High-strength low-etch polyamide composition and method for producing the same

Abstract

The application discloses a kind of high-strength low-etch polyamide compositions and preparation method thereof, by following by weight parts of raw materials composition: polyamide resin 50-55%;Filler 30-40%;Flame retardant 7-9%;Synergistic flame retardant 1-4%;Antioxidant 0.01-1%;Processing aid 0-2%.The beneficial effects of the application include: by optimizing the formula design of flame retardant and synergistic flame retardant, significantly improve the flame retardant efficiency, under the same flame retardant effect, the amount of flame retardant is lower than traditional phosphorus-nitrogen complex system, and the material mechanical property is more excellent;Selected flame retardant has not easy to precipitate and low corrosion characteristics, effectively solve the corrosion problem of metal conductor when nylon material contacts metal due to corrosive, current and environmental factors, thereby expanding the application in metal insert injection molding parts;At the same time, the synergistic effect of low addition amount of flame retardant and antioxidant gives material wide processing window, combined with high mechanical property and low corrosiveness, so that the polyamide composition has wide application prospect in the field of automobile, electronic and electrical equipment.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a high-strength, low-corrosion polyamide composition and its preparation method. Background Technology

[0002] Polyamide (nylon), as a high-performance engineering plastic, is renowned for its excellent mechanical strength, superior wear resistance, good chemical corrosion resistance, and efficient self-lubricating properties, and is widely used in automotive manufacturing, electronics, and mechanical engineering. However, its inherent hygroscopicity can lead to reduced dimensional stability, and its poor weather resistance makes it prone to oxidation and discoloration with long-term exposure. Furthermore, its inherently insufficient flame retardant properties significantly limit its application in harsh environments such as high temperature, high humidity, or areas with open flame risks. To address these limitations, modification techniques have become a key breakthrough: blending modification can effectively enhance the mechanical properties of the material; filler reinforcement (such as the introduction of glass fiber) can significantly improve heat resistance and dimensional stability; nanocomposite technology further optimizes electrical conductivity and mechanical strength; and in particular, by adding specific flame retardants, the flame retardant properties of nylon can be significantly improved, overcoming its flammability. These synergistic modification techniques have collectively expanded the application potential of nylon in precision components of electronic devices, critical automotive parts, and other applications requiring high flame retardancy and long-term stability.

[0003] Flame retardant modification of nylon mainly relies on additive flame retardants, which can be divided into four categories: halogenated flame retardants possess high flame retardant efficiency, but release toxic gases at high temperatures and corrode processing equipment; phosphorus-based flame retardants have excellent environmental performance, but easily release acidic substances, leading to material degradation; nitrogen-based flame retardants have low toxicity and high thermal stability, but the addition amount usually needs to exceed 20%, resulting in a significant decrease in the material's mechanical properties; inorganic flame retardants are environmentally friendly and low in cost, however, high filler ratios severely degrade the material's processing fluidity and toughness. These technical shortcomings—including environmental hazards, equipment corrosion risks, loss of mechanical strength, and reduced processing adaptability—limit the reliable application of flame-retardant nylon in electronics, automotive, and other fields. Therefore, developing flame-retardant nylon materials that combine high flame retardant efficiency, low corrosion, and excellent mechanical properties has become a key technological focus that the industry urgently needs to overcome.

[0004] For example, Chinese patent CN202211722762.3 discloses a low-electrochemical-corrosion flame-retardant polyamide composition and its preparation method. By introducing a novel high-heat-resistant structural flame retardant through formulation design, the corrosion of polyamide materials by flame retardant degradation during processing is significantly reduced, effectively overcoming the defects of low temperature resistance and strong corrosion of phosphorus-nitrogen system. At the same time, the synergistic effect of molecular sieve and acid absorbent is used to reduce the residue of small molecules in processing, further inhibiting material corrosion.

[0005] In addition, Chinese patent CN202211722745.X discloses a high-strength, low-exudation halogen-free flame-retardant polyamide composition and its preparation method. By introducing a novel structural flame retardant through formulation design, the flame retardant efficiency is improved by balancing the char layer thickness and flowability during combustion. At the same time, a modified synergist is used, which works synergistically with the flame retardant to further enhance efficiency. Furthermore, surface treatment is used to improve compatibility with polyamide resin and avoid the risk of exudation.

[0006] For example, Chinese patent CN202511250698.7 discloses a composite polyamide composite material modified with a composite intumescent flame retardant and its preparation method. The composite polyamide composite material modified with the composite intumescent flame retardant can significantly improve the limiting oxygen index and fire resistance rating with a low addition amount of the composite intumescent flame retardant, without affecting the mechanical properties of the polyamide material.

[0007] The aforementioned patents focus primarily on the flame-retardant properties of nylon materials, while research on low-additive, low-corrosion flame-retardant systems is relatively lacking. However, such properties are crucial for the practical application of flame-retardant nylon. Summary of the Invention

[0008] To fill a technological gap, this invention provides a high-strength, low-corrosion polyamide composition and its preparation method. The high-strength, low-corrosion polyamide composition of this invention solves the corrosion problem caused by current and environment when polyamide materials come into contact with metal conductors by optimizing the formulation of flame retardants and synergistic flame retardants, thus expanding the application of metal inserts in injection molding. At the same time, by utilizing the low addition amount of flame retardants and the synergistic effect of antioxidants, the material is given a wide processing window and can be applied in the fields of automobiles, electronics and electrical appliances.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A high-strength, low-corrosion polyamide composition, comprising the following raw materials by weight percentage of the total composition:

[0011] Polyamide resin 50-55%;

[0012] Filler 30-40%;

[0013] Flame retardant 7-9%;

[0014] Synergistic flame retardant 1-4%, preferably 3%;

[0015] Antioxidant 0.01-1%;

[0016] Processing aids 0-2%.

[0017] The flame retardant is a combination of phosphorus-based flame retardant A and phosphorus-based flame retardant B, with a weight ratio of 1:1 to 4:1.

[0018] The synergistic flame retardant is 1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, with a weight ratio of 2:1 to 9:1.

[0019] The present invention is further configured such that the polyamide resin can be one or more of PA6T (Nylon 6T), PA9T (Nylon 9T), PA10T (Nylon 10T), PA10T / X (poly(decanediamine terephthalamide / copolymer, where X represents a comonomer, such as hexamethylenediamine), PA46 (Nylon 46), PA4T (Nylon 4T), PA5T (Nylon 5T), PA5T / X (poly(pentanediamine terephthalamide / copolymer, where X represents a comonomer), PA6 (Nylon 6), PA56 (Nylon 56), PA66 (Nylon 66), PA6 / 66 (Nylon 6 / 66 copolymer), PA66 / 6 (Nylon 66 / 6 copolymer), PA66 / 6T (Nylon 66 / 6T copolymer), PA12 (Nylon 12), and PA612 (Nylon 612); preferably, the polyamide resin in the present invention is PA6 (Nylon 6). Those skilled in the art will understand that as long as the polyamide resins described above are well compatible with the flame retardant system and synergistic system of the present invention and can be melt-blended, they can all achieve the technical effects of the present invention.

[0020] The present invention is further configured such that the filler may be selected from one or more of glass fiber, aramid fiber, carbon fiber, basalt fiber, whiskers, glass microspheres, calcium carbonate, wollastonite, mica, kaolin, and talc; preferably, the filler is glass fiber, and the performance parameters of the filler meet the following requirements: alkali content < 0.8%, bulk density 0.6-0.8 g / cm³, monofilament diameter 7-13 μm, chopped length 2-5 mm, and moisture content ≤ 0.05%.

[0021] The present invention further specifies that the phosphorus-based flame retardant A is diethylaluminum hypophosphite, and its properties meet the following requirements: phosphorus content 22%-25%, density 1.10-1.40 g / cm³, decomposition temperature (TGA method, 1% weight loss) > 300℃, particle size 20-40 μm, and moisture content ≤ 0.3%.

[0022] The phosphorus-based flame retardant B is diisobutyl aluminum hypophosphite, and its performance meets the following requirements: phosphorus content 18%-20%, total moisture and low volatile matter ≤0.5%, bulk density 300-350 kg / m³, and decomposition temperature (TGA method, 1% weight loss) >300℃.

[0023] The present invention is further configured such that the antioxidant is N-(2,3-dihydro-2-thio-1H-benzimidazole-5-yl)acetamide, which belongs to the thiobenzimidazole class of antioxidants, and the antioxidant has a density of 1.42±0.1 g / cm³ and a melting point of 300-307℃.

[0024] The present invention is further configured such that the processing aid is an organic aid that has both internal and external lubrication functions and does not affect the flame retardant properties.

[0025] The present invention is further configured such that the processing aid is silicone powder, preferably a mixture of phenyl silicone and silicon dioxide in a 1:1 mass ratio. In the present invention, the processing aid may also be selected from one or more of silicone masterbatch, PETS, montmorillonite wax, polyethylene wax, oxidized polyethylene wax, and calcium stearate, as long as it has both internal and external lubrication functions and does not affect flame retardant properties.

[0026] This invention significantly improves flame retardant efficiency by combining diethylaluminum hypophosphite and diisobutylaluminum hypophosphite: their thermal decomposition behaviors are complementary, simultaneously blocking gas-phase free radical reactions and condensed-phase heat transfer; simultaneously, two ionic liquids with different structures are combined as synergistic flame retardants (1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate), synergistically enhancing the flame retardant effect through a triple mechanism of catalytic char formation, gas-phase inhibition, and interfacial enhancement. Compared with conventional phosphorus-nitrogen flame retardant systems, this system reduces the amount of flame retardant added by more than 30% while achieving the same flame retardant effect, and the lower addition amount significantly improves the mechanical properties of the material; the synergistic effect of the flame retardant and antioxidant provides a wide processing window, as well as advantages of high mechanical properties and low corrosivity, making this polyamide composition promising for broad applications in the automotive, electronics, and electrical appliance industries. The processing window is referenced to the color change during processing; the yellowing specific thermogravimetric analysis is more sensitive to processing temperature and better meets the evaluation requirements of end products.

[0027] Choosing the pentyl (C5) chain length in synergistic flame retardants facilitates the provision of appropriate intermolecular forces in ionic liquids. This avoids the high viscosity caused by strong electrostatic interactions in short chains (such as ethyl) and the decreased fluidity caused by excessive van der Waals forces in long chains (such as octyl). This allows pentyl-containing ionic liquids to effectively lubricate highly filled polymer systems and improve melt flowability during high-temperature processing. Furthermore, the pentyl chain length (C5) has a high degree of matching with the molecular structure of nylon, facilitating uniform dispersion. Moreover, the pentyl (C5) chain length in synergistic flame retardants has a high decomposition temperature (>300℃), meeting the processing temperature requirements of nylon. Further, the pentyl chain length helps the ionic liquid form a more stable char layer during combustion; its carbon chain can participate in char formation without generating excessive combustible volatiles due to excessive length. Short chains lack sufficient thermal stability, while long chains negatively impact flame retardancy.

[0028] The present invention also provides a method for preparing the high-strength, low-corrosion polyamide composition, characterized by comprising the following steps:

[0029] S1. Control the moisture content of the polyamide resin to ≤2000ppm;

[0030] S2. Weigh the dried polyamide resin, flame retardant, synergistic flame retardant, antioxidant, and processing aids according to the formula ratio, and mix them evenly with a high-speed mixer to obtain mixture A; separately weigh the filler to obtain material B;

[0031] S3. The mixture A is fed into the main feed port of the twin-screw extruder, and the material B is added through the side feed port. After melt extrusion, granulation and drying, the polyamide composition is obtained. The temperature of the melt extrusion is 240-300℃ and the screw speed is 300-400 rpm.

[0032] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0033] 1. The flame retardants diethylaluminum hypophosphite and diisobutylaluminum hypophosphite of this invention have different decomposition temperatures. The two compounded together can complement each other in thermal decomposition behavior, extending the flame retardant action window and covering the flame retardant requirements of the polymer throughout the entire process from melting to combustion. Diethylaluminum hypophosphite mainly releases PO· free radicals to quench the combustion chain reaction in the gas phase, while diisobutylaluminum hypophosphite mainly produces an expandable char layer in the condensed phase. Its branched structure can bring excellent melt strength, making the melt less prone to dripping during combustion. The two work synergistically to block the gas phase free radical reaction and heat transfer in the condensed phase during combustion, thereby improving the flame retardant efficiency.

[0034] 2. The synergist of this invention is composed of two ionic liquids, which synergistically enhance flame retardant efficiency through multiple effects: catalytic char formation, gas-phase dilution, and interfacial enhancement. The Lewis acid (PF5) generated from the high-temperature decomposition of 1-pentyl-3-methylimidazolium hexafluorophosphate catalyzes the dehydration of polyamide to form a dense char layer. Simultaneously, the HF and other gases produced by the decomposition of this ionic liquid dilute combustible gases and capture free radicals. Crucially, 1-pentyl-3-methylimidazolium trifluoromethanesulfonate decomposes at high temperatures to produce fluorine- and sulfur-containing inert gases (such as CF3H and SO2), forming a unique 'gas-solid' bidirectional synergy with the aforementioned Lewis acid catalytic system. The char layer formed by Lewis acid catalysis provides ample interfacial reaction time for gas dilution and free radical capture, while the gaseous products effectively prevent premature char layer breakage. The synergy of the two ionic liquids significantly improves flame retardant efficiency, achieving a V-0 rating with a total addition of as low as 3%, which is unattainable with existing technologies (using a single ionic liquid as a synergist).

[0035] 3. Compared with conventional phosphorus-nitrogen flame retardant systems, the synergistic effect of the flame retardant and the synergistic flame retardant of this invention achieves a reduction of more than 30% in the amount of flame retardant added while maintaining the same flame retardant effect. The low addition amount significantly improves the mechanical properties of the material. At the same time, the flame retardant has low corrosivity and less precipitation, and the reduction in the amount added further reduces the risk of corrosion.

[0036] 4. The antioxidant of this invention effectively interrupts the oxidation chain reaction by capturing free radicals generated during the thermal oxidation of the polymer, thereby delaying the yellowing and mechanical property degradation of nylon during high-temperature processing and long-term thermal aging. Compared with traditional phosphite and phosphate antioxidants, it exhibits superior yellowing resistance. Simultaneously, the synergistic effect of the flame retardant and antioxidant provides a wider processing window. This achieves excellent flame retardant properties, low corrosion, low exudation, high strength, wide processing window, and broad application range in the polyamide composition, enhancing the product's market competitiveness. Attached Figure Description

[0037] This invention has no accompanying drawings. Detailed Implementation

[0038] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to 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.

[0039] It should be noted that the percentage of each component in the following embodiments is based on the total weight of the composition. Those skilled in the art will understand that the flame retardant and synergistic mechanisms described in this invention are merely reasonable explanations of experimental phenomena and do not constitute a limitation on the technical solution of this invention. The scope of protection of this invention is determined by the components and proportions defined in the claims.

[0040] The embodiments and comparative examples of the present invention use the following materials, but are not limited to the following materials:

[0041] Polyamide resin, trade name YH400, produced by Yueyang Petrochemical;

[0042] Flame retardant, trade name D13 (diisobutylaluminum hypophosphite, corresponding to phosphorus-based flame retardant B of the present invention), is produced by CLARIANT;

[0043] Flame retardant, trade name ADP (diethylaluminum hypophosphite, corresponding to phosphorus-based flame retardant A of the present invention), is produced by Hebei Xinxinyuan Energy Co., Ltd.

[0044] Flame retardant, the flame retardant used in the comparative example, trade name OP1314 (a conventional phosphorus-based flame retardant used in the comparative example), produced by CLARIANT;

[0045] Synergistic flame retardant, 1-pentyl-3-methylimidazolium hexafluorophosphate, produced by Jinjinle (Hunan) Chemical Co., Ltd.;

[0046] Synergistic flame retardant, 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, produced by Henan Weitixi Chemical Technology Co., Ltd.;

[0047] The filler, glass fiber, trade name ECS301HP-3, is produced by Chongqing International Composite Materials Co., Ltd.

[0048] Processing aid, trade name silicone powder, produced by Chengdu Silike Technology Co., Ltd.

[0049] Antioxidant, N-(2,3-dihydro-2-thio-1H-benzimidazol-5-yl)acetamide, produced by Wuhan Yijia Yi Biotechnology Co., Ltd.;

[0050] Antioxidant 9228, a phosphite antioxidant, is produced by Dover Chemical Corporation.

[0051] Example 1

[0052] This embodiment provides a high-strength, low-corrosion polyamide composition, which is composed of the following raw materials in percentage by weight of the total composition: 50-55% polyamide resin; 30-40% filler; 7-9% flame retardant; 1-4% synergistic flame retardant, preferably 3%; 0.01-1% antioxidant; and 0-2% processing aid.

[0053] In this embodiment, the polyamide resin is preferably PA6.

[0054] Preferably, the filler is glass fiber, and its performance parameters meet the following requirements: alkali content < 0.8%, bulk density 0.6-0.8 g / cm³, monofilament diameter 7-13 μm, chopped length 2-5 mm, and moisture content ≤ 0.05%.

[0055] Preferably, the flame retardant is a composition of phosphorus-based flame retardant A and phosphorus-based flame retardant B, with a weight ratio of 1:1 to 4:1. Specifically, phosphorus-based flame retardant A (diethylaluminum hypophosphite) has the following properties: phosphorus content 22%-25%, density 1.10-1.40 g / cm³, decomposition temperature (TGA method, 1% loss) > 300℃, particle size 20-40 μm, and moisture content ≤ 0.3%; phosphorus-based flame retardant B (diisobutylaluminum hypophosphite) has the following properties: phosphorus content 18%-20%, total moisture and low volatile matter ≤ 0.5%, bulk density 300-350 kg / m³, and decomposition temperature (TGA method, 1% loss) > 300℃.

[0056] Preferably, the synergistic flame retardant is 1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, with a weight ratio of 2:1 to 9:1.

[0057] Preferably, the antioxidant is N-(2,3-dihydro-2-thio-1H-benzimidazole-5-yl)acetamide, which has a density of 1.42±0.1 g / cm³ and a melting point of 300-307℃.

[0058] In this embodiment, the processing aid is an organic additive that has both internal and external lubrication functions and does not affect the flame retardant properties. The processing aid is selected from one or more of silicone powder, silicone masterbatch, PETS, montmorillonite wax, polyethylene wax, oxidized polyethylene wax, and calcium stearate. Preferably, the processing aid is silicone powder, which is a mixture of phenyl silicone and silicon dioxide in a 1:1 mass ratio.

[0059] In this embodiment, the polyamide composition is prepared as follows:

[0060] Weigh the dried raw materials according to the weight percentages shown in Table 1: polyamide resin, flame retardant, synergistic flame retardant, antioxidant, and processing aid. The moisture content of the polyamide resin (PA6-YH400) should be controlled below 2000 ppm. Add PA6-YH400, flame retardant ADP (diethylaluminum hypophosphite), flame retardant D13 (diisobutylaluminum hypophosphite), synergistic flame retardant (1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, weight ratio 2:1), antioxidant (N-(2,3-dihydro-2-thio-1H-benzimidazole-5-yl)acetamide), and processing aid (silicone powder) to a high-speed mixer and mix thoroughly to obtain mixture A. Separately weigh glass fiber (ECS301HP-3) as a filler, denoted as material B.

[0061] Mixture A is fed into the main feed port of a twin-screw extruder, while material B is added through the side feed port. The mixture is then melt-extruded, granulated, and dried to obtain polyamide composition granules. The process parameters of the twin-screw extruder are: zone 1 temperature 240℃, zone 2 temperature 250℃, zone 3 temperature 260℃, zone 4 temperature 260℃, zone 5 temperature 260℃, zone 6 temperature 250℃, die head temperature 260℃, and screw speed 350 rpm.

[0062] Preparation of test strips for polyamide compositions:

[0063] The polyamide composition material prepared in Example 1 was dried in a forced-air drying oven at 120°C for 4 hours, and then injection molded into standard specimens at an injection molding temperature of 280-300°C. The injection-molded mechanical property specimens were conditioned in a standard laboratory environment (23°C, 50%RH) for 24 hours before testing. The test results are shown in Table 2.

[0064] Test methods for each performance indicator:

[0065] Tensile properties: According to ISO 527 method, specimen size: 170*10*4mm, test speed 5mm / min.

[0066] Bending performance: According to ISO 178 method, the sample size is 80*10*4mm, and the test speed is 2mm / min.

[0067] Notched impact performance: according to ISO 179 method, spline size: 80*10*4mm.

[0068] Flame retardant performance: According to UL94 method, the sample size is 127*12.7*1.6mm.

[0069] Resistance to exudation: A 150*100*3.2mm sample was placed in an environmental chamber with the following settings: temperature 85℃, humidity 85%RH, time 250h. The state of the surface exudate was visually evaluated.

[0070] Color evaluation (processing): The color of the injection molded sample is visually evaluated and divided into three levels from light to dark: light, slightly yellow, and dark.

[0071] Color evaluation (high temperature storage): The color of the injection molded sample after being stored at 120℃ for 24 hours is visually evaluated and classified into three levels from slight yellowing to moderate yellowing and severe yellowing.

[0072] Electrochemical corrosion performance: A cylindrical copper wire with a diameter of 1 cm was inserted into the flame-retardant polyamide material with a current of 1 mA. The device was placed in an environmental chamber at 85°C and 85%RH for 500 hours. At the end of the experiment, the electrochemical corrosion performance was evaluated by assessing the degree of corrosion on the surface of the copper wire in contact with the flame-retardant nylon. The corrosion performance was divided into three levels from light to severe: no corrosion, slight corrosion, and severe corrosion.

[0073] Example 2

[0074] The preparation method of this embodiment is basically the same as that of Example 1, except that the formulation composition is different. Specifically, according to the weight percentage of the formulation shown in Table 1, the weight ratio of 1-pentyl-3-methylimidazolium hexafluorophosphate to 1-pentyl-3-methylimidazolium trifluoromethanesulfonate in the synergistic flame retardant is adjusted to 9:1 (i.e., the sum of 2.7% and 0.3%), while the other components and their amounts remain unchanged. The preparation process and testing conditions are the same as those in Example 1, and the performance test results are shown in Table 2.

[0075] Example 3

[0076] The preparation method of this embodiment is basically the same as that of Example 1, except that the formulation composition is different. Specifically, according to the formulation weight percentages shown in Table 1, the weight ratio of flame retardant D13 to flame retardant ADP is adjusted to 1:4 (i.e., flame retardant D13 and flame retardant ADP are 1.6% and 6.4% respectively), while other components and their amounts remain unchanged. The preparation process and testing conditions are the same as those of Example 1, and the performance test results are shown in Table 2.

[0077] Comparative Example 1

[0078] The preparation method of this comparative example is basically the same as that of Example 1, except that the formulation composition is different. Specifically, according to the weight percentage of the formulation shown in Table 1, the conventional phosphorus-based flame retardant OP1314 (addition amount of 16%) is used to replace the compound flame retardant of this invention, and no synergistic flame retardant is added. Other components and dosages are the same as in Example 1. The preparation process and testing conditions are the same as in Example 1, and the performance test results are shown in Table 2.

[0079] Comparative Example 2

[0080] The preparation method of this comparative example is basically the same as that of Example 1, except that the formulation composition is different. Specifically, the amount of conventional phosphorus-based flame retardant OP1314 added was increased to 18% according to the weight percentage of the formulation shown in Table 1, and no synergistic flame retardant was added. Other components and amounts are the same as in Example 1. The preparation process and testing conditions are the same as in Example 1, and the performance test results are shown in Table 2.

[0081] Comparative Example 3

[0082] The preparation method of this comparative example is basically the same as that of Example 1, except for the different formulation composition. Specifically, according to the weight percentages of the formulation shown in Table 1, only flame retardant D13 (4%) and ADP (4%) were added, but no synergistic flame retardant was added (i.e., both ionic liquid synergists were 0%). Other components and amounts were the same as in Example 1. The preparation process and testing conditions were the same as in Example 1, and the performance test results are shown in Table 2.

[0083] Comparative Example 4

[0084] The preparation method of this comparative example is basically the same as that of Example 1, except for the different formulation composition. Specifically, according to the weight percentages of the formulation shown in Table 1, only flame retardant D13 (4%) and ADP (4%) were added, and only one synergistic flame retardant (1-pentyl-3-methylimidazolium hexafluorophosphate, added at 3%) was added. Other components and amounts were the same as in Example 1. The preparation process and testing conditions were the same as in Example 1, and the performance test results are shown in Table 2.

[0085] Comparative Example 5

[0086] The preparation method of this comparative example is basically the same as that of Example 1, except for the different formulation composition. Specifically, according to the weight percentages of the formulation shown in Table 1, only flame retardant D13 (8%) and ADP (0%) were added, along with a compound synergistic flame retardant (1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, added at 2% and 1% respectively). Other components and their amounts are the same as in Example 1. The preparation process and testing conditions are the same as in Example 1, and the performance test results are shown in Table 2.

[0087] Comparative Example 6

[0088] The preparation method of this comparative example is basically the same as that of Example 1, except that the formulation composition is different. Specifically, according to the weight percentages of the formulation shown in Table 1, only flame retardants D13 (0) and ADP (8%) are added, along with a compound synergistic flame retardant (1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, added at 2% and 1% respectively). Other components and amounts are the same as in Example 1. The preparation process and testing conditions are the same as in Example 1, and the performance test results are shown in Table 2.

[0089] Comparative Example 7

[0090] The preparation method of this comparative example is basically the same as that of Example 1, except that the formulation composition is different. Specifically, according to the weight percentage of the formulation shown in Table 1, the antioxidant is replaced with conventional phosphite antioxidant 9228, and the addition amount is 0.3%. Other components and amounts are the same as in Example 1. The preparation process and testing conditions are the same as in Example 1, and the performance test results are shown in Table 2.

[0091] Comparative Example 8

[0092] The preparation method of this comparative example is basically the same as that of Example 1, except that the formulation composition is different. Specifically, according to the weight percentage of the formulation shown in Table 1, the antioxidant is replaced with conventional phosphite antioxidant 9228, and the addition amount is 0.8%. Other components and amounts are the same as in Example 1. The preparation process and testing conditions are the same as in Example 1, and the performance test results are shown in Table 2.

[0093] Table 1: Composition of the polyamide compositions of Examples 1-3 and Comparative Examples 1-8:

[0094]

[0095] Table 2: Performance test results of the polyamide compositions of Examples 1-3 and Comparative Examples 1-8:

[0096]

[0097] As shown in Tables 1 and 2, the polyamide material prepared by this invention achieves a UL94V0 flame retardant rating with a significantly reduced amount of flame retardant added, while also possessing low corrosivity, high mechanical properties, and excellent color stability.

[0098] The comparison between Examples 1-3 and Comparative Examples 1-2 shows that, compared with conventional phosphorus-nitrogen flame retardant systems, the present invention achieves significant improvements in mechanical properties, corrosion inhibition, and precipitation stability, while reducing the amount of flame retardant added by more than 30%.

[0099] Example 1, compared with Comparative Examples 3-4, confirms that the two-component flame-retardant compound system achieves simultaneous blocking of gas-phase free radical reaction and condensed-phase heat transfer through the difference in thermal decomposition temperature, and its flame-retardant efficiency is better than that of the single-component system.

[0100] Example 1, compared with Comparative Examples 5-6, shows that the two-component synergistic system enhances the flame retardant effect through a triple mechanism of catalytic char formation, gas-phase free radical inhibition, and interfacial enhancement.

[0101] Example 1, compared with Comparative Examples 7-8, further demonstrates that specific antioxidants can efficiently neutralize free radicals and block photodegradation, delaying the yellowing process of nylon, and exhibiting better color retention than conventional phosphate ester systems.

[0102] Comparative Examples 3-4 show that using only flame retardants (D13 and ADP) without synergists cannot achieve V-0. Comparative Examples 5-6 show that using only one flame retardant (D13 or ADP) plus two synergists also cannot achieve V-0. This invention uses both "D13 and ADP flame retardants" and "1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate synergists," achieving V-0. Furthermore, the total amount of flame retardant added (8-9%) is significantly lower than the 16-18% in Comparative Examples 1-2. This indicates a synergistic effect between "D13 + ADP flame retardants" and "1-pentyl-3-methylimidazolium hexafluorophosphate + 1-pentyl-3-methylimidazolium trifluoromethanesulfonate synergists," constructing a complete "gas-phase-condensed-phase" dual-effect flame retardant network, resulting in a significant improvement in flame retardant efficiency.

[0103] In summary, the polyamide composition of this invention achieves synergistic breakthroughs in flame retardancy, corrosivity, exudation, mechanical strength, processing window, and applicability, significantly enhancing the product's market competitiveness.

[0104] It should be noted that the drying conditions and processing temperature should be adjusted according to the characteristics of different types of polyamide resins. Generally speaking, the preferred drying temperature for aliphatic polyamides (such as PA6, PA66, PA46, PA56, PA6 / 66, PA66 / 6, PA12, PA612) is 80-120℃, and the preferred drying temperature for semi-aromatic polyamides (such as PA6T / X, PA9T, PA10T, PA10T / X, PA4T, PA5T, PA5T / X, PA66 / 6T, PA6T / 6T) is 100-140℃. Regardless of the type of polyamide resin, its moisture content should be controlled below 2000ppm before melt extrusion. Those skilled in the art can determine the optimal drying conditions and processing temperature through routine experiments based on the specific polyamide resin selected.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, low-corrosion polyamide composition, characterized in that: It consists of the following raw materials in percentage by weight of the total composition: Polyamide resin 50-55%; Filler 30-40%; Flame retardant 7-9%; Synergistic flame retardant 1-4%; Antioxidant 0.01-1%; Processing aids 0-2%; The flame retardant is a combination of phosphorus-based flame retardant A and phosphorus-based flame retardant B, with a weight ratio of 1:1 to 4:

1. The synergistic flame retardant is a composition of 1-pentyl-3-methylimidazolium hexafluorophosphate and 1-pentyl-3-methylimidazolium trifluoromethanesulfonate, with a weight ratio of 2:1 to 9:

1.

2. The high-strength, low-corrosion polyamide composition according to claim 1, characterized in that, The filler is glass fiber.

3. The high-strength, low-corrosion polyamide composition according to claim 1, characterized in that, The phosphorus-based flame retardant A is diethylaluminum hypophosphite, and the phosphorus-based flame retardant B is diisobutylaluminum hypophosphite.

4. The high-strength, low-corrosion polyamide composition according to claim 1, characterized in that, The antioxidant is N-(2,3-dihydro-2-thio-1H-benzimidazol-5-yl)acetamide.

5. The high-strength, low-corrosion polyamide composition according to claim 1, characterized in that, The polyamide resin is nylon 6.

6. The high-strength, low-corrosion polyamide composition according to claim 1, characterized in that, The processing aid is an organic additive that has both internal and external lubrication functions.

7. The high-strength, low-corrosion polyamide composition according to claim 6, characterized in that, The processing aid is silicone powder.

8. A method for preparing a high-strength, low-corrosion polyamide composition according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Control the moisture content of the polyamide resin to ≤2000ppm; S2. Weigh the dried polyamide resin, flame retardant, synergistic flame retardant, antioxidant, and processing aids according to the formula ratio, and mix them evenly with a high-speed mixer to obtain mixture A; separately weigh the filler to obtain material B; S3. Mixture A is fed into the main feed port of a twin-screw extruder, and material B is added through the side feed port. After melt extrusion, granulation and drying, the polyamide composition is obtained.

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