Modified PET-based automobile seat skin composite material and preparation method thereof

Abstract

The invention relates to the technical field of polyethylene glycol terephthalate, and particularly discloses an automobile seat skin composite material based on modified PET and a preparation method. The composite material comprises modified PET resin, a flexibilizer, a wear-resistant filler, an anti-ultraviolet agent and a polyfunctional group reaction aid, and the polyfunctional group reaction aid is a compound containing at least three active functional groups capable of participating in carboxyl, hydroxyl or epoxy group reaction in molecules. The compatilizer can be subjected to in-situ reaction with the end group of the modified PET resin and the active group of the compatilizer in the melting processing process, and a three-dimensional cross-linked network is formed in the material. The preparation method comprises the steps of modified PET resin preparation, raw material drying and the like. The problems that an existing material is poor in comprehensive performance, insufficient in long-acting stability and the like are solved, and the composite material is excellent in mechanical property, wear resistance, ultraviolet resistance and hydrolysis resistance, moderate in cost, environmentally friendly, recoverable, simple in preparation process and capable of being widely applied to production of the automobile seat skin.

Description

Technical Field

[0001] This invention relates to the field of polyethylene terephthalate (PET) technology, and more specifically to a modified PET-based automotive seat upholstery composite material and its preparation method. Background Technology

[0002] As a core component of automotive interiors, car seat upholstery directly impacts the texture, comfort, durability, and safety of the interior, while also meeting industry demands for lightweighting, environmental friendliness, and low cost. Currently, commonly used materials for car seat upholstery include natural leather, PU leather, PVC leather, and ordinary polyethylene terephthalate (PET)-based composites. Natural leather offers excellent texture and comfort, but is expensive, difficult to maintain, and suffers from resource scarcity. PU and PVC leathers are soft to the touch and moderately priced, but have poor aging and abrasion resistance, and are prone to cracking and delamination with long-term use. Furthermore, some PVC leathers contain harmful volatile organic compounds, failing to meet environmental protection requirements. Ordinary PET materials offer advantages such as low cost, good chemical resistance, ease of processing, and recyclability, but they also suffer from slow crystallization, poor impact toughness, insufficient scratch resistance, and inadequate hydrolysis and UV resistance. When directly applied to car seat upholstery, they cannot meet the mechanical performance and environmental adaptability requirements during long-term use, limiting their widespread application in the automotive interior sector.

[0003] To improve the performance defects of PET materials, current technologies often employ single modification methods (such as grafting modification, blending modification, or filler modification) to modify PET. However, single modification methods cannot simultaneously achieve comprehensive properties such as toughness, wear resistance, UV resistance, and hydrolysis resistance. Furthermore, the modified material often exhibits poor compatibility with other components, leading to uneven component dispersion and weak interfacial bonding, resulting in unstable mechanical properties of the composite material and failing to meet the stringent requirements of automotive seat upholstery. Simultaneously, the molecular chain bonding in existing modified PET composites is predominantly linear, leaving room for improvement in interfacial bonding strength, and resulting in insufficient long-term stability of mechanical properties and hydrolysis resistance. Therefore, developing a modified PET automotive seat upholstery composite material with excellent comprehensive performance, a simple and feasible preparation process, moderate cost, and tight internal bonding has become a key research focus in the field of automotive interior materials. Summary of the Invention

[0004] The purpose of this invention is to provide a modified PET-based automotive seat cover composite material and its preparation method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a modified PET-based automotive seat cover composite material, comprising, by weight: 60-85 parts modified PET resin, 5-15 parts toughening agent, 3-10 parts wear-resistant filler, 0.5-2.5 parts UV stabilizer, 0.3-1.8 parts hydrolysis stabilizer, 0.2-1.2 parts lubricant, 1-5 parts compatibilizer, and 0.1-0.5 parts multifunctional reaction aid.

[0006] The modified PET resin described above is a compound of maleic anhydride-grafted PET and epoxy chain-extended PET, with a weight ratio of (2-4):1. The multifunctional reaction aid is a compound containing at least three active functional groups in its molecule that can participate in the reaction of carboxyl, hydroxyl, or epoxy groups; it can react in situ with the end groups of the modified PET resin and the active groups of the compatibilizer during melt processing to form a three-dimensional cross-linked network within the material.

[0007] Modified PET resin is formed by compounding maleic anhydride-grafted PET with epoxy chain-extended PET. Combined with specific proportions of toughening agents, wear-resistant fillers, and multifunctional reaction aids, a synergistic modification system is constructed to fundamentally improve the performance defects of ordinary PET. Maleic anhydride-grafted PET introduces maleic anhydride polar groups into the PET molecular chain, improving compatibility with toughening agents, wear-resistant fillers, and other components, reducing component aggregation, and decreasing the degree of entanglement in the PET molecular chain, thus improving the processing fluidity of PET. Epoxy chain-extended PET reacts with the carboxyl and hydroxyl groups at the ends of the PET molecular chain through epoxy chain extenders. This not only extends the PET molecular chain and increases the degree of chain entanglement, improving the mechanical strength of the material, but also blocks the carboxyl groups at the ends of the PET molecular chain (the carboxyl group is the core active site for PET hydrolysis), thereby significantly improving the material's hydrolysis resistance. Multifunctional reactive additives are compounds containing at least three active functional groups that can participate in the reaction of carboxyl, hydroxyl, or epoxy groups. During melt processing, they react in situ with the end groups (carboxyl and hydroxyl) of the modified PET resin and the active groups (maleic anhydride groups) of the compatibilizer, forming a mild three-dimensional cross-linked network within the material. This mild cross-linked network does not affect the material's processing flowability and toughness; instead, it significantly enhances the interfacial bonding force between components and strengthens the interaction between molecular chains, thereby improving the composite material's mechanical strength, long-term stability of hydrolysis resistance, and aging resistance. The synergistic effect of the components gives the composite material excellent toughness, wear resistance, UV resistance, and hydrolysis resistance, while also being cost-effective, environmentally friendly, and non-toxic, meeting the requirements for automotive seat upholstery.

[0008] Preferably, the multifunctional reaction aid is selected from at least one of triallyl isocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPTMA), and pentaerythritol triacrylate (PETA).

[0009] Preferably, the toughening agent is a compound of ethylene-methyl acrylate copolymer (EMA) and methyl methacrylate-butadiene-styrene copolymer grafted with maleic anhydride (MBS-g-MAH), with a weight ratio of (1-3):1; the grafting rate of the methyl methacrylate-butadiene-styrene copolymer grafted with maleic anhydride is 0.4-0.8%. EMA has good flexibility and compatibility with PET, and can be uniformly dispersed in the PET matrix to form flexible regions, initially improving the impact toughness of the composite material, while also improving the processing flowability of the composite material; MBS-g-MAH uses butadiene rubber (BR) as an elastic core and methyl methacrylate (MMA) as a rigid shell. The elastic core can absorb the impact energy during PET melting and processing and product use, preventing crack initiation and propagation, while the rigid shell can form a good interfacial bond with the PET and EMA matrices, avoiding toughening agent agglomeration, and balancing the toughness and rigidity of the product. The maleic anhydride (MAH) grafting groups on the MBS-g-MAH molecular chain... It can chemically react with the terminal hydroxyl and carboxyl groups of the PET matrix, and simultaneously form physical entanglement with the EMA molecular chain, further improving the interfacial compatibility between the toughening agent and PET and EMA, improving the flowability of the compound system, ensuring smooth melt processing, and ultimately enabling the mechanical properties of PET automotive interior leather, such as impact strength and elongation at break, to meet the requirements of this invention. When EMA is compounded with MBS-g-MAH, EMA can help improve the dispersion of MBS-g-MAH in the PET matrix. The synergistic effect of the two can significantly improve the impact toughness and crack resistance of the material without reducing the strength of the composite material, meeting the toughness requirements of automotive seat leather during long-term use.

[0010] Preferably, the wear-resistant filler is nano-alumina modified with silane coupling agent KH-560, the nano-alumina having a particle size of 50-200 nm, and the amount of silane coupling agent used for modification being 2.0-3.0% of the weight of the nano-alumina. Nano-alumina itself possesses high hardness and high wear resistance, and can be uniformly dispersed in the composite matrix, forming "rigid support points" to improve the surface hardness and scratch resistance of the material. The silane coupling agent KH-560 hydrolyzes to generate hydroxyl groups. One end of the hydrolyzed KH-560 undergoes a hydrolysis-condensation reaction with the hydroxyl groups on the surface of the nano-alumina, while the other end can react with the polar groups and active groups of multifunctional reaction aids in the modified PET resin. This effectively improves the compatibility between the nano-alumina and the matrix, solves the problem of easy agglomeration and uneven dispersion of nanoparticles, enhances the interfacial bonding force between the filler and the matrix, avoids the decrease in material mechanical properties caused by filler agglomeration, and further fixes the dispersion state of the nano-alumina through the effect of a slightly three-dimensional cross-linked network, improving the long-term wear resistance.

[0011] Preferably, the UV stabilizer is a compound of benzotriazole and modified inorganic nano-TiO2, with a weight ratio of (3-6):1. The modified inorganic nano-TiO2 has a particle size of 15-30 nm and is surface-modified with silane coupling agent KH-550. Benzotriazole (such as UV-327) is an organic UV stabilizer that selectively absorbs short-wave ultraviolet light in the 290-340 nm range and converts it into low-energy heat, effectively preventing the degradation of PET molecular chains by ultraviolet light and delaying the aging of the material. Inorganic nano-TiO2 is an inorganic UV stabilizer that absorbs long-wave ultraviolet light in the 340-400 nm range, forming complementary absorption with UV-327 to completely cover the harmful ultraviolet band. At the same time, nano-TiO2 also has a certain reflection and scattering effect. After modification with KH-550, its dispersibility is significantly improved, and its heat resistance and stability are high, maintaining its UV stabilization effect for a long time. It is also non-toxic and environmentally friendly. The combination of the two can achieve synergistic UV protection through "complementary absorption + reflection". Compared with a single UV protectant, the UV protection effect is more comprehensive and longer-lasting. At the same time, the mild three-dimensional cross-linked network can fix the dispersion state of the UV protectant, preventing it from migrating and being lost during long-term use, further improving weather resistance and effectively delaying the yellowing, aging and cracking of car seat surfaces under long-term sun exposure.

[0012] Preferably, the anti-hydrolysis agent is a carbodiimide-based anti-hydrolysis agent. Carbodiimide-based anti-hydrolysis agents can react with the carboxyl groups at the ends of the PET molecular chains, blocking the carboxyl groups and preventing the PET molecular chains from undergoing hydrolytic breakage in humid and hot environments. This significantly improves the hydrolysis resistance of the composite material, making it suitable for the humid and hot environment of automotive interiors. Simultaneously, the synergistic effect with the mild three-dimensional cross-linked network formed by multifunctional reactive additives can further block water molecule penetration, enhancing the long-term effectiveness of the hydrolysis resistance.

[0013] Preferably, the compatibilizer is a styrene-maleic anhydride copolymer. The maleic anhydride groups in the styrene-maleic anhydride copolymer (SMA) can react with the polar groups in the modified PET resin and toughening agent, as well as the active groups of the multifunctional reaction aid, to further improve the compatibility between the components, ensure the uniform dispersion of the components of the composite material, improve the stability of the material properties, and at the same time help promote the formation of a mild three-dimensional cross-linked network.

[0014] Preferably, the lubricant is a compound of pentaerythritol stearate (PETS) and ethylene bis-stearamide (EBS) in a weight ratio of (1.5-3):1. PETS has excellent thermal stability, with a melting point of 54-58℃, and shows no significant decomposition or volatilization below 280℃. It has good compatibility with the PET matrix and other components, effectively improving the processing fluidity of the material and reducing frictional resistance during processing. EBS can improve the demolding performance of the material and improve the surface smoothness of the composite material. The synergistic effect of the two can significantly improve the processing performance of the composite material, ensuring that the surface of the molded product is flat and smooth, meeting the appearance requirements of automotive seat leather.

[0015] Preferably, the raw materials for preparing the epoxy chain-extended PET include PET chips, an epoxy chain extender, and an antioxidant. The epoxy chain extender is a bisphenol A type epoxy resin, used at 0.8-1.5% of the weight of the PET chips. The antioxidant is a hindered phenol, used at 0.1-0.3% of the weight of the PET chips. The epoxy chain extender is a bisphenol A type epoxy resin, which has moderate reactivity and can undergo a mild and sufficient chain extension reaction with the carboxyl and hydroxyl groups at the ends of the PET molecular chain, extending the PET molecular chain, increasing the degree of molecular chain entanglement, thereby improving the molecular weight and mechanical strength of the modified PET resin, and simultaneously enhancing the material's resistance to hydrolysis, avoiding excessive crosslinking or insufficient chain extension. The hindered phenolic antioxidant (such as 1010) can prevent the PET molecular chain from undergoing thermal oxidative degradation during the epoxy chain extension reaction, protecting the integrity of the molecular chain structure, ensuring the smooth progress of the epoxy chain extension reaction, and simultaneously improving the heat resistance of the modified PET resin, preventing molecular chain breakage at high temperatures from affecting the in-situ reaction effect of the multifunctional reactive additives. This preparation method for epoxy chain-extended PET ensures that the mechanical properties and hydrolysis resistance of the modified PET resin meet the design requirements, providing a good foundation for the comprehensive performance of the composite material and the formation of a mild three-dimensional cross-linked network by multifunctional reaction aids.

[0016] On the other hand, the present invention also discloses a method for preparing the above-mentioned automotive seat cover composite material based on modified PET, characterized by comprising the following steps:

[0017] S1: Preparation of modified PET resin: Maleic anhydride-grafted PET and epoxy chain-extended PET are mixed evenly in a weight ratio to obtain modified PET resin.

[0018] S2: Raw material drying: Dry the wear-resistant filler, UV stabilizer, hydrolysis inhibitor, multifunctional reaction aid, lubricant, and compatibilizer, and store them in a sealed container in a dry environment for later use;

[0019] S3: Mixing and granulation: After drying, the raw materials, except for the multifunctional reaction aids, are mixed evenly with the modified PET resin and toughening agent, and then fed into a twin-screw extruder for melt extrusion and granulation to obtain composite material masterbatch;

[0020] S4: Molding and processing: The composite material masterbatch is dried, then mixed with a multifunctional reactive agent and injection molded. After cooling to room temperature, the finished automotive seat surface composite material is obtained.

[0021] In step S3, the screw speed of the twin-screw extruder is 180-260 r / min, the feeding rate is 20-40 kg / h, and the temperatures of each section of the extruder are as follows: feeding section 230-240℃, melting section 245-260℃, metering section 260-265℃, and die head section 265-270℃. In step S4, the molding pressure is 8-15 MPa, the cooling temperature is 20-35℃, and the cooling time is 5-15 min.

[0022] The preparation method of maleic anhydride grafted PET is as follows: PET chips are mixed with maleic anhydride at a weight ratio of 100:(2-5), and 0.2-0.4% of the weight of PET chips as initiator benzoyl peroxide (BPO) is added. The mixture is then melt-grafted at 240-260℃ and a screw speed of 180-220r / min.

[0023] The preparation method of epoxy chain extended PET is as follows: PET chips are mixed with epoxy chain extender and antioxidant, and melted and reacted at 260-280℃ and screw speed of 180-220r / min.

[0024] The beneficial effects of this invention are as follows:

[0025] The composite material uses modified PET as the matrix, which is cheaper than natural leather and PU leather. It is also environmentally friendly, non-toxic, and recyclable. The amount of multifunctional reactive additives used is small, which will not significantly increase the production cost, meeting the requirements of environmental protection and low cost in automotive interiors. Through multi-component synergistic modification, especially the slight three-dimensional cross-linked network formed by multifunctional reactive additives, the composite material has excellent mechanical properties, wear resistance, UV resistance, and hydrolysis resistance. It has high surface hardness, scratch resistance, and is not prone to yellowing and cracking. It has a long service life, and the long-term stability of mechanical and hydrolysis resistance is significantly improved. The preparation process is simple and feasible, enabling large-scale industrial production with high production efficiency and high product qualification rate. The composite material has good processing fluidity, and the slight three-dimensional cross-linked network does not affect the molding performance of the material. It can be molded by injection molding, calendering, and other methods, adapting to the production needs of different styles of car seat covers, with strong adaptability. Compared with existing ordinary PET-based composite materials, the overall performance is significantly improved. Compared with single modified PET composite materials, the performance is more comprehensive and stable, and it can completely replace the PU leather, PVC leather, and other materials commonly used in existing car seat covers, with broad application prospects. Detailed Implementation

[0026] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0027] It should be noted that all reagents and raw materials used in this invention are commercially available, and the reagents are of analytical grade.

[0028] PET sheets were purchased from Jiangsu Baiyixin Industrial Co., Ltd., model AM-10. EMA (ethylene-methyl acrylate copolymer) was purchased from Dongguan Shenghao Plastic Raw Materials Co., Ltd., model AC1125. MBS-g-MAH was purchased from Shanghai Better Chemical Co., Ltd., model GM-701. Carbodiimide anti-hydrolysis agent was from Suzhou Keshengtong New Material Technology Co., Ltd., brand name Bio-SAH™ 362Powder. SMA (styrene-maleic anhydride copolymer) was from Hangzhou Yuhao Chemical Technology Co., Ltd., CAS number 9011-13-6. Epoxy chain extender was purchased from Jiangsu Sanmu Group Co., Ltd., model SM-618.

[0029] Preparation of modified nano-alumina:

[0030] 100 parts by weight of nano alumina were dried and stirred at 120°C for 2 hours. Then, the dried nano alumina was put into a reaction vessel containing a mixed solvent of ethanol and deionized water (volume ratio of ethanol to water was 9:1). The solid content was controlled at 15%. The mixture was dispersed at 3000 rpm for 30 minutes and then treated with ultrasound (400w) for 20 minutes to obtain a uniform and stable nano alumina suspension.

[0031] In another container, weigh 2.5 parts by weight of silane coupling agent KH-560, mix KH-560 with ethanol and deionized water in a weight ratio of 1:15:5, adjust the pH value to about 4.5 with acetic acid, and continuously stir in a 60°C water bath to carry out the hydrolysis reaction for 45 minutes until the solution becomes clear and transparent, and obtain the completely hydrolyzed KH-560 hydrolysate.

[0032] KH-560 hydrolysate was added dropwise to nano-alumina suspension under stirring at 300 rpm. The temperature of the reaction system was raised to 80℃, and the surface grafting reaction was carried out at this temperature and under constant stirring for 4 hours.

[0033] After the reaction was completed, the reaction mixture was naturally cooled to room temperature. The solid product was collected by centrifugation and washed three times with ethanol and deionized water to remove unreacted coupling agent and byproducts. Finally, the washed modified nano alumina was placed in a vacuum drying oven and dried at 100°C for 6 hours to obtain modified nano alumina.

[0034] Preparation of modified inorganic nano-TiO2:

[0035] In a dry beaker, mix 2.0 g KH-550 with 200 mL anhydrous ethanol. While stirring, slowly add 10 mL deionized water, then add acetic acid to adjust the pH to about 4.5 to obtain a mixture. Keep the mixture at a constant temperature of 55 °C and stir for 50 min to allow it to fully hydrolyze and obtain a clear and transparent hydrolysate.

[0036] In another container, 100g of dry nano-TiO2 was mixed with 200mL of anhydrous ethanol and dispersed for 12min using an ultrasonic cell disruptor (400W power) to break up the original agglomerates. Hydrolysate was added dropwise at 400rpm. After the addition was complete, the reaction system was heated to 70±5℃ and continuously refluxed and stirred for 2h to ensure full grafting.

[0037] After the reaction was completed, the suspension was cooled to room temperature and then filtered to collect the solid. The filter cake was washed three times with anhydrous ethanol to remove the physically adsorbed coupling agent. The washed solid was placed in a vacuum drying oven and dried at 80°C for 12 hours to completely remove the solvent. The dried modified nano-TiO2 block was gently ground and passed through a 200-mesh sieve to obtain modified inorganic nano-TiO2.

[0038] Preparation of maleic anhydride-grafted PET:

[0039] PET chips and maleic anhydride were mixed at a weight ratio of 100:3.5, and 0.3% (by weight) of initiator BPO was added. The mixture was fed into a twin-screw extruder and melt-grafted at 250°C and 200 r / min under nitrogen protection. The mixture was then extruded and granulated, and dried at 150°C and -0.08 MPa vacuum for 4 hours to obtain maleic anhydride-grafted PET. The temperature ranges of the twin-screw extruder (from hopper to die) were: Zone 1: 240°C, Zone 2: 250°C, Zone 3: 260°C, Zone 4: 265°C, Zone 5: 265°C, and Die: 260°C.

[0040] Preparation of epoxy chain extended PET:

[0041] 100 parts of PET chips, 1.2 parts of epoxy chain extender, and 0.1 parts of antioxidant 1010 were mixed evenly and fed into a twin-screw extruder. The mixture was melted and reacted under nitrogen protection at 270°C and a screw speed of 200 r / min. The mixture was then extruded and granulated, and dried at 150°C and a vacuum of -0.08 MPa for 4 hours to obtain epoxy chain extended PET. The temperature range of the twin-screw extruder (from hopper to die) was: Zone 1: 235°C, Zone 2: 245°C, Zone 3: 255°C, Zone 4: 260°C, Zone 5: 260°C, and Die: 255°C.

[0042] Example 1

[0043] A modified PET-based automotive seat cover composite material, comprising the following components by weight: 72 parts of modified PET resin (a blend of maleic anhydride-grafted PET and epoxy chain-extended PET in a weight ratio of 3:1), 9 parts of toughening agent (a blend of EMA and MBS-g-MAH in a weight ratio of 2:1), 6 parts of modified nano-alumina, 1.5 parts of UV stabilizer (UV-327 and modified nano-TiO2 in a weight ratio of 4:1), 0.9 parts of carbodiimide anti-hydrolysis agent, 0.6 parts of lubricant (a blend of PETS and EBS in a weight ratio of 2:1), 3 parts of SMA, and 0.3 parts of TAIC.

[0044] The preparation method is as follows:

[0045] S1: Preparation of modified PET resin: Maleic anhydride-grafted PET and epoxy chain-extended PET are mixed evenly at a weight ratio of 3:1 to obtain modified PET resin.

[0046] S2: Raw material drying: The modified nano alumina is dried at 110℃ for 3.5h, the UV stabilizer, carbodiimide anti-hydrolysis agent, and TAIC are dried at 85℃ for 2.5h, and the lubricant and SMA are dried at 90℃ for 2.2h. After all raw materials are dried, they are sealed and stored in a dry environment with a relative humidity of 35% for later use.

[0047] S3: Mixing and granulation: The dried raw materials (except TAIC) are mixed evenly with the modified PET resin and toughening agent according to the above weight parts, and fed into a twin-screw extruder. The screw speed of the twin-screw extruder is 220 r / min, the feeding speed is 30 kg / h, and the temperatures of each section are as follows: feeding section 235℃, melting section 250℃, metering section 262℃, and die head section 268℃. The mixture is melt-extruded and granulated to obtain composite material masterbatch.

[0048] S4: Molding and processing: The composite material masterbatch is dried at 100℃ for 4 hours, then mixed with the dried TAIC and fed into a calender. It is calendered at 248℃ and molding pressure of 11MPa, and then cooled at 28℃ for 10 minutes to obtain the finished automotive seat surface composite material.

[0049] Example 2

[0050] A modified PET-based automotive seat cover composite material, comprising the following components by weight: 60 parts of modified PET resin (a blend of maleic anhydride-grafted PET and epoxy chain-extended PET in a weight ratio of 2:1), 5 parts of toughening agent (a blend of EMA and MBS-g-MAH in a weight ratio of 1:1), 3 parts of modified nano-alumina, 0.5 parts of UV stabilizer (UV-327 and modified nano-TiO2 in a weight ratio of 3:1), 0.3 parts of carbodiimide anti-hydrolysis agent, 0.2 parts of lubricant (a blend of PETS and EBS in a weight ratio of 1.5:1), 1 part of SMA, and 0.1 parts of TMPTMA.

[0051] The preparation method is as follows:

[0052] S1: Preparation of modified PET resin: Maleic anhydride-grafted PET and epoxy chain-extended PET are mixed evenly at a weight ratio of 2:1 to obtain modified PET resin.

[0053] S2: Raw material drying: The modified nano alumina is dried at 100℃ for 3 hours, the UV stabilizer, carbodiimide anti-hydrolysis agent, and TMPTMA are dried at 80℃ for 2 hours, and the lubricant and SMA are dried at 80℃ for 2 hours. After all raw materials are dried, they are sealed and stored in a dry environment with a relative humidity of 30% for later use.

[0054] S3: Mixing and granulation: The dried raw materials (except TMPTMA) are mixed evenly with the modified PET resin and toughening agent according to the above weight parts, and fed into a twin-screw extruder. The screw speed of the twin-screw extruder is 180 r / min, the feeding speed is 20 kg / h, and the temperatures of each section are as follows: feeding section 230℃, melting section 245℃, metering section 260℃, and die head section 265℃. The mixture is melt-extruded and granulated to obtain composite material masterbatch.

[0055] S4: Molding process: The composite material masterbatch is dried at 90℃ for 3 hours, then mixed with the dried TMPTMA and fed into an injection molding machine. It is then injection molded at 250℃ and a molding pressure of 8MPa, and then cooled at 20℃ for 5 minutes to obtain the finished automotive seat surface composite material.

[0056] Example 3

[0057] A modified PET-based automotive seat cover composite material, comprising the following components by weight: 85 parts of modified PET resin (a blend of maleic anhydride-grafted PET and epoxy chain-extended PET in a weight ratio of 4:1), 15 parts of toughening agent (a blend of EMA and MBS-g-MAH in a weight ratio of 3:1), 10 parts of modified nano-alumina, 2.5 parts of UV stabilizer (UV-327 and modified nano-TiO2 in a weight ratio of 6:1), 1.8 parts of carbodiimide anti-hydrolysis agent, 1.2 parts of lubricant (a blend of PETS and EBS in a weight ratio of 3:1), 5 parts of SMA, and 0.5 parts of PETA.

[0058] The preparation method is as follows:

[0059] S1: Preparation of modified PET resin: Maleic anhydride-grafted PET and epoxy chain-extended PET are mixed evenly at a weight ratio of 4:1 to obtain modified PET resin.

[0060] S2: Raw material drying: The modified nano alumina is dried at 120℃ for 4 hours, the UV stabilizer, carbodiimide anti-hydrolysis agent, and PETA are dried at 90℃ for 3 hours, and the lubricant and SMA are dried at 100℃ for 2.5 hours. After all raw materials are dried, they are sealed and stored in a dry environment with a relative humidity of 35% for later use.

[0061] S3: Mixing and granulation: The dried raw materials (except PETA) are mixed evenly with the modified PET resin and toughening agent according to the above weight parts, and fed into a twin-screw extruder. The screw speed of the twin-screw extruder is 260 r / min, the feeding speed is 40 kg / h, and the temperatures of each section are as follows: feeding section 240℃, melting section 260℃, metering section 265℃, and die head section 270℃. The mixture is melt-extruded and granulated to obtain composite material masterbatch.

[0062] S4: Molding and processing: The composite material masterbatch is dried at 110℃ for 5 hours, then mixed with dried PETA and fed into a calender. It is calendered at 255℃ and a molding pressure of 15MPa, and then cooled at 35℃ for 15 minutes to obtain the finished automotive seat surface composite material.

[0063] Example 4

[0064] A modified PET-based automotive seat cover composite material, comprising the following components by weight: 78 parts of modified PET resin (a blend of maleic anhydride-grafted PET and epoxy chain-extended PET in a weight ratio of 3.5:1), 12 parts of toughening agent (a blend of EMA and MBS-g-MAH in a weight ratio of 2.5:1), 8 parts of modified nano-alumina, 2 parts of UV stabilizer (UV-327 and modified nano-TiO2 in a weight ratio of 5:1), 1.5 parts of carbodiimide anti-hydrolysis agent, 0.9 parts of lubricant (a blend of PETS and EBS in a weight ratio of 2.5:1), 4 parts of SMA, and 0.4 parts of TAIC.

[0065] The preparation method is as follows:

[0066] S1: Preparation of modified PET resin: Maleic anhydride-grafted PET and epoxy chain-extended PET are mixed evenly at a weight ratio of 2.5:1 to obtain modified PET resin.

[0067] S2: Raw material drying: The modified nano alumina is dried at 115℃ for 3.8h, the UV stabilizer, carbodiimide anti-hydrolysis agent, and TAIC are dried at 88℃ for 2.8h, and the lubricant and SMA are dried at 95℃ for 2.3h. After all raw materials are dried, they are sealed and stored in a dry environment with a relative humidity of 38% for later use.

[0068] S3: Mixing and granulation: The dried raw materials (except TAIC) are mixed evenly with the modified PET resin and toughening agent according to the above weight parts, and fed into a twin-screw extruder. The screw speed of the twin-screw extruder is 240 r / min, the feeding speed is 35 kg / h, and the temperatures of each section are as follows: feeding section 238℃, melting section 255℃, metering section 263℃, and die head section 269℃. The mixture is melt-extruded and granulated to obtain composite material masterbatch.

[0069] S4: Molding process: The composite material masterbatch is dried at 105℃ for 4.5h, then mixed with the dried TAIC and fed into an injection molding machine. It is injection molded at 265℃ and molding pressure of 13MPa, and then cooled at 32℃ for 15min to obtain the finished automotive seat surface composite material.

[0070] Comparative Example 1

[0071] Compared with Example 1, the difference is that the modified PET resin is a single maleic anhydride-grafted PET, with a weight of 72 parts, and no epoxy chain-extended PET is added.

[0072] Comparative Example 2

[0073] Compared with Example 1, the difference is that the toughening agent is a single EMA, with a weight of 9 parts, and MBS-g-MAH is not added.

[0074] Comparative Example 3

[0075] Compared with Example 1, the difference is that the wear-resistant filler is unmodified nano-alumina, with a weight of 6 parts.

[0076] Comparative Example 4

[0077] The difference from Example 1 is that the UV stabilizer is a single UV-327, with a weight of 1.5 parts, and no modified nano-TiO2 is added.

[0078] Comparative Example 5

[0079] The difference from Example 1 is that the multifunctional reaction auxiliary TAIC was not added.

[0080] The composite material samples prepared in Examples 1-4 and Comparative Examples 1-5 were subjected to relevant performance tests. The test methods and standards are as follows:

[0081] 1. Tensile strength: Tested according to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets". A tensile testing machine was used to apply axial tension to the specimen at a tensile speed of 50 mm / min. The maximum tensile force at fracture was recorded, and the tensile strength was calculated based on the specimen's cross-sectional area.

[0082] 2. Impact strength: Tested according to GB / T 1843-2008 "Determination of impact strength of plastic cantilever beam". Fix the specimen on the support of the cantilever beam impact testing machine, select a suitable impact pendulum, and let it fall freely along the impact direction of the specimen to impact the specimen and record the impact absorbed energy. Calculate the impact strength of the unnotched cantilever beam based on the specimen dimensions.

[0083] 3. Surface Hardness: The test shall be conducted in accordance with GB / T 2411-2008 "Determination of Indentation Hardness (Shore Hardness) of Plastics and Hard Rubbers using Hardness Testers". Place the composite material sample flat on a rigid support surface, ensuring the sample surface is free of oil and damage. Use a Shore D hardness tester and press the indenter vertically into the sample surface (avoiding edge effects). After the reading stabilizes, record the Shore D hardness value. Take multiple measurements and average the results.

[0084] 4. Scratch Resistance: The test shall be conducted in accordance with GB / T 44507-2024 "Test Methods for Scratch Resistance of Artificial Leather and Synthetic Leather - Determination and Evaluation of Surface Scratch Resistance". The composite material sample shall be flattened and fixed. A scratch resistance tester shall be used, with a suitable tungsten carbide metal scraping head (1mm diameter recommended). The load shall be set to 10N, the number of scraping cycles to 100, and a suitable scraping speed. The sample surface shall be scraped uniformly. After scraping, the surface condition of the sample shall be observed to determine whether there are obvious scratches.

[0085] 5. UV Resistance: Tested according to GB / T 16422.2-2014 "Laboratory Light Source Exposure Test Methods for Plastics - Part 2: Xenon Arc Lamp". The initial yellowing index YI0 of the sample was measured. The sample was then placed in a xenon arc lamp aging test chamber, and the irradiation time was set to 1000 hours to simulate a natural UV irradiation environment. After irradiation, the yellowing index YI1 of the sample was measured again, and the difference in yellowing index ΔYI = YI1 - YI0 was calculated.

[0086] 6. Hydrolysis resistance: Tested according to GB / T 15905-1995 "Test Method for Damp Heat Aging of Vulcanized Rubber". Measure the initial tensile strength of the sample, place the sample in a damp heat aging test chamber, set the temperature to 85℃ and humidity to 85%, age for 1000 hours, remove the sample, cool to room temperature, and measure its tensile strength again. Calculate the tensile strength retention rate after aging (strength after aging / initial strength × 100%).

[0087] The performance test results are shown in Table 1.

[0088] Table 1 Performance Test Results

[0089] Sample Tensile strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Surface hardness (Shore D) Scratch resistance UV yellowing index Tensile strength retention rate (%) Example 1 70.2 43.5 79 No obvious scratches 1.8 89.7 Example 2 62.3 35.7 72 No obvious scratches 2.5 82.5 Example 3 75.8 48.9 85 No obvious scratches 1.2 93.6 Example 4 73.5 46.2 82 No obvious scratches 1.5 91.2 Comparative Example 1 58.7 38.4 70 Obvious scratches 2.8 75.3 Comparative Example 2 68.5 29.6 78 No obvious scratches 1.9 88.9 Comparative Example 3 65.3 36.8 74 Severe scratches 2.0 86.4 Comparative Example 4 69.8 42.7 79 No obvious scratches 3.7 89.2 Comparative Example 5 67.6 41.9 78 No obvious scratches 1.9 86.9

[0090] As shown in the table above, the composite materials prepared in the embodiments of the present invention are superior to those in the comparative examples in terms of performance. Specific analysis is as follows:

[0091] Comparative Example 1 used maleic anhydride-grafted PET as the modified PET resin without adding epoxy chain-extended PET. Its tensile strength (58.7 MPa) and hydrolytic tensile strength retention rate (75.3%) were significantly lower than those of Example 1, and its scratch resistance and surface hardness also decreased. The reason is that maleic anhydride-grafted PET cannot achieve both "improved processing fluidity" and "enhanced mechanical strength and hydrolytic resistance," and it cannot provide sufficient epoxy group active sites for multifunctional reaction aids, resulting in the inability to fully exert the reinforcing effect of the mild three-dimensional cross-linked network.

[0092] Comparative Example 2, using EMA as a single toughening agent without the addition of core-shell MBS-g-MAH, showed a significantly lower impact strength (29.6 kJ / m²) than Example 1 (43.5 kJ / m²), a decrease of 31.9%. This indicates that the toughening effect of EMA alone is limited and cannot meet the toughness requirements of automotive seat upholstery. However, when EMA is combined with MBS-g-MAH, the rubber core of MBS-g-MAH can absorb impact energy, and its grafted maleic anhydride groups can react with modified PET resin and multifunctional reactive additives, enhancing the interfacial bonding with the matrix. The two work synergistically to improve toughness.

[0093] Comparative Example 3 used unmodified nano-alumina as a wear-resistant filler. Its surface hardness (74 Shore D) was lower than that of Example 1, and its scratch resistance was poor (severe scratches). This is because unmodified nano-alumina has poor compatibility with the PET matrix, is prone to agglomeration, and cannot form uniform "rigid support points." Furthermore, it cannot combine with the mild three-dimensional cross-linked network formed by multifunctional reactive additives, thus failing to fix its dispersion state. In contrast, the nano-alumina modified with the silane coupling agent KH-560 showed significantly improved compatibility with the matrix. With the fixing effect of the mild three-dimensional cross-linked network, it can be uniformly dispersed in the matrix, significantly improving the wear resistance and surface hardness of the material.

[0094] Comparative Example 4 used UV-327 as a single UV stabilizer, and its UV yellowing index (3.7) was significantly higher than that of Example 1 (1.8), indicating a poorer UV protection effect. This is because a single organic UV stabilizer cannot completely cover the harmful UV wavelengths and is prone to migration and loss under long-term irradiation. However, when UV-327 is combined with modified nano-TiO2, complementary absorption of the entire UV wavelength can be achieved, and the slightly three-dimensional cross-linked network can fix the dispersion state of the UV stabilizer, preventing its migration and loss, thus synergistically improving the UV protection performance.

[0095] The only difference between Comparative Example 5 and Example 1 is the absence of a multifunctional reactive agent. Test data showed that the tensile strength of Example 1 (70.2 MPa) was 3.5% higher than that of Comparative Example 6 (67.8 MPa), and the retention rate of hydrolysis-resistant tensile strength (89.7%) was 3.2% higher than that of Comparative Example 6 (86.9%). Meanwhile, the impact strength and surface hardness of Example 1 were essentially the same as those of Comparative Example 5, indicating that the mild three-dimensional cross-linked network formed by the multifunctional reactive agent only strengthens the interfacial bonding and molecular chain interaction strength of each component, without affecting the toughness and processing performance of the material. This further verifies the core role of the multifunctional reactive agent: significantly improving the long-term stability of mechanical properties and hydrolysis resistance without compromising the original excellent properties of the material.

[0096] In summary, this invention modifies PET resin by compounding maleic anhydride-grafted PET with epoxy chain-extended PET, and combines it with toughening agents, modified wear-resistant fillers, and compounded UV stabilizers. Multifunctional reaction aids form a mild three-dimensional cross-linked network. Combined with a reasonable preparation process, the components work synergistically to significantly improve the mechanical properties, wear resistance, UV resistance, and hydrolysis resistance of the composite material.

[0097] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations.

[0098] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A composite material for automotive seat upholstery based on modified PET, characterized in that, The product comprises, by weight: 60-85 parts modified PET resin, 5-15 parts toughening agent, 3-10 parts wear-resistant filler, 0.5-2.5 parts UV stabilizer, 0.3-1.8 parts hydrolysis stabilizer, 0.2-1.2 parts lubricant, 1-5 parts compatibilizer, and 0.1-0.5 parts multifunctional reaction aid; wherein the modified PET resin is a compound of maleic anhydride-grafted PET and epoxy chain-extended PET in a weight ratio of (2-4):1; wherein the multifunctional reaction aid is a compound containing at least three active functional groups in its molecule that can participate in the reaction of carboxyl, hydroxyl, or epoxy groups, which reacts in situ with the end groups of the modified PET resin and the active groups of the compatibilizer during melt processing to form a three-dimensional cross-linked network inside the material.

2. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The multifunctional reaction aid is selected from at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

3. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The toughening agent is a compound of ethylene-methyl acrylate copolymer and methyl methacrylate-butadiene-styrene copolymer grafted with maleic anhydride in a weight ratio of (1-3):

1.

4. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The wear-resistant filler is nano-alumina modified with silane coupling agent KH-560.

5. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The UV stabilizer is a compound of benzotriazole and modified inorganic nano-TiO2 in a weight ratio of (3-6):1, wherein the inorganic nano-TiO2 is surface-modified by silane coupling agent KH-550.

6. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The anti-hydrolysis agent is a carbodiimide-based anti-hydrolysis agent.

7. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The compatibilizer is a styrene-maleic anhydride copolymer.

8. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The lubricant is a compound of pentaerythritol stearate and ethylene bis-stearamide in a weight ratio of (1.5-3):

1.

9. The automotive seat cover composite material based on modified PET according to claim 1, characterized in that, The raw materials for preparing the epoxy chain-extended PET include PET chips, epoxy chain extender, and antioxidant. The epoxy chain extender is bisphenol A type epoxy resin, and the antioxidant is hindered phenol.

10. A method for preparing a modified PET-based automotive seat cover composite material according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Preparation of modified PET resin: Maleic anhydride-grafted PET and epoxy chain-extended PET are mixed evenly in a weight ratio to obtain modified PET resin. S2: Raw material drying: Dry the wear-resistant filler, UV stabilizer, hydrolysis inhibitor, multifunctional reaction aid, lubricant, and compatibilizer, and store them in a sealed container in a dry environment for later use; S3: Mixing and granulation: After drying, the raw materials, except for the multifunctional reaction aids, are mixed evenly with the modified PET resin and toughening agent, and then fed into a twin-screw extruder for melt extrusion and granulation to obtain composite material masterbatch; S4: Molding and processing: The composite material masterbatch is dried, then mixed with a multifunctional reactive agent and injection molded. After cooling to room temperature, the finished automotive seat surface composite material is obtained.