Polyamide resin composition and molded body

Abstract

To provide a polyamide resin composition which includes polyamide resin including a component unit derived from norbornane diamine, and which enables shortening of molding time and has improved tracking resistance, and to provide a molded body of the polyamide resin composition.SOLUTION: A polyamide resin composition is provided, including crystalline polyamide resin (A), boron nitride (B), and a CTI improver (C) including at least one selected from a polyolefin resin or an endothermic filler, wherein the polyamide resin (A) includes a component unit (Aa) derived from dicarboxylic acid and a component unit (Ab) derived from diamine, the unit (Aa) derived from the dicarboxylic acid includes a component unit derived from aromatic dicarboxylic acid or alicyclic dicarboxylic acid, and the component unit (Ab) derived from the diamine includes a component unit derived from norbornane diamine.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Polyamide resin compositions have been known as molding materials. Polyamide resin compositions are widely used as materials for various parts, such as automobile parts and electric / electronic parts, and are known to produce molded articles with excellent mechanical strength.

[0003] For example, Patent Document 1 discloses a polyamide resin composition containing a semi-aromatic polyamide resin composed of specific components and specific amounts of additives such as a lubricant and a flame retardant. Patent Document 1 states that the polyamide resin composition has excellent moldability, reflow heat resistance, and flame retardancy.

[0004] Patent Document 2 discloses a polyamide resin composition containing a semi-aromatic polyamide resin, a spherical filler, and a plate-like filler, and states that the polyamide resin composition can reduce the linear expansion coefficient of a molded article.

[0005] Patent Document 3 discloses a polyamide resin composition containing a polyamide resin, a polyolefin resin or elastomer, a particulate inorganic filler, and a fibrous inorganic reinforcing material. Patent Document 3 states that the polyamide resin composition provides a molded article that has improved mechanical properties and high-temperature rigidity and that is inhibited from losing strength due to the anisotropy of the fibrous reinforcing material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2020-535249 [Patent Document 2] Special Publication No. 2011-503328 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-213011 Summary of the Invention [Problem to be solved by the invention]

[0007] When a polyamide resin composition is used in automobile parts (such as bus bars) and electric / electronic parts, a voltage is applied to the molded article, which can cause the temperature of the molded article to rise. Therefore, it is desirable to use a polyamide resin composition with excellent heat resistance.

[0008] Here, polyamide resins containing component units derived from norbornanediamine, as described in Patent Document 1, are known as polyamide resins capable of increasing the glass transition temperature of the polyamide resin, which is one of the indicators of heat resistance. However, for polyamide resins containing component units derived from norbornanediamine, further improvement in the molding time required when molding a polyamide resin composition to produce a molded article has been desired.

[0009] Furthermore, when molded articles of polyamide resin compositions are used for the above-mentioned automotive parts and electrical / electronic parts, tracking failure may occur, and therefore there is a demand for polyamide resin compositions with improved tracking resistance.

[0010] An object of the present invention is to provide a polyamide resin composition containing a polyamide resin containing component units derived from norbornanediamine, which can shorten the molding time and has improved tracking resistance, and a molded product thereof. [Means for solving the problem]

[0011] In order to solve the above problems, one aspect of the present invention relates to the following polyamide resin compositions [1] to [6]. [1] A crystalline polyamide resin (A), Boron nitride (B), a CTI improver (C) containing at least one selected from the group consisting of a polyolefin resin or an endothermic filler; Including, The crystalline polyamide resin (A) contains a component unit (Aa) derived from a dicarboxylic acid and a component unit (Ab) derived from a diamine, The dicarboxylic acid-derived component unit (Aa) includes an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid-derived component unit, The diamine-derived component units (Ab) include component units derived from norbornanediamine that account for 10 mol % or more and less than 50 mol % of the total number of moles of the diamine-derived component units (Ab), and component units derived from aliphatic diamines having 4 to 18 carbon atoms that account for 50 mol % or more and 90 mol % or less of the total number of moles of the diamine-derived component units (Ab). Polyamide resin composition. [2] The content of the boron nitride (B) is 0.01% by mass or more and 5.00% by mass or less, based on the total mass of the polyamide resin composition. [1] The polyamide resin composition according to [1]. [3] The volume average particle size of the boron nitride (B) is 70 μm or less. [1] or [2]. The polyamide resin composition. [4] The content of the CTI improver (C) is 5% by mass or more and 15% by mass or less, based on the total mass of the polyamide resin composition. The polyamide resin composition according to any one of [1] to [3]. [5] The content of the CTI improver (C) is 7.5% by mass or more and 15% by mass or less, based on the total mass of the polyamide resin composition. [4] The polyamide resin composition according to [4]. [6] The crystallization rate, which is measured by a differential scanning calorimeter (DSC) and is represented by the difference between the melting point of the polyamide resin composition and the crystallization temperature of the polyamide resin composition, is 50°C or less. The polyamide resin composition according to any one of [1] to [5].

[0012] Another aspect of the present invention for solving the above problems relates to the following molded article [7]. [7] A molded article obtained by molding the polyamide resin composition according to any one of [1] to [6]. [Effects of the Invention]

[0013] The present invention provides a polyamide resin composition containing a polyamide resin containing component units derived from norbornanediamine, which can shorten the molding time and has improved tracking resistance, and a molded product thereof. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0015] 1. Polyamide resin composition The polyamide resin composition according to the present embodiment comprises a crystalline polyamide resin (A), boron nitride (B), and a CTI improver (C) containing at least one selected from the group consisting of a polyolefin resin and an endothermic filler. The polyamide resin (A) comprises dicarboxylic acid-derived component units (Aa) and diamine-derived component units (Ab), wherein the dicarboxylic acid-derived component units (Aa) comprise aromatic dicarboxylic acid- or alicyclic dicarboxylic acid-derived component units, and the diamine-derived component units (Ab) comprise norbornanediamine-derived component units that account for 10 mol % to less than 50 mol % of the total molar number of the diamine-derived component units (Ab), and 50 mol % to 90 mol % of the total molar number of the diamine-derived component units (Ab) derived from an aliphatic diamine having from 4 to 18 carbon atoms.

[0016] As described above, polyamide resin compositions using polyamide resins containing component units derived from norbornanediamine have long molding times. Norbornanediamine has a bicyclo skeleton, which is a bulky and rigid cyclic structure in its molecular structure, thereby reducing molecular mobility and increasing the glass transition temperature of the polyamide resin. On the other hand, the amount of crystallization sites contained in the molecular structure is reduced, which is thought to slow the crystallization rate of the polyamide resin and lengthen the time it takes for the polyamide resin to crystallize. This is thought to be the reason for the long molding times of the polyamide resin compositions.

[0017] In response to this, the present inventors have discovered that the molding time of a polyamide resin composition can be shortened by incorporating boron nitride as a nucleating agent into the polyamide resin composition. Boron nitride has a high affinity with polyamide resin, and can increase the contact area between boron nitride particles and the polyamide resin. This increases the interface area between boron nitride and the polyamide resin, enhancing the nucleating effect of boron nitride, and thereby promoting the crystallization of the polyamide resin. As a result, it is believed that the crystallization rate of the polyamide resin can be increased, thereby shortening the molding time of the polyamide resin composition.

[0018] However, it has been found that when voltage is applied to molded articles of polyamide resin compositions containing boron nitride, tracking fracture is likely to occur, which is thought to be due to the high heat dissipation properties of boron nitride.

[0019] During use, minute liquid films derived from atmospheric moisture form on the surface of a molded article of a polyamide resin composition. When a voltage is applied parallel to the surface of a resin component with these minute liquid films attached, a leakage current flows between the electrodes through the minute liquid films, generating Joule heat. This causes the minute liquid films to evaporate, forming dry areas (dry zones) between the liquid films. Because the insulation resistance of the dry zones is higher than that of the areas where the minute liquid films are formed, a high voltage is applied to both ends of the dry zone when a leakage current attempts to flow, resulting in scintillation discharge. When scintillation discharge occurs, the surface of the molded article is carbonized and deteriorated, and carbides are precipitated on the surface of the molded article. When scintillation discharge occurs repeatedly, the carbonized areas grow from the carbides precipitated on the surface of the molded article, and the carbonized areas bridge the electrodes, leading to dielectric breakdown (tracking breakdown).

[0020] Here, when the polyamide resin composition contains boron nitride, heat from inside the molded body is released to the outside of the molded body through the boron nitride, which is thought to facilitate the formation of the dry zone at the surface of the molded body or in the vicinity thereof where boron nitride is present. That is, when the polyamide resin composition contains boron nitride, the dry zone is likely to be formed on the surface of the molded body. As a result, scintillation discharge is likely to occur, and tracking failure is likely to occur.

[0021] Therefore, the present inventors have found that by adding a CTI improver containing at least one selected from the group consisting of polyolefin resins and endothermic fillers to the polyamide resin composition containing boron nitride, it is possible to shorten the molding time while improving the tracking resistance. The reasons for this are thought to be as follows.

[0022] When a polyolefin resin is contained in a polyamide resin composition, the water repellency of the surface of the molded article can be improved. This makes it difficult for liquid to adhere to the surface of the molded article, and the formation of minute liquid films derived from moisture in the atmosphere is also suppressed. As a result, the generation of the leakage current is suppressed, and tracking breakdown is less likely to occur.

[0023] Furthermore, when a heat-absorbing filler is contained in the polyamide resin composition, it is believed that the heat-absorbing filler can absorb most of the heat energy supplied to the surface of the molded article when the scintillation discharge occurs. Since the heat energy absorbed by the heat-absorbing filler is consumed in the decomposition reaction of the heat-absorbing filler, the amount of heat energy supplied to the surface of the molded article can be reduced, and carbonization deterioration of the surface of the molded article can be suppressed. As a result, tracking fracture can be suppressed.

[0024] For these reasons, the polyamide resin composition according to this embodiment can improve tracking resistance while shortening the molding time.

[0025] 1-1. Crystalline polyamide resin (A) In this specification, "crystalline polyamide resin" refers to a polyamide resin whose melting point can be measured by a differential scanning calorimeter (DSC). Specifically, it refers to a polyamide resin that exhibits an endothermic peak with a half-width of 15°C or less when heated at a rate of 10°C / min in a differential scanning calorimeter (DSC). The crystalline polyamide resin (A) forms crystals in a molded product, which can increase the mechanical strength (such as tensile strength) of the molded product.

[0026] The crystalline polyamide resin (A) contains component units (Aa) derived from a dicarboxylic acid and component units (Ab) derived from a diamine.

[0027] (Component unit (Aa) derived from dicarboxylic acid) The dicarboxylic acid-derived component units (Aa) include component units derived from aromatic dicarboxylic acids or alicyclic dicarboxylic acids. Of these, the dicarboxylic acid-derived component units (Aa) preferably include component units derived from aromatic dicarboxylic acids.

[0028] Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2-methylterephthalic acid, and naphthalenedicarboxylic acid, etc. Among these, the aromatic dicarboxylic acid is preferably terephthalic acid.

[0029] The content of the component units derived from terephthalic acid is preferably 40 mol% or more and 100 mol% or less, more preferably 50 mol% or more and 100 mol% or less, and even more preferably 75 mol% or more and 100 mol% or less, based on the total number of moles of the component units (Aa) derived from dicarboxylic acids.

[0030] Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid and its esters.

[0031] The content of the component units derived from the alicyclic dicarboxylic acid is preferably 20 mol % or more and 80 mol % or less, and more preferably 25 mol % or more and 75 mol % or less, relative to the total number of moles of the component units (Aa) derived from the dicarboxylic acid.

[0032] The dicarboxylic acid-derived component unit (Aa) may contain other dicarboxylic acid-derived component units. Examples of other dicarboxylic acids include aliphatic dicarboxylic acids.

[0033] Examples of the aliphatic dicarboxylic acid include aliphatic dicarboxylic acids having 4 to 20 carbon atoms. The number of carbon atoms is preferably 6 to 12. Examples of such aliphatic dicarboxylic acids include adipic acid, azelaic acid, and sebacic acid. Among these, adipic acid and sebacic acid are preferred, and adipic acid is more preferred.

[0034] The content of the component units derived from other dicarboxylic acids is preferably 0 mol% or more and 5 mol% or less, more preferably 0 mol% or more and less than 2 mol%, even more preferably 0 mol% or more and less than 1 mol%, and particularly preferably 0 mol%, relative to the total number of moles of the component units (Aa) derived from dicarboxylic acids.

[0035] (Diamine-derived component unit (Ab)) In this embodiment, the diamine-derived component units (Ab) include component units derived from norbornanediamine and component units derived from an aliphatic diamine having 4 to 18 carbon atoms. Norbornanediamine has a rigid cyclic structure containing a bicyclo skeleton, which reduces the mobility of the molecular chains of the polyamide resin. Therefore, diamines having this structure can increase the glass transition temperature (Tg) of the crystalline polyamide resin (A) compared to diamines not having this structure. As a result, when the crystalline polyamide resin (A) includes component units derived from norbornanediamine, the mechanical strength (such as tensile strength) of the molded article in a high-temperature environment can be increased.

[0036] Furthermore, according to the findings of the present inventors, when a voltage is applied to a molded article, causing a rise in the temperature of the surface of the molded article, the more likely the molecular motion is to be activated, the more likely the molded article is to suffer from dielectric breakdown (tracking breakdown). In contrast, crystalline polyamide resins (A) having the rigid cyclic structure of norbornanediamine have low molecular chain mobility, and therefore are less likely to experience activation of molecular motion due to a rise in temperature. Therefore, crystalline polyamide resins (A) containing component units derived from norbornanediamine are likely to improve the tracking resistance of molded articles.

[0037] The number of carbon atoms in the aliphatic diamine is preferably 4 or more and 12 or less, and more preferably 6 or more and 12 or less. Examples of the aliphatic diamine include linear alkylenediamines and branched alkylenediamines.

[0038] Examples of the linear alkylenediamine include 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, and 1,12-diaminododecane. Among these, 1,6-diaminohexane, 1,9-nonanediamine, and 1,10-diaminodecane are preferred, with 1,6-diaminohexane being more preferred. The linear alkylenediamine may be used alone or in combination of two or more.

[0039] Examples of the branched alkylenediamine include 2,2-dimethyldiaminopropane, 1,1-dimethyl-1,4-diaminobutane, 1-ethyl-1,4-diaminobutane, 1,2-dimethyl-1,4-diaminobutane, 1,3-dimethyl-1,4-diaminobutane, 1,4-dimethyl-1,4-diaminobutane, 2,3-dimethyl-1,4-diaminobutane, 2-methyl-1,5-diaminopentane, 2,5-dimethyl-1,6-diaminohexane, 2,4 -Dimethyl-1,6-diaminohexane, 3,3-dimethyl-1,6-diaminohexane, 2,2-dimethyl-1,6-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, 2,4,4-trimethyl-1,6-diaminohexane, 2,4-diethyl-1,6-diaminohexane, 2,3-dimethyl-1,7-diaminoheptane, 2,4-dimethyl-1,7-diaminoheptane, 2,5-dimethyl-1,7-diaminoheptane, 2,2- Dimethyl-1,7-diaminoheptane, 2-methyl-4-ethyl-1,7-diaminoheptane, 2-ethyl-4-methyl-1,7-diaminoheptane, 2,2,5,5-tetramethyl-1,7-diaminoheptane, 3-isopropyl-1,7-diaminoheptane, 3-isooctyl-1,7-diaminoheptane, 2-methyl-1,8-diaminooctane, 1,3-dimethyl-1,8-diaminooctane, 1,4-dimethyl-1,8-diaminooctane, 2, Examples of branched alkylene diamines include 4-dimethyl-1,8-diaminooctane, 3,4-dimethyl-1,8-diaminooctane, 4,5-dimethyl-1,8-diaminooctane, 2,2-dimethyl-1,8-diaminooctane, 3,3-dimethyl-1,8-diaminooctane, 4,4-dimethyl-1,8-diaminooctane, 3,3,5-trimethyl-1,8-diaminooctane, 2,4-diethyl-1,8-diaminooctane, and 5-methyl-1,9-diaminononane. Among these, 2-methyl-1,5-diaminopentane is preferred. Branched alkylene diamines may be used alone or in combination of two or more.

[0040] The diamine-derived component units (Ab) comprise, relative to the total number of moles of the diamine-derived component units (Ab), 10 mol % to less than 50 mol % of component units derived from norbornanediamine and 50 mol % to 90 mol % of component units derived from the aliphatic diamine; preferably, 10 mol % to 40 mol % of component units derived from norbornanediamine and 60 mol % to 90 mol % of component units derived from the aliphatic diamine; and more preferably, 10 mol % to 35 mol % of component units derived from norbornanediamine and 65 mol % to 90 mol % of component units derived from the aliphatic diamine.

[0041] The diamine-derived component unit (Ab) may contain other diamine-derived component units. Examples of other diamines include alicyclic diamine-derived component units having 4 to 20 carbon atoms and aromatic diamine-derived component units.

[0042] Examples of the alicyclic diamine having 4 to 20 carbon atoms include 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 2,5-bisaminomethylnorbornane, and 2,6-bisaminomethylnorbornane. Examples of the aromatic diamine include metaxylylenediamine.

[0043] The constituent units of the crystalline polyamide resin (A) and their ratios can be calculated from the charge ratios when the crystalline polyamide resin (A) is prepared, or can be measured by the NMR method.

[0044] 1 In the case of H-NMR measurement, for example, a nuclear magnetic resonance apparatus (ECX400 model manufactured by JEOL Ltd.) is used, the solvent is deuterated orthodichlorobenzene, the sample concentration is 20 mg / 0.6 mL, the measurement temperature is 120 °C, and the observation nucleus is 1The conditions are H (400 MHz), sequence is single pulse, pulse width is 5.12 μsec (45° pulse), repetition time is 7.0 sec, and the number of accumulations is 500 or more. The reference chemical shift is set to 0 ppm for hydrogen in tetramethylsilane, but similar results can also be obtained by setting the peak derived from residual hydrogen in deuterated orthodichlorobenzene at 7.10 ppm as the reference value for the chemical shift. 1 Peaks such as H can be assigned by conventional methods.

[0045] 13 In the case of C-NMR measurement, for example, a nuclear magnetic resonance apparatus (ECP500 model manufactured by JEOL Ltd.) is used as the measurement apparatus, a mixed solvent of ortho-dichlorobenzene / heavy benzene (80 / 20% by volume) is used as the solvent, the measurement temperature is 120°C, and the observation nucleus is 13 The conditions were: C (125 MHz), single pulse proton decoupling, 45° pulse, repetition time 5.5 seconds, accumulation number 10,000 or more, and chemical shift reference value 27.50 ppm. Assignment of various signals was performed based on the standard method, and quantification could be performed based on the accumulated value of signal intensity.

[0046] The dicarboxylic acid-derived component units of the crystalline polyamide resin (A) may include component units derived from biomass-derived dicarboxylic acids, and the diamine-derived component units may include component units derived from biomass-derived diamines. The crystalline polyamide resin (A) may also be a biomass-derived crystalline polyamide resin (A) obtained by polymerizing raw materials including biomass-derived raw materials.

[0047] In order to improve the thermal stability during compounding and molding and to further increase the mechanical strength, at least some of the molecular terminal groups of the crystalline polyamide resin (A) may be blocked with a terminal blocking agent. For example, when the molecular terminal is a carboxyl 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.

[0048] Examples of monoamines include aliphatic monoamines such as methylamine, ethylamine, propylamine, and butylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; and aromatic monoamines such as aniline and toluidine. Examples of monocarboxylic acids include aliphatic monocarboxylic acids having 2 to 30 carbon atoms such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid. The aromatic monocarboxylic acid and alicyclic monocarboxylic acid may have a substituent on the ring structure portion.

[0049] In this embodiment, the ratio of the total number of carbon atoms constituting the aromatic rings to the total number of carbon atoms constituting the constituent units contained in the crystalline polyamide resin (A) is preferably 30% to 45%, more preferably 30% to 42.5%, even more preferably 35% to 42%, and particularly preferably 39% to 41%. A ratio of 30% or more can further enhance the mechanical strength (e.g., tensile strength) of the molded article. Furthermore, a ratio of 45% or less can reduce the proportion of aromatic rings in the molecular chain of the crystalline polyamide resin (A), making it less likely for the surface of the resin member to carbonize even when a voltage is applied to the surface of the resin member. This can further enhance the tracking resistance of the molded article. The carbon atom ratio can be adjusted by the combination of dicarboxylic acid and diamine used to prepare the crystalline polyamide resin (A) and the content ratio of the aromatic dicarboxylic acid and aromatic diamine. The carbon atom ratio can be calculated from the charge ratio or measured by NMR. The NMR method can be the same as described above. The total number of carbon atoms is determined by multiplying the number of carbon atoms in the repeating units contained in the crystalline polyamide resin (A) by the molar ratio of the repeating units in the crystalline polyamide resin (A), and adding up the results for each repeating unit. The total number of carbon atoms constituting the aromatic rings is determined by multiplying the number of carbon atoms in the repeating units contained in the crystalline polyamide resin (A) by the molar ratio of the repeating units in the crystalline polyamide resin (A), and adding up the results for each repeating unit. The carbon atom ratio can be calculated from the feed ratio or measured by NMR. The NMR method can be the same as described above.

[0050] The crystalline polyamide resin (A) can be produced by the same method as known polyamide resins, for example, by polycondensing a dicarboxylic acid and a diamine in a homogeneous solution. Specifically, as described in WO 03 / 085029, the dicarboxylic acid and the diamine are heated in the presence of a catalyst to obtain a low-order condensate, and then a melt of the low-order condensate is subjected to shear stress to polycondense the low-order condensate.

[0051] The content of the crystalline polyamide resin (A) is preferably 80% by mass or more and 100% by mass or less, more preferably 85% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 100% by mass or less, based on the total mass of the polyamide resin composition. When the content is 80% by mass or more, the mechanical strength and tracking resistance of the polyamide resin composition can be sufficiently improved. When the content is 100% by mass or less, the polyamide resin composition can sufficiently contain other components described below.

[0052] (Physical Properties) From the viewpoint of further increasing the mechanical strength and heat resistance of the molded article, the melting point of the crystalline polyamide resin (A) is preferably 280°C or higher, more preferably 290°C or higher, and even more preferably 300°C or higher. Furthermore, from the viewpoint of facilitating molding of the polyamide resin composition without excessively increasing the molding temperature, the melting point of the crystalline polyamide resin (A) is preferably 340°C or lower. The melting point of the crystalline polyamide resin (A1) can be measured by differential scanning calorimetry (DSC).

[0053] The melting point of the crystalline polyamide resin (A) can be adjusted to the above range by adjusting the composition of the crystalline polyamide resin (A). For example, the melting point can be increased by increasing the content of the component unit derived from terephthalic acid, which will be described later.

[0054] Furthermore, the crystalline polyamide resin (A) preferably has a glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) of 130°C to 180°C, more preferably 140°C to 175°C, and even more preferably 150°C to 170°C. A glass transition temperature (Tg) of 130°C or higher increases the temperature at which molecular mobility becomes significantly more active, thereby suppressing molecular mobility and more sufficiently improving the heat resistance and tracking resistance of the polyamide resin composition and molded article. A glass transition temperature (Tg) of 180°C or lower makes it easier to maintain the fluidity of the resin composition without excessively increasing the mold temperature during molding, thereby improving molding processability.

[0055] The heat of fusion (ΔH) of the crystalline polyamide resin (A) measured by differential scanning calorimetry (DSC) is preferably greater than 5 J / g. The heat of fusion is an index of the crystallinity of a resin, and a larger heat of fusion indicates higher crystallinity. When the heat of fusion (ΔH) of the crystalline polyamide resin (A) exceeds 5 J / g, the crystallinity is increased, and the mechanical strength (such as bending strength) of the resulting molded article can be increased. The upper limit of the heat of fusion (ΔH) is not particularly limited, but is, for example, 100 J / g.

[0056] The melting point and heat of fusion (ΔH) of the crystalline polyamide resin (A) can be measured using a differential scanning calorimeter (DSC220C model, manufactured by Seiko Instruments Inc.).

[0057] Specifically, approximately 5 mg of crystalline polyamide resin (A) is sealed in a measuring aluminum pan and heated from room temperature to 350°C at 10°C / min. To completely melt the resin, it is held at 350°C for 3 minutes and then cooled to 30°C at 10°C / min. After leaving it at 30°C for 5 minutes, it is heated a second time to 350°C at 10°C / min. The temperature (°C) of the endothermic peak during this second heating is taken as the melting point (Tm) of the crystalline polyamide resin (A), and the inflection point corresponding to the glass transition is taken as the glass transition temperature (Tg). The heat of fusion (ΔH) is determined from the area of ​​the endothermic peak during melting during the first heating process in accordance with JIS K7122.

[0058] The intrinsic viscosity [η] of the crystalline polyamide resin (A), measured in 96.5% sulfuric acid at 25°C, is preferably 0.9 dL / g to 1.2 dL / g, more preferably 1.0 dL / g to 1.2 dL / g, and particularly preferably 1.0 dL / g to 1.1 dL / g. When the intrinsic viscosity [η] of the crystalline polyamide resin (A) is 0.9 dL / g or higher, the mechanical strength (e.g., bending strength) of the molded article is easily increased. When the intrinsic viscosity [η] is 1.2 dL / g or lower, the fluidity of the resin composition during molding is less likely to be impaired. The intrinsic viscosity [η] can be adjusted by adjusting the molar ratio of the dicarboxylic acid-derived component unit (Aa) to the diamine-derived component unit (Ab). Specifically, the closer the molar ratio of the carboxylic acid-derived component unit (Aa) to the diamine-derived component unit (Ab) is to 1:1, the higher the intrinsic viscosity can be. It can also be adjusted by the amount of end-capping of the crystalline polyamide resin (A).

[0059] The intrinsic viscosity [η] of the crystalline polyamide resin (A) can be measured as follows. 0.5 g of the crystalline polyamide resin (A) is dissolved in 50 ml of a 96.5% sulfuric acid solution to prepare a sample solution. The number of seconds it takes for the resulting solution to flow down at 25°C ± 0.05°C is measured using an Ubbelohde viscometer, and the intrinsic viscosity [η] is calculated based on the following formula: [η]=ηSP / (C*(1+0.205ηSP)) [η]: Intrinsic viscosity (dl / g) ηSP: Specific viscosity C: Sample concentration (g / dl) t: Number of seconds for sample solution to flow down (seconds) t0: Number of seconds the blank sulfuric acid flows (seconds) ηSP=(t-t0) / t0

[0060] 1-2. Boron nitride (B) In this embodiment, the polyamide resin composition contains boron nitride (B). The boron nitride (B) can function as a particulate nucleating agent.

[0061] The average particle size of the boron nitride (B) is preferably 70 μm or less, more preferably 50 μm or less, even more preferably 10 μm or less, and particularly preferably 5 μm or less. When the average particle size is 70 μm or less, the specific surface area of ​​the boron nitride (B) increases, further enhancing the nucleating effect at the interface with the crystalline polyamide resin (A). This further promotes crystallization of the crystalline polyamide resin (A), thereby further shortening the molding time for the polyamide resin composition. The lower limit of the average particle size is not particularly limited, but is, for example, 0.5 μm. The average particle size can be measured by dynamic image analysis or laser diffraction / scattering. When measured by laser diffraction / scattering, the average particle size may be the particle size D50, the particle size at which the cumulative value from the smallest particle size reaches 50% of the total in the cumulative distribution of particle sizes on a volume basis.

[0062] The shape of the boron nitride (B) particles is preferably scaly or plate-like. This facilitates layer-like arrangement of the boron nitride (B) in the polyamide resin composition. It is believed that the crystalline polyamide resin (A), which has a high affinity for boron nitride, penetrates between the boron nitride layers, increasing the contact area between the boron nitride (B) and the crystalline polyamide resin (A). This enhances the nucleating effect of the boron nitride (B), further accelerating the crystallization of the crystalline polyamide resin (A), thereby shortening the molding time of the polyamide resin composition.

[0063] In this specification, "scale-like or plate-like" means a shape in which the area when observed from a predetermined angle (when viewed from a plane) is larger than the area when observed from an angle perpendicular to the observation direction. More specifically, in "scale-like" or "plate-like" inorganic particles, the projected area when viewed from a plane in a direction in which the projected area is maximum is preferably 10 times the projected area when viewed from a plane in a direction perpendicular to the above direction.

[0064] The content of boron nitride (B) is preferably 0.01% by mass or more and 5.00% by mass or less, and more preferably 0.025% by mass or more and 1.00% by mass or less, based on the total mass of the polyamide resin composition.

[0065] 1-3.CTI improver (C) In this embodiment, the polyamide resin composition contains a CTI improver (C) containing at least one selected from the group consisting of a polyolefin resin and an endothermic filler. In this specification, the term "endothermic filler" refers to an inorganic filler that absorbs heat generated during discharge, etc. The endothermic filler is preferably an inorganic compound that absorbs heat and undergoes its own decomposition reaction. In this embodiment, the polyamide resin composition may contain at least one of a polyolefin resin and an endothermic filler, or may contain both. However, from the viewpoint of improving toughness and impact resistance, it is preferable to contain a polyolefin resin, and more preferably to contain only a polyolefin resin.

[0066] The content of the CTI improver (C) is preferably 5% by mass or more and 15% by mass or less, more preferably 7.5% by mass or more and 15% by mass or less, based on the total mass of the polyamide resin composition. A content of 5% by mass or more can further improve the tracking resistance of the polyamide resin composition and its molded article. A content of 15% by mass or less can maintain molding processability and mechanical properties (especially toughness).

[0067] The content of the CTI improver (C) is preferably 7.5 mass% or more and 20.0 mass% or less, more preferably 10.0 mass% or more and 20.0 mass% or less, and even more preferably 15.0 mass% or more and 20.0 mass% or less, based on the total mass of the crystalline polyamide resin (A) and the CTI improver (C).

[0068] 1-3-1. Polyolefin resin Examples of polyolefin resins include ethylene polymers, propylene polymers, butene polymers, and copolymers of these olefins (e.g., ethylene-α-olefin copolymers), etc. Among these, ethylene polymers are preferred.

[0069] Examples of the α-olefin other than ethylene in the ethylene-α-olefin copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc. Among these, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene are preferred.

[0070] The polyolefin resin preferably includes a modified polyolefin resin. Specifically, the polyolefin resin preferably includes a modified polyolefin resin having a polyolefin unit and a functional group structural unit. The modified polyolefin resin can be obtained by modifying a polyolefin resin before modification with a compound containing a functional group structural unit.

[0071] Examples of the functional group structural unit include functional groups containing heteroatoms. Examples of functional groups containing heteroatoms include carboxylic acid groups (including carboxylic acid anhydride groups), ester groups, ether groups, aldehyde groups, and ketone groups. Among these, carboxylic acid groups (including carboxylic acid anhydride groups) are preferred. That is, the modified polyolefin resin is preferably modified with an unsaturated carboxylic acid or its derivatives.

[0072] Examples of compounds containing carboxylic acid groups include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and phthalic acid. Examples of compounds containing carboxylic acid anhydride groups include dicarboxylic acid anhydrides having α,β-unsaturated bonds such as maleic anhydride, itaconic anhydride, and phthalic anhydride. Of these, maleic anhydride is preferred. The maleic anhydride-modified polyolefin resin reacts with the terminal amino groups of the crystalline polyamide resin (A) and bonds to the crystalline polyamide resin (A), thereby reducing the number of terminal groups in the crystalline polyamide resin (A). This reduces the hydrophilicity of the polyamide resin composition, which is thought to enhance the water repellency of the molded product and further improve tracking resistance.

[0073] The content of the functional group structural unit (modification amount) of the modified polyolefin resin is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 0.2% by mass or more and 3.0% by mass or less, and even more preferably 0.5% by mass or more and 1.5% by mass or less. When the content of the functional group structural unit is within the above range, the impact resistance and elongation of the resin composition tend to be improved.

[0074] The content (modification amount) of the functional group structural unit of the modified polyolefin resin can be calculated from the charge ratio when preparing the modified polyolefin resin, or can be measured by the NMR method. For the NMR method, the same method as described for the crystalline polyamide resin (A) can be used.

[0075] The modified polyolefin resin is obtained by graft-modifying an unmodified polyolefin resin with a compound containing a functional group structural unit.

[0076] Graft modification can be carried out by various conventionally known methods. For example, it may be carried out by a melt modification method in which the polyolefin resin before modification is melted using an extruder and a graft monomer is added to carry out graft copolymerization, or it may be carried out by a solution modification method in which the polyolefin resin before modification is dissolved in a solvent and a graft monomer is added to carry out graft copolymerization. In either case, it is preferable to carry out the reaction in the presence of a radical initiator in order to efficiently graft copolymerize the graft monomer.

[0077] The content of the polyolefin resin is preferably 3% by mass or more and 15% by mass or less, and more preferably 5% by mass or more and 10% by mass or less, relative to the total mass of the polyamide resin composition. A content of 3% by mass or more can further enhance the water repellency of a molded article of the polyamide resin composition, thereby further enhancing the tracking resistance of the molded article. A content of 15% by mass or less can improve the mold releasability of the polyamide resin composition from a mold and shorten the cooling time during molding.

[0078] 1-3-2. Heat-absorbing filler Examples of the endothermic filler material include zinc borate (xZnO·yB2O3·zH2O (where (x, y, z) can be any of (2,3,0), (4,1,0), (1,2,0), (1,1,0), (3,2,0), (2,3,3.5), (2,3,4), (2,3,5.5), (2,2,3), and (4,1,1), with (2,3,0), (4,1,0), (1,2,0), (1,1,0), and (3,2,0) being preferred (i.e., anhydrous zinc borate is preferred), and (2,3,0) being more preferred)), magnesium borate, calcium borate, borate, borate compounds such as aluminum borate, calcium dimethylphosphinate, magnesium dimethylphosphinate, aluminum dimethylphosphinate, zinc dimethylphosphinate, calcium ethylmethylphosphinate, magnesium ethylmethylphosphinate, aluminum ethylmethylphosphinate, zinc ethylmethylphosphinate, calcium diethylphosphinate, magnesium diethylphosphinate, aluminum diethylphosphinate, zinc diethylphosphinate, calcium methyl-n-propylphosphinate, methyl-n-propylphosphinate Phosphinate compounds such as magnesium methyl-n-propylphosphinate, aluminum methyl-n-propylphosphinate, zinc methyl-n-propylphosphinate, calcium methane di(methylphosphinate), magnesium methane di(methylphosphinate), aluminum methane di(methylphosphinate), zinc methane di(methylphosphinate), calcium benzene-1,4-(dimethylphosphinate), magnesium benzene-1,4-(dimethylphosphinate), aluminum benzene-1,4-(dimethylphosphinate), zinc benzene-1,4-(dimethylphosphinate), calcium methylphenylphosphinate, magnesium methylphenylphosphinate, aluminum methylphenylphosphinate, zinc methylphenylphosphinate, calcium diphenylphosphinate, magnesium diphenylphosphinate, aluminum diphenylphosphinate, and zinc diphenylphosphinate, as well as magnesium hydroxide, aluminum phosphate, aluminum oxide (alumina), transition alumina, boehmite (aluminum oxide monohydrate), aluminum silicate, and aluminum hydroxide.Among these, borate compounds and phosphinate compounds are preferred as endothermic fillers, with borate compounds being more preferred, and zinc borate being particularly preferred. Borate compounds are less likely to produce compounds that can decompose polyamide resins when thermally decomposed. Therefore, the mechanical strength of the resin member is less likely to decrease due to the heat generated during kneading of the polyamide resin composition, and cracks are less likely to occur when the temperature changes from high to low. This can further improve the heat shock resistance of the resin member. Furthermore, zinc borate has a high decomposition onset temperature and a large endothermic capacity, which can further improve the tracking resistance of polyamide resin compositions and resin members containing the same. Furthermore, since the zinc borate is anhydrous zinc borate, water is not released by the dehydration reaction, which can suppress deterioration of the polyamide resin and, as a result, can easily increase its strength.

[0079] Examples of the shape of the heat-absorbing filler include spherical, plate-like, scale-like, rectangular parallelepiped, needle-like, etc. Among these, plate-like and rectangular parallelepiped shapes are preferred.

[0080] The volume average particle diameter (D50) of the endothermic filler is preferably 0.1 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 15 μm or less. When the volume average particle diameter (D50) of the endothermic filler is 0.1 μm or more, the endothermic filler can be finely dispersed in the polyamide resin composition or a resin part molded therefrom, thereby reducing the likelihood of a decrease in strength. Furthermore, when the volume average particle diameter (D50) of the endothermic filler is 30 μm or less, the specific surface area of ​​the endothermic filler can be increased, making it easier to absorb heat generated by discharge. Furthermore, when the content of the endothermic filler is the same, when the volume average particle diameter (D50) is 30 μm or less, a larger amount of the endothermic filler can be dispersed in the polyamide resin composition or a resin part molded therefrom, thereby reducing the average distance between the endothermic filler and the crystalline polyamide resin (A), making it easier to absorb heat generated by discharge. This can further improve the tracking resistance of the resin part. The volume average particle size (D50) can be measured by using a laser diffraction method.

[0081] The heat absorption capacity of the endothermic filler is preferably 450 J / g or more, more preferably 500 J / g or more. A heat absorption capacity of 450 J / g or more allows the endothermic filler to more easily absorb heat generated when a voltage is applied to the resin member, making the surface and interior of the molded article less susceptible to carbonization. This allows the tracking resistance of the polyamide resin composition and molded article to be more sufficiently improved. The upper limit of the heat absorption capacity is not particularly limited, but is, for example, 2200 J / g. The heat absorption capacity can be measured using a thermogravimetric differential thermal analyzer (TG-DTA). Specifically, a thermogravimetric differential thermal analyzer (TG / DTA6200, manufactured by Seiko Instruments Inc.) is used, and heating is performed in a nitrogen atmosphere from room temperature at a heating rate of 10°C / min. The heat absorption capacity (area of ​​the recess) is determined from the obtained DTA curve.

[0082] The content of the endothermic filler is preferably 0.1% by mass or more and 30% 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. A content of 0.1% by mass or more can effectively absorb the thermal energy resulting from scintillation discharge that occurs when a voltage is applied to the molded article, thereby further suppressing carbonization degradation of the molded article and further improving tracking resistance. A content of 30% by mass or less can sufficiently increase the content of the crystalline polyamide resin (A), thereby sufficiently increasing the mechanical strength (particularly toughness) of the resin member.

[0083] 1-4.Other ingredients The polyamide resin composition may contain other known components.

[0084] Examples of other components include nucleating agents other than boron nitride, copper-based stabilizers, lubricants, colorants, reinforcing agents, heat stabilizers, corrosion resistance improvers, anti-drip agents, ion scavengers, elastomers (rubbers), antistatic agents, mold release agents, antioxidants (phenols, amines, sulfurs, phosphorus compounds, etc.), heat stabilizers other than those mentioned above (lactone compounds, vitamin E compounds, hydroquinones, etc.), light stabilizers (benzotriazoles, triazines, benzophenones, benzoates, hindered amines, oxanilides, etc.), other polymers (polyolefins, olefin copolymers such as ethylene-propylene copolymers, ethylene-1-butene copolymers, olefin copolymers such as propylene-1-butene copolymers, polystyrene, polycarbonate, polyacetal, polysulfone, polyphenylene oxide, fluororesin, silicone resin, LCP, etc.).

[0085] (Nucleating agents other than boron nitride) Examples of nucleating agents include metal salt compounds such as sodium 2,2-methylenebis(4,6-di-t-butylphenyl)phosphate, aluminum tris(pt-butylbenzoate), and stearates; sorbitol compounds such as bis(p-methylbenzylidene)sorbitol and bis(4-ethylbenzylidene)sorbitol; and inorganic substances such as talc, calcium carbonate, and hydrotalcite. Among these, talc is preferred from the viewpoint of further increasing the crystallinity of the resin member. These nucleating agents may be used alone or in combination.

[0086] Talc generally contains hydrous magnesium silicate (SiO2: 58-64%, MgO: 28-32%, Al2O3: 0.5-5%, Fe2O3: 0.3-5%) as its main component. The average particle size of the talc is not particularly limited, but is preferably 1-15 μm. When the average particle size of the talc is within the above range, the talc can be easily dispersed in the crystalline polyamide resin (A) without impairing the fluidity of the polyamide resin composition. From the same viewpoint, the average particle size of the talc is more preferably 1-7.5 μm. The average particle size of the talc can be measured by a laser diffraction method, for example, using a Shimadzu particle size distribution analyzer (SALD-2000A) manufactured by Shimadzu Corporation.

[0087] The content of the nucleating agent other than boron nitride is preferably 0.10 parts by mass or more and 5.00 parts by mass or less, and more preferably 0.10 parts by mass or more and 3.00 parts by mass or less, relative to the total mass of the polyamide resin composition. When the content of the nucleating agent is within the above range, the crystallinity of the polyamide resin is easily increased sufficiently, and sufficient mechanical strength is easily obtained.

[0088] (copper stabilizer) The copper-based stabilizer includes (i) a salt of a halogen and a metal element of Group 1 or 2 of the periodic table (a halogen metal salt), and (ii) a copper compound. The copper-based stabilizer can impart heat resistance (heat aging resistance) to the polyamide resin composition, enabling it to withstand high temperatures, for example, of 150°C or higher.

[0089] (i) Examples of the halogen metal salt include potassium iodide, potassium bromide, potassium chloride, sodium iodide, and sodium chloride. Of these, potassium iodide and potassium bromide are preferred as the halogen metal salt. Only one type of halogen metal salt may be included, or two or more types may be included.

[0090] (ii) Examples of copper compounds include copper halides, copper sulfate, acetate, propionate, benzoate, adipate, terephthalate, salicylate, nicotinate, stearate, and copper chelate compounds (compounds of copper with ethylenediamine or ethylenediaminetetraacetic acid, etc.). Of these, copper compounds such as copper iodide, copper (I) bromide, copper (II) bromide, copper (I) chloride, and copper acetate are preferred. Only one type of copper compound may be contained, or two or more types may be contained.

[0091] The mass ratio of (i) the halogen metal salt to (ii) the copper compound is preferably adjusted so that the molar ratio of halogen to copper is 0.5 / 1 to 100 / 1, more preferably 2 / 1 to 40 / 1, from the viewpoint of facilitating improvement in the heat resistance of the molded body and the corrosion resistance during production.

[0092] Examples of copper-based stabilizers include a mixture of 10% by mass of copper(I) iodide and 90% by mass of potassium iodide, and a mixture of 14.3% by mass of copper(I) iodide and 85.7% by mass of potassium iodide / calcium distearate (98:2 mass ratio).

[0093] The content of the copper-based stabilizer is preferably 0.01 mass% or more and 3.00 mass% or less, more preferably 0.02 mass% or more and 1.00 mass% or less, and even more preferably 0.03 mass% or more and 0.50 mass% or less, relative to the total mass of the polyamide resin composition.

[0094] (lubricant) The lubricant can improve the injection flowability of the polyamide resin composition and improve the appearance of the resulting resin part. The lubricant can be a metal salt of a fatty acid, such as a metal salt of an oxycarboxylic acid or a metal salt of a higher fatty acid.

[0095] The hydroxycarboxylic acid constituting the hydroxycarboxylic acid metal salt may be an aliphatic hydroxycarboxylic acid or an aromatic hydroxycarboxylic acid. Examples of the aliphatic hydroxycarboxylic acid include aliphatic hydroxycarboxylic acids having 10 to 30 carbon atoms, such as α-hydroxymyristic acid, α-hydroxypalmitic acid, α-hydroxystearic acid, α-hydroxyeicosanoic acid, α-hydroxydocosanoic acid, α-hydroxytetraeicosanoic acid, α-hydroxyhexaeicosanoic acid, α-hydroxyoctaeicosanoic acid, α-hydroxytriacontanoic acid, β-hydroxymyristic acid, 10-hydroxydecanoic acid, 15-hydroxypentadecanoic acid, 16-hydroxyhexadecanoic acid, 12-hydroxystearic acid, and ricinoleic acid. Examples of the aromatic hydroxycarboxylic acid include salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, gallic acid, mandelic acid, and trovic acid.

[0096] Examples of the metal constituting the metal oxycarboxylic acid salt include alkali metals such as lithium, and alkaline earth metals such as magnesium, calcium and barium.

[0097] Of these, the metal oxycarboxylic acid salt is preferably a metal salt of 12-hydroxystearic acid, and more preferably magnesium 12-hydroxystearate and calcium 12-hydroxystearate.

[0098] Examples of the higher fatty acids that constitute the higher fatty acid metal salts include higher fatty acids having 15 to 30 carbon atoms, such as stearic acid, oleic acid, behenic acid, behenic acid, and montanic acid.

[0099] Examples of metals constituting the above higher fatty acid metal salts include calcium, magnesium, barium, lithium, aluminum, zinc, sodium, and potassium.

[0100] Of these, the higher fatty acid metal salts are preferably calcium stearate, magnesium stearate, barium stearate, calcium behenate, sodium montanate, and calcium montanate.

[0101] The content of the lubricant is preferably 0.01% by mass or more and 1.30% by mass or less relative to the total mass of the polyamide resin composition. When the content of the lubricant is 0.01% by mass or more, the fluidity during molding tends to be improved, and the appearance of the obtained molded product tends to be improved. When the content of the lubricant is 1.30% by mass or less, gas due to decomposition of the lubricant is unlikely to be generated during molding, and the appearance of the product tends to be good.

[0102] (Reinforcement material) The reinforcing material can impart high mechanical strength to the polyamide resin composition. The reinforcing material may be an inorganic filler. Examples of the reinforcing material include fibrous reinforcing materials such as glass fiber, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, zinc oxide whiskers, milled fiber, and cut fiber, as well as granular reinforcing materials. One of these may be used alone, or two or more may be used in combination. Among these, wollastonite, glass fiber, and potassium titanate whiskers are preferred because they can easily increase the mechanical strength of the resin member, and wollastonite or glass fiber is more preferred.

[0103] From the viewpoints of moldability of the polyamide resin composition and the mechanical strength and heat resistance of the resulting resin part, the average fiber length of the fibrous reinforcing material may be, for example, from 1 μm to 20 mm, preferably from 5 μm to 10 mm, and the aspect ratio of the fibrous reinforcing material may be, for example, from 5 to 2000, preferably from 30 to 600.

[0104] The average fiber length and average fiber diameter of the fibrous reinforcing material can be measured by the following method. 1) The polyamide resin composition is dissolved in a hexafluoroisopropanol / chloroform solution (0.1 / 0.9% by volume), and then filtered to obtain a filtrate. 2) Disperse the filtered material obtained in 1) above in water, and measure the fiber length (Li) and fiber diameter (di) of each of 300 randomly selected fibers using an optical microscope (magnification: 50x). The number of fibers with fiber length Li is taken as qi, and the weight-average length (Lw) is calculated using the following formula, which is the average fiber length of the fibrous reinforcement. Weight average length (Lw) = (Σqi × Li 2 ) / (Σqi×Li) Similarly, the number of fibers with a fiber diameter Di is taken as 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 fibrous reinforcing material. Weight average diameter (Dw)=(Σri×Di 2 ) / (Σri×Di)

[0105] The content of the reinforcing material is not particularly limited, but can be, for example, 15% by mass or more and 70% by mass or less relative to the total mass of the polyamide resin composition. From the viewpoint of suppressing a decrease in the initial airtightness and the rate at which the airtightness is maintained after repeated thermal shocks, which is caused by the fluidity and elastic modulus of the polyamide resin composition being changed by the addition of the reinforcing material, the content of the reinforcing material is preferably 15% by mass or more and 50% by mass or less relative to the total mass of the polyamide resin composition.

[0106] 1-5. Physical properties of polyamide resin compositions The crystallization rate, which is expressed as the difference between the melting point and the crystallization temperature of the polyamide resin composition as measured by a differential scanning calorimeter (DSC), is preferably 50°C or less, more preferably 30°C or less. In a polyamide resin composition having such a crystallization rate, the crystallization rate of the crystalline polyamide resin (A) is sufficiently fast, so that the molding time of the polyamide resin composition can be further shortened. The lower limit of the crystallization rate is not particularly limited, but is, for example, 10°C.

[0107] The melting point of the polyamide resin composition can be measured by the same method as that for the melting point of the crystalline polyamide resin (A). The crystallization temperature of the polyamide resin composition can be determined by using the exothermic peak temperature (°C) during the cooling process in the above-mentioned melting point measurement method as the crystallization temperature.

[0108] 1-6. Method for producing polyamide resin composition The polyamide resin composition can be produced by a known resin blending method, such as mixing the above-mentioned crystalline polyamide resin (A), boron nitride (B), CTI improver (C), and other components as needed, using a Henschel mixer, V-blender, ribbon blender, or tumbler blender, or by mixing, melt-kneading the resulting mixture in a single-screw extruder, multi-screw extruder, kneader, or Banbury mixer, followed by granulation or pulverization. The melting temperature during melt-kneading is preferably at least 10°C above the melting point (Tm) of the polyamide resin (A1) and not more than 20°C above the melting point (Tm).

[0109] 2. Molded body The molded article of the present invention is obtained by molding the polyamide resin composition of the present invention. The polyamide resin composition provides the molded article with improved tracking resistance.

[0110] The molded article can be produced using the polyamide resin composition by a conventional melt molding method, such as compression molding, injection molding, etc. For example, the polyamide resin composition of the present invention can be put into a molten state in an injection molding machine whose cylinder temperature is adjusted to the melting point of the crystalline polyamide resin (A) or higher, for example, about 280°C to 350°C, and then introduced into a mold of a predetermined shape to produce a molded article.

[0111] The shape of the molded article produced using the polyamide resin composition of the present invention is not particularly limited, and may take various shapes depending on the application.

[0112] Examples of applications of molded articles of the polyamide resin composition in this embodiment include vehicle structural parts, vehicle-mounted items, housings for electronic devices, housings for home appliances, structural parts, machine parts, various automobile parts, electronic device parts, medical devices, etc. As described above, the polyamide resin composition can improve the tracking resistance of molded articles, and therefore, among these applications, it can be particularly suitably used for electronic device parts. [Example]

[0113] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0114] 1. Synthesis / preparation of materials 1-1. Synthesis of crystalline polyamide resin (A) <Preparation of Polyamide Resin (PA-1) (6T / NBDAT)> 259.5 g (1562.0 mmol) of terephthalic acid, 81.3 g (1046.5 mmol) of 1,6-diaminohexane, 26.2 g (515.46 mmol) of norbornanediamine, 0.37 g of sodium hypophosphite monohydrate as a catalyst, and 81.8 g of distilled water were placed in a 1 L autoclave and purged with nitrogen. Stirring was initiated at 190 °C, and the internal temperature was raised to 250 °C over 3 hours. At this time, the internal pressure of the autoclave was increased to 3.0 MPa. After the reaction was continued for 1 hour, the low-order condensation product was discharged into the atmosphere through a spray nozzle installed at the bottom of the autoclave and extracted. The low-order condensation product was then cooled to room temperature, crushed in a crusher to a particle size of 1.5 mm or less, and dried at 110 °C for 24 hours.

[0115] Next, this low-order condensate was placed in a tray-type solid-state polymerization reactor, and after replacing with nitrogen, the temperature was raised to 215°C over about 1 hour and 30 minutes, followed by reaction for 1 hour and 30 minutes, and then the temperature was lowered to room temperature.

[0116] The obtained prepolymer was then melt-polymerized in a twin-screw extruder with a screw diameter of 30 mm and L / D=36 at a barrel set temperature of 330°C, a screw rotation speed of 200 rpm, and a resin feed rate of 6 kg / h to obtain a polyamide resin (PA-1).

[0117] The resulting polyamide resin (PA-1) had an intrinsic viscosity [η] of 0.97 dl / g, a melting point (Tm) of 312°C, a glass transition temperature (Tg) of 160°C, and a heat of fusion (ΔH) of 46 J / g. Furthermore, calculated from the charge ratio, the content of component units derived from terephthalic acid among the component units derived from dicarboxylic acid was 100 mol%, and the content of component units derived from 1,6-diaminohexane among the component units derived from diamine was 65 mol%, and the content of component units derived from norbornanediamine was 35 mol%.

[0118] <Preparation of Polyamide Resin (PA-2) (6T / 6I)> 2800 g (24.1 mol) of 1,6-diaminohexane, 2774 g (16.7 mol) of terephthalic acid, 1196 g (7.2 mol) of isophthalic acid, 5.7 g of sodium hypophosphite monohydrate as a catalyst, 36.6 g (0.30 mol) of benzoic acid as a molecular weight modifier, and 545 g of distilled water were placed in a 13.6 L autoclave and purged with nitrogen. Stirring was initiated at 190 °C, and the internal temperature was raised to 250 °C over 3 hours. At this time, the internal pressure of the autoclave was increased to 3.03 MPa. After the reaction was continued for 1 hour, the low-order condensation product was discharged into the atmosphere through a spray nozzle installed at the bottom of the autoclave and extracted. The low-order condensation product was then cooled to room temperature, pulverized in a pulverizer to a particle size of 1.5 mm or less, and dried at 110 °C for 24 hours. The intrinsic viscosity [η] of the resulting low-order condensation product was 0.15 dL / g.

[0119] Next, this low-order condensate was placed in a tray-type solid-state polymerization reactor, and after purging with nitrogen, the temperature was raised to 180°C over approximately 1 hour and 30 minutes. After that, the reaction was continued for 1 hour and 30 minutes, and the temperature was lowered to room temperature. The intrinsic viscosity [η] of the resulting prepolymer was 0.20 dL / g.

[0120] The obtained prepolymer was then melt-polymerized in a twin-screw extruder with a screw diameter of 30 mm and L / D=36 at a barrel set temperature of 330°C, a screw rotation speed of 200 rpm, and a resin feed rate of 6 kg / h to obtain a polyamide resin (PA-2).

[0121] The resulting polyamide resin (PA-2) had an intrinsic viscosity [η] 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. The composition of the resulting polyamide resin (PA-2) was such that, among the dicarboxylic acid-derived component units, the content of component units derived from terephthalic acid was 70 mol%, the content of component units derived from isophthalic acid was 30 mol%, and the content of component units derived from 1,6-diaminohexane among the diamine-derived component units was 100 mol%.

[0122] 1-2. Nucleating agent (b) Talc (average particle size 6 μm) was used. (B): Boron nitride "FS-1" (average particle size 1.5 μm) manufactured by JFE Mineral Co., Ltd. was used.

[0123] 1-3.CTI improver (C) The polyolefin resin (acid-modified ethylene-α-olefin copolymer) "MH5020" manufactured by Mitsui Chemicals, Inc. was used.

[0124] 1-4.Other ingredients 1-4-1. Copper-based stabilizers A mixture of 10% by mass of copper (I) iodide and 90% by mass of potassium iodide was used.

[0125] 1-4-2. Lubricants Sodium montanate was used.

[0126] 1-4-3. Reinforcement material Glass fiber (FT756D, manufactured by Owing Corning, containing a sizing agent having a carboxyl group) was used as a reinforcing material.

[0127] 2. Measurement The physical properties of each of the above resins were measured by the following methods.

[0128] <Melting point (Tm), glass transition temperature (Tg)> The melting point (Tm) and glass transition temperature (Tg) of the polyamide resin were measured using a differential scanning calorimeter (DSC220C, manufactured by Seiko Instruments Inc.). Specifically, approximately 5 mg of polyamide resin was sealed in an aluminum pan for measurement and set in the differential scanning calorimeter. The polyamide resin was then heated from room temperature to 350°C at 10°C / min. To completely melt the resin, it was held at 350°C for 3 minutes and then cooled to 30°C at 10°C / min. After leaving it at 30°C for 5 minutes, it was heated a second time to 350°C at 10°C / min. The temperature (°C) of the endothermic peak during this second heating was taken as the melting point (Tm) of the polyamide resin, and the inflection point corresponding to the glass transition was taken as the glass transition temperature (Tg).

[0129] <Heat of fusion (ΔH)> The heat of fusion (ΔH) of the polyamide resin was calculated from the area of ​​the exothermic peak of crystallization during the first heating process in accordance with JIS K 7122 (2012).

[0130] <Intrinsic viscosity [η]> The intrinsic viscosity [η] of the polyamide resin was calculated by dissolving 0.5 g of the polyamide resin in 50 ml of a 96.5% sulfuric acid solution, measuring the flow time of the resulting solution at 25°C ± 0.05°C using an Ubbelohde viscometer, and then calculating the intrinsic viscosity [η] based on the formula: [η] = ηSP / (C(1 + 0.205ηSP)). [η]: Intrinsic viscosity (dl / g) ηSP: Specific viscosity C: Sample concentration (g / dl) t: Number of seconds for sample solution to flow down (seconds) t0: Number of seconds the blank sulfuric acid flows (seconds) ηSP=(t-t0) / t0

[0131] 3. Preparation of polyamide resin composition The above materials were mixed in a tumbler blender in the composition ratios (unit: parts by mass) shown in Table 1, and melt-kneaded using a 30 mmφ vented twin-screw extruder at a cylinder temperature of 300 to 335°C. The kneaded mixture was then extruded into strands and cooled in a water bath. The strands were then taken up in a pelletizer and cut to obtain pellet-shaped polyamide resin compositions 1 to 4.

[0132] The melting point of the polyamide resin composition was measured in the same manner as for the crystalline polyamide resin (A). The exothermic peak during the cooling process was taken as the crystallization temperature, and the crystallization temperature of the polyamide resin composition was measured. The difference between the measured melting point and the crystallization temperature was then taken as the crystallization rate of the polyamide resin composition.

[0133] 4. Evaluation <Moldability> The obtained polyamide resin composition was molded using the following injection molding machine under the following molding conditions to obtain an ASTM dumbbell-shaped test piece Type I having a thickness of 3.2 mm. Molding machine: EC75N-2A (manufactured by Toshiba Machine Co., Ltd.) Cylinder temperature: Among the polyamide resins to be added, the melting point of the polyamide resin with the highest melting point + 10°C Mold temperature: 200℃ Injection setting speed: 50mm / sec

[0134] In molding the above-mentioned ASTM dumbbell-shaped test piece Type I, moldability was evaluated by checking whether or not any polyamide resin composition remained in the mold when the test piece was released from the mold. More specifically, molding of ASTM dumbbell-shaped test piece Type I was performed multiple times while changing the cooling time, and it was checked whether or not any polyamide resin composition remained in the mold after the test piece was removed for each molding. If the cooling time is insufficient, the polyamide resin composition remains in the mold, resulting in poor mold release. The minimum cooling time [s] at which no polyamide resin composition remained in the mold after the test piece was removed was measured.

[0135] <Tracking resistance> The obtained polyamide resin composition was molded under the following molding conditions using the following injection molding machine to obtain a test piece of 200 mm x 130 mm x 3 mm. Molding machine: EC75N-2A, manufactured by Toshiba Machine Co., Ltd. Cylinder temperature: Melting point of polyamide resin (A) + 10°C Mold temperature: 200℃ Injection setting speed: 500mm / sec

[0136] The comparative tracking index (CTI) [V], which is an index of tracking resistance, was measured for the obtained test piece in accordance with IEC 60112 under the following conditions. Test solution: Ammonium chloride (0.1% concentration) aqueous solution Testing machine: YST-1000V (Yamayo Testing Instruments Co., Ltd.) Test room temperature: 23℃

[0137] The composition and evaluation results of each polyamide resin composition are shown in Table 1. The composition values ​​in Table 1 represent parts by mass.

[0138] [Table 1]

[0139] The results of Comparative Example 1 and Reference Example show that there is room for improvement in moldability of polyamide resin compositions using polyamide resins containing norbornanediamine.The results of Polyamide Resin Compositions 1 and 2 also show that in polyamide resin compositions using polyamide resins containing norbornanediamine, the inclusion of boron nitride and polyolefin resins can shorten the molding time and improve tracking resistance. [Industrial Applicability]

[0140] The polyamide resin composition according to the present invention can improve tracking resistance, and is therefore useful for applications such as electric and electronic parts.

Claims

1. A crystalline polyamide resin (A), Boron nitride (B), a CTI improver (C) containing at least one selected from the group consisting of a polyolefin resin and an endothermic filler; Including, The crystalline polyamide resin (A) contains a component unit (Aa) derived from a dicarboxylic acid and a component unit (Ab) derived from a diamine, The dicarboxylic acid-derived component unit (Aa) includes an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid-derived component unit, The diamine-derived component units (Ab) include component units derived from norbornanediamine that account for 10 mol % or more and less than 50 mol % of the total number of moles of the diamine-derived component units (Ab), and component units derived from aliphatic diamines having 4 to 18 carbon atoms that account for 50 mol % or more and 90 mol % or less of the total number of moles of the diamine-derived component units (Ab). Polyamide resin composition.

2. The content of the boron nitride (B) is 0.01% by mass or more and 5.00% by mass or less, based on the total mass of the polyamide resin composition. The polyamide resin composition according to claim 1.

3. The average particle size of the boron nitride (B) is 70 μm or less. The polyamide resin composition according to claim 1.

4. The content of the CTI improver (C) is 5% by mass or more and 15% by mass or less, based on the total mass of the polyamide resin composition. The polyamide resin composition according to claim 1.

5. The content of the CTI improver (C) is 7.5% by mass or more and 15% by mass or less, based on the total mass of the polyamide resin composition. The polyamide resin composition according to claim 4.

6. a crystallization rate, which is measured by a differential scanning calorimeter (DSC) and is expressed as the difference between the melting point of the polyamide resin composition and the crystallization temperature of the polyamide resin composition, of 50°C or less; The polyamide resin composition according to claim 1.

7. A molded article obtained by molding the polyamide resin composition according to any one of claims 1 to 6.

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