A flame-retardant PA66 material for automotive applications and its preparation method

Abstract

This application provides a flame-retardant PA66 material for automotive applications and its preparation method. The flame-retardant PA66 material comprises the following components by weight: 65 parts PA66; 14-21 parts main flame retardant; 5-7 parts antimony trioxide; 6-10 parts POE-g-MAH; 0.3-0.5 parts 3-aminopropane-1-phosphonic acid; 0.8-1.2 parts calcium mucinate; 0.6-1.2 parts lubricant; 0.6-1 parts antioxidant; 0.1-0.4 parts catalyst; and 0.05-0.15 parts defoamer. This application achieves comprehensive improvement in mechanical, thermal, electrical, and flame-retardant properties by crosslinking and coordinating PA66, POE-g-MAH, 3-aminopropane-1-phosphoric acid, and calcium mucinate, and by employing a segmented feeding and temperature-controlled twin-screw extrusion process, thus protecting the structure of the flame-retardant PA66 material.

Description

Technical Field

[0001] This application relates to the field of engineering plastics, specifically to a flame-retardant PA66 material for automotive applications and its preparation method. Background Technology

[0002] As the automotive industry places increasingly higher demands on safety performance, the application of flame-retardant materials in automobile manufacturing is becoming increasingly important.

[0003] Engineering plastics, due to their lightweight, high strength, and ease of molding, are used to replace metal parts. PA66, as an engineering plastic, possesses excellent mechanical strength, heat resistance, and corrosion resistance. However, PA66 itself is a flammable material and does not meet the fire safety standards of the automotive industry. To improve the flame retardant properties of PA66, it needs to be modified by adding flame retardants. Currently, the synergistic system composed of brominated flame retardants and antimony trioxide is a classic solution for achieving high-efficiency flame retardancy. However, adding large amounts of brominated flame retardants can lead to a decrease in the mechanical properties of the material and the combustion products have toxic smoke. There are also compatibility issues between flame retardants and PA66, which can cause the flame retardant to precipitate during processing, and the added flame retardant can also increase the cost of the material. With the popularization of electric vehicles, the flame retardant materials for battery packs have new requirements for electrical performance.

[0004] Therefore, there is a need for a flame-retardant PA66 material for automotive applications and its preparation method that can meet flame retardant requirements, maintain or even improve the mechanical and electrical properties of the material, reduce the toxicity of combustion products, and simultaneously achieve good mechanical, thermal, and electrical properties. Summary of the Invention

[0005] This invention provides a flame-retardant PA66 material for automotive applications and its preparation method.

[0006] In one aspect, this application provides a flame-retardant PA66 material for automotive applications, comprising the following raw materials in parts by weight: 65 parts PA66; 14-21 parts main flame retardant; 5-7 parts antimony trioxide; 6-10 parts POE-g-MAH; 0.3-0.5 parts 3-aminopropane-1-phosphoric acid; 0.8-1.2 parts calcium mucinate; 0.6-1.2 parts lubricant; 0.6-1 parts antioxidant; 0.1-0.4 parts catalyst; and 0.05-0.15 parts defoamer.

[0007] Through the above technical solutions, PA66 is used as the matrix resin in this application to ensure that the product has a certain mechanical strength. At the same time, the moisture content of PA66 must be strictly controlled to enhance the stability of the material. The flame retardant system improves the flame retardant rating through the synergistic effect of the main flame retardant and antimony trioxide.

[0008] POE-g-MAH is a toughening agent. As a block elastomer with g-MAH (maleic anhydride grafted) onto the POE (polyolefin elastomer) main chain, it possesses both good mechanical properties and reactive groups. It can undergo amidation reaction with the terminal amino groups of PA66 molecules, and the good interfacial bonding balances the contradiction between toughening and flame retardancy. The amino terminus of 3-aminopropane-1-phosphoric acid can undergo condensation reaction with the carboxyl terminus of the PA66 molecular chain. Both participate in the interfacial improvement, which improves melt strength and thermal stability. The introduction of different polar groups and chain segments further enhances the entanglement and interaction between molecular chains, which not only improves the mechanical properties and processing properties of the material, but also significantly improves the heat aging resistance and stress cracking resistance during long-term use. Thus, the resulting flame-retardant PA66 material has both excellent flame retardancy and comprehensive mechanical properties in automotive applications. The phosphonic acid group in 3-aminopropane-1-phosphoric acid may decompose to generate phosphates or phosphorus-containing oxides during combustion, promoting the formation of a carbonized layer on the PA66 surface, which isolates heat and oxygen and inhibits combustion.

[0009] Calcium mucoconate, acting as a stabilizer and nucleating agent, improves crystallinity, dimensional stability, and mechanical strength. Furthermore, calcium mucoconate binds to the phosphonic acid groups of 3-aminopropane-1-phosphate via ionic and coordinate bonds. Therefore, the participation of 3-aminopropane-1-phosphate in the interface improvement reaction further enhances the stability and uniform dispersion of calcium mucoconate in the system, improves compatibility, and thus further strengthens the effect of calcium mucoconate, effectively optimizing mechanical properties. Lubricants reduce melt viscosity, improve flowability, facilitate smoother injection molding, and reduce mold wear. Antioxidants inhibit thermo-oxidative aging and extend the service life of materials under high-temperature environments. Catalysts promote the reaction efficiency of flame-retardant systems, increase the grafting rate of the amidation reaction, and improve mechanical and flame-retardant properties. Defoamers eliminate bubbles generated during processing, improving the appearance and internal density of the product.

[0010] In some embodiments, the primary flame retardant is a halogenated flame retardant.

[0011] In some of the above embodiments, halogenated flame retardants are used as the main flame retardants. When they decompose at the combustion temperature, they produce hydrogen halides or halogen free radicals that react with combustion free radicals, thereby blocking combustion.

[0012] In some embodiments, the primary flame retardant is a brominated epoxy resin.

[0013] In some of the above embodiments, brominated epoxy resin is used as the main flame retardant. Its decomposition temperature is higher than 350°C, which can adapt to the melt processing conditions of PA66. Its high molecular weight makes the migration and volatility of bromine extremely low, effectively maintaining the flame retardant effect, while giving the material a certain rigidity and maintaining the mechanical properties of the material. When combined with antimony trioxide, it can generate antimony tribromide under combustion conditions, which improves the capture rate of gaseous free radicals and thus improves the flame retardant performance.

[0014] In some embodiments, the calcium mucoconate is manufactured using the following technical solutions:

[0015] Mucoconic acid was dissolved in deionized water to prepare a 5-15 wt% mucoconic acid solution.

[0016] A 5-10 wt% homogeneous calcium hydroxide slurry is prepared by mixing and stirring calcium hydroxide with water. The calcium hydroxide slurry is then added to the mucoacinic acid solution, and the pH value is controlled at 6.8-7.2 to obtain a neutralized reaction solution.

[0017] The neutralized reaction solution was purified to obtain a clear solution, which was then crystallized to obtain crystals.

[0018] The moisture and organic acid residues of the obtained crystals are removed, and the crystals are dried, pulverized and graded to obtain calcium mucinate micro powder with an average particle size of 0.3-0.5 μm.

[0019] In some of the above embodiments, by controlling the pH of the reaction system within the range of 6.8-7.2, not only is the complete neutralization reaction ensured, but side reactions are also avoided, thereby improving the product yield and quality. After purification to remove unreacted solid impurities, the resulting clear liquid can be crystallized to obtain high-purity calcium mucoconate crystals with low impurity content. Further drying, pulverizing, and classification processes yield micro-powder with an average particle size of 0.3-0.5 μm, exhibiting good dispersibility and solubility.

[0020] Calcium mucinate is bonded to the phosphonic acid groups of 3-aminopropane-1-phosphoric acid through ionic and coordinate bonds. The phosphonic acid groups decompose at high temperatures and react with calcium ions to generate stable calcium phosphate compound residues. These residues enhance the density and heat resistance of the char layer. Compared to saturated fatty acid calcium such as calcium stearate, it is less likely to decompose into free acid prematurely under the processing conditions of PA66 and other engineering plastics at 250-280℃, thus reducing the risk of hydrolysis or acid catalysis of PA66. It maintains the stability of the mechanical properties and electrochemical resistance index of the product. Compared to inorganic calcium salts such as organic calcium salts and calcium phosphate, it does not participate in chain structure regulation during PA66 melt processing. It can avoid deterioration of the synergistic flame retardancy.

[0021] In some embodiments, the lubricant is at least one of pentaerythritol tetrastearate, ethylene bis-stearamide, and zinc stearate.

[0022] In some of the above embodiments, pentaerythritol tetrastearate is used as a lubricant to achieve both internal and external lubrication effects; ethylene bis-stearamide has both polar amide groups and non-polar long chains, and has high thermal stability, which can reduce melt viscosity and improve fluidity in the molten system; zinc stearate can form low friction on the die surface, and can also neutralize by-products of halogenated flame retardants, buffer acidity and improve CTI value; pentaerythritol tetrastearate, ethylene bis-stearamide, and zinc stearate at least one of them can synergistically stabilize the twin-screw extrusion process to improve die life, reduce surface defects and precipitation, extend material life, and maintain mechanical and electrical properties.

[0023] In some embodiments, the antioxidant is a compound system of hindered phenolic antioxidants and phosphite antioxidants; the hindered phenolic antioxidants include at least one of antioxidant 1010 and antioxidant 1098, and the phosphite antioxidant is antioxidant 168.

[0024] In some of the above embodiments, the hindered phenolic antioxidant (ArOH) can capture free radicals (R•, ROO•) generated by polymer degradation at high temperatures or during use, and the reaction equation is as follows:

[0025] ROO• + ArOH → ROOH + ArO•

[0026] R• + ArOH → RH + ArO•

[0027] Phenolic oxygen free radicals (ArO•) significantly inhibit oxidation by creating a steric hindrance effect on the active sites of free radicals. Phosphite antioxidants (P(OR)3) mainly react rapidly with hydroperoxides (ROOH) generated during the processing stage, and the reaction equation is as follows:

[0028] R 1 OOH + P(OR 2 )3→ R 1 OH + O = P(OR) 2 )3

[0029] P(OR 2 )3+ ArO• → ArOH + O=P(OR 2 )3

[0030] Phenolic antioxidants reduce peroxides to harmless alcohols in the early stages of oxidation and inhibit the regeneration of phenolic oxygen free radicals in the later stages. Antioxidant 1098 is superior to antioxidant 1010 in terms of material appearance stability and aging resistance. Antioxidant 1010 has lower cost and better processing stability. Antioxidant 1098, antioxidant 1010, and at least one of antioxidants 168 synergistically form a closed-loop antioxidant chain to maintain the mechanical properties and appearance stability of the material.

[0031] In some embodiments, the catalyst includes at least one of zinc oxide and magnesium oxide.

[0032] In some of the embodiments described above, the Zn on the surface of zinc oxide or magnesium oxide 2+ or Mg 2+ It can coordinate with the carbonyl oxygen in the terminal carboxyl group of PA66 molecule and the carbonyl oxygen in the anhydride group of toughening agent POE-g-MAH to form Lewis acid activation center; this coordination can reduce the activation energy of chemical reaction, thereby promoting the amidation reaction between the amino group at the terminal of PA66 and the anhydride group of POE-g-MAH, and increasing the chemical reaction rate.

[0033] In some embodiments, the defoamer is methyl silicone oil.

[0034] In some of the above embodiments, methyl silicone oil can promote the aggregation, rupture and escape of small bubbles formed by the vaporization of air or trace moisture entrained in the material, thereby playing a defoaming role and ensuring the stability of the material's appearance.

[0035] Secondly, this application provides a method for preparing flame-retardant PA66 material for automotive applications, comprising:

[0036] Provide raw materials for automotive flame-retardant PA66 materials according to any embodiment of the first aspect;

[0037] The raw materials are mixed, melt-co-extruded, cooled, and pelletized to obtain automotive flame-retardant PA66 material.

[0038] In some embodiments, the raw material for the automotive flame-retardant PA66 material according to any embodiment of the first aspect is provided by the following preparation steps:

[0039] S1: Provide raw materials for automotive flame-retardant PA66 material according to any embodiment of the first aspect;

[0040] S2: The main flame retardant, antimony trioxide, lubricant, antioxidant and catalyst are mixed in the first high-speed mixer to obtain the first additive package;

[0041] S3: Two loss-in-weight feeders are used, one for PA66 and the other for the first mixed additive package. The two feeders feed the material simultaneously and continuously into the main feed port of the front section of the twin-screw extruder according to the set formula ratio.

[0042] S4: Using the third loss-in-weight feeder, add POE-g-MAH from the first side feed port in the middle section of the twin-screw extruder barrel;

[0043] S5: Mix 3-aminopropane-1-phosphoric acid, calcium mucinate, and the remaining lubricant in a second high-speed mixer to obtain a second additive package;

[0044] S6: Using the fourth loss-in-weight feeder, add the second additive package from the second side feed port in the middle section of the twin-screw extruder barrel;

[0045] S7: Methyl silicone oil is directly injected into a dedicated injection port at the rear of the twin-screw extruder barrel via a metering pump;

[0046] S8: The molten material extruded from the twin-screw extruder head is cooled by air and cut into granules, then subjected to quality inspection and packaging, and finally stored in the warehouse.

[0047] In some of the above embodiments, step S1 ensures that each functional raw material can play a full role in subsequent steps through the scientific selection and proportioning of raw materials, laying the foundation for the preparation of automotive flame-retardant PA66 materials; in step S2, 0.2-0.6 parts of lubricant, antioxidant, and catalyst are uniformly attached to the main flame retardant and antimony trioxide using a high-speed mixer to form a homogeneous mixture; in step S3, the material is simultaneously and continuously fed into the main feed port of the extruder using two loss-in-weight feeders to achieve continuous, stable, and high-precision batching, thereby stabilizing material performance and ensuring smooth material conveying; in step S4, the toughening effect of POE-g-MAH depends on the complete molecular chain and must be added from the side feed port in the middle section of the twin-screw extruder barrel to avoid structural damage caused by high shear at the main port; in step S5, 3-aminopropane-1-phosphate and calcium mucinate are mixed in advance so that they are uniformly contacted before entering the extruder, which is conducive to the rapid formation of ionic and coordination bonds in the molten state; 3-aminopropane-1-phosphate or calcium mucinate can be added directly alone. 2+ Excessive local concentration may lead to uneven reaction or agglomeration; placing the remaining lubricant in the second additive package can reduce melt viscosity and improve material flowability in the middle and later stages; in step S6, the amino group of 3-aminopropane-1-phosphoric acid can be efficiently condensed with the carboxyl group at the chain end of PA66 in the molten state, avoiding thermal degradation and side reactions caused by premature addition in the early stage; Ca 2+The phosphonic acid group of 3-aminopropane-1-phosphoric acid forms a stable ionic and coordination bond network under relatively mild shear conditions, improving the density and stability of the carbon layer. At this time, the addition can also reduce the interference on the rheology of the upstream melt, suppress viscosity fluctuations caused by premature reaction, and ensure a smooth extrusion process. In step S7, methyl silicone oil is directly injected into the special injection port at the rear of the twin-screw extruder barrel through a metering pump, which can achieve precise control of the dosage and ensure that it acts directly on the molten material that needs defoaming. In step S8, the molten material is cooled and solidified by air cooling, then cut into regular particles with smooth surfaces and no burrs, and then undergoes quality inspection to test flame retardant performance, smoke toxicity, and aging resistance. After passing the inspection, it is sealed and packaged and stored in the warehouse.

[0048] In some embodiments, the selected twin-screw extruder has 10 temperature control zones and 1 die head; its structure and temperature configuration are as follows: Zone 1 has a temperature of 200-220°C and is equipped with a main feed port for adding PA66 and additive packages; Zone 5 has a temperature of 230-250°C and is equipped with a first side feed port; Zone 6 has a temperature of 230-250°C and is equipped with a second side feed port; Zone 7 has a temperature of 160-180°C and is equipped with a vacuum exhaust port; Zone 8 has a temperature of 160-180°C and is equipped with an injection port for injecting defoamer; in addition, Zone 2 has a temperature of 250-270°C, Zones 3-4 have a temperature of 260-280°C, Zones 9-10 have a temperature of 160-180°C, and the die head temperature is 250-270°C.

[0049] In some of the above embodiments, the process employs segmented temperature control, causing the material to sequentially undergo preheating (zone 1), rapid melting (zone 2), high-temperature mixing (zones 3-4), and cooling reaction (zones 5-6). Cooling in zone 5 protects the molecular chain structure of the toughening agent POE-g-MAH from being damaged by excessive temperature and shear force, while simultaneously providing the optimal reaction temperature for the catalyst. This promotes the amidation reaction between the amino terminus of PA66 and the anhydride terminus of POE-g-MAH, the subsequent amidation reaction between the carboxyl terminus of PA66 and the amino terminus of 3-aminopropane-1-phosphate, and the Ca2+ reaction between the 3-aminopropane-1-phosphate phosphonic acid terminus and calcium mucinate. 2+The formation of ionic and coordinate bonds enhances the mechanical properties of the final product. Furthermore, the vacuum exhaust port in zone 7 effectively removes moisture and volatile substances. Simultaneously, the method employs segmented feeding, adding PA66 and additives at the front end, while POE-g-MAH, 3-aminopropane-1-phosphoric acid, and calcium mucinate are added from the side feed port in the middle of the barrel to protect their molecular structure. Defoamer is precisely injected at the injection port (zone 8), eliminating small bubbles formed by the vaporization of air or trace amounts of moisture entrained in the material, ultimately improving the material's density and mechanical properties. The die head temperature is set at 250-270℃ to maintain a high temperature and ensure good melt flowability and pressure. The resulting material, formed through the die orifice of a twin-screw extruder, has a smooth surface and uniform dimensions.

[0050] In summary, compared with the prior art, the beneficial effects of this application are at least as follows:

[0051] Compared to traditional flame-retardant PA66 materials, this invention involves an amidation reaction between the amino terminus of PA66 and the anhydride terminus of POE-g-MAH, forming a strong chemical bond interface that significantly improves compatibility, enhances interfacial stress transfer, and achieves excellent toughening effects. It also solves the problem of mechanical property degradation caused by traditional toughening agents while maintaining the stability of the flame-retardant system. The amidation of the carboxyl terminus of PA66 with the amino terminus of 3-aminopropane-1-phosphate and the synergistic effect of POE-g-MAH improve the interface, enhance melt strength and rheological stability, reduce fracture and uneven flow during processing, and improve intermolecular forces, enabling the material to maintain excellent mechanical properties and aging resistance even under long-term high-temperature environments. Furthermore, the Ca2+ of the 3-aminopropane-1-phosphate phosphonic acid terminus and the Ca2+ of calcium mucinate... 2+ The components are bonded together through ionic and coordinate bonds, generating stable calcium phosphate compounds during combustion. These compounds enhance the density and heat resistance of the char layer, effectively blocking heat and oxygen, and further improving flame retardancy. Simultaneously, calcium mucoconate is not easily decomposed under processing conditions, avoiding side reactions and enhancing the material's electrical properties. Because calcium mucoconate is bonded to the phosphonic acid groups of 3-aminopropane-1-phosphate through ionic and coordinate bonds, 3-aminopropane-1-phosphate participates in the interface improvement reaction, further improving the stability and uniform dispersion of calcium mucoconate in the system, enhancing compatibility, strengthening the role of calcium mucoconate, and further optimizing mechanical properties. Therefore, the combined addition of 3-aminopropane-1-phosphate, POE-g-MAH, and calcium mucoconate achieves a synergistic improvement in flame retardancy and mechanical properties. Detailed Implementation

[0052] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0055] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0056] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0057] PA66, CAS number 32131-17-2, model PA66 EPR27;

[0058] Brominated epoxy resin, CAS number 68928-70-1, model KBE-2010k; Sb2O3, average particle size: 1.0μm;

[0059] Pentaerythritol tetrastearate, CAS number 115-83-3;

[0060] Ethylene bis-stearamide, CAS number 110-30-5;

[0061] Zinc stearate, CAS number 557-05-1, model selected is zinc stearate N208;

[0062] Antioxidant 1010, CAS number 6683-19-8;

[0063] Antioxidant 1098, CAS number 23128-74-7, light transmittance ≥97%;

[0064] Antioxidant 168, CAS number 31570-04-4;

[0065] POE-g-MAH, CAS number 9006-26-2;

[0066] 3-Aminopropane-1-phosphoric acid, CAS number 13138-33-5;

[0067] Mucoconic acid, CAS number 3588-17-8;

[0068] Calcium stearate, CAS number 1592-23-0, average particle size: 0.5μm;

[0069] Calcium acetate, CAS number 62-54-4, average particle size: 0.5μm;

[0070] Zinc oxide, CAS number 1314-13-2, average particle size: 0.5μm;

[0071] Magnesium oxide, CAS number 1309-48-4, average particle size: 0.5μm;

[0072] Methyl silicone oil, CAS number 63148-62-9, viscosity: 1000-3000 cSt;

[0073] Twin-screw extruder: Screw diameter: 65-75mm, L / D ratio: 40-44, Specific torque ≥12Nm / cm 3 Rated speed: 300-600rpm, ten-temperature zone plus head temperature control system.

[0074] Preparation Example

[0075] Mucoconic acid was dissolved in deionized water at 30°C to prepare a 10 wt% mucoconic acid solution.

[0076] A 5 wt% uniform calcium hydroxide slurry was prepared by mixing and stirring calcium hydroxide with water.

[0077] The above calcium hydroxide slurry was slowly added dropwise to the above mucoacinic acid solution under stirring conditions, while the pH of the solution was monitored and controlled at 7, and the solution was kept at 30°C and stirred for 45 minutes to obtain the neutralized reaction solution.

[0078] The neutralized reaction solution was stirred at 35°C for 1 hour and filtered while hot to obtain a clear solution.

[0079] Add ethanol twice the volume of the clarified liquid to the above clarified liquid, stir for 6 hours, and filter to obtain crystals;

[0080] The obtained crystals were washed with 5°C ice-cold ethanol to remove entrained moisture and organic acid residues, and then dried under reduced pressure at 45°C to constant weight. The dried calcium mucinate was pulverized using an air jet mill, and calcium mucinate micro powder with an average particle size of 0.5 μm was obtained by air jet classification.

[0081] Example 1

[0082] For the preparation of a flame-retardant PA66 material for automotive applications:

[0083] Formula ratio:

[0084] PA66: 65 servings;

[0085] Brominated epoxy resin: 18 parts;

[0086] Antimony trioxide: 6 parts;

[0087] POE-g-MAH: 8 copies;

[0088] 3-Aminopropane-1-phosphoric acid: 0.4 parts;

[0089] Calcium mucoconnate micro powder: 1 part;

[0090] Lubricant (Pentaerythritol tetrastearate, Ethylene bis-stearamide, Zinc stearate): Pentaerythritol tetrastearate: 0.5 parts, Ethylene bis-stearamide: 0.3 parts, Zinc stearate: 0.2 parts, Total: 1 part;

[0091] Antioxidants (Antioxidant 1010, Antioxidant 1098, Antioxidant 168): Antioxidant 1010: 0.3 parts, Antioxidant 1098: 0.1 parts, Antioxidant 168: 0.4 parts, Total: 0.8 parts;

[0092] Zinc oxide: 0.3 parts;

[0093] Methyl silicone oil: 0.1 parts;

[0094] Preparation method:

[0095] S1: Weigh the brominated epoxy resin, antimony trioxide, pentaerythritol tetrastearate, antioxidant 1010, antioxidant 1098, antioxidant 168 and zinc oxide according to the formula ratio, and then mix them in the first high-speed mixer to obtain the first additive package.

[0096] S2: Use two loss-in-weight feeders, one for the weighed PA66 and the other for the first additive package; the two feeders simultaneously and continuously feed the material into the main feed port at the front of the twin-screw extruder according to the formula ratio;

[0097] S3: Using a third loss-in-weight feeder, add POE-g-MAH from the first side feed port in the middle section of the twin-screw extruder barrel;

[0098] S4: Mix 3-aminopropane-1-phosphoric acid, calcium mucinate, ethylene bis-stearamide, and zinc stearate in a second high-speed mixer to obtain a second additive package;

[0099] S5: Using the fourth loss-in-weight feeder, add the second additive package from the second side feed port in the middle section of the twin-screw extruder barrel;

[0100] S6: Methyl silicone oil is directly injected into a dedicated injection port at the rear of the twin-screw extruder barrel via a metering pump;

[0101] S7: The molten material extruded from the twin-screw extruder head is cooled and shaped by air cooling, then cut into uniform particles with a length of about 3mm by a pelletizer, and then inspected for quality and packaged before being stored in the warehouse.

[0102] Process parameters:

[0103] High-speed mixer: Speed: 2500 rpm;

[0104] Twin-screw extruder: 10 temperature control zones and 1 die head; screw speed: 300 rpm.

[0105] Temperature in the temperature control zone:

[0106] Zone 1 (Main Feed Inlet): 220℃;

[0107] Zone 2: 250℃;

[0108] Zones 3-4: 270℃;

[0109] Zone 5 (First side feeding port): 240℃;

[0110] Zone 6 (Second side feeding port): 230℃;

[0111] Zone 7 (vacuum exhaust port): 180℃;

[0112] Zone 8 (injection port): 170℃;

[0113] Zones 9-10: 180℃;

[0114] Machine head: 250℃.

[0115] Example 2

[0116] For the preparation of a flame-retardant PA66 material for automotive applications:

[0117] Similar to Example 1, except that 18 parts of brominated epoxy resin in the formulation are replaced with 14 parts of brominated polystyrene (CAS No. 88497-56-7, model FR-671), that is, the same mass of bromine is used for replacement.

[0118] Example 3

[0119] For the preparation of a flame-retardant PA66 material for automotive applications:

[0120] It is largely the same as Example 1, except that the amount of POE-g-MAH in the formulation is 4 parts.

[0121] Example 4

[0122] For the preparation of a flame-retardant PA66 material for automotive applications:

[0123] It is largely the same as Example 1, except that the amount of POE-g-MAH in the formulation is 6 parts.

[0124] Example 5

[0125] For the preparation of a flame-retardant PA66 material for automotive applications:

[0126] It is largely the same as Example 1, except that the amount of POE-g-MAH in the formulation is 10 parts.

[0127] Example 6

[0128] For the preparation of a flame-retardant PA66 material for automotive applications:

[0129] It is largely the same as Example 1, except that the amount of POE-g-MAH in the formulation is 12 parts.

[0130] Example 7

[0131] For the preparation of a flame-retardant PA66 material for automotive applications:

[0132] It is largely the same as Example 1, except that the amount of 3-aminopropane-1-phosphoric acid in the formulation is 0.2 parts.

[0133] Example 8

[0134] For the preparation of a flame-retardant PA66 material for automotive applications:

[0135] It is largely the same as Example 1, except that the amount of 3-aminopropane-1-phosphoric acid in the formulation is 0.3 parts.

[0136] Example 9

[0137] For the preparation of a flame-retardant PA66 material for automotive applications:

[0138] It is largely the same as Example 1, except that the amount of 3-aminopropane-1-phosphoric acid in the formulation is 0.5 parts.

[0139] Example 10

[0140] For the preparation of a flame-retardant PA66 material for automotive applications:

[0141] It is largely the same as Example 1, except that the amount of 3-aminopropane-1-phosphoric acid in the formulation is 0.6 parts.

[0142] Example 11

[0143] For the preparation of a flame-retardant PA66 material for automotive applications:

[0144] The formula is largely the same as Example 1, except that 0.3 parts of zinc oxide are replaced with 0.15 parts of magnesium oxide; that is, the mass conversion is based on the equimolar amount of metal.

[0145] Comparative Example 1

[0146] Compared with Example 1, Comparative Example 1 did not add 3-aminopropane-1-phosphoric acid, but replaced 3-aminopropane-1-phosphoric acid with an equal amount of POE-g-MAH. All POE-g-MAH were added together during feeding, and the remaining preparation steps and parameters were the same as in Example 1.

[0147] Comparative Example 2

[0148] Compared with Example 1, in Comparative Example 2, 1 part of calcium acetate was used instead of 1 part of calcium mucinate micro powder, and the remaining preparation steps and parameters were the same as in Example 1.

[0149] Comparative Example 3

[0150] Compared with Example 1, in Comparative Example 3, 1 part calcium stearate was used instead of 1 part calcium mucinate powder, and the remaining preparation steps and parameters were the same as in Example 1.

[0151] Test section

[0152] The testing standards corresponding to the testing items are shown in Table 1 below:

[0153] Table 1

[0154]

[0155] The results of combustion performance, mechanical properties, and electrical properties are shown in Table 2 below:

[0156] Table 2

[0157]

[0158] This invention introduces a specific ratio of 3-aminopropane-1-phosphate and calcium mucinate into a PA66 matrix, thereby improving the electrical and mechanical properties of the material while maintaining high flame retardancy. Test results show that this synergistic system enables the relative tracking index of the embodiment to meet the high safety level requirements for battery pack materials used in electric vehicles. At the same time, the tensile strength and flexural strength are higher than those of the comparative example, showing that the mechanical strength of the material can be maintained or even improved after the introduction of the flame retardant system. The limiting oxygen index is also higher than that of the comparative example, showing excellent flame retardant performance.

[0159] As shown in Examples 1-2, brominated epoxy resin exhibits high thermal stability when used as a halogenated main flame retardant. In the twin-screw extrusion process, the epoxy structure improves the compatibility with the matrix and reduces migration. Furthermore, the decomposition products synergistically generate SbBr3 with Sb2O3, effectively capturing free radicals generated during combustion. Under the same halogen content, the flame retardant effect and other properties are superior to brominated polystyrene.

[0160] As shown in Examples 1 and 3-6, when the mass fraction of POE-g-MAH is 6-10 parts, the flexible segments of POE absorb impact energy, and the maleic anhydride graft (g-MAH) reacts with the terminal amino groups of PA66 to form amide bonds, improving interfacial bonding. When the mass fraction of POE-g-MAH is less than 6 parts, the grafting is insufficient, and the mechanical properties decrease. When it is more than 12 parts, the proportion of PA66 matrix decreases and the dispersion of flame retardant is hindered. Excessive toughening agent also reduces tensile strength and flexural strength. This flame-retardant PA66 material takes into account both flame retardant performance and mechanical properties within this ratio range.

[0161] As shown in Examples 1 and 7-10, when the mass fraction of 3-aminopropane-1-phosphoric acid is 0.3-0.5 parts and other components remain unchanged, the amino group of 3-aminopropane-1-phosphoric acid can react with the carboxyl group of PA66 to form an amide bond, and the phosphonic acid group can react with the Ca group of calcium mucinate. 2+ The components are bonded through ionic and coordinate bonds. When the mass fraction of 3-aminopropane-1-phosphoric acid is less than 0.3 parts, it is insufficiently crosslinked with PA66 and insufficiently coordinated with calcium mucinate, resulting in insufficient density of the char layer formed during combustion. When the mass fraction is greater than 0.5 parts, it may lead to localized gelation. Therefore, when 6-10 parts of POE-g-MAH and 0.3-0.5 parts of 3-aminopropane-1-phosphoric acid are used together, both flame retardancy and mechanical properties can be improved. The optimal performance is achieved with 8 parts of POE-g-MAH and 0.4 parts of 3-aminopropane-1-phosphoric acid. This may be because, at the above mass fractions, POE-g-MAH and 3-aminopropane-1-phosphoric acid achieve the best synergistic regulation of interface modification. At the same time, the modification of 3-aminopropane-1-phosphoric acid enables calcium mucinate to achieve more uniform and stable dispersion in the material based on bonding, thus giving full play to its mechanical reinforcement and flame retardant effects.

[0162] As shown in Examples 1 and 11, zinc oxide exhibits a better catalytic effect than magnesium oxide; this is because Zn 2+ Lewis acids are more reactive than Mg. 2+ Under the same processing time, it can more effectively activate the carboxyl group of PA66 and the anhydride group of POE-g-MAH, reduce the activation energy of the amidation reaction, and promote interfacial bonding; under the same processing conditions, its mechanical properties are superior to those of magnesium oxide.

[0163] According to Example 1 and Comparative Example 1, if 3-aminopropane-1-phosphate is missing and replaced with POE-g-MAH, the Ca of calcium mucinate will increase. 2+ The ionic and coordinate bonds at the carboxyl end of PA66 are weaker than those at the phosphonic acid group, resulting in insufficient cross-linking of PA66 and a decline in mechanical, electrical, and thermal properties. Since the phosphonic acid group also has certain flame-retardant properties, without 3-aminopropane-1-phosphoric acid, a stable calcium phosphate compound cannot be generated during combustion to form a char layer to improve density and heat resistance, thus reducing flame-retardant properties. Experiments show that this application can achieve a synergistic improvement in flame retardancy and mechanical properties by using a small amount of 3-aminopropane-1-phosphoric acid in conjunction with POE-g-MAH interface modification.

[0164] As shown in Example 1 and Comparative Examples 2-3, compared to calcium stearate and calcium acetate, an equal amount of calcium mucocarboxylate can achieve better mechanical, flame retardant, and electrical properties through interfacial modification with 3-aminopropane-1-phosphoric acid and POE-g-MAH. This may be because calcium mucocarboxylate is less prone to premature separation of free acid during processing, thus reducing the risk of hydrolysis, and it also fails to generate stable calcium phosphate compounds as a char layer during combustion to maintain flame retardancy.

[0165] The appearance of the above-mentioned embodiments and comparative examples showed no discoloration, cracks, bubbles, or particulate matter upon visual inspection; the toxicity level of the flue gas reached ZA1 after testing according to the GB / T 20285-2006 method.

[0166] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A flame-retardant PA66 material for automotive applications, characterized in that, By weight parts, including the following mass parts of substances: PA66 65 parts; Main flame retardant 14-21 parts; Antimony trioxide 5-7 parts; POE-g-MAH 6-10 parts; 3-Aminopropane-1-phosphonic acid 0.3-0.5 parts; Calcium muconate 0.8-1.2 parts; Lubricant 0.6-1.2 parts; Antioxidant 0.6-1 parts; Catalyst 0.1-0.4 parts; Defoaming agent 0.05-0.15 parts.

2. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The main flame retardant is a halogen-based flame retardant.

3. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The main flame retardant is a brominated epoxy resin.

4. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The calcium muconate is made by the following technical scheme: Dissolve muconic acid in deionized water to prepare a 5-15wt% muconic acid solution; Mix and stir calcium hydroxide with water to prepare a 5-10wt% uniform calcium hydroxide water slurry, add the calcium hydroxide water slurry to the muconic acid solution, control the pH value to be 6.8-7.2, and obtain a neutralized reaction liquid; Purify the neutralized reaction liquid to obtain a clear liquid, and crystallize to obtain crystals; Remove the water and organic acid residues from the obtained crystals, and dry, crush, and grade to obtain calcium muconate powder with an average particle size of 0.3-0.5μm.

5. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The lubricant is at least one of pentaerythritol tetra stearate, ethylene bis stearic amide, and zinc stearate.

6. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The antioxidant is a compounded system of hindered phenolic antioxidant and phosphite antioxidant; the hindered phenolic antioxidant includes at least one of antioxidant 1010 and antioxidant 1098, and the phosphite antioxidant is antioxidant 168.

7. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The catalyst includes at least one of zinc oxide and magnesium oxide.

8. The flame-retardant PA66 material for automotive use according to claim 1, characterized by, The defoaming agent is methyl silicone oil.

9. A process for the preparation of a flame-retardant PA 66 material for automotive applications, characterized in that, Including: Providing raw materials of the vehicle flame-retardant PA66 material according to any one of claims 1-8; Mixing and melting the raw materials to obtain the vehicle flame-retardant PA66 material by co-extrusion, cooling, and granulation.

Images