Flame-retardant polyamide composition, process for its preparation and use

Abstract

The present application relates to a kind of flame-retardant polyamide compositions and its preparation method and application.The flame-retardant polyamide compositions, including the following weight parts of component:PA6T / 66 resin 28~70 parts, PA6I / 6T resin 5~25 parts, flame retardant 10~21 parts.The flame-retardant polyamide compositions of the present application has good stability of mechanical properties (tensile strength) in long-period heat retention injection molding, and can be applied to long-time molding cycle large product in the field of automobile industry.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a flame-retardant polyamide composition, its preparation method, and its application. Background Technology

[0002] Semi-aromatic polyamides (PPA) combine the excellent properties of aromatic polyamides with the good molding and processability of aliphatic polyamides. After years of development, they have become one of the most important types of specialty engineering plastics. Through flame-retardant modification, they are widely used in electronics, automotive, and other industries. Currently, common PPA varieties on the market include PA4T, PA6T, PA9T, PA10T, PA11T, and PA12T. Among them, PA6T has the highest market share among semi-aromatic polyamide resins due to its readily available raw materials, excellent performance, and high cost-effectiveness.

[0003] The melting point of homopolymer PA6T exceeds its decomposition temperature. To lower its melting point, it is generally necessary to copolymerize it by introducing a third monomer, such as adipic acid, to obtain PA6T / 66.

[0004] While polymerizing the 66-segment can lower the resin's melting point, the 66-segment also makes PA6T / 66 prone to decomposition in the molten state. This leads to a serious problem with PA6T / 66 during injection molding: large parts (such as busbars and coil frames for new energy vehicles) have long molding cycles, and some of the melt remains in the injection molding machine barrel for extended periods, resulting in significant decomposition. As the injection modulus increases, the mechanical properties of the parts gradually deteriorate, failing to meet product design requirements. This problem makes PA6T / 66 material unsuitable for the long molding cycles of large parts in the automotive industry.

[0005] To address these issues, a large amount of antioxidant is typically added to prevent significant decomposition of PA6T / 66 in the molten state over a long period. However, this approach significantly degrades the initial mechanical properties of the material.

[0006] Therefore, new technologies need to be developed to solve the problem that the current PA6T / 66 material is difficult to adapt to injection molding with long molding cycles. Summary of the Invention

[0007] The primary objective of this invention is to overcome the problems existing in the current PA6T / 66 material and to provide a flame-retardant polyamide composition.

[0008] A further object of the present invention is to provide a method for preparing the above-mentioned flame-retardant polyamide composition.

[0009] A further object of the present invention is to provide the application of the above-described flame-retardant polyamide composition in the preparation of automotive parts.

[0010] The above-mentioned objective of the present invention is achieved through the following technical solution: A flame-retardant polyamide composition comprising the following components in parts by weight: 28-70 parts of PA6T / 66 resin 5-25 parts of PA6I / 6T resin 10-21 parts flame retardant; The flame retardant is at least one of phosphorus-based flame retardants or bromine-based flame retardants; the phosphorus-based flame retardant is at least one of organic phosphonates or phosphate esters. In the PA6I / 6T resin, the molar ratio of 6I repeating units to 6T repeating units is (6~8.6):(1.4~4).

[0011] This invention improves the retention rate of mechanical properties (tensile strength) of a flame-retardant polyamide composition during long-cycle injection molding by adding PA6I / 6T resin with a specific molar ratio of repeating units to the composition and controlling the amount of PA6I / 6T resin. This makes the composition suitable for manufacturing large parts with long molding cycles in the automotive industry. The principle is as follows: by adding a certain amount of PA6I / 6T resin to the system, the copolymer segments in the PA6T / 66 resin are disrupted by amide exchange during processing, effectively shortening the 66 segments in the PA6T / 66 resin. This prevents significant decomposition of the PA6T / 66 resin in the molten state during long-cycle injection molding, thus ensuring that the flame-retardant polyamide composition maintains good mechanical properties after long-cycle injection molding.

[0012] The inventors discovered that when the proportion of 6I repeating units in PA6I / 6T resin is too high, PA6I / 6T resin itself is prone to decomposition at high temperatures; when the proportion of 6I repeating units in PA6I / 6T resin is too low, the amide exchange with PA6T / 66 copolymer is weak. Neither of these situations can effectively maintain the good mechanical properties of the flame-retardant polyamide composition during long-cycle residence injection molding.

[0013] When the amount of PA6I / 6T resin is too small, the amide exchange with PA6T / 66 resin is weak; PA6I / 6T resin is more easily decomposed than PA6T / 66 resin. When the amount of PA6I / 6T resin is too large, more resin decomposes in the flame-retardant polyamide composition. Neither of these situations can effectively maintain the good mechanical properties of the flame-retardant polyamide composition during long-term residence injection molding.

[0014] Furthermore, compared to methods that add large amounts of antioxidants, PA6I / 6T resin itself has good strength and toughness, so it has minimal impact on the mechanical properties of the flame-retardant polyamide composition, thus giving the flame-retardant polyamide composition good initial mechanical properties. The inventors discovered that the type of flame retardant also has a significant impact on the retention of mechanical properties of flame-retardant polyamide compositions during long-cycle dwell injection molding. By selecting specific flame retardants, the retention rate of mechanical properties of flame-retardant polyamide compositions during long-cycle dwell injection molding can be avoided from decreasing significantly. The reason for this may be that specific flame retardants can prevent the formation of strong acidic substances in the melt due to high-temperature degradation, which would lead to resin decomposition.

[0015] In this invention, the sum of the masses of PA6T / 66 resin and PA6I / 6T resin accounts for at least 40 wt% of the flame-retardant polyamide composition.

[0016] The specific amounts of PA6T / 66 resin can be 28, 30, 32, 35, 38, 42, 40, 45, 48, 50, 55, 58, 60, 62, 65, 68, or 70 parts by weight, or any range formed by any two of the above values; the specific amounts of PA6I / 6T resin can be 5, 8, 10, 12, 15, 18, 20, 22, or 25 parts by weight, or any range formed by any two of the above values; the specific amounts of flame retardant can be 10, 12, 15, 18, or 20 parts by weight, or any range formed by any two of the above values.

[0017] Preferably, the mass ratio of PA6T / 66 resin to PA6I / 6T resin is 31~48:5~22; more preferably, it is 36~48:5~17; and even more preferably, it is 36~43:10~17. By adjusting the mass ratio of PA6T / 66 resin to PA6I / 6T resin, the resulting flame-retardant polyamide composition can exhibit better mechanical property stability during long-cycle heat retention injection molding.

[0018] Preferably, the relative viscosity of the PA6T / 66 resin is 2.0 to 2.4; specifically, it can be 2.0, 2.1, 2.2, 2.3, 2.4 or any two of the above values ​​forming a range.

[0019] In this invention, the relative viscosity of the PA6T / 66 resin can be measured according to the test standard GBT 10247-2008-2.

[0020] Preferably, in the PA6T / 66 resin, the molar ratio of 6T repeating units to 66 repeating units is (5-6):(4-5).

[0021] In this invention, the molar ratio of 6T repeating units to 66 repeating units in PA6T / 66 resin can be determined by NMR. The specific process can be as follows: 20 mg of PA6T / 66 resin was dissolved in 0.6 mL of a mixed solvent of hexafluoroisopropanol and deuterated chloroform (volume ratio of hexafluoroisopropanol to deuterated chloroform: 3:1). The 13C-NMR was then measured at room temperature using a Bruker AV 500 nuclear magnetic resonance spectrometer. In the 6T repeating unit, the carbon atom adjacent to the carbonyl group of the benzene ring appeared near 137.51 ppm; in the 66 repeating unit, the carbon atom adjacent to the carbonyl group of the adipic acid appeared near 36.63 ppm. Therefore, the molar ratio of the 6T and 66 repeating units can be expressed as the ratio of the integrated areas of the peaks at 137.51 ppm and 36.63 ppm.

[0022] In this invention, PA6T / 66 resin can be either commercially available or manufactured in-house.

[0023] Preferably, the process of self-producing PA6T / 66 resin can be as follows: hexamethylenediamine, terephthalic acid and adipic acid first undergo a salt formation reaction to obtain an amide salt; the raw materials including the amide salt then undergo a polycondensation reaction to obtain the PA6T / 66 resin.

[0024] More preferably, the salt-forming reaction is carried out at a temperature of 130-150°C for 4-6 hours.

[0025] More preferably, the molar ratio of p-hexamethylenediamine, terephthalic acid and adipic acid is 5:(2.5~3):(2~2.5).

[0026] More preferably, the reaction conditions for the polycondensation reaction are: inert atmosphere, 2.0~3.0 MPa, 250~280℃, and 10~20 hours.

[0027] More preferably, the polycondensation reaction is carried out in the presence of a catalyst.

[0028] More preferably, the mass of the catalyst is 0.05 to 0.2% of the mass of the amide salt.

[0029] More preferably, the catalyst includes, but is not limited to, sodium hypophosphite.

[0030] More preferably, the raw material further includes a capping agent.

[0031] More preferably, the molar amount of the capping agent is 1 to 3% of the molar amount of the amide salt.

[0032] More preferably, the capping agent includes, but is not limited to, benzoic acid.

[0033] More preferably, the raw material also includes water.

[0034] More preferably, the water accounts for 18-25% of the mass of the raw material.

[0035] Preferably, the relative viscosity of the PA6I / 6T resin is 1.8 to 2.2; specifically, it can be 1.8, 1.9, 2.0, 2.1, 2.2 or any two of the above values ​​within a range.

[0036] In this invention, the relative viscosity of the PA6I / 6T resin can be measured according to the test standard GBT 10247-2008-2.

[0037] In this invention, the molar ratio of 6I repeating units to 6T repeating units in PA6I / 6T resin can be determined by nuclear magnetic resonance (NMR). The specific process can be as follows: 20 mg of PA6I / 6T resin was dissolved in 0.6 mL of a mixed solvent of hexafluoroisopropanol and deuterated chloroform (volume ratio of hexafluoroisopropanol to deuterated chloroform: 3:1), and then 13C-NMR was measured at room temperature using a Bruker AV 500 nuclear magnetic resonance spectrometer. In the 6I repeating unit, the carbon atom adjacent to the carbonyl group of the benzene ring appeared around 134.86 ppm, and in the 6T repeating unit, the carbon atom adjacent to the carbonyl group of the benzene ring appeared around 137.51 ppm. Therefore, the molar ratio of the 6I and 6T repeating units can be expressed as the ratio of the integrated areas of the peaks at 134.86 ppm and 137.51 ppm.

[0038] In this invention, the molar ratio of 6I repeating units to 6T repeating units in the PA6I / 6T resin can specifically be 6.0:4.0, 6.2:3.8, 6.5:3.5, 6.8:3.2, 7.0:3.0, 7.2:2.8, 7.5:2.5, 7.8:2.2, 8.0:2.0, 8.2:1.8, 8.5:1.5, or any range formed by any two of the above values.

[0039] Preferably, in the PA6I / 6T resin, the molar ratio of 6I repeating units to 6T repeating units is (6.5~8.5):(1.5~3.5). More preferably, in the PA6I / 6T resin, the molar ratio of 6I repeating units to 6T repeating units is (7.5~8.5):(1.5~2.5). Even more preferably, in the PA6I / 6T resin, the molar ratio of 6I repeating units to 6T repeating units is (8.0~8.5):(1.5~2.0).

[0040] By adjusting the molar ratio of 6I repeating units and 6T repeating units within a certain range, the obtained flame-retardant polyamide composition exhibits better mechanical property stability during long-cycle thermal hysteresis injection molding.

[0041] In this invention, PA6I / 6T resin can be either commercially available or manufactured in-house.

[0042] Preferably, the process of self-producing PA6I / 6T resin can be as follows: p-hexamethylenediamine, isophthalic acid and terephthalic acid first undergo a salt formation reaction to obtain an amide salt; the raw materials including the amide salt then undergo a polycondensation reaction to obtain the PA6I / 6T resin.

[0043] More preferably, the salt-forming reaction is carried out at a temperature of 130-150°C for 4-6 hours.

[0044] More preferably, the molar ratio of p-hexamethylenediamine, isophthalic acid and terephthalic acid is 10:(6~8.6):(1.4~4).

[0045] More preferably, the reaction conditions for the polycondensation reaction are: inert atmosphere, 2.0~3.0 MPa, 250~280℃, and 10~20 hours.

[0046] More preferably, the polycondensation reaction is carried out in the presence of a catalyst.

[0047] More preferably, the mass of the catalyst is 0.05 to 0.2% of the mass of the amide salt.

[0048] More preferably, the catalyst includes, but is not limited to, sodium hypophosphite.

[0049] More preferably, the raw material further includes a capping agent.

[0050] More preferably, the molar amount of the capping agent is 1 to 3% of the molar amount of the amide salt.

[0051] More preferably, the capping agent includes, but is not limited to, benzoic acid.

[0052] More preferably, the raw material also includes water.

[0053] More preferably, the water accounts for 18-25% of the mass of the raw material.

[0054] To improve the (initial) mechanical properties of the flame-retardant polyamide composition, reinforcing fillers may also be added to the flame-retardant polyamide composition of the present invention.

[0055] Preferably, the flame-retardant polyamide composition further includes 15 to 50 parts of reinforcing filler; specifically, it can be 15, 20, 23, 25, 28, 30, 32, 35, 38, 42, 40, 45, 48, 50 or any two of the above values ​​forming a range.

[0056] More preferably, the reinforcing filler includes, but is not limited to, at least one of fiber fillers, sheet fillers, and granular fillers.

[0057] More preferably, the fiber filler includes, but is not limited to, at least one of glass fiber, carbon fiber, or graphite fiber.

[0058] More preferably, the fiber filler is a round fiber.

[0059] More preferably, the average diameter of the cross-section of the circular fiber is 5~15μm and the average length is 2~5mm.

[0060] More preferably, the sheet-like filler is at least one selected from kaolin, montmorillonite, mica, bentonite, talc, and mica.

[0061] More preferably, the granular filler is at least one of calcium carbonate, quartz, feldspar, zeolite, and perlite.

[0062] More preferably, the average particle size of the sheet-like filler and the granular filler is independently 1~30μm.

[0063] Preferably, the organic phosphonate is an alkyl phosphonate; more preferably, the alkyl phosphonate is a dialkyl phosphonate; even more preferably, the dialkyl phosphonate is at least one of dimethyl phosphonate, diethyl phosphonate, methyl ethyl phosphonate, and ethylhexyl phosphonate; and even more preferably, the dialkyl phosphonate is at least one of aluminum diethyl phosphonate and sodium diethyl phosphonate.

[0064] Preferably, the phosphate ester flame retardant is at least one of triphenyl phosphate, resorcinol bis(diphenyl phosphate), and bisphenol A bis(diphenyl phosphate).

[0065] More preferably, the brominated flame retardant is at least one selected from brominated epoxy, brominated polystyrene, brominated polycarbonate, and decabromodiphenyl ethane.

[0066] Preferably, the flame-retardant polyamide composition further includes 0-2 parts of other additives.

[0067] More preferably, the other additives include, but are not limited to, at least one of lubricants or antioxidants.

[0068] Typically, the amount of lubricant used is 0.1 to 1 part, and the amount of antioxidant used is 0.1 to 1 part.

[0069] More preferably, the lubricant includes, but is not limited to, at least one of rice bran wax, low-density polyethylene, silicone oil, or stearate.

[0070] More preferably, the antioxidant includes, but is not limited to, at least one of phenolic antioxidants, amine antioxidants, or sulfur antioxidants.

[0071] The preparation method of the above flame-retardant polyamide composition includes the following steps: The components are mixed, melt-extruded, and granulated to obtain the flame-retardant polyamide composition.

[0072] Preferably, the temperature of the melt extrusion is 150~340℃; the screw length-to-diameter ratio of the extruder for the melt extrusion is 40~55:1, and the screw speed is 50~250r / min.

[0073] The application of the above-mentioned flame-retardant polyamide composition in the preparation of automotive parts is also within the scope of protection of this invention.

[0074] An automotive component is made from the above-mentioned flame-retardant polyamide composition.

[0075] Preferably, the automotive component is a busbar, coil frame, battery pack housing, connector, etc., in a new energy vehicle.

[0076] Compared with the prior art, the beneficial effects of the present invention are: The flame-retardant polyamide composition of the present invention exhibits good stability of mechanical properties (tensile strength) during long-cycle thermal hysteresis injection molding, making it suitable for large parts with long molding cycles in the automotive industry. Furthermore, compared to methods involving the addition of large amounts of antioxidants, the PA6I / 6T resin itself possesses good strength and toughness, thus having minimal impact on the mechanical properties of the flame-retardant polyamide composition, resulting in excellent initial mechanical properties. Detailed Implementation

[0077] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0078] The reagents used in the various embodiments and comparative examples of this invention are described below: I. PA6T / 66 PA6T / 66-1: Homemade, method as follows: (1) The amide salt was obtained by reacting p-hexamethylenediamine, terephthalic acid and adipic acid at 140℃ for 5 h; wherein the molar ratio of hexamethylenediamine, terephthalic acid and adipic acid was 5:2.5:2.5; (2) The amide salt, catalyst (sodium hypophosphite), end-capping agent (benzoic acid), and water were mixed and added to a reactor under a nitrogen atmosphere and a pressure of 2.5 MPa. The mixture was reacted at 260°C for 12 h to obtain PA6T / 66-1. The relative viscosity of PA6T / 66-1 was 2.12, and the molar ratio of 6T repeating units to 66 repeating units was 5:5. The mass of the catalyst was 0.1 wt% of the amide salt, the molar amount of the end-capping agent was 2% of the molar amount of the amide salt, and the mass of water was 20 wt% of the total mass of the raw materials (the raw materials refer to water, end-capping agent, and amide salt). PA6T / 66-2: Self-made, the method differs from PA6T / 66-1 in that: in step (1), the molar ratio of hexamethylenediamine, terephthalic acid and adipic acid is 5:3:2; the relative viscosity of PA6T / 66-2 is 2.18, and the molar ratio of 6T repeating unit and 66 repeating unit is 3:2; PA6T / 66-3: self-made, the method is different from PA6T / 66-1 in that: in step (2), the reaction time is 18h; the relative viscosity of PA6T / 66-3 is 2.35, and the molar ratio of 6T repeating unit and 66 repeating unit is 5:5; II. PA6I / 6T PA6I / 6T-1: Self-made, the method differs from PA6T / 66-1 in that: in step (1), the raw materials are adjusted to hexamethylenediamine, isophthalic acid and terephthalic acid, with a molar ratio of 10:8.5:1.5. The relative viscosity of PA6I / 6T-1 is 1.98, and the molar ratio of 6I repeating unit and 6T repeating unit is 8.5:1.5; PA6I / 6T-2: Self-made, the method differs from PA6I / 6T-1 in that: in step (1), the molar ratio of hexamethylenediamine, isophthalic acid and terephthalic acid is 10:8:2. The relative viscosity of PA6I / 6T-2 is 2.01, and the molar ratio of 6I repeating unit and 6T repeating unit is 8:2; PA6I / 6T-3: Self-made, the method differs from PA6I / 6T-1 in that: in step (1), the molar ratio of hexamethylenediamine, isophthalic acid and terephthalic acid is 10:7.5:2.5. The relative viscosity of PA6I / 6T-3 is 2.01, and the molar ratio of 6I repeating unit and 6T repeating unit is 7.5:2.5; PA6I / 6T-4: Self-made, the method differs from PA6I / 6T-1 in that: in step (1), the molar ratio of hexamethylenediamine, isophthalic acid and terephthalic acid is 10:6.5:3.5. The relative viscosity of PA6I / 6T-4 is 2.02, and the molar ratio of 6I repeating unit and 6T repeating unit is 6.5:3.5; PA6I / 6T-5: Self-made, the method differs from PA6I / 6T-2 in that: in step (2), the reaction time is 16h. The relative viscosity of PA6I / 6T-5 is 2.18, and the molar ratio of 6I repeating units to 6T repeating units is 8:2; PA6I / 6T-6: Self-made, the method differs from PA6I / 6T-1 in that: in step (1), the molar ratio of hexamethylenediamine, isophthalic acid and terephthalic acid is 10:5:5. The relative viscosity of PA6I / 6T-6 is 1.97, and the molar ratio of 6I repeating unit and 6T repeating unit is 5:5; PA6I / 6T-7: Self-made, the method differs from PA6I / 6T-1 in that: in step (1), the molar ratio of hexamethylenediamine, isophthalic acid and terephthalic acid is 10:9:1. The relative viscosity of PA6I / 6T-7 is 2.02, and the molar ratio of 6I repeating unit and 6T repeating unit is 9:1; PA6I / 6T-A: PA6I / 6T, Selar PA 3426, manufactured by DuPont, with a molar ratio of 7:3 between the 6I repeating unit and the 6T repeating unit; III. Other reagents Reinforcing filler: Glass fiber, Chongqing International Composite Materials, ECS301HP-3-H, with an average length of 3mm and an average cross-sectional diameter of 10μm; Flame retardant 1#: aluminum diethylphosphonate, purchased from Clariant Exolit OP 1230 flame retardant; Flame retardant #2: Triphenyl phosphate, WSFR-TPP, Zhejiang Wansheng Technology; Flame retardant #3: Brominated polystyrene, Xurui SR-3010; Flame retardant 4#: Brominated polycarbonate, SABIC PC 105B; Flame retardant #5: Red phosphorus, purchased from Tongcheng Xinde FR9950T; Flame retardant 6#: melamine polyphosphate, purchased from BUDIT 3141 in Budenheim, Germany; Other additives #1: Antioxidant, commercially available, RIANOX 1098; Other additives #2: Lubricant, Clariant, LICOCARE RBW 360.

[0079] Unless otherwise specified, all components used in the parallel examples and comparative examples (e.g., reinforcing fillers, other additives 1#, other additives 2#) are the same commercially available products.

[0080] The flame-retardant polyamide compositions of the embodiments and comparative examples of the present invention were prepared by the following method: (1) Weigh each component according to the proportion, and put all components except the reinforcing filler and flame retardant into the high-speed mixer and mix them evenly to obtain a mixture.

[0081] (2) The mixture is fed into the main feed port of a twin-screw extruder, the reinforcing filler is added from the first side feed port of the twin-screw extruder, and the flame retardant is added from the second side feed port of the twin-screw extruder. After mixing, melting, homogenizing, extrusion and granulation, a flame-retardant polyamide composition is obtained. The extruder temperature is set in the following order for each zone: 150℃, 310℃, 330℃, 320℃, 270℃, 260℃, 280℃, 300℃, and 310℃. The rotation speed is 80 r / min, and the screw length-to-diameter ratio is 46:1.

[0082] The flame-retardant polyamide compositions provided in the embodiments and comparative examples of this invention were subjected to performance testing according to the following test methods: The flame-retardant polyamide composition was subjected to heat retention injection molding: the injection temperature was 325℃, the residence time between adjacent molds was 3 minutes, and 5 molds were continuously injected. The tensile strength of the specimens from the 1st and 5th molds was tested according to ISO 527-1 / -2:2012. The tensile strength of the specimen from the 1st mold was used as the initial tensile strength. The tensile strength retention rate was obtained by dividing the tensile strength of the specimen from the 5th mold by the tensile strength of the specimen from the 1st mold. A higher tensile strength retention rate indicates that the flame-retardant polyamide composition is more suitable for injection molding with long molding cycles.

[0083] Examples 1-16 Examples 1-16 provide a series of flame-retardant polyamide compositions, the formulations of which are shown in Table 1.

[0084] Table 1. Formulations (parts by weight) for Examples 1-16

[0085] Continued from Table 1

[0086] Comparative Examples 1-8 Comparative Examples 1-8 provide a series of flame-retardant polyamide compositions, the formulations of which are shown in Table 2.

[0087] Table 2 Formulations (parts by weight) for Comparative Examples 1-8

[0088] The properties of the flame-retardant polyamide compositions of each embodiment and comparative example were determined according to the test methods mentioned above, and the test results are shown in Table 3.

[0089] Table 3 Performance test results of the flame-retardant polyamide compositions of each example and comparative example

[0090] As can be seen from Table 3: The tensile strength (initial tensile strength) of the first injection molded samples of the flame-retardant polyamide compositions in Examples 1-16 were all 158 MPa or higher, and the tensile strength retention rate of the fifth injection molded samples was all 88% or higher. This indicates that the flame-retardant polyamide compositions of the present invention can maintain good tensile strength in long-cycle thermal retention injection molding and are suitable for preparing large parts with long molding cycles in the automotive industry.

[0091] Comparative Example 1 did not add PA6I / 6T resin and replaced it with an equal amount of PA6T / 66; Comparative Example 2 added PA6I / 6T resin with too low 6I repeating unit content; Comparative Example 3 added PA6I / 6T resin with too high 6I repeating unit content; Comparative Examples 4 and 6 added too much PA6I / 6T resin; Comparative Example 5 added too little PA6I / 6T resin. All of these resulted in the flame-retardant polyamide compositions having difficulty maintaining good tensile strength during long-cycle heat retention injection molding. Furthermore, the initial tensile strength of the flame-retardant polyamide compositions of Comparative Examples 2, 4, and 6 was also relatively low.

[0092] The flame retardants used in Comparative Examples 7 and 8 were unsuitable, which made it difficult to maintain good tensile strength of the flame-retardant polyamide compositions during long-cycle thermal hysteresis injection molding.

[0093] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A flame-retardant polyamide composition, characterized in that, The components include the following parts by weight: 28-70 parts of PA6T / 66 resin 5-25 parts of PA6I / 6T resin 10-21 parts flame retardant; The flame retardant is at least one of phosphorus-based flame retardants or bromine-based flame retardants; the phosphorus-based flame retardant is at least one of organic phosphonates or phosphate esters. In the PA6I / 6T resin, the molar ratio of 6I repeating units to 6T repeating units is (6~8.6):(1.4~4).

2. The flame-retardant polyamide composition according to claim 1, characterized in that, The mass ratio of PA6T / 66 resin to PA6I / 6T resin is (31~48):(5~22).

3. The flame-retardant polyamide composition according to claim 1, characterized in that, The relative viscosity of the PA6T / 66 resin is 2.0~2.4; And / or, The relative viscosity of the PA6I / 6T resin is 1.8~2.

2.

4. The flame-retardant polyamide composition according to claim 1, characterized in that, In the PA6I / 6T resin, the molar ratio of 6I repeating units to 6T repeating units is (6.5~8.5):(1.5~3.5); preferably (7.5~8.5):(1.5~2.5), and more preferably (8.0~8.5):(1.5~2.0).

5. The flame-retardant polyamide composition according to claim 1, characterized in that, The organic phosphonate is an alkyl phosphonate, preferably a dialkyl phosphonate, more preferably at least one of dimethyl phosphonate, diethyl phosphonate, methyl ethyl phosphonate, and ethylhexyl phosphonate, and even more preferably at least one of aluminum diethyl phosphonate and sodium diethyl phosphonate. And / or, The phosphate ester flame retardant is at least one of triphenyl phosphate, resorcinol bis(diphenyl phosphate), and bisphenol A bis(diphenyl phosphate); And / or, The brominated flame retardant is at least one of brominated epoxy, brominated polystyrene, brominated polycarbonate, and decabromodiphenyl ethane.

6. The flame-retardant polyamide composition according to claim 1, characterized in that, The flame-retardant polyamide composition further includes 15-50 parts of reinforcing filler and 0-2 parts of other additives.

7. A method for preparing the flame-retardant polyamide composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: The components are mixed, melt-extruded, and granulated to obtain the flame-retardant polyamide composition.

8. The use of the flame-retardant polyamide composition according to any one of claims 1 to 6 in the preparation of automotive parts.

9. An automotive component, characterized in that, It is prepared by any of the flame-retardant polyamide compositions according to claims 1 to 6.

10. The automotive component according to claim 9, characterized in that, The automotive components are busbars, coil frames, battery pack housings, or connectors.

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