Polyamide resin composition and molded article

Abstract

To provide a polyamide resin composition containing a high-melting point polyamide resin and a bromine-based flame retardant and capable of controlling a pellet diameter, and to provide a molded article using the polyamide resin composition.SOLUTION: A polyamide resin composition comprising a polyamide resin (A) having a melting point of 280 °C. or higher as measured by differential scanning calorimetry (DSC), a bromine-based flame retardant (B), and a reinforcing material (C), wherein the content of the bromine-based flame retardant (B) is 5.0% by mass to 30.0% by mass with respect to the total mass of the polyamide resin composition, and the number-average particle diameter of the bromine-based flame retardant (B) in the polyamide resin composition is 1.0 μm to 5.5 μm.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 and are known to have excellent mechanical strength in molded articles. In particular, for applications such as automotive parts and electric / electronic parts, high flame retardancy may be required, and it is known that a flame retardant is added to the polyamide resin composition to enhance the flame retardancy of the polyamide resin composition.

[0003] For example, Patent Document 1 discloses a polyamide resin composition containing 60 to 75 parts by mass of (A) a polyamide resin, (B) a melamine cyanurate flame retardant, and (C) a fatty acid ester of a polyalkylene polyhydric alcohol in a predetermined ratio. Patent Document 1 states that a polyamide resin composition having good flame retardancy, good tensile elongation at break, and good moldability has been obtained.

[0004] Patent Document 2 discloses a polyamide resin composition containing a polyamide resin (A), a melamine cyanurate flame retardant (B), and a surfactant (C) containing at least one fatty acid ester of a polyalkylene polyhydric alcohol in a predetermined ratio. Patent Document 2 states that a polyamide resin composition having good flame retardancy has been obtained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-79281 [Patent Document 2] International Publication No. 2008 / 149892 Summary of the Invention [Problem to be solved by the invention]

[0006] Among such polyamide resin compositions, polyamide resin compositions containing a polyamide resin having a high melting point (hereinafter also referred to as "high-melting-point polyamide resin") are known to be excellent in heat resistance and therefore suitable for use at high temperatures.

[0007] Polyamide resin compositions are processed into molded articles by a process such as injection molding, in which pellets of the polyamide resin composition are plasticized (melted or softened) and molded. When a high-melting polyamide resin, which has a melting point higher than that of general-purpose polyamide resins, is used, a greater amount of heat is required for plasticization compared to when general-purpose polyamide resins are used. When a larger amount of heat is required, the size of the polyamide resin composition pellets has a greater impact on the ease of plasticization of the polyamide resin in the injection molding machine cylinder. Specifically, when pellets of the polyamide resin composition are plasticized in the injection molding machine cylinder, they are plasticized by applying heat to the pellets via heater heating and screw shear heating within the injection molding machine cylinder. However, large pellets require a longer plasticization time, resulting in reduced productivity. To improve this, attempts have been made to increase the heating temperature, screw rotation speed, or back pressure to increase shear heating in the screw. However, if the temperature of the polyamide resin composition increases too much, thermal decomposition of the polyamide resin may occur. Therefore, efforts have been made to reduce the size of polyamide resin composition pellets to increase their specific surface area, thereby making it easier to apply heat to the pellets, thereby enabling them to be plasticized in a shorter time and increasing productivity.

[0008] The polyamide resin composition is pelletized, for example, by melt-kneading the various components constituting the polyamide resin composition, forming them into strands, and cutting them. In this case, if it is desired to reduce the size of the pellets without providing a separate process for crushing the pellets of the polyamide resin composition, it is possible to reduce the diameter of the strands obtained after melt-kneading (reducing the pellet diameter) and shorten the cutting interval of the strands (shortening the pellet length).

[0009] However, although the pellet length can be shortened to some extent by adjusting the cutting interval, when attempting to reduce the pellet diameter, even if the diameter is reduced to a certain extent, the strand breaks when being taken up, and there is a limit to how small the pellet diameter can be reduced.

[0010] In Patent Documents 1 and 2, a melamine cyanurate-based flame retardant is used as a flame retardant. However, due to its low heat resistance, melamine cyanurate-based flame retardants are difficult to fully function as a flame retardant when the polyamide resin composition contains a high-melting-point polyamide resin. Therefore, when the polyamide resin composition contains a high-melting-point polyamide resin, a brominated flame retardant is sometimes used. Applications of flame-retardant polyamide resin compositions include electrical and electronic components such as connectors. Due to the trend toward smaller and thinner components, resin compositions are required to have high fluidity during injection molding. According to the inventors' research, when a brominated flame retardant is used in combination with a high-melting-point polyamide resin composition, the pellet diameter of the polyamide resin composition cannot be sufficiently reduced, and the surface area cannot be sufficiently increased, resulting in a problem of insufficient heating efficiency during melting or softening.

[0011] An object of the present invention is to provide a polyamide resin composition containing a high-melting point polyamide resin and a brominated flame retardant, in which the pellet diameter can be controlled, and to provide a molded article using the polyamide resin composition. [Means for solving the problem]

[0012] In order to solve the above problems, one aspect of the present invention relates to the following polyamide resin compositions [1] to [6].

[0013] [1] A polyamide resin (A) having a melting point of 280°C or higher as measured by a differential scanning calorimeter (DSC), a brominated flame retardant (B); a reinforcement material (C); A polyamide resin composition comprising: the content of the brominated flame retardant (B) is 5.0% by mass to 30.0% by mass relative to the total mass of the polyamide resin composition; In the polyamide resin composition, the number average particle size of the brominated flame retardant (B) is 1.0 μm to 5.5 μm. Polyamide resin composition.

[0014] [2] The content of the brominated flame retardant (B) is 5.0% by mass to 20.0% by mass relative to the total mass of the polyamide resin composition. [1] The polyamide resin composition according to [1].

[0015] [3] The brominated flame retardant (B) includes a brominated flame retardant (B-1) having a weight average molecular weight of 1,000 to 5,000. [1] or [2]. The polyamide resin composition.

[0016] [4] The brominated flame retardant (B) includes a brominated flame retardant (B-2) having a weight average molecular weight of 100,000 or more. The polyamide resin composition according to any one of [1] to [3].

[0017] [5] The 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 unit (Aa) includes a terephthalic acid-derived unit, The diamine-derived component unit (Ab) includes a 1,6-diaminohexane-derived component unit. The polyamide resin composition according to any one of [1] to [4].

[0018] [6] A polyamide resin (A) having a melting point of 280°C or higher as measured by a differential scanning calorimeter (DSC), a brominated flame retardant (B); a reinforcement material (C); A pelletized polyamide resin composition comprising: the content of the brominated flame retardant (B) is 5.0% by mass to 30.0% by mass relative to the total mass of the polyamide resin composition; The pellet diameter of the polyamide resin composition is 1.0 mm to 1.8 mm. Polyamide resin composition.

[0019] In order to solve the above problems, one aspect of the present invention relates to the following molded article [7].

[0020] [7] A product obtained by molding the polyamide resin composition according to any one of [1] to [6]. Molded body. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a polyamide resin composition containing a high-melting point polyamide resin and a brominated flame retardant, in which the pellet diameter can be controlled, and a molded article using the polyamide resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0023] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0024] 1. Polyamide resin composition The polyamide resin composition according to the present embodiment comprises a polyamide resin (A) having a melting point of 280°C or higher as measured by differential scanning calorimetry (DSC), a brominated flame retardant (B), and a reinforcing material (C), wherein the content of the brominated flame retardant (B) is 5.0 to 30.0% by mass relative to the total mass of the polyamide resin composition. Furthermore, it is preferred that the number average particle size of the brominated flame retardant (B) in the polyamide resin composition is 1.0 to 5.5 μm.

[0025] The problem of strand breakage due to the reduction in pellet diameter is a problem that occurs particularly when a brominated flame retardant is added to a high-melting-point polyamide resin. The following factors are thought to be the factors that make the above-mentioned strand breakage more likely to occur when a brominated flame retardant is added to a high-melting-point polyamide resin.

[0026] When a brominated flame retardant is contained, the brominated flame retardant often has low affinity with polyamide resins, and is therefore likely to disperse in the polyamide resin composition and form domains (flame retardant domains). Furthermore, brominated flame retardants often have a lower melting point than polyamide resins, which means that the melt viscosity of the brominated flame retardant is likely to decrease when the polyamide resin composition containing the brominated flame retardant is melt-kneaded to produce it. In particular, when a high-melting-point polyamide resin is used, the temperature applied during the melt-kneading of the polyamide resin composition must be increased, which further reduces the melt viscosity of the brominated flame retardant. It is generally known that in two-component immiscible polymer liquids, a large difference in viscosity between the matrix viscosity and the dispersed domain viscosity makes it difficult to reduce the dispersed domain size. Therefore, the flame retardant domain size is difficult to reduce in a high-melting-point polyamide resin (matrix).

[0027] Because the tensile strength of brominated flame retardants tends to be lower than that of polyamide resins, in polyamide resin compositions in which brominated flame retardants are dispersed in a polyamide resin matrix to form flame retardant domains, the flame retardant domains tend to have a lower tensile strength than the matrix. In this case, when tensile stress is applied to the polyamide resin composition when it is drawn into a strand, the flame retardant domains, which have low tensile strength, tend to break. If relatively large flame retardant domains are present in the polyamide resin composition, the breaks are less likely to reach the polyamide resin (matrix) with high mechanical strength and inhibit the break from progressing. Furthermore, when a flame retardant domain breaks, tensile stress is concentrated in the unbroken portion (e.g., the matrix) in a cross section perpendicular to the longitudinal direction (tensile direction) of the strand containing the flame retardant domain. However, if the size of the broken flame retardant domain is relatively large, the area of ​​the unbroken portion in the cross section becomes smaller, resulting in particularly large tensile stress being applied to the unbroken portion. Therefore, it is believed that even a matrix having a relatively high tensile strength may break, resulting in strand breakage.

[0028] The reason why the polyamide resin composition containing the high-melting point polyamide resin and the brominated flame retardant can reduce the pellet diameter, increase the surface area, and improve the heating efficiency during melting or softening is not entirely clear, but is thought to be as follows.

[0029] By setting the content of the brominated flame retardant (B) to 5.0% by mass or more relative to the total mass of the polyamide resin composition, sufficient flame retardancy can be imparted to the molded article, and even if it is 30.0% by mass or less, sufficient flame retardancy can be imparted. Furthermore, by setting the content of the brominated flame retardant (B) to 30.0% by mass or less, the volume occupied by flame retardant domains with low mechanical strength (or the occupied area in a cross section perpendicular to the longitudinal direction of the strand) can be reduced, and the frequency of collisions between flame retardants during melt-kneading of the polyamide resin composition can be reduced, making it easier to reduce the size of the flame retardant domains.

[0030] By setting the number-average particle diameter of the brominated flame retardant (B) in the polyamide resin composition to 5.5 μm or less, even if breakage occurs within the flame retardant domain when the polyamide resin composition is drawn into a strand, the breakage quickly reaches the polyamide resin (matrix), which has high mechanical strength, thereby suppressing the progression of the breakage and preventing excessive concentration of tensile stress in other parts of the polyamide resin composition. Furthermore, interfacial delamination between the flame retardant domain and the polyamide resin is unlikely to occur, and even if interfacial delamination (which could trigger breakage) does occur, it is limited to a relatively small area, thereby suppressing the progression of the breakage. In this way, strand breakage is unlikely to occur, making it easier to reduce the pellet diameter, which tends to improve heating efficiency during melting or softening.

[0031] Furthermore, by making the number average particle size of the brominated flame retardant (B) in the polyamide resin composition 1.0 μm or more, excessive decrease in the crystallinity of the polyamide resin (A) is suppressed, and rigidity in a high temperature environment (Tg or higher) is easily increased.

[0032] The number average particle size of the brominated flame retardant (B) can be controlled, for example, by the following method. By reducing the content of the brominated flame retardant (B) relative to the total mass of the polyamide resin composition, the frequency of collisions between flame retardants during melt-kneading of the polyamide resin composition can be reduced, and the number average particle size can be controlled to an appropriate size by increasing the shear stress applied during melting, for example, by appropriately increasing the screw rotation speed during melt-kneading. However, the method for controlling the number average particle size is not limited to the above method.

[0033] 1-1. Polyamide resin (A) The polyamide resin (A) is a polyamide resin having a melting point of 280°C or higher as measured by a differential scanning calorimeter (DSC). The polyamide resin (A) forms crystals in a molded product, which can increase the mechanical strength (such as bending strength) of the molded product. The method for measuring the melting point of the polyamide resin (A) will be described later.

[0034] Examples of polyamide resins having a melting point of 280°C or higher include semi-aromatic polyamide resins and aliphatic polyamide resins having component units derived from an aliphatic diamine having four carbon atoms and component units derived from an aliphatic dicarboxylic acid having six carbon atoms (hereinafter also referred to as "aliphatic polyamide resins containing PA46"). Among these, the polyamide resin (A) is preferably a semi-aromatic polyamide resin. Note that the semi-aromatic polyamide is a polyamide containing structural units derived from a diamine and structural units derived from a dicarboxylic acid, in which the structural units derived from the diamine include structural units derived from an aliphatic diamine or structural units derived from an alicyclic diamine, and the structural units derived from the dicarboxylic acid include structural units derived from an aromatic dicarboxylic acid, or a polyamide in which the structural units derived from the diamine include structural units derived from an aromatic diamine, and the structural units derived from the dicarboxylic acid include structural units derived from an aliphatic dicarboxylic acid or structural units derived from an alicyclic dicarboxylic acid.

[0035] Among semi-aromatic polyamide resins, from the viewpoint of easily increasing the mechanical strength (such as bending strength) of a molded article, polyamide resins in which the dicarboxylic acid-derived component units (Aa) include terephthalic acid-derived component units and the diamine-derived component units (Ab) include 1,6-diaminohexane-derived component units are preferred. Furthermore, among such polyamide resins, polyamide 6T6I, polyamide 6T66, and polyamide 6TDT are more preferred, with polyamide 6T66 being even more preferred.

[0036] The polyamide resin (A) is, for example, a polyamide resin containing a component unit (Aa) derived from a dicarboxylic acid and a component unit (Ab) derived from a diamine. Hereinafter, the polyamide resin containing the component unit (Aa) derived from a dicarboxylic acid and the component unit (Ab) derived from a diamine will be described.

[0037] 1-1-1. Dicarboxylic acid-derived component units (Aa) In the case of a semi-aromatic polyamide resin, the component units (Aa) derived from a dicarboxylic acid preferably include component units derived from an aromatic dicarboxylic acid, and more preferably include component units derived from terephthalic acid.

[0038] In the case of a semi-aromatic polyamide resin, the content of component units derived from aromatic dicarboxylic acids is preferably 40 mol% to 100 mol%, more preferably 50 mol% to 100 mol%, and even more preferably 60 mol% to 80 mol%, relative to the total number of moles of component units (Aa) derived from dicarboxylic acids.

[0039] In the case of a semi-aromatic polyamide resin, the content of component units derived from terephthalic acid is preferably 40 mol% to 100 mol%, more preferably 45 mol% to 80 mol%, even more preferably 50 mol% to 70 mol%, and particularly preferably 55 mol% to 65 mol%, relative to the total number of moles of component units (Aa) derived from dicarboxylic acids. When the content is 40 mol% or more, the aromatic ring concentration in the polyamide resin (A) increases, and the heat resistance and strength of the molded product tend to be improved.

[0040] The dicarboxylic acid-derived component units (Aa) may contain component units derived from other dicarboxylic acids. Examples of other dicarboxylic acids include aromatic dicarboxylic acids other than terephthalic acid, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Of these, aliphatic dicarboxylic acids are preferred. That is, in the case of a semi-aromatic polyamide resin, the dicarboxylic acid-derived component units (Aa) preferably contain component units derived from an aromatic dicarboxylic acid and component units derived from an aliphatic dicarboxylic acid, and more preferably contain component units derived from terephthalic acid and component units derived from an aliphatic dicarboxylic acid.

[0041] In the case of semi-aromatic polyamide resins, examples of the aliphatic dicarboxylic acids 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.

[0042] In the case of a semi-aromatic polyamide resin, the content of the component units derived from the above-mentioned aliphatic dicarboxylic acid is preferably 0 mol % to 60 mol %, more preferably 20 mol % to 55 mol %, even more preferably 30 mol % to 50 mol %, and particularly preferably 35 mol % to 45 mol %, relative to the total number of moles of the component units (Aa) derived from the dicarboxylic acid.

[0043] Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid and its esters.

[0044] Examples of aromatic dicarboxylic acids other than terephthalic acid include isophthalic acid, 2-methylterephthalic acid, and naphthalenedicarboxylic acid.

[0045] In the case of a semi-aromatic polyamide resin, the content of component units derived from aromatic dicarboxylic acids other than terephthalic acid and alicyclic dicarboxylic acids is preferably 0 mol % to 80 mol %, more preferably 20 mol % to 80 mol %, and even more preferably 25 mol % to 75 mol %, relative to the total number of moles of component units (Aa) derived from dicarboxylic acids.

[0046] In the case of an aliphatic polyamide resin, the content of component units derived from aliphatic dicarboxylic acids is preferably 80 mol% to 100 mol%, more preferably 90 mol% to 100 mol%, based on the total number of moles of component units (Aa) derived from dicarboxylic acids, and even more preferably comprises substantially only aliphatic dicarboxylic acids. In this paragraph, "comprising substantially only aliphatic dicarboxylic acids" means that the content of component units derived from the aliphatic dicarboxylic acids is 99 mol% to 100 mol% based on the total number of moles of component units (Aa) derived from dicarboxylic acids. Examples of the aliphatic dicarboxylic acids 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, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, and diglycolic acid. Among these, adipic acid and sebacic acid are preferred, and adipic acid is more preferred.

[0047] In the case of an aliphatic polyamide resin including PA46, the dicarboxylic acid-derived unit (Aa) may include an alicyclic dicarboxylic acid-derived unit. Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid and its esters.

[0048] 1-1-2. Diamine-derived component units (Ab) The diamine-derived component unit (Ab) includes, for example, a component unit derived from an aliphatic diamine having 4 to 15 carbon atoms, a component unit derived from an alicyclic diamine having 4 to 20 carbon atoms, and a component unit derived from an aromatic diamine.

[0049] The number of carbon atoms in the aliphatic diamine is preferably 4 to 12. Examples of the aliphatic diamine include linear alkylenediamines and branched alkylenediamines.

[0050] 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, in the case of semi-aromatic polyamide resins, 1,6-diaminohexane, 1,9-nonanediamine, and 1,10-diaminodecane are preferred, with 1,6-diaminohexane being more preferred. In the case of aliphatic polyamide resins containing PA46, 1,4-diaminobutane is preferred. The linear alkylenediamine may be contained alone or in combination of two or more types.

[0051] 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 ,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-1,8-diaminooctane is preferred.

[0052] In the case of semi-aromatic polyamide resins, the content of the component units derived from the aliphatic diamine is preferably 30 mol% to 100 mol%, and more preferably 70 mol% to 100 mol%, relative to the total number of moles of the component units (Ab) derived from the diamine. In the case of aliphatic polyamide resins, the content of the component units derived from the aliphatic diamine is preferably 80 mol% to 100 mol%, and more preferably 90 mol% to 100 mol%, relative to the total number of moles of the component units (Ab) derived from the diamine, and it is even more preferable that the polyamide resin contains substantially only aliphatic diamines. In this paragraph, "containing substantially only aliphatic diamines" means that the content of the component units derived from the aliphatic diamine is 99 mol% to 100 mol%, relative to the total number of moles of the component units (Ab) derived from the diamine.

[0053] 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, etc. Examples of the aromatic diamine include metaxylylenediamine, etc.

[0054] In the case of a semi-aromatic polyamide resin, the content of the component units derived from the above-mentioned alicyclic diamine and aromatic diamine is preferably 0 mol % to 70 mol %, more preferably 0 mol % to 30 mol %, relative to the total number of moles of the component units (Ab) derived from diamine.

[0055] The respective structural units of the polyamide resin (A) and their ratios can be calculated from the charge ratios when the polyamide resin (A) is prepared, or can be measured by the NMR method.

[0056] 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.

[0057] 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.

[0058] The dicarboxylic acid-derived component units of the 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 polyamide resin (A) may also be a biomass-derived polyamide resin (A) obtained by polymerizing raw materials including biomass-derived raw materials.

[0059] 1-1-3. Physical properties of polyamide resin (A) From the viewpoint of further increasing the mechanical strength of the molded article, the melting point of the polyamide resin (A) is 280° C. or higher, preferably 290° C. or higher, and more preferably 300° C. or higher. Furthermore, from the viewpoint of suppressing decomposition of the amide bond of the polyamide resin (A), the melting point of the polyamide resin (A) is preferably 330° C. or lower.

[0060] The melting point of the polyamide resin (A) can be adjusted to the above range by adjusting the composition of the polyamide resin (A). For example, the melting point can be increased by increasing the content of component units derived from terephthalic acid, which will be described later.

[0061] The polyamide resin (A) preferably has a glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) of 70°C to 145°C, more preferably 75°C to 125°C, and even more preferably 80°C to 100°C. When the glass transition temperature (Tg) is 70°C or higher, the temperature at which molecular mobility becomes active in a high-temperature environment increases, thereby suppressing molecular mobility and making it easier to improve heat resistance. When the glass transition temperature (Tg) is 145°C or lower, the fluidity and crystallinity of the polyamide resin composition can be easily improved, and heating efficiency can be easily improved, without excessively increasing the mold temperature during molding.

[0062] The heat of fusion (ΔH) of the polyamide resin (A) measured by differential scanning calorimetry (DSC) is preferably greater than 5 J / g, and more preferably greater than 5 J / g and not greater than 100 J / g. The heat of fusion is an indicator of the crystallinity of a resin, with a larger heat of fusion indicating higher crystallinity. When the heat of fusion (ΔH) of the polyamide resin (A) exceeds 5 J / g, the crystallinity is increased, thereby enabling the mechanical strength (such as bending strength) of the resulting molded article to be increased. When the heat of fusion (ΔH) of the polyamide resin (A) is 100 J / g or less, molding shrinkage can be suppressed, and the dimensional accuracy of the resulting molded article can be improved.

[0063] The melting point and heat of fusion (ΔH) of polyamide resin (A) are measured using a differential scanning calorimeter (DSC220C, manufactured by Seiko Instruments Inc.). Specifically, approximately 5 mg of 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, the pan is held at 350°C for 3 minutes and then cooled to 30°C at 10°C / min. After leaving the pan at 30°C for 5 minutes, the pan 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 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 calculated from the area of ​​the endothermic peak during the first heating process, in accordance with JIS K7122:2012.

[0064] The polyamide resin (A) preferably has an intrinsic viscosity [η] of 0.7 dL / g to 1.2 dL / g, more preferably 0.75 dL / g to 1.1 dL / g, even more preferably 0.75 dL / g to 1.0 dL / g, and particularly preferably 0.8 dL / g to 1.0 dL / g. When the polyamide resin (A) has an intrinsic viscosity [η] of 0.7 dL / g or more, the mechanical strength (e.g., bending strength) of the molded article can be sufficiently increased. When the intrinsic viscosity [η] is 1.2 dL / g or less, the fluidity of the resin composition during molding can be prevented from being impaired. The intrinsic viscosity [η] can be adjusted by adjusting the molar ratio of the dicarboxylic acid-derived component unit (Aa) and the diamine-derived component unit (Ab). Specifically, the closer the molar ratio of the component unit (Aa) derived from carboxylic acid to the component unit (Ab) derived from diamine is to 1:1, the higher the intrinsic viscosity can be. The intrinsic viscosity can also be adjusted by the amount of end-capping of the polyamide resin (A).

[0065] The intrinsic viscosity [η] of polyamide resin (A) is a value measured as follows: 0.5 g of polyamide resin (A) is dissolved in 50 ml of 96.5% sulfuric acid solution to prepare a sample solution. The flow time of the obtained solution at 25°C ± 0.05°C is measured using an Ubbelohde viscometer, and the intrinsic viscosity [η] is calculated according to 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 for blank sulfuric acid to flow (seconds) ηSP=(t-t0) / t0

[0066] The polyamide resin (A) can be produced by the same method as that for known polyamide resins, for example, by polycondensing a dicarboxylic acid and a diamine in a homogeneous solution. Specifically, the polyamide resin (A) can be produced by heating a dicarboxylic acid and a diamine in the presence of a catalyst to obtain a low-order condensate, as described in WO 03 / 085029, and then applying shear stress to a melt of the low-order condensate to polycondense it.

[0067] The amount of terminal carboxy groups in the polyamide resin (A) is preferably 20 mmol / kg to 200 mmol / kg, more preferably 40 mmol / kg to 170 mmol / kg. When the amount of terminal carboxy groups is 200 mmol / kg or less, the number of terminal carboxy groups that can act as acid catalysts to promote thermal decomposition during heating is reduced, making it easier to suppress a decrease in molecular weight due to thermal decomposition.

[0068] The amount of terminal carboxyl groups is a value measured using NMR. Specifically, for example, 30 mg of polyamide resin is dissolved in 0.5 mL of deuterated hexafluoroisopropanol (HFIP) to prepare a sample for NMR measurement. NMR measurement of the prepared sample is performed using a nuclear magnetic resonance spectrometer (ECA-500, manufactured by JEOL Ltd.). The molecular weight of the polyamide resin is calculated from the peak areas of hydrogen atoms of each component constituting the polyamide resin in the obtained spectrum. The amount of terminal carboxyl groups ([COOH], unit: mmol / kg) is calculated using the peak areas of hydrogen atoms specific to the terminal carboxyl groups and the molecular weight value.

[0069] The amount of terminal amino groups in the polyamide resin (A) is preferably 30 mmol / kg to 200 mmol / kg, more preferably 50 mmol / kg to 200 mmol / kg, and even more preferably 50 mmol / kg to 150 mmol / kg. When the amount of terminal amino groups is 200 mmol / kg or less, hydrolysis during melt processing can be suppressed.

[0070] The amount of terminal amino groups is measured by the following method. 1 g of polyamide resin is dissolved in 35 mL of phenol, and 2 mL of methanol is added to prepare a sample solution. Using thymol blue as an indicator, the sample solution is titrated with a 0.01 N hydrochloric acid solution using a potentiometric titrator (Metrohm) until the solution turns from blue to yellow, and the amount of terminal amino groups ([NH2], unit: mmol / kg) is measured.

[0071] The content of polyamide resin (A) is preferably 20% by mass to 80% by mass, more preferably 30% by mass to 70% by mass, and more preferably 35% by mass to 60% by mass, based on the total mass of the polyamide resin composition. When the content is 20% by mass or more, the bending strength and toughness of the polyamide resin composition can be further increased. When the content is 80% by mass or less, the flame retardant (B) and other components described below can be sufficiently contained in the polyamide resin composition.

[0072] 1-2. Brominated flame retardants (B) The brominated flame retardant (B) can impart flame retardancy to the polyamide resin composition and its molded article.

[0073] In the polyamide resin composition according to this embodiment, a part or all of the brominated flame retardant (B) may be dispersed in the polyamide resin composition to form domains (flame retardant domains), or may not form flame retardant domains. When flame retardant domains are formed, the number average particle size of the brominated flame retardant (B) in the polyamide resin composition is preferably 1.0 μm to 5.5 μm, more preferably 2.0 μm to 5.0 μm, and even more preferably 3.0 μm to 5.0 μm. When the particle size is 1.0 μm or more, rigidity in a high-temperature environment (above Tg) tends to be increased. When the particle size is 5.5 μm or less, the pellet diameter can be easily reduced, and reflow heat resistance can be easily improved.

[0074] The number-average particle diameter of the brominated flame retardant (B) in the polyamide resin composition is measured as follows. The polyamide resin composition is embedded in an epoxy resin and polished to expose the cross section of the embedded polyamide resin composition. If the polyamide resin composition contains a fibrous reinforcing material (C), the polishing is performed so that the length direction of the fibers of the fibrous reinforcing material (C) is approximately parallel to the cross section exposed by polishing. The exposed cross section of the polyamide resin composition is then observed using a scanning electron microscope to obtain an image. The flame retardant in the obtained image (100x magnification, one image) is binarized and extracted, and the circle-equivalent diameter (1 pixel = 1 μm, 2000 to 3000 particles) is measured. Note that the flame retardant can be distinguished from other components in the obtained image based on differences in contrast and shape. However, if the difference in contrast is small and difficult to distinguish, it can also be distinguished by methods such as obtaining elemental distribution using energy dispersive X-ray spectroscopy (EDX). ·SEM device: JSM-IT700HR / LV (manufactured by JEOL Ltd.) Pretreatment: Resin embedding, mechanical polishing, carbon deposition Conditions: Acceleration voltage 10 kV, backscattered electron image acquisition Image analysis software: Win ROOF 2018 (MITANIcorporation)

[0075] Examples of the brominated flame retardant (B) include brominated polystyrene, polybrominated styrene, brominated polyphenylene ether, etc. Among these, it is preferable that the brominated flame retardant (B) includes brominated polystyrene.

[0076] Brominated polystyrene is a brominated polystyrene or poly-α-methylstyrene. In the brominated polystyrene, some of the hydrogen atoms bonded to the carbon atoms forming the aromatic ring are preferably substituted with bromine atoms, and the hydrogen atoms forming the alkyl chain forming the main skeleton of the polymer are preferably not substantially substituted with bromine atoms. The bromine content of the brominated polystyrene is preferably 55% to 71% by mass, more preferably 65% ​​to 70% by mass.

[0077] "Hydrogen atoms forming the alkyl chain that forms the main skeleton of the polymer are not substantially substituted with bromine atoms" means that the proportion of hydrogen atoms forming the alkyl chain that forms the main skeleton of the polymer that are substituted with bromine atoms is preferably 0.0% to 0.5% by mass, more preferably 0.0% to 0.2% by mass, and even more preferably 0.0% to 0.1% by mass. By setting the proportion in this range, thermal stability tends to be improved.

[0078] The content of the flame retardant (B) is 5.0 to 30.0% by mass, preferably 5.0 to 20.0% by mass, and more preferably 10.0 to 20.0% by mass, relative to the total mass of the polyamide resin composition. When the content of the flame retardant (B) is 20.0% by mass or less, flame retardant domains with low mechanical strength are further reduced, and the frequency of collisions between flame retardants during melt-kneading of the polyamide resin composition is further reduced, making it possible to further reduce the size of the flame retardant domains, which further reduces strand breakage and makes it easier to reduce the pellet diameter.

[0079] The brominated flame retardant (B) may be a brominated flame retardant (B-1) having a weight-average molecular weight of 1,000 to 5,000 (hereinafter simply referred to as "brominated flame retardant (B-1)") or a brominated flame retardant (B-2) having a weight-average molecular weight of 100,000 or more (hereinafter simply referred to as "brominated flame retardant (B-2)"). Either of these may be contained, but it is preferable to contain a brominated flame retardant (B-1) from the viewpoint of improving the flowability of the polyamide resin composition during molding processing and improving moldability when molding a molded article having a thin wall portion such as a connector. Furthermore, by using a brominated flame retardant (B-2) having a higher melt viscosity than the brominated flame retardant (B-1) in addition to the brominated flame retardant (B-1), it becomes easier to adjust the viscosity difference between the polyamide resin (A) and the brominated flame retardant (B), so it is more preferable to contain both the brominated flame retardant (B-1) and the brominated flame retardant (B-2).

[0080] (Brominated flame retardants (B-1)) The weight-average molecular weight (Mw) of the brominated flame retardant (B-1) is 1,000 to 5,000, preferably 2,000 to 4,500. When Mw is 1,000 or more, the flame retardant is easily finely dispersed without impairing toughness, and breakage in the flame retardant domains is less likely to occur when the strand is taken up, making it easier to reduce the diameter of the pellets. When Mw is 5,000 or less, the flowability of the polyamide resin composition during molding processing can be improved. The weight-average molecular weight is a value calculated in terms of polystyrene using gel permeation chromatography (GPC) with chloroform as the mobile phase and a differential refractometer detector at a column temperature of 40°C.

[0081] The melt mass flow rate (MFR) of the brominated flame retardant (B-1) is preferably 300 g / 10 min to 900 g / 10 min, more preferably 400 g / 10 min to 900 g / 10 min. An MFR of 900 g / 10 min or less reduces breakage in the flame retardant domain during strand take-up, facilitating pellet size reduction, without impairing toughness or other properties. An MFR of 300 g / 10 min or more appropriately adjusts the viscosity difference between the polyamide resin (A) and the brominated flame retardant (B), making it easier to adjust the number average particle size, while achieving high fluidity during melting or softening and facilitating uniform heat transfer. The MFR is a value measured in accordance with JIS K7210-1:2014 under a load of 1200 g and at 270°C.

[0082] The content of the brominated flame retardant (B-1) is preferably 5.0% by mass to 30.0% by mass, more preferably 5.0% by mass to 20.0% by mass, and even more preferably 10.0% by mass to 20.0% by mass, relative to the total mass of the polyamide resin composition. When the content of the flame retardant (B-1) is 5.0% by mass or more, sufficient flame retardancy can be imparted to the molded article. When the content of the flame retardant (B-1) is 30.0% by mass or less, flame retardant domains with low mechanical strength are further reduced, and the frequency of collisions between flame retardants during melt-kneading of the polyamide resin composition is further reduced, thereby making it easier to reduce the pellet diameter.

[0083] (Brominated flame retardants (B-2)) The weight-average molecular weight (Mw) of the brominated flame retardant (B-2) is 100,000 or more, preferably 100,000 to 300,000. When the Mw is 100,000 or more, when used in combination with the brominated flame retardant (B-1), the difference in melt viscosity between the polyamide resin (A) and the brominated flame retardant (B) becomes smaller, making it easier to reduce the number-average particle size of the brominated flame retardant (B), and thus easier to reduce the pellet size. When the Mw is 300,000 or less, the flowability during molding of the polyamide resin composition is improved. The weight-average molecular weight is a value calculated in terms of polystyrene, measured using gel permeation chromatography (GPC) with chloroform as the mobile phase and a differential refractometer detector at a column temperature of 40°C.

[0084] The melt mass flow rate (MFR) of the brominated flame retardant (B-2) is preferably 10 g / 10 min or less, more preferably 0.1 g / 10 min to 5 g / 10 min. When the MFR is 10 g / 10 min or less, the difference in melt viscosity between the polyamide resin (A) and the brominated flame retardant (B) is reduced when used in combination with the brominated flame retardant (B-1). This reduces the number average particle size of the brominated flame retardant (B), making it easier to reduce the pellet size. When the MFR is 0.1 g / 10 min or more, the flowability of the polyamide resin composition during molding processing is improved. The MFR is a value measured in accordance with JIS K7210-1:2014 under a load of 1200 g and at a temperature of 270°C.

[0085] The content of the flame retardant (B-2) is preferably 0.0% by mass to 10.0% by mass, and more preferably 1.0% by mass to 8.0% by mass, relative to the total mass of the polyamide resin composition. When the content of the flame retardant (B-2) is 1.0% by mass or more, the difference in melt viscosity between the polyamide resin (A) and the brominated flame retardant (B) becomes small, making it easier to reduce the number average particle size of the brominated flame retardant (B), and therefore easier to reduce the pellet size. When the content of the flame retardant (B-2) is 10.0% by mass or less, it is easier to improve the fluidity during molding of the polyamide resin composition.

[0086] When both the brominated flame retardant (B-1) and the brominated flame retardant (B-2) are contained, the mass ratio of the content of the brominated flame retardant (B-1) in the polyamide resin composition as the numerator to the content of the brominated flame retardant (B-2) as the denominator is preferably 1 / 1 to 5 / 1, more preferably 2 / 1 to 3 / 1. When the mass ratio is 1 / 1 or more, the flowability of the polyamide resin composition during molding processing is likely to be improved. When the mass ratio is 5 / 1 or less, the difference in melt viscosity between the polyamide resin (A) and the brominated flame retardant (B) is likely to be small, and the number average particle size of the brominated flame retardant (B) can be easily reduced.

[0087] 1-3. Reinforcement material (C) The reinforcing material (C) can impart higher tensile strength to the polyamide resin composition and the molded article.

[0088] The cross-sectional aspect ratio of the reinforcing material (C) is preferably 1.0 or more and less than 10.0, more preferably 1.0 to 4.0. The cross-sectional shape of the reinforcing material (C) is, for example, elliptical, flat, or circular, and is preferably circular.

[0089] In this specification, the "cross section" of the reinforcing material (C) refers to a cross section cut in a direction perpendicular to the longitudinal direction of the fiber. The "aspect ratio" refers to the value of the ratio of the first line segment to the second line segment, where the longest line segment among the line segments passing through the center of the cross section and connecting the opposing edges of the cross section is designated as the first line segment, and the line segment perpendicular to the longest line segment is designated as the second line segment. The aspect ratio can be determined by determining the weight-average major axis (Dw) and weight-average minor axis (dw) using the method described below and calculating the ratio (Dw / dw) between them.

[0090] The type of reinforcing material (C) is not particularly limited, and examples thereof include glass fiber, carbon fiber, wollastonite, potassium titanate whisker, calcium carbonate whisker, aluminum borate whisker, magnesium sulfate whisker, sepiolite, xonotlite, zinc oxide whisker, milled fiber, cut fiber, wholly aromatic polyamide fiber (e.g., polyparaphenylene terephthalamide fiber, polymetaphenylene terephthalamide fiber, polyparaphenylene isophthalamide fiber, polymetaphenylene isophthalamide fiber, and fiber obtained from a condensate of diaminodiphenyl ether with terephthalic acid or isophthalic acid), boron fiber, liquid crystal polyester fiber, etc. Among these, glass fiber and carbon fiber are preferred, and glass fiber is more preferred, because they tend to increase the strength (rigidity) and heat resistance of the resulting polyamide resin composition.

[0091] The average fiber diameter (weight average major axis (Dw)) of the reinforcing material (C) is, for example, 1 μm to 50 μm, preferably 5 μm to 30 μm, and more preferably 5 μm to 20 μm. The average fiber length of the reinforcing material (C) is, for example, 500 μm to 10 mm, and preferably 700 μm to 5 mm. In this specification, the term "fiber diameter" refers to the length of the longest line segment (the first line segment) among the line segments connecting opposing edges in the cross section of the fibrous reinforcing material.

[0092] The average fiber length of the reinforcing material (C) 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) The filtered material obtained in 1) above is dispersed in water, and the major and minor diameters (the major diameter is Di and the minor diameter is di. Here, the major diameter refers to the first line segment in the fiber cross section, and the minor diameter refers to the second line segment) and fiber length (Li) of each of 300 randomly selected fibers are measured using an optical microscope (magnification: 50x). The number of fibers with a fiber length of Li is designated as qi, and the weight-average length (Lw) is calculated based on the following formula, which is the average fiber length of the reinforcing material (C). Weight average length (Lw) = (Σqi × Li 2 ) / (Σqi×Li) Similarly, the number of fibers having a major diameter Di is defined as Ri, and the number of fibers having a minor diameter di is defined as ri. The weight average diameters (weight average major diameter Dw, weight average minor diameter dw) are calculated based on the following formula, and these are defined as the average major diameter and average minor diameter of the reinforcing material (C). Weight average major axis (Dw) = (ΣRi × Di 2 ) / (ΣRi×Di) Weight average short diameter (dw)=(Σri×di 2 ) / (Σri×di)

[0093] The reinforcing material (C) may be bundled with a sizing agent. Examples of the sizing agent include acrylic, acrylic / maleic acid-modified, epoxy, urethane, urethane / maleic acid-modified, and urethane / epoxy-modified compounds. The sizing agents may be used alone or in combination. Of these, urethane-based ones are preferred.

[0094] The content of the reinforcing material (C) is preferably 20.0% by mass to 40.0% by mass, and more preferably 25.0% by mass to 35.0% by mass, relative to the total mass of the polyamide resin composition. A content of 20.0% by mass or more can further increase the strength of molded articles of the polyamide resin composition. Furthermore, a content of 40.0% by mass or less can easily reduce the total contact area between the polyamide resin (A) and the reinforcing material. This can easily reduce the interface area between the reinforcing material and the polyamide resin (A), which have different mechanical strengths, thereby reducing stress concentration when pulling up the strand and facilitating the reduction of pellet diameter. That is, a content of 40% by mass or less can reduce the pellet diameter and facilitate the improvement of heating efficiency during melting or softening.

[0095] 1-4.Other ingredients The polyamide resin composition may contain other known components.

[0096] Examples of other components include flame retardant synergists, nucleating agents, lubricants, anti-drip agents, halogen scavengers, colorants, heat stabilizers, corrosion resistance improvers, anti-drip agents, ion scavengers, elastomers (rubbers), antistatic agents, mold release agents, antioxidants (phenols, amines, sulfur compounds, phosphorus compounds, etc.), heat stabilizers other than those mentioned above (lactone compounds, vitamin E compounds, hydroquinones, etc.), light stabilizers (benzotriazoles, triazines, benzophenones, benzoates, hindered amines, oxanilides, etc.), polymers (olefin copolymers such as ethylene-propylene copolymers, ethylene-1-butene copolymers, olefin copolymers such as propylene-1-butene copolymers, polycarbonate, polyacetal, polysulfone, polyphenylene oxide, fluororesin, silicone resin, LCP, etc.).

[0097] (Flame retardant synergist) Any known flame retardant aid can be used as long as it significantly enhances the flame retardant effect when used in combination with the brominated flame retardant (B). Specific examples include antimony compounds such as antimony trioxide, antimony tetraoxide, antimony pentoxide, and sodium antimonate; zinc borates such as 2ZnO·3B2O3, 4ZnO·B2O3·H2O, and 2ZnO·3B2O3·3.5H2O; zinc stannate; zinc phosphate; calcium borate; and calcium molybdate. These aids may be used alone or in combination. Among these, sodium antimonate, zinc borate, zinc phosphate, and zinc stannate are preferred, with sodium antimonate and anhydrous zinc borate (2ZnO·3B2O3) being more preferred.

[0098] The content of the flame retardant aid is preferably 0.5 to 5.0% by mass, and more preferably 1.0 to 3.0% by mass, based on the total mass of the polyamide resin composition.

[0099] (nucleating agent) The nucleating agent can promote the crystallization of the polyamide resin (A), thereby further increasing the tensile strength and elastic modulus of the resin workpiece.

[0100] 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 of two or more.

[0101] 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 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.

[0102] The content of the nucleating agent is preferably 0.1 to 5.0 parts by mass, and more preferably 0.1 to 3.0 parts by mass, relative to the total mass of the polyamide resin composition. When the content of the nucleating agent is within the above range, the crystallinity of the resin member is easily increased sufficiently, and sufficient mechanical strength is easily obtained.

[0103] (lubricant) The lubricant improves the injection flowability of the polyamide resin composition and improves 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.

[0104] The oxycarboxylic acid constituting the oxycarboxylic acid metal salt 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 trovic acid.

[0105] 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.

[0106] 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.

[0107] Examples of the higher fatty acids constituting 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.

[0108] Examples of metals constituting the above higher fatty acid metal salts include calcium, magnesium, barium, lithium, aluminum, zinc, sodium, and potassium.

[0109] Of these, the higher fatty acid metal salts are preferably calcium stearate, magnesium stearate, barium stearate, calcium behenate, sodium montanate, and calcium montanate.

[0110] The content of the lubricant is preferably 0.01% by mass to 1.3% by mass relative to the total mass of the polyamide resin composition. When the content of the lubricant is 0.01% by mass or more, the fluidity during molding tends to be improved, and the appearance of the obtained molded product tends to be improved. When the content of the lubricant is 1.3% by mass or less, gas due to decomposition of the lubricant is unlikely to be generated during molding, and the appearance of the product tends to be good.

[0111] (Anti-drip agent) Anti-drip agents are additives used to prevent resin droplets from forming during combustion tests of molded polyamide resin compositions (e.g., tests according to the UL94 standard (1991)). Examples of anti-drip agents include maleic acid-modified styrene-ethylene-butylene-styrene (SEBS) copolymers and fluororesins.

[0112] (Halogen scavenger) When a halogen-containing compound is used as the flame retardant, the halogen scavenger is preferably contained in the polyamide resin composition. The halogen scavenger can capture halide ions generated when a molded article of the polyamide resin composition containing the halogen-containing compound is burned, thereby suppressing the generation of harmful substances. Examples of halogen scavengers include hydrotalcite.

[0113] 1-5. Pellet diameter of polyamide resin composition The polyamide resin composition according to the present embodiment may be in the form of pellets, preferably in the form of a cylinder or an elliptical cylinder. When the polyamide resin composition is in the form of pellets, the pellet diameter is preferably 1.0 mm to 1.8 mm, more preferably 1.2 mm to 1.8 mm, and even more preferably 1.5 mm to 1.8 mm.

[0114] The pellet diameter of the polyamide resin composition is the average value of pellet diameters obtained by randomly selecting 10 pellets and measuring each one with a ruler, calipers, micrometer, etc. The pellet length of the polyamide resin composition described below is the average value of pellet lengths obtained by randomly selecting 10 pellets and measuring each one with a ruler, calipers, micrometer, etc. The pellet diameter of each pellet is the average value of the minimum diameter (minor diameter in the case of an ellipse) and the maximum diameter (major diameter in the case of an ellipse) of the cross section (e.g., a circular or elliptical cross section), and the pellet length is the maximum length of the pellet in the direction perpendicular to the cross section.

[0115] By setting the pellet diameter of the polyamide resin composition to 1.8 mm or less, the surface area of ​​the polyamide resin composition can be increased, as described above, and the heating efficiency during melting or softening tends to be improved.

[0116] Furthermore, by making the pellet diameter of the polyamide resin composition 1.0 mm or more, the bridging phenomenon occurring when the polyamide resin is not yet sufficiently melted or softened in the early stages of heating is more easily suppressed, and the polyamide resin is more easily fed uniformly into the molding machine, which makes it easier to improve the heating efficiency when melting or softening the polyamide resin.

[0117] 2. Method for producing polyamide resin composition The method for producing the polyamide resin composition according to the present embodiment includes, for example, a melt-mixing step of melt-mixing the polyamide resin (A), the brominated flame retardant (B), the reinforcing material (C), and, if necessary, other components, and may also include, if necessary, a pelletizing step of processing the resulting mixture into pellets using a pelletizer or the like.

[0118] In the melt-mixing step, the components are simultaneously or sequentially charged into a mixing device such as a Henschel mixer, V-blender, tumbler mixer, or ribbon blender, and then melt-kneaded using a single-screw extruder, multi-screw extruder, kneader, Banbury mixer, or the like. In particular, the use of a device with excellent kneading performance, such as a multi-screw extruder, kneader, or Banbury mixer, allows for the production of a high-quality polyamide resin composition in which the components are more uniformly dispersed. Furthermore, other additives, such as antioxidants, can be added at any of these stages as needed.

[0119] The melting temperature during melt-kneading is preferably the melting point (Tm) of the polyamide resin (A) + 10°C or higher and the melting point (Tm) of the polyamide resin (A) + 30°C or lower.

[0120] The screw rotation speed during melt-kneading is preferably 170 rpm to 800 rpm, more preferably 200 rpm to 700 rpm, and even more preferably 300 rpm to 600 rpm. By setting the rotation speed to 170 rpm or higher, it is possible to increase the shear stress applied to the molten polyamide resin composition, thereby facilitating the reduction of the number average particle size of the brominated flame retardant (B). By setting the rotation speed to 800 rpm or lower, it is possible to easily suppress the excessive shear heat generated by melt-kneading, and thus to easily suppress the decomposition of the amide bond in the polyamide resin (A).

[0121] In the pelletizing step, the polyamide resin composition melt-kneaded in the melt-kneading step is extruded in the form of strands from a die having a round or other opening, cooled, and then the strands are taken up and cut into pellets.

[0122] At this time, the pellet diameter can be reduced by uniaxially stretching the strand in the longitudinal direction due to the difference in peripheral speed between the speed of extrusion from the die and the speed of taking up the strand. The pellet diameter can also be controlled by the opening diameter of the die.

[0123] The opening diameter of the die is preferably 2.0 mm to 5.0 mm, and more preferably 3.0 mm to 4.0 mm, in which case the strand can be stably taken up.

[0124] The strand take-up speed is preferably 60 m / min to 120 m / min, and more preferably 60 m / min to 100 m / min. Within this range, the strand can be stably taken up easily.

[0125] The pellet length is preferably 2 mm to 10 mm, more preferably 2 mm to 5 mm. Within this range, pellets can be stably supplied to the plasticizing section (cylinder) during injection molding.

[0126] 3. Molded body The molded article according to this embodiment is obtained by molding the above-described polyamide resin composition.

[0127] 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 according to the present embodiment can be introduced into an injection molding machine whose cylinder temperature is adjusted to a temperature equal to or higher than the melting point of the polyamide resin (A), for example, in the range of 280°C to 350°C, to be in a molten state, and then introduced into a mold having a predetermined shape, thereby producing a molded article.

[0128] The shape of the molded article according to this embodiment is not particularly limited, and may take various shapes depending on the application.

[0129] Examples of applications of the molded article according to 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, molded articles having good heat resistance and flame retardancy can be efficiently molded, and therefore, among these applications, they can be particularly suitably used for electronic device parts.

[0130] The polyamide resin composition according to the present embodiment has high fluidity during molding, and therefore can be suitably used for molded articles having thin-walled portions, such as connectors, etc. More specifically, it can be suitably used for molded articles having thin-walled portions whose thinnest portion is 1 mm or less. [Example]

[0131] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0132] 1. Synthesis / preparation of materials 1-1. Synthesis of polyamide resin (A) <Polyamide resin PA-1 (6T66)> 2515 g (15.1 mol) of terephthalic acid, 2800 g (24.1 mol) of 1,6-diaminohexane, 1325 g (9.0 mol) of adipic acid, 5.7 g of sodium hypophosphite monohydrate, and 554 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 3.01 MPa. After the reaction was continued for 1 hour, the low-order condensate was discharged into the atmosphere through a spray nozzle installed at the bottom of the autoclave and extracted. The extracted low-order condensate was 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.

[0133] Next, this low-order condensate was placed in a tray-type solid-state polymerization reactor, and after nitrogen substitution, the temperature was raised to 220°C over approximately 1 hour and 30 minutes. The low-order condensate was then reacted for 1 hour and cooled to room temperature. Subsequently, polyamide (high condensate) was further melt-polymerized in a twin-screw extruder with a screw diameter of 30 mm and L / D = 36 at a barrel setting temperature of 330°C, a screw rotation speed of 200 rpm, and a resin feed rate of 6 kg / hour to obtain polyamide resin PA-1.

[0134] The resulting polyamide resin PA-1 had an intrinsic viscosity [η] of 0.8 dL / g, a melting point (Tm) of 320°C, a glass transition temperature (Tg) of 95°C, and a heat of fusion (ΔH) of 49 J / g. The composition of the resulting polyamide resin PA-1 was such that the content of terephthalic acid-derived units relative to the total moles of dicarboxylic acid-derived units was 62.5 mol%, the content of adipic acid-derived units was 37.5 mol%, and the content of 1,6-diaminohexane-derived units relative to the total moles of diamine-derived units was 100 mol%. The amount of terminal amino groups in the polyamide resin PA-1 was 113 mmol / kg, and the amount of terminal carboxyl groups was 52 mmol / kg.

[0135] 1-2. Brominated flame retardants (B) 1-2-1. Brominated flame retardants (B-1) with a weight-average molecular weight of 1,000 to 5,000 Brominated polystyrene (Albemarle, HP-3010, bromine content: 68% by mass, weight-average molecular weight (Mw): 4,000, melt mass-flow rate (MFR): 490 g / 10 min) The MFR is a value measured under a load of 1200 g and at a temperature of 270°C in accordance with JIS K7210-1:2014.

[0136] 1-2-2. Brominated flame retardants with a weight-average molecular weight of 100,000 or more (B-2) Brominated polystyrene (Albemarle, HP-7010, bromine content: 68% by mass, weight-average molecular weight (Mw): 226,000, melt mass-flow rate (MFR): 0.34 g / 10 min) The MFR is a value measured under a load of 1200 g and at a temperature of 270°C in accordance with JIS K7210-1:2014.

[0137] 1-3. Reinforcement material (C) Glass fiber (ECS03-615, manufactured by Central Glass Co., Ltd., cross-sectional aspect ratio: 1.0)

[0138] 1-4-1.Flame retardant synergists Sodium antimonate (SA-A, manufactured by Nippon Seiko Co., Ltd.)

[0139] 1-4-2. Nucleating agent Talc (average particle size 6.0 μm)

[0140] 1-4-3. Lubricants Calcium montanate

[0141] 1-4-4. Anti-drip agent m-SEBS (maleated SEBS, manufactured by Asahi Chemicals Corporation, Tuftec M1913)

[0142] 1-4-5. Halogen scavengers Hydrotalcite (NAOX-33, manufactured by Toda Kogyo Co., Ltd.)

[0143] 2. Measurement The physical properties of each of the above resins were measured by the following methods.

[0144] <Polyamide resin melting point (Tm) and 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).

[0145] <Heat of fusion (ΔH)> The heat of fusion (ΔH) of the polyamide resin was determined from the area of ​​the exothermic peak of crystallization during the first temperature rise in accordance with JIS K 7122:2012.

[0146] <Intrinsic viscosity [η]> The intrinsic viscosity [η] of the polyamide resin was calculated by dissolving 0.5 g of the polyamide resin in 50 ml of a 96.5% sulfuric acid solution, measuring the flow time of the resulting solution at 25°C ± 0.05°C using an Ubbelohde viscometer, and then calculating the intrinsic viscosity [η] based on the formula: [η] = ηSP / (C(1 + 0.205ηSP)). [η]: Intrinsic viscosity (dl / g) ηSP: Specific viscosity C: Sample concentration (g / dl) t: Number of seconds for sample solution to flow down (seconds) t0: Number of seconds for blank sulfuric acid to flow (seconds) ηSP=(t-t0) / t0

[0147] <Terminal carboxyl group amount> 30 mg of polyamide resin was dissolved in 0.5 mL of deuterated hexafluoroisopropanol (HFIP) to prepare a sample for NMR measurement. NMR measurement of the sample was performed using a nuclear magnetic resonance spectrometer (ECA-500, JEOL Ltd.). The molecular weight of the polymer was calculated from the peak area derived from hydrogen atoms of each component constituting the polyamide resin in the obtained spectrum. The amount of terminal carboxyl groups ([COOH], unit: mmol / kg) was calculated using the peak area derived from hydrogen atoms specific to the terminal carboxyl groups and the molecular weight obtained above.

[0148] <Amount of terminal amino groups> 1 g of polyamide resin was dissolved in 35 mL of phenol and mixed with 2 mL of methanol to prepare a sample solution. Using thymol blue as an indicator, the sample solution was titrated with 0.01 N hydrochloric acid solution using a potentiometric titrator (Metrohm) from blue to yellow, and the amount of terminal amino groups ([NH2], unit: mmol / kg) was measured.

[0149] 3-1. Preparation of polyamide resin composition of Example 1 The above materials were mixed in a tumbler blender in the composition ratios (units: parts by mass) shown in Table 1, and melt-kneaded using a 30 mmφ vented twin-screw extruder at a cylinder temperature of 300 to 335°C and a screw rotation speed of 400 rpm. The actual temperature of the composition in the cylinder was 350°C due to the influence of shear heat. The kneaded mixture was then extruded into strands using a die with an opening diameter of 3.5 mmφ and cooled in a water bath. The strands were then taken up using a pelletizer, and the maximum take-up speed (m / min) of the pelletizer was set as the upper limit speed at which the strands could be taken up without breaking. The strands were taken up and cut at the maximum take-up speed, thereby obtaining the polyamide resin composition of Example 1.

[0150] 3-2. Preparation of polyamide resin compositions of Example 2 and Comparative Examples 1 to 3 The above materials were changed to the composition ratio (unit: parts by mass) shown in Table 1, the screw rotation speed was set to the rotation speed shown in Table 1, and the maximum take-up speed of the pelletizer was measured in the same manner as above. The pellets were taken up at the maximum take-up speed and cut, thereby obtaining polyamide resin compositions of Example 2 and Comparative Examples 1 to 3.

[0151] 4. Characterization of polyamide resin compositions <Number average particle size of brominated flame retardant (B)> The number average particle diameter of the brominated flame retardant (B) in the polyamide resin composition was measured as follows. The polyamide resin composition was embedded in an epoxy resin, and polished so that the cross section of the embedded polyamide resin composition was exposed. At this time, when the polyamide resin composition contained a fibrous reinforcing material (C), the polyamide resin composition was polished so that the length direction of the fibers of the fibrous reinforcing material (C) was approximately parallel to the cross section exposed by polishing. Thereafter, the exposed cross section of the polyamide resin composition was observed with a scanning electron microscope, and an image was obtained. The flame retardant in the obtained image (magnification 100x, number of images 1) was binarized and extracted, and the circle equivalent diameter (1 pixel = 1 μm, 2000 to 3000 particles) was measured. ·SEM device: JSM-IT700HR / LV (manufactured by JEOL Ltd.) Pretreatment: Resin embedding, mechanical polishing, carbon deposition Conditions: Acceleration voltage 10 kV, backscattered electron image acquisition Image analysis software: Win ROOF 2018 (MITANIcorporation)

[0152] <Pellet diameter> Measure the minor and major diameters of the pellet cross section with a vernier caliper and calculate the average diameter. Measure 10 pellets and calculate the average value.

[0153] Table 1 shows the composition, production conditions, and evaluation results of each polyamide resin composition.

[0154] [Table 1]

[0155] Comparison of Examples 1 and 2 with Comparative Examples 1 to 3 revealed that the pellet size of polyamide resin compositions containing a predetermined amount of brominated flame retardant (B) and having a number average particle size of 1.0 μm to 5.5 μm could be controlled. Furthermore, the use of these pelletized polyamide resin compositions improved the heating efficiency during melting or softening, enabling uniform melting or softening in a short time. [Industrial Applicability]

[0156] The polyamide resin composition of the present invention contains a high-melting-point polyamide resin and a flame retardant, and can improve heating efficiency during melting or softening. Therefore, the present invention is useful in fields where heat resistance and flame retardancy are required, such as the field of electronic components.

Claims

1. a polyamide resin (A) having a melting point of 280°C or higher as measured by a differential scanning calorimeter (DSC); a brominated flame retardant (B); A reinforcing material (C); A polyamide resin composition comprising: the content of the brominated flame retardant (B) is 5.0% by mass to 30.0% by mass relative to the total mass of the polyamide resin composition; In the polyamide resin composition, the number average particle size of the brominated flame retardant (B) is 1.0 μm to 5.5 μm. Polyamide resin composition.

2. The content of the brominated flame retardant (B) is 5.0% by mass to 20.0% by mass relative to the total mass of the polyamide resin composition. The polyamide resin composition according to claim 1.

3. The brominated flame retardant (B) includes a brominated flame retardant (B-1) having a weight average molecular weight of 1,000 to 5,000. The polyamide resin composition according to claim 1.

4. The brominated flame retardant (B) further contains a brominated flame retardant (B-2) having a weight average molecular weight of 100,000 or more. The polyamide resin composition according to claim 3.

5. The 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 a terephthalic acid-derived component unit, The diamine-derived component unit (Ab) includes a 1,6-diaminohexane-derived component unit. The polyamide resin composition according to claim 1.

6. a polyamide resin (A) having a melting point of 280°C or higher as measured by a differential scanning calorimeter (DSC); a brominated flame retardant (B); A reinforcing material (C); A pelletized polyamide resin composition comprising: the content of the brominated flame retardant (B) is 5.0% by mass to 30.0% by mass relative to the total mass of the polyamide resin composition; The pellet diameter of the polyamide resin composition is 1.0 mm to 1.8 mm. Polyamide resin composition.

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

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