined from the area of the endothermic peak in the second heating process in accordance with JIS K7122.

[0096] (Intrinsic viscosity [η]) The intrinsic viscosity [η] of the polyamide resin was measured by dissolving 0.5 g of the polyamide resin in 50 ml of a 96.5% sulfuric acid solution, measuring the flow-down seconds of the resulting solution under the condition of 25 °C ± 0.05 °C using an Ubbelohde viscometer, and calculating based on the formula: [η] = ηSP / (C(1 + 0.205ηSP)). [η]: Intrinsic viscosity (dl / g) ηSP: Specific viscosity C: Sample concentration (g / dl) t: Flow-down seconds of the sample solution (seconds) t0: Flow-down seconds of the blank sulfuric acid (seconds) ηSP = (t - t0) / t0

[0097] (Amount of terminal amino groups) 1 g of the polyamide resin was dissolved in 35 mL of phenol, 2 mL of methanol was mixed to obtain a sample solution. Then, using thymol blue as an indicator, a titration was carried out on the sample solution with 0.01 N HCl aqueous solution to determine the amount of terminal amino groups ([NH2], unit: mmol / kg).

[0098] 1. Synthesis / Preparation of Materials 1-1. Synthesis of Polyamide Resin (Synthesis Example 1) 259.5 g (1561.7 mmol) of terephthalic acid, 118.9 g (1023.1 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 an autoclave with an internal volume of 1 L, and purged with nitrogen. Stirring was started 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 continuing the reaction for 1 hour, atmospheric release was carried out from the spray nozzle installed at the bottom of the autoclave to extract the low-order condensate. Then, after cooling this low-order condensate to room temperature, the low-order condensate was pulverized with a pulverizer to a particle size of 1.5 mm or less and dried at 110 °C for 24 hours.

[0099] Next, this low-order condensate was placed in a stepwise solid-phase polymerization apparatus. After nitrogen substitution, the temperature was raised to 215°C over about 1 hour and 30 minutes. Then, it was reacted for 1 hour and 30 minutes and cooled to room temperature.

[0100] Thereafter, the obtained prepolymer was melt-polymerized using 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 supply rate of 6 kg / h to obtain Polyamide Resin 1.

[0101] The limiting viscosity [η] of the obtained Polyamide Resin 1 was 0.97 dl / g, the melting point (Tm) was 312°C, the glass transition temperature (Tg) was 167°C, the heat of fusion (ΔH) was 44 mJ / mg, and the amount of terminal amino groups was 30 mmol / kg.

[0102] (Synthesis Example 2) 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), and 119.6 g (720 mmol), respectively. 3.66 g (30 mmol) of benzoic acid was added, and 5.7 g of sodium hypophosphite monohydrate and 545 g of distilled water were used. Polyamide Resin 2 was obtained in the same manner as in Synthesis Example 1.

[0103] The limiting viscosity of the obtained Polyamide Resin 2 was 1.0 dl / g, the melting point (Tm) was 330°C, the glass transition temperature (Tg) was 125°C, the heat of fusion (ΔH) was 50 J / g, and the amount of terminal amino groups was 25 mmol / kg.

[0104] 1-2. Glass Fiber · Glass fiber surface-modified by acid modification (manufactured by Owens Corning: FT-2A, average fiber diameter: 10.5 μm, average fiber length: 3 mm, sizing agent: polymer of carboxylic acid anhydride-containing unsaturated vinyl monomer) · Glass fiber surface-modified by epoxy resin (manufactured by Nippon Electric Glass Co., Ltd.: ECS-03T-747H, average fiber diameter: 10.5 μm, average fiber length: 3 mm, sizing agent: epoxy resin) · Glass fibers surface-modified with urethane resin (manufactured by Nippon Electric Glass Co., Ltd.: ECS03T-222H, average fiber diameter: 10.5 μm, average fiber length: 3 mm, sizing agent: urethane resin)

[0105] 1-3. Lubricant Sodium montanate (manufactured by Clariant, LICOMONT NAV101, "LICOMONT" is the company's registered trademark)

[0106] 1-4. Nucleating agent · Talc (fine particle talc)

[0107] 2. Preparation of polyamide resin composition The above materials were mixed in a tumbler blender at the composition ratios (unit: parts by mass) shown in Table 1, and melt-kneaded at a cylinder temperature of 300 - 335 °C using a 30 mmφ vented twin-screw extruder. Then, the kneaded product was extruded into strands and cooled in a water tank. Thereafter, the strands were taken up by a pelletizer and cut to obtain a pelletized polyamide resin composition.

[0108] 3. Evaluation The obtained polyamide resin composition was evaluated according to the following criteria.

[0109] 3-1. Flow length Each polyamide resin composition was injected under the following conditions using a bar flow mold with a width of 10 mm and a thickness of 0.5 mm, and the flow length (mm) of the polyamide resin composition in the mold was measured. Note that a longer flow length indicates better injection fluidity. Molding machine: EC75N-2A, manufactured by Toshiba Machine Co., Ltd. Injection set pressure: 2000 kg / cm 2 Molding machine cylinder temperature: 335 °C Mold temperature: 160 °C

[0110] 3-2. Retention rate of flow length before and after blending of glass fibers The flow length of the polyamide resin composition containing the glass fiber was compared with the flow length of a polyamide resin composition containing the same amount of additives but not containing the glass fiber, and the maintenance rate of the flow length before and after the incorporation of the glass fiber was calculated.

[0111] 3-3. Tensile strength (initial) 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 pieces were left in a nitrogen atmosphere at 23°C for 24 hours in accordance with ASTM D638. Then, a tensile test was carried out in an atmosphere at 23°C and a relative humidity of 50% in accordance with ASTM D638 to measure the tensile strength.

[0112] 3-4. Tensile strength (after high temperature and high humidity treatment) The test piece was left at a temperature of 121°C, 2 atmospheres, and 100% RH for 500 hours, after which it was allowed to cool to 23°C and subjected to a tensile test in accordance with ASTM D638 at a temperature of 23°C and a relative humidity of 50% to measure the tensile strength.

[0113] 3-5. Tensile strength retention rate The initial tensile strength was compared with the tensile strength after high-temperature and high-humidity treatment, and the ratio (retention rate) of the tensile strength after high-temperature and high-humidity treatment to the initial tensile strength was calculated.

[0114] Table 1 shows the composition, flow length, flow length retention rate, tensile strength (initial), tensile strength (after high temperature and high humidity treatment), and tensile strength retention rate of the prepared polyamide resin composition.

[0115] [Table 1]

[0116] As is clear from Table 1, the polyamide resin having the component unit (b2) derived from the diamine represented by the formula (1) can suppress the decrease in fluidity due to the blending of glass fiber containing a surface treatment agent or a sizing agent having an acidic group (comparison between Example 1 and Comparative Example 2). Further, the polyamide resin having the component unit (b2) derived from the diamine represented by the formula (1) can suppress the decrease in mechanical strength under high temperature and high humidity environment.

[0117] In addition, a resin composition similar to that of Example 1 was prepared except that the polyamide resin was PA6T (100 mol% of diamine was HDMA), but it did not melt under the above conditions and could not be injection molded, so evaluation could not be performed.

[0118] Also, it was newly confirmed that the fluidity decreases even when other modified glass fibers other than acid-modified glass fibers are added. In these cases, even when the above polyamide resin is used in combination, the decrease in fluidity cannot be sufficiently suppressed, and the decrease in mechanical strength after high temperature and high humidity treatment cannot be sufficiently suppressed (comparison between Example 1 and Reference Examples 5 to 8). From these facts, it can be seen that by combining the polyamide resin having the component unit (b2) derived from the diamine represented by the formula (1) and the acid-modified glass fiber, high compatibility between fluidity and mechanical strength after high temperature and high humidity treatment can be achieved.

[0119] This application claims priority based on Japanese Patent Application No. 2022-003322 filed on January 12, 2022. All the contents described in the specification of the said application are incorporated herein by reference.

Industrial Applicability

[0120] According to the polyamide resin composition of the present disclosure, it is possible to achieve both an improvement in mechanical strength and suppression of a decrease in fluidity by adding glass fiber treated with a sizing agent or a surface treatment agent having an acidic group. Therefore, the present disclosure is expected to expand the applicability of polyamide resins to various applications and contribute to the further spread of polyamide resins.

Claims

1. 20% by mass or more and 85% by mass or less of a polyamide resin based on the total mass of the polyamide resin composition, and 15% by mass or more and 70% by mass or less of glass fibers containing a surface treatment agent or a sizing agent based on the total mass of the polyamide resin composition, wherein the surface treatment agent or the sizing agent has an acidic group, the polyamide resin comprises 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 comprises a component unit derived from an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, the component unit (b) derived from the diamine 50 mol% or more and 90 mol% or less of a component unit (b1) derived from an alkylenediamine having 4 to 18 carbon atoms with respect to the total number of moles of the component unit (b) derived from the diamine, and 10 mol% or more and less than 50 mol% of a component unit (b2) derived from a diamine represented by the following formula (1) with respect to the total number of moles of the component unit (b) derived from the diamine are included, a polyamide resin composition. 【Chemical 1】 (In formula (1), m and n are each independently 0 or 1, -X- is a single bond, or a divalent group selected from the group consisting of -O-, -S-, -SO ２ -, -CO- and -CH ２ -)

2. The acidic group possessed by the surface treatment agent or the sizing agent is a carboxy group, an acid anhydride group, or a carboxylic acid ester group. The polyamide resin composition according to Claim 1.

3. The polyamide resin contains 10 mol% or more and less than 45 mol% of a component unit (b2) derived from the diamine represented by the formula (1) with respect to the total number of moles of the component unit (b) derived from the diamine. The polyamide resin composition according to Claim 1.

4. The component unit (b1) derived from the alkylenediamine having 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.

5. The linear alkylenediamine or the 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 4.

6. The aromatic dicarboxylic acid or the alicyclic dicarboxylic acid is terephthalic acid, naphthalenedicarboxylic acid, or cyclohexanedicarboxylic acid. The polyamide resin composition according to claim 1.

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

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

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

10. It is a resin composition for in-vehicle members. The polyamide resin composition according to any one of claims 1 to 9.

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

12. It is an in-vehicle member. The polyamide molded article according to claim 11.

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