Polyamide / modified syndiotactic polystyrene composite material for automotive intake manifold and preparation method of polyamide / modified syndiotactic polystyrene composite material

Abstract

The invention provides a polyamide / modified syndiotactic polystyrene composite material for a vehicle intake manifold and a preparation method of the polyamide / modified syndiotactic polystyrene composite material. The composite material comprises the following components in parts by weight: 31-58 parts of a polyamide 66 / 6T copolymer; 10 to 20 parts by weight of modified syndiotactic polystyrene; 28 to 37 parts by weight of glass fiber; 3-8 parts by weight of a compatilizer; 0.5-2 parts by weight of a processing aid; and 0.5 to 1.5 parts by weight of black bright master batch. The polyamide 66 / 6T copolymer and the modified syndiotactic polystyrene are blended and modified, so that the excellent mechanical property of the composite material can be ensured, the water absorption resistance, the solvent resistance and the explosion resistance of the intake manifold can be effectively improved, and the service life of the intake manifold is prolonged.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and in particular to a polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds and its preparation method. Background Technology

[0002] As a key component of the engine, the intake manifold's main function is to guide airflow and distribute the combustible mixture within the cylinders, ensuring complete combustion. Because the intake manifold operates in environments of heat, vibration, and oil accumulation for extended periods, it requires excellent high-temperature resistance, mechanical properties, dimensional stability, chemical stability, and thermal aging stability. Furthermore, in the event of abnormal engine backfire, high-pressure gas from the power stroke flows back into the intake manifold, causing a sudden pressure surge within the manifold cavity, reaching peak pressures of several or even tens of atmospheres instantaneously. Therefore, the intake manifold's burst pressure must exceed this peak pressure to prevent damage and ensure user safety under abnormal conditions, requiring high burst resistance. Currently, commonly used intake manifolds include metal and plastic types. Compared to traditional metal intake manifolds, plastic intake manifolds offer advantages such as lighter weight, lower cost, greater design flexibility, smoother inner surfaces, and lower flow resistance. In existing technologies, the plastic materials used to manufacture intake manifolds are generally glass fiber reinforced polyamide 6 or polyamide 66. However, glass fiber reinforced polyamide 6 or polyamide 66 is prone to water absorption and deformation. Water absorption also leads to a significant decrease in the material's mechanical strength. Furthermore, in the presence of solvents, the corrosion resistance of glass fiber reinforced polyamide 6 or polyamide 66 is greatly reduced, thus affecting its service life. At the same time, due to the low tensile strength of glass fiber reinforced polyamide 6 or polyamide 66, the burst pressure resistance of plastic intake manifolds is often lower than the pressure inside the intake manifold during engine backfire, posing a significant risk to reliability in use. Summary of the Invention

[0003] This application aims to address the technical problems of glass fiber reinforced polyamide 6 or polyamide 66 in automotive intake manifolds, such as easy water absorption leading to deformation, poor corrosion resistance in solvent environments, and low burst resistance. It proposes a polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds and its preparation method. By blending polyamide 66 / 6T copolymer with modified syndiotactic polystyrene, the composite material can be guaranteed to possess excellent mechanical properties while effectively improving the intake manifold's water absorption resistance, solvent resistance, and burst resistance, thereby extending its service life.

[0004] To achieve the above objectives, this application adopts the following technical solution: A polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds, comprising the following components in parts by weight: Polyamide 66 / 6T copolymer: 31-58 parts by weight; modified syndiotactic polystyrene: 10-20 parts by weight; glass fiber: 28-37 parts by weight; compatibilizer: 3-8 parts by weight; processing aid: 0.5-2 parts by weight; black gloss masterbatch: 0.5-1.5 parts by weight.

[0005] Furthermore, the density of the polyamide 66 / 6T copolymer is 1.13-1.15 g / cm³. 3 It has a melting point of 260℃-270℃ and a relative viscosity of 2.4-3.0.

[0006] Furthermore, the modified syndiotactic polystyrene comprises the following components by weight: 88-92 parts by weight of syndiotactic polystyrene; 8-10 parts by weight of maleic anhydride-grafted polyphenylene ether; 0.2-0.7 parts by weight of lubricant; and 0.2-0.5 parts by weight of antioxidant.

[0007] Furthermore, the lubricant is one or a mixture of any two or more of the following: modified ethylene bis-fatty acid amide, pentaerythritol stearate, and montan wax, in any proportion.

[0008] Furthermore, the preparation method of the modified syndiotactic polystyrene includes the following steps: weighing syndiotactic polystyrene, maleic anhydride-grafted polyphenylene ether, lubricant, and antioxidant, mixing them evenly in a high-speed mixer, placing them in the main feed port of a parallel twin-screw extruder, melting and extruding them through the parallel twin-screw extruder, then pelletizing and drying them.

[0009] Furthermore, the parallel twin-screw extruder has a length-to-diameter ratio of 48:1, a processing temperature of 270℃-310℃ in each zone, a die head temperature of 300℃±5℃, and a vacuum degree of ≤-0.09MPa.

[0010] Furthermore, the glass fiber is a hydrolysis-resistant, alkali-free chopped glass fiber, the glass fiber monofilament diameter is 7-17μm, and the glass fiber chopped length is 3-20mm.

[0011] Furthermore, the compatibilizer is a maleic anhydride-styrene copolymer.

[0012] Furthermore, the processing aids are mold release agents and heat stabilizers.

[0013] Furthermore, the release agent is a silicone masterbatch, and the carrier resin of the silicone masterbatch is polyamide 6 with a siloxane content of ≥40%.

[0014] Furthermore, the heat stabilizer is an organic copper salt heat stabilizer.

[0015] Furthermore, the black glossy masterbatch comprises, by weight, the following components: 28-65 parts by weight of polyamide 6 resin; 10-25 parts by weight of polyamide 6I / 6T copolymer; 0.2-0.9 parts by weight of lubricant; 0.2-0.5 parts by weight of antioxidant; 0.2-0.5 parts by weight of anti-photoaging agent; 10-20 parts by weight of inorganic carbon black masterbatch; and 15-25 parts by weight of organic aniline black masterbatch.

[0016] Furthermore, the relative viscosity of the polyamide 6 resin is 2.0-2.7.

[0017] Furthermore, the density of the polyamide 6I / 6T copolymer is 1.17-1.19 g / cm³. 3 .

[0018] Furthermore, the lubricant is one or a mixture of any two or more of the following: modified ethylene bis-fatty acid amide, pentaerythritol stearate, and montan wax, in any proportion.

[0019] Furthermore, the antioxidants used in the modified syndiotactic polystyrene and the black glossy masterbatch are all mixtures of hindered phenolic antioxidants and phosphite antioxidants.

[0020] Furthermore, the anti-photoaging agent is a mixture of ultraviolet absorber and light stabilizer.

[0021] Furthermore, the carrier resin of the inorganic carbon black masterbatch is polyamide 6, and the inorganic carbon black content is 35%-45%.

[0022] Furthermore, the carrier resin of the organic aniline black masterbatch is polyamide 6, and the organic aniline black content is 35%-45%.

[0023] Furthermore, the preparation method of the black glossy masterbatch includes the following steps: S1. Weigh out the polyamide 6 resin, polyamide 6I / 6T copolymer, lubricant, antioxidant, anti-photoaging agent, inorganic carbon black masterbatch, and organic aniline black masterbatch and mix them evenly in a high-speed mixer. S2. The premixed material obtained in S1 is fed into the main feed port of a parallel twin-screw extruder and melt-extruded through the parallel twin-screw extruder; wherein, the length-to-diameter ratio of the parallel twin-screw extruder is 48:1, the processing temperature of each zone is set to 200℃-260℃, the die head temperature is set to 250℃±5℃, and the vacuum degree is ≤-0.09MPa. S3. The material extruded from the head of the parallel twin-screw extruder is subjected to underwater pelleting, dehydration in a dewatering machine, drying in an oven, and screening by a vibrating screen to obtain black glossy masterbatch.

[0024] Furthermore, the particle size of the particles obtained after pelleting in S3 is 3-4 mm; the moisture content of the particles after dehydration in the dewatering machine is ≤0.2%.

[0025] A method for preparing a polyamide / modified syndiotactic polystyrene composite material for an automotive intake manifold as described above includes the following steps: The weighed polyamide 66 / 6T copolymer, modified syndiotactic polystyrene, compatibilizer, processing aid, and black glossy masterbatch were mixed evenly in a high-speed mixer and then fed into the main feed port of a parallel twin-screw extruder. Glass fiber was then added to the side feed port of the parallel twin-screw extruder according to a weight ratio. The mixture was then melt-blended, extruded, and granulated in the parallel twin-screw extruder to obtain the polyamide / modified syndiotactic polystyrene composite material for the automotive intake manifold. The parallel twin-screw extruder had a length-to-diameter ratio of 48:1, processing temperatures in each zone were set to 250℃-290℃, the die head temperature was set to 280℃±5℃, and the vacuum degree was ≤-0.09MPa.

[0026] The beneficial effects of this application are: Polyamide 66 / 6T copolymer is a polyamide resin synthesized from polyamide 66 salt and polyamide 6T salt as main raw materials through melt polycondensation. It is equivalent to introducing a benzene ring structure into the polyamide 66 molecular chain, but its benzene ring content does not exceed 50%. Compared to polyamide 66 or polyamide 6, polyamide 66 / 6T copolymer retains the processability of polyamide 66 while possessing the advantages of polyamide 6T, such as high mechanical properties, low water absorption, strong corrosion resistance, and good heat resistance. Meanwhile, syndiotactic polystyrene has a rigid benzene ring structure in its molecular chain. The benzene rings are regularly arranged on both sides of the molecular chain, resulting in crystallization and restricting the movement of the molecular chain. This gives syndiotactic polystyrene high strength, high hardness, low water absorption, and strong corrosion resistance. Furthermore, syndiotactic polystyrene has a very small difference in shrinkage rate between the flow direction and the vertical direction during injection molding, i.e., the shrinkage equilibrium is close to 1, thus exhibiting good dimensional stability. This application combines the molecular structure characteristics of polyamide 66 / 6T copolymer and syndiotactic polystyrene, using maleic anhydride-polystyrene copolymer as a compatibilizer, polyamide 66 / 6T copolymer as the continuous phase, and syndiotactic polystyrene as the dispersed phase. Through compatibilization technology, polyamide 66 / 6T copolymer and syndiotactic polystyrene are blended and modified. The resulting composite material not only retains the easy processability, high mechanical properties, low water absorption, and good temperature resistance of polyamide 66 / 6T copolymer, but also, while ensuring the excellent mechanical properties of the composite material, syndiotactic polystyrene can further reduce the hygroscopicity of the material, improve solvent resistance, dimensional stability, and warping resistance. Therefore, it can meet the requirements for use in automotive intake manifolds. More importantly, this application selects polyamide 66 / 6T with a melting point of 260℃-270℃, which allows for similar processing conditions to modified syndiotactic polystyrene, which also has a melting point of 260℃-270℃. This ensures that the blend of polyamide 66 / 6T and syndiotactic polystyrene maintains good structural stability under high-temperature processing conditions, thereby guaranteeing the excellent comprehensive properties of the composite material. Furthermore, the density of syndiotactic polystyrene is 1.10-1.13 g / cm³. 3 It is a lightweight material among engineering plastics, with a density of 1.13-1.15 g / cm³ compared to polyamide 6 and polyamide 66. 3 This helps reduce the weight and cost of parts, and further enhances the application of lightweight materials in automotive applications.

[0027] Unmodified syndiotactic polystyrene is a non-polar crystalline polymer with poor thermodynamic compatibility with polar substances such as polyamide and glass fiber. Direct blending with them results in poor mechanical properties of the composite material. Adding conventional compatibilizers, such as maleic anhydride-grafted syndiotactic polystyrene or sulfonated syndiotactic polystyrene, directly to glass fiber-reinforced polyamide / syndiotactic polystyrene composites can improve compatibility. However, for intake manifolds with complex structures and unique shapes, this still fails to meet technical requirements, leading to localized air leaks due to poor material compatibility. Air leaks in the intake manifold will produce abnormal noises, and the vehicle will experience vibrations, unstable idling, weak acceleration, and frequent stalling. This application enhances the material's compatibility through two methods. The first method is to polarize syndiotactic polystyrene by grafting maleic anhydride-modified polyphenylene ether. In maleic anhydride-grafted modified polyphenylene ether, the polyphenylene ether is completely compatible with the amorphous phase in syndiotactic polystyrene. The blend exhibits only one glass transition temperature, demonstrating good compatibility and thus improving the impact properties of syndiotactic polystyrene. The abundant active groups in maleic anhydride-grafted modified polyphenylene ether—maleic anhydride—can coat the surface of syndiotactic polystyrene, thereby achieving polarization modification and improving the compatibility of syndiotactic polystyrene with polyamide 66 / 6T copolymer and glass fiber. The second approach uses maleic anhydride-polystyrene copolymer as a compatibilizer. This method leverages the similar molecular structures of both polystyrene and syndiotactic polystyrene in the compatibilizer, resulting in good compatibility. Simultaneously, the maleic anhydride in the compatibilizer can strongly react with the terminal amino groups on the polyamide 66 / 6T copolymer molecular chain, achieving reaction compatibilization and strengthening the interfacial adhesion between the two polymers to improve compatibility.

[0028] This application utilizes commercially available inorganic carbon black masterbatch and organic aniline black masterbatch, combined with polyamide 6 and polyamide 6I / 6T copolymer, to prepare a glossy black masterbatch through blending modification. This effectively improves the dispersion uniformity of the colorant, reduces the carbon black diameter, and prevents uneven dispersion of the colorant in the intake manifold or excessively large carbon black diameter, which could cause cracking and leakage in the intake manifold and thus affect its burst resistance. Furthermore, in preparing the glossy black masterbatch, this application uses low-viscosity polyamide 6 and polyamide 6I / 6T copolymer as the carrier resin, which further reduces the melt viscosity of the composite material, improves processing fluidity, provides good anti-fiber floating effect, and thus ensures that the intake manifold has excellent appearance quality. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In the description of this application, the experimental methods, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, are all commercially available.

[0030] The following disclosure provides many different implementations or examples for carrying out this application. To simplify the disclosure of this application, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0031] The sources of the main raw materials in the following embodiments and comparative examples of the present invention are as follows: Polyamide 66 / 6T copolymer, grade C1504T, density 1.145 g / cm³ 3 Melting point 267℃, purchased from Shandong Guangyin New Materials Co., Ltd. Meta-dimethyl polystyrene, grade 90ZC, was purchased from Idemitsu Kosan Co., Ltd. Polyamide 6, brand name HY-2500A, was purchased from Jiangsu Haiyang Nylon New Material Co., Ltd. Polyamide 6I / 6T copolymer, grade T2134, density 1.18 g / cm³ 3 Purchased from Changzhou Shuotian New Materials Co., Ltd. Glass fiber, grade ECS-10-3.0-T435TM, fiber diameter 10μm, chopped length 3.0mm, purchased from Taishan Glass Fiber Co., Ltd. Maleic anhydride-grafted polyphenylene ether, brand name KT-24, was purchased from Shenyang Ketong Plastics Co., Ltd. Maleic anhydride-polystyrene copolymer, grade SMA-700, was purchased from Jiaxing Huawen Chemical Co., Ltd. Organic copper salt heat stabilizer, brand name H3336, purchased from Bruggemann. Silicone masterbatch, brand name MB50-11, 50% siloxane content, purchased from Dow Corning. Pentaerythritol stearate, brand name Glycolube P, CAS Registry No.: 115-83-3, purchased from Lonza. Inorganic carbon black masterbatch, grade CB8093H, with an inorganic carbon black content of 40% and a carbon black diameter of 18nm, was purchased from Muil Chemical. The organic aniline black masterbatch, brand name PA-1066, with an organic aniline black content of 40%, was purchased from Zhejiang Jiahua Fine Chemicals Co., Ltd. Antioxidant 1098, brand name Irganox 1098, CAS Registry Number: 23128-74-7, purchased from BASF. Antioxidant 168, brand name Irganox 168, CAS Registry No.: 31570-04-4, purchased from BASF. UV absorber UV-234, brand name Tinuvn 234, CAS Registry No.: 70321-86-7, purchased from BASF. The light stabilizer is UV-944, brand name Chimassorb 944, CAS Registry No.: 71878-19-8, purchased from BASF. The remaining reagents are standard commercially available products.

[0032] The testing methods used in the performance testing of the corresponding products in the various embodiments and comparative examples of this invention are as follows: Appearance: Plastic particles are injection molded into samples with dimensions of 60*60*3mm. The surface gloss and fiber looseness of the samples are visually inspected and graded as excellent, good, or moderate.

[0033] The density was determined according to ISO 1183 method, and the medium was pure water.

[0034] Water absorption rate: Plastic particles were injection molded into samples with dimensions of 60*60*3mm. The samples were first dried in an oven at 50℃±2℃ for 144h until the weight was constant and the mass change was within ±0.1mg. Then, the constant-weighted samples were immersed in distilled water at 23℃±2℃ for 24h.

[0035] Tensile strength was determined according to ISO 527 method, with a gauge length of 75 mm, a test speed of 5 mm / min, and a specimen type of 1A.

[0036] The tensile modulus was determined according to ISO 527 method, with a gauge length of 75 mm, a test speed of 1 mm / min, and a spline type of 1A.

[0037] Bending strength was determined according to ISO 178 method, with a span of 64 mm, a test speed of 2 mm / min, and a sample size of 80*10*4 mm.

[0038] The notched impact strength of the simply supported beam was determined according to ISO 179 method, with a pendulum energy of 4J and a spline type of 1eA.

[0039] Thermal aging properties – tensile strength retention rate – were determined according to ISO 188 and ISO 527 methods, with a gauge length of 75 mm, a test speed of 5 mm / min, and a specimen type of 1A. Thermal aging conditions: 140℃, 1000 h.

[0040] Thermal aging performance – the retention rate of notched impact strength of simply supported beams was determined according to ISO 188 and ISO 179 methods, with a pendulum energy of 4J and a spline type of 1eA. Thermal aging conditions: 140℃, 1000h.

[0041] Solvent resistance – tensile strength retention was determined according to ISO 527 method, gauge length 75 mm, test speed 5 mm / min, and specimen type 1A. Specimen pretreatment: First, the specimens were dried in an oven at 130℃ for 4 hours until constant weight was achieved and the mass change was within ±0.1 mg. Then, the specimens were immersed in a cooling solution (a 1:1 volume ratio mixture of ethylene glycol and water) for 1000 hours. Finally, the specimens were removed, placed in aluminum foil bags, and stored at 23℃±2℃ for 24 hours. Example 1

[0042] Preparation of modified syndiotactic polystyrene Weigh each component according to the following parts by weight: Syndiotactic polystyrene: 90 parts by weight; maleic anhydride-grafted polyphenylene ether: 9 parts by weight; pentaerythritol stearate: 0.6 parts by weight; antioxidant 1098: 0.2 parts by weight; antioxidant 168: 0.2 parts by weight.

[0043] The weighed syndiotactic polystyrene, maleic anhydride-grafted polyphenylene ether, pentaerythritol stearate, antioxidant 1098 and antioxidant 168 were mixed evenly in a high-speed mixer, and then placed in the main feed port of a parallel twin-screw extruder. After being melt-extruded by the parallel twin-screw extruder, the mixture was pelletized and dried to obtain modified syndiotactic polystyrene.

[0044] The parallel twin-screw extruder has a length-to-diameter ratio of 48:1, a processing temperature of 270℃-310℃ in each zone, a die head temperature of 300℃±5℃, and a vacuum degree of ≤-0.09MPa.

[0045] Preparation of black glossy masterbatch Weigh each component according to the following parts by weight: Polyamide 6 resin: 50 parts by weight; Polyamide 6I / 6T copolymer: 17 parts by weight; Pentaerythritol stearate: 0.6 parts by weight; Antioxidant 1098: 0.2 parts by weight; Antioxidant 168: 0.2 parts by weight; UV absorber UV-234: 0.2 parts by weight; Light stabilizer UV-944: 0.3 parts by weight; Inorganic carbon black masterbatch: 16.5 parts by weight; Organic aniline black masterbatch: 15 parts by weight.

[0046] The weighed polyamide 6 resin, polyamide 6I / 6T copolymer, pentaerythritol stearate, antioxidant 1098, antioxidant 168, ultraviolet absorber UV-234, light stabilizer UV-944, inorganic carbon black masterbatch, and organic aniline black masterbatch are mixed evenly in a high-speed mixer. The mixture is then placed in the main feed port of a parallel twin-screw extruder. After melt extrusion in the parallel twin-screw extruder, the mixture is subjected to underwater pelletizing, dehydration in a dewatering machine, drying in an oven, and sieving by a vibrating screen to obtain black glossy masterbatch.

[0047] The parallel twin-screw extruder has an aspect ratio of 48:1, a processing temperature of 200℃-260℃ in each zone, a die head temperature of 250℃±5℃, and a vacuum degree of ≤-0.09MPa; the particle size of the particles obtained after underwater pelletizing is 3-4mm; and the moisture content of the particles after dehydration is ≤0.2%.

[0048] Polyamide / modified syndiotactic polystyrene composite material for preparing automotive intake manifolds Weigh each component according to the following parts by weight: Polyamide 66 / 6T copolymer: 48.5 parts by weight; modified syndiotactic polystyrene: 15 parts by weight; glass fiber: 30 parts by weight; maleic anhydride-styrene copolymer: 4 parts by weight; silicone masterbatch: 0.5 parts by weight; organic copper salt heat stabilizer: 0.5 parts by weight; black gloss masterbatch: 1.5 parts by weight.

[0049] The weighed polyamide 66 / 6T copolymer, modified syndiotactic polystyrene, maleic anhydride-styrene copolymer, silicone masterbatch, organic copper salt heat stabilizer, and black gloss masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / modified syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

[0050] The parallel twin-screw extruder has a length-to-diameter ratio of 48:1, a processing temperature of 250℃-290℃ in each zone, a die head temperature of 280℃±5℃, and a vacuum degree of ≤-0.09MPa. Example 2

[0051] A method for preparing a polyamide / modified syndiotactic polystyrene composite material for an automotive intake manifold includes the following steps: Weigh each component according to the following parts by weight: Polyamide 66 / 6T copolymer: 35.5 parts by weight; modified syndiotactic polystyrene: 20 parts by weight; glass fiber: 35 parts by weight; maleic anhydride-styrene copolymer: 7 parts by weight; silicone masterbatch: 0.5 parts by weight; organic copper salt heat stabilizer: 0.5 parts by weight; black gloss masterbatch: 1.5 parts by weight.

[0052] The weighed polyamide 66 / 6T copolymer, modified syndiotactic polystyrene, maleic anhydride-styrene copolymer, silicone masterbatch, organic copper salt heat stabilizer, and black gloss masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / modified syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

[0053] The parallel twin-screw extruder has a length-to-diameter ratio of 48:1, a processing temperature of 250℃-290℃ in each zone, a die head temperature of 280℃±5℃, and a vacuum degree of ≤-0.09MPa.

[0054] The modified syndiotactic polystyrene and black glossy masterbatch used in this embodiment are the same as those in Example 1. Example 3

[0055] Preparation of black glossy masterbatch Weigh each component according to the following parts by weight: Polyamide 6 resin: 35 parts by weight; Polyamide 6I / 6T copolymer: 20 parts by weight; Pentaerythritol stearate: 0.6 parts by weight; Antioxidant 1098: 0.2 parts by weight; Antioxidant 168: 0.2 parts by weight; UV absorber UV-234: 0.2 parts by weight; Light stabilizer UV-944: 0.3 parts by weight; Inorganic carbon black masterbatch: 18.5 parts by weight; Organic aniline black masterbatch: 25 parts by weight.

[0056] The weighed polyamide 6 resin, polyamide 6I / 6T copolymer, pentaerythritol stearate, antioxidant 1098, antioxidant 168, ultraviolet absorber UV-234, light stabilizer UV-944, inorganic carbon black masterbatch, and organic aniline black masterbatch are mixed evenly in a high-speed mixer. The mixture is then placed in the main feed port of a parallel twin-screw extruder. After melt extrusion in the parallel twin-screw extruder, the mixture is subjected to underwater pelletizing, dehydration in a dewatering machine, drying in an oven, and sieving by a vibrating screen to obtain black glossy masterbatch.

[0057] The parallel twin-screw extruder has an aspect ratio of 48:1, a processing temperature of 200℃-260℃ in each zone, a die head temperature of 250℃±5℃, and a vacuum degree of ≤-0.09MPa; the particle size of the particles obtained after underwater pelletizing is 3-4mm; and the moisture content of the particles after dehydration is ≤0.2%.

[0058] Polyamide / modified syndiotactic polystyrene composite material for preparing automotive intake manifolds Weigh each component according to the following parts by weight: Polyamide 66 / 6T copolymer: 48.5 parts by weight; modified syndiotactic polystyrene: 15 parts by weight; glass fiber: 30 parts by weight; maleic anhydride-styrene copolymer: 4 parts by weight; silicone masterbatch: 0.5 parts by weight; organic copper salt heat stabilizer: 0.5 parts by weight; black gloss masterbatch: 1.5 parts by weight. The modified syndiotactic polystyrene used is the same as in Example 1.

[0059] The weighed polyamide 66 / 6T copolymer, modified syndiotactic polystyrene, maleic anhydride-styrene copolymer, silicone masterbatch, organic copper salt heat stabilizer, and black gloss masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / modified syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

[0060] The parallel twin-screw extruder has a length-to-diameter ratio of 48:1, a processing temperature of 250℃-290℃ in each zone, a die head temperature of 280℃±5℃, and a vacuum degree of ≤-0.09MPa.

[0061] Comparative Example 1 A method for preparing a polyamide / syndiotactic polystyrene composite material includes the following steps: Weigh each component according to the following parts by weight: Polyamide 66 / 6T copolymer: 48.5 parts by weight; Syndiotactic polystyrene: 15 parts by weight; Glass fiber: 30 parts by weight; Maleic anhydride-styrene copolymer: 4 parts by weight; Silicone masterbatch: 0.5 parts by weight; Organic copper salt heat stabilizer: 0.5 parts by weight; Black gloss masterbatch: 1.5 parts by weight.

[0062] The weighed polyamide 66 / 6T copolymer, syndiotactic polystyrene, maleic anhydride-styrene copolymer, silicone masterbatch, organic copper salt heat stabilizer, and black gloss masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

[0063] The black glossy masterbatch used in this comparative example is the same as that in Example 1. The difference between this comparative example 1 and Example 1 is that the syndiotactic polystyrene used is unmodified.

[0064] Comparative Example 2 A method for preparing a polyamide material includes the following steps: Weigh each component according to the following parts by weight: Polyamide 66 / 6T copolymer: 63.5 parts by weight; glass fiber: 30 parts by weight; maleic anhydride-styrene copolymer: 4 parts by weight; silicone masterbatch: 0.5 parts by weight; organic copper salt heat stabilizer: 0.5 parts by weight; black gloss masterbatch: 1.5 parts by weight.

[0065] The weighed polyamide 66 / 6T copolymer, maleic anhydride-styrene copolymer, silicone masterbatch, organic copper salt heat stabilizer, and black gloss masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

[0066] The black glossy masterbatch used in this comparative example is the same as that in Example 1. The difference between this comparative example 2 and Example 1 above is that modified syndiotactic polystyrene was not added.

[0067] Comparative Example 3 A method for preparing a polyamide / syndiotactic polystyrene composite material includes the following steps: Weigh each component according to the following parts by weight: Polyamide 66: 48.5 parts by weight; Modified syndiotactic polystyrene: 15 parts by weight; Glass fiber: 30 parts by weight; Maleic anhydride-styrene copolymer: 4 parts by weight; Silicone masterbatch: 0.5 parts by weight; Organic copper salt heat stabilizer: 0.5 parts by weight; Black gloss masterbatch: 1.5 parts by weight.

[0068] The weighed polyamide 66, modified syndiotactic polystyrene, maleic anhydride-styrene copolymer, silicone masterbatch, organic copper salt heat stabilizer, and black gloss masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

[0069] The modified syndiotactic polystyrene and black glossy masterbatch used in this comparative example are the same as those in Example 1. The difference between this comparative example 3 and Example 1 is that the polyamide 66 / 6T copolymer is replaced with polyamide 66.

[0070] Performance testing To verify the performance of the composite materials obtained in the above embodiments and comparative examples, the density, water absorption, tensile strength, flexural strength, notched impact strength of simply supported beams, thermal aging performance, and solvent resistance of the composite materials obtained in the above embodiments and comparative examples were tested. The test results are shown in Table 1.

[0071] Table 1. Composite material performance test results obtained from each embodiment and comparative example.

[0072] The test results of Examples 1-3 above clearly show that the polyamide / modified syndiotactic polystyrene composite material prepared using this application not only possesses excellent mechanical properties but also exhibits water absorption resistance and solvent resistance, making it suitable for automotive intake manifolds and thus improving their burst resistance and service life. Specifically, this application combines the molecular structural characteristics of polyamide 66 / 6T copolymer and syndiotactic polystyrene, using maleic anhydride-polystyrene copolymer as a compatibilizer, polyamide 66 / 6T copolymer as the continuous phase, and syndiotactic polystyrene as the dispersed phase. Through compatibilization technology, polyamide 66 / 6T copolymer and syndiotactic polystyrene are blended and modified. The resulting composite material not only maintains the processability, high mechanical properties, low water absorption, and good temperature resistance of polyamide 66 / 6T copolymer, but also, while ensuring excellent mechanical properties, syndiotactic polystyrene can further reduce the material's hygroscopicity, improve solvent resistance, dimensional stability, and warpage resistance, thus meeting the requirements for automotive intake manifolds.

[0073] The test results from Comparative Example 1 and Example 1 show that the lack of modification of syndiotactic polystyrene resulted in poor bonding ability with polyamide 66 / 6T and glass fiber, leading to a decrease in tensile strength, tensile modulus, flexural strength, and notched impact strength of simply supported beams by 5.1%, 6.3%, 3.7%, and 4.9%, respectively. Correspondingly, the retention rates of thermal aging performance (tensile strength retention rate, notched impact strength retention rate, and solvent resistance performance (tensile strength retention rate) also decreased.

[0074] The test results from Comparative Example 2 and Example 1 show that, without the addition of modified syndiotactic polystyrene, both the density and water absorption rate of the composite material are increased. This is because the density of syndiotactic polystyrene is 1.10-1.13 g / cm³. 3 Syndiotactic polystyrene is a lightweight material among engineering plastics, and its molecular structure contains benzene rings, resulting in low water absorption. In terms of mechanical properties, it is a non-polar, highly crystalline material with relatively high tensile strength, tensile modulus, and flexural strength, but its notched impact strength is relatively low. Correspondingly, tensile strength, tensile modulus, and flexural strength decrease by 8.6%, 20.6%, and 7.1%, respectively, while notched impact strength increases by 7.7%. Consequently, under high temperatures and in the presence of solvents, the aging resistance and solvent resistance of unmodified syndiotactic polystyrene significantly decrease.

[0075] The test results from Comparative Example 3 and Example 1 show that replacing the polyamide 66 / 6T copolymer with polyamide 66 significantly increases the water absorption rate of the composite material, which is due to the high water absorption rate of polyamide 66. Tensile strength, tensile modulus, flexural strength, and notched strength of simply supported beams decreased by 11.2%, 24.6%, 9.2%, and 4.2%, respectively. Correspondingly, under high temperature and solvent conditions, replacing the polyamide 66 / 6T copolymer with polyamide 66 significantly reduces aging resistance and solvent resistance.

[0076] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0077] The preparation method of a polyamide / modified syndiotactic polystyrene composite material for an automotive intake manifold provided in this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. 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 of the technical features; and these 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 polyamide / modified syndiotactic polystyrene composite material for an automotive intake manifold, characterized in that, It includes the following components in parts by weight: Polyamide 66 / 6T copolymer: 31-58 parts by weight; modified syndiotactic polystyrene: 10-20 parts by weight; glass fiber: 28-37 parts by weight; compatibilizer: 3-8 parts by weight; processing aid: 0.5-2 parts by weight; black gloss masterbatch: 0.5-1.5 parts by weight.

2. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 1, characterized in that: The density of the polyamide 66 / 6T copolymer is 1.13-1.15 g / cm³. 3 It has a melting point of 260℃-270℃ and a relative viscosity of 2.4-3.

0.

3. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 1, characterized in that: The modified syndiotactic polystyrene comprises the following components by weight: 88-92 parts by weight of syndiotactic polystyrene; 8-10 parts by weight of maleic anhydride-grafted polyphenylene ether; 0.2-0.7 parts by weight of lubricant; and 0.2-0.5 parts by weight of antioxidant.

4. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 3, characterized in that: The preparation method of the modified syndiotactic polystyrene includes the following steps: weighing syndiotactic polystyrene, maleic anhydride-grafted polyphenylene ether, lubricant and antioxidant are mixed evenly in a high-speed mixer, and then placed in the main feed port of a parallel twin-screw extruder. After melt extrusion by the parallel twin-screw extruder, the mixture is pelletized and dried.

5. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 1, characterized in that: The glass fiber is a hydrolysis-resistant, alkali-free chopped glass fiber with a single filament diameter of 7-17 μm and a chopped length of 3-20 mm.

6. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 1, characterized in that: The compatibilizer is a maleic anhydride-styrene copolymer.

7. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 1, characterized in that: The processing aids are release agents and heat stabilizers.

8. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 1, characterized in that: The black glossy masterbatch comprises, by weight, the following components: 28-65 parts by weight of polyamide 6 resin; 10-25 parts by weight of polyamide 6I / 6T copolymer; 0.2-0.9 parts by weight of lubricant; 0.2-0.5 parts by weight of antioxidant; 0.2-0.5 parts by weight of anti-photoaging agent; 10-20 parts by weight of inorganic carbon black masterbatch; and 15-25 parts by weight of organic aniline black masterbatch.

9. The polyamide / modified syndiotactic polystyrene composite material for automotive intake manifolds as described in claim 8, characterized in that: The preparation method of the black glossy masterbatch includes the following steps: S1. Weigh out the polyamide 6 resin, polyamide 6I / 6T copolymer, lubricant, antioxidant, anti-photoaging agent, inorganic carbon black masterbatch, and organic aniline black masterbatch and mix them evenly in a high-speed mixer. S2. The premixed material obtained in S1 is fed into the main feed port of a parallel twin-screw extruder and melt-extruded inside the parallel twin-screw extruder. S3. The material extruded from the head of the parallel twin-screw extruder is subjected to underwater pelleting, dehydration in a dewatering machine, drying in an oven, and screening by a vibrating screen to obtain black glossy masterbatch.

10. A method for preparing a polyamide / modified syndiotactic polystyrene composite material for an automotive intake manifold as described in any one of claims 1-9, characterized in that, Includes the following steps: The weighed polyamide 66 / 6T copolymer, modified syndiotactic polystyrene, compatibilizer, processing aid, and black glossy masterbatch are mixed evenly in a high-speed mixer and then added to the main feed port of a parallel twin-screw extruder. Glass fiber is then added to the side feed port of the parallel twin-screw extruder according to the weight ratio. After melt blending, extrusion, and granulation in the parallel twin-screw extruder, the polyamide / modified syndiotactic polystyrene composite material for the automotive intake manifold is obtained.

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