Macromolecular pincushion structure toughening agent, thin-walled plastic part polypropylene composite material and preparation method

Abstract

The present application relates to a kind of macromolecular pompon structure toughening agent, thin-walled plastic part polypropylene composite material and preparation method, macromolecular pompon structure toughening agent, pentaerythritol is as ball core, the ball core is sequentially grafted SEBS chain, POE chain and fatty alcohol chain by multi-step esterification reaction, and the pompon-like molecular structure of molecular chain outward divergent is formed;The preparation process of the toughening agent, sequentially form half ester carboxylic acid structure, complete ball core hydroxyl amplification, finally realize the grafting of each molecular chain by esterification reaction.The present application can significantly improve the impact toughness of polypropylene while considering material rigidity and melt flowability, can meet the application demand of large complex thin-walled plastic product.

Description

Technical Field

[0001] This invention relates to the field of polypropylene composite materials, and more specifically, to a macromolecular pompon-structure toughening agent, a thin-walled plastic part polypropylene composite material, and a preparation method thereof. Background Technology

[0002] Polypropylene (PP), a typical semi-crystalline polyolefin polymer, boasts advantages such as low density, excellent processability, and low cost, making it one of the most widely used thermoplastic materials in injection molding. It is extensively used in structural and aesthetic plastic parts for automotive bumpers, dashboards, and aerospace and marine equipment. However, with the increasing demands for lightweight, thin-walled, and structurally complex plastic products in the automotive and equipment manufacturing sectors, the difficulty of balancing toughness, rigidity, and processing fluidity in traditional polypropylene materials is becoming increasingly prominent, making it challenging to meet the comprehensive performance requirements of complex thin-walled plastic parts.

[0003] In existing technologies, two main modification methods are used to improve the performance of polypropylene: one is to modify polypropylene by introducing inorganic fillers such as talc and calcium carbonate to improve the material's modulus and rigidity; however, this method usually significantly reduces the material's impact toughness and melt flowability, which is detrimental to the molding and processing of thin-walled products. The other method is to toughen polypropylene by introducing polyolefin elastomers or styrene-based elastomers, such as physically blending polypropylene with POE (polyolefin elastomer) or SEBS (hydrogenated styrene-butadiene-styrene block copolymer). Although these elastomers can improve the impact performance of polypropylene materials to some extent, their introduction is often accompanied by a significant decrease in the material's modulus and melt flowability, making it difficult to meet the requirements of large, thin-walled plastic parts that balance high modulus, high flowability, and high impact performance.

[0004] In addition, elastomers such as POE and SEBS are usually dispersed in the polypropylene matrix as independent rubber phases. Under long-term use or high-temperature conditions, they are prone to problems such as phase region coarsening, interface debonding and elastomer migration, which leads to a significant decline in the mechanical properties of composite materials over time, thus restricting their application in fields such as automobiles where long-term stability is required. Summary of the Invention

[0005] The technical problem this invention aims to solve is to provide a macromolecular pompon-structure toughening agent with better toughening effect, stronger interfacial bonding with PP, and the ability to maintain high melt flowability of composite materials. It also provides a simple synthesis process, well-defined reaction conditions, and low cost method for preparing the macromolecular pompon-structure toughening agent. Furthermore, it provides a polypropylene composite material suitable for the injection molding performance requirements of thin-walled plastic parts.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: a macromolecular pom-pom toughening agent is constructed, with pentaerythritol as the core. The core is grafted with SEBS chain, POE chain and fatty alcohol chain in sequence through a multi-step esterification reaction to form a pom-pom molecular structure with the molecular chains diverging outward. In the preparation process of the toughening agent, a half-ester carboxylic acid structure is formed in sequence, the hydroxyl groups of the core are expanded, and finally the grafting of each molecular chain is achieved through an esterification reaction.

[0007] According to the above scheme, the SEBS chain is grafted onto the globular core via a ring-opening esterification reaction between maleic anhydride-grafted SEBS and some hydroxyl groups of pentaerythritol, and the ring-opening esterification reaction generates a half-ester carboxylic acid structure; the hydroxyl amplification of the globular core is achieved by reacting 2,2-dihydroxymethylpropionic acid with the remaining hydroxyl groups of pentaerythritol, and the remaining hydroxyl groups are the hydroxyl groups that have not reacted with the maleic anhydride-grafted SEBS. According to the above scheme, the POE chain is grafted onto the globular core through an esterification reaction between maleic anhydride-grafted POE and all the amplified hydroxyl groups, and the esterification reaction generates a half-ester carboxylic acid structure; the fatty alcohol chain is grafted onto the globular core through an esterification reaction between the fatty alcohol and the half-ester carboxylic acid structure, and the half-ester carboxylic acid structure is the half-ester carboxylic acid structure generated by the reaction of maleic anhydride-grafted POE and the amplified hydroxyl groups. This invention also provides a method for preparing a macromolecular pom-pom structure toughening agent, characterized by comprising the following steps: S1. Place maleic anhydride-grafted SEBS and maleic anhydride-grafted POE in an oven and dry them. S2. Place 3-8 parts by weight of pentaerythritol in a reaction vessel, heat to 130-135℃, introduce nitrogen gas, stir mechanically, add 52-72 parts by weight of maleic anhydride grafted SEBS, and keep the reaction at the temperature for 1-2 hours. S3. Control the temperature of the reactor to rise to 150-160℃, add 6-16 parts by weight of 2,2-dihydroxymethylpropionic acid in batches, add esterification catalyst, and keep the reaction at the temperature for 1-1.5h. S4. Control the temperature of the reactor to 130-135℃, add 160-192 parts by weight of maleic anhydride-grafted POE, and keep the reaction at the temperature for 1-2 hours. S5. Control the reaction temperature to 150-160℃, add 24-36 parts by weight of fatty alcohol, keep the reaction at this temperature for 1.5-2 hours, stop the nitrogen gas supply, reduce the pressure and continue the reaction under vacuum for 1-2 hours. S6. Stop heating and wait for the reactor to cool down before taking out the solid reactants. Granulate the solid reactants to obtain a macromolecular pom-pom toughening agent. According to the above scheme, the catalyst is one of p-toluenesulfonic acid, stannous octoate, and tetrabutyl titanate, and the amount added is 0.1wt%-0.3wt% of the total reactant mass.

[0008] According to the above scheme, the grafting rate of maleic anhydride to POE is 1%-1.5%, and the grafting rate of maleic anhydride to SEBS is 1.4%-2.0%.

[0009] According to the above scheme, the fatty alcohol is one or more combinations of lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol.

[0010] The present invention also provides a thin-walled plastic part polypropylene composite material, characterized in that, by weight parts, its components include: 45-60 parts polypropylene, 20-35 parts hyperbranched polyester modified inorganic filler, 15-20 parts macromolecular pom-pom structure toughening agent, 0.2-0.8 parts antioxidant, and 0.1-0.3 parts nucleating agent.

[0011] According to the above scheme, the preparation process of the hyperbranched polyester modified inorganic filler is as follows: The inorganic filler was dried in a vacuum drying oven. The hyperbranched polyester was ground into fine powder. The hyperbranched polyester powder and the inorganic filler were immersed in a dimethylformamide solution and ultrasonically dispersed using an ultrasonic vibrating head. The mixture was then allowed to settle and the solvent on top of the precipitate was removed. The precipitate was then removed and placed in a vacuum drying oven to dry, thus obtaining the hyperbranched polyester modified inorganic filler.

[0012] This invention also provides a method for preparing thin-walled polypropylene composite materials for plastic parts, characterized by comprising the following steps: S1. Weigh out polypropylene, hyperbranched polyester modified inorganic filler, macromolecular pom-pom toughening agent, antioxidant, and nucleating agent according to the proportion, and put them into a high-speed mixer and mix for 3-5 minutes. S2. Add the above mixture to the feed port of the twin-screw extruder, melt-blend the mixture, extrude, cool, and granulate.

[0013] The macromolecular pompon-structure toughening agent, thin-walled polypropylene composite material for plastic parts, and preparation method of the present invention have the following beneficial effects: 1. In the macromolecular pom-pom toughening agent of the present invention, POE segments and SEBS segments are simultaneously anchored on the polyester structure and dispersed in the polypropylene matrix at the micro-nano scale. The elastomeric toughening network formed by the interweaving of POE chains and SEBS chains enables the material to exhibit higher fracture energy absorption capacity under impact load, thereby demonstrating a stronger toughening effect.

[0014] 2. In the macromolecular pom-pom toughening agent of the present invention, the grafting of fatty alcohol not only reduces the surface polarity of the toughening agent, making it more compatible with the PP matrix, but also reduces the apparent viscosity of the toughening agent, thereby improving the problem of significant decrease in fluidity caused by the increase of rubber phase content in traditional rubber toughening systems.

[0015] 3. The macromolecular pom-pom toughening agent of the present invention forms chain entanglement with the polypropylene matrix at multiple points. The multi-point anchoring molecular structure requires the interface to overcome multiple linkages simultaneously for debonding, which significantly reduces the possibility of interface failure, thereby enhancing the interfacial bonding between the polypropylene matrix and the elastic phase and ensuring the long-term stability of the polypropylene material.

[0016] 4. The thin-walled plastic parts polypropylene composite material of the present invention has high impact strength, flexural modulus, melt flowability and stability. When it is used to prepare thin-walled plastic parts, it still has good mechanical properties and processing properties, and is suitable for the design and application of thin-walled plastic parts. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of a fluffy molecular structure. Detailed Implementation

[0018] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] This invention relates to a macromolecular pom-pom toughening agent with pentaerythritol as the core. Some of its hydroxyl groups undergo ring-opening esterification with maleic anhydride-grafted SEBS to generate a hemi-ester carboxylic acid structure. 2,2-Dihydroxymethylpropionic acid reacts with the remaining hydroxyl groups of pentaerythritol to amplify the hydroxyl groups in the core. All the amplified hydroxyl groups react with maleic anhydride-grafted POE to generate a hemi-ester carboxylic acid structure. Finally, a fatty alcohol undergoes esterification with the hemi-ester carboxylic acid structure. Thus, the SEBS chain, POE chain, and fatty alcohol are grafted onto the core, forming a pom-pom-like molecular structure with outwardly diverging molecular chains. Figure 1 As shown.

[0020] SEBS and POE molecular chains can intertwine to form an elastomer synergistic toughening network, resulting in better toughening effect. Grafted fatty alcohol chains can reduce the surface polarity and apparent viscosity of the toughening agent, thereby enhancing the compatibility of the toughening agent with the PP matrix and improving the melt flowability of the PP composite material.

[0021] The specific preparation steps of the macromolecular pom-pom toughening agent of the present invention are as follows: S1. Place the weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE in an 80℃ oven and dry for 12 hours.

[0022] S2: Place 3-8 parts by weight of pentaerythritol in a reactor, heat to 130-135℃, introduce nitrogen gas, mechanically stir, add 52-72 parts by weight of maleic anhydride grafted SEBS, and keep the reaction at this temperature for 1-2 hours.

[0023] S3: Control the temperature of the reactor to rise to 150-160℃, add 6-16 parts by weight of 2,2-dihydroxymethylpropionic acid in batches, add esterification catalyst, and keep the reaction at the temperature for 1-1.5h.

[0024] S4: Control the temperature of the reactor to 130-135℃, add 160-192 parts by weight of maleic anhydride-grafted POE, and keep the reaction at this temperature for 1-2 hours.

[0025] S5: Control the reaction temperature to 150-160℃, add 24-36 parts by weight of fatty alcohol, keep the reaction at this temperature for 1.5-2 hours, stop the nitrogen gas supply, reduce the pressure and evacuate to continue the reaction for 1-2 hours.

[0026] S6: Stop heating, wait for the reactor to cool down, take out the solid reactants, and granulate them to obtain a macromolecular pom-pom toughening agent.

[0027] Furthermore, the catalyst used is preferably one of p-toluenesulfonic acid, stannous octoate, and butyl titanate, and the amount added is 0.1wt%-0.3wt% of the total reactant mass.

[0028] Furthermore, the grafting rate of maleic anhydride-grafted POE is 1%-1.5%, and the grafting rate of maleic anhydride-grafted SEBS is 1.4%-2.0%.

[0029] Furthermore, the fatty alcohol used is preferably one or a combination of lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol.

[0030] The weight proportions of each component in a thin-walled polypropylene composite material are as follows: 45-60 parts of polypropylene 20-35 parts of hyperbranched polyester modified inorganic filler 15-20 parts of macromolecular pom-pom structure toughening agent Antioxidant 0.2-0.8 parts Nucleating agent 0.1-0.3 parts The preparation process of thin-walled plastic parts made of PP composite material is as follows: S1. Weigh out polypropylene, hyperbranched polyester modified inorganic filler, macromolecular pom-pom toughening agent, antioxidant, and nucleating agent according to the above proportions, and mix them in a high-speed mixer for 3-5 minutes.

[0031] S2. Add the above mixture to the feed port of the twin-screw extruder, melt-blend the mixture, extrude, cool, and granulate it. The temperature zones are set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃.

[0032] The preparation process of the hyperbranched polyester modified inorganic filler in this invention is as follows: The inorganic filler was dried in a vacuum drying oven at 80°C for 12 hours. The hyperbranched polyester was ground into fine powder. The hyperbranched polyester powder and the inorganic filler were immersed in a dimethylformamide solution and ultrasonically dispersed for 1 hour using an ultrasonic vibrating head. Then, the mixture was allowed to stand and precipitate for 24 hours. The solvent on the precipitate was removed, and the precipitate was then taken out and dried in a vacuum drying oven at 90°C to obtain the hyperbranched polyester modified inorganic filler.

[0033] Furthermore, the hyperbranched polyester is commercially available, and its ends contain a large number of polar groups and non-polar flexible chains in a certain proportion. The inorganic filler is one or more of the following: talc, nano-calcium carbonate, wollastonite, kaolin, mica, barium sulfate, and silicon dioxide. The weight ratio of the hyperbranched polyester to the inorganic filler is 1:8 to 10.

[0034] Furthermore, the antioxidant is a hindered phenolic primary antioxidant and a phosphite secondary antioxidant in a weight ratio of 1 to 1.5-1.

[0035] Furthermore, the nucleating agent component is mainly composed of α-nucleating agent and β-nucleating agent mixed in a weight ratio of 10:1 to 2, wherein the α-nucleating agent is mainly a phosphate-based α-nucleating agent and the β-nucleating agent is mainly an aromatic diamide-based β-nucleating agent.

[0036] In this invention, the SEBS and POE molecular chains in the macromolecular pom-pom structure toughening agent are uniformly formed in a specific ratio to create an elastomer-based synergistic toughening network, resulting in better toughening performance than commercially available toughening agents and solving the problem of poor toughening effect on thin-walled plastic parts. Secondly, due to the special macromolecular spherical structure of this toughening agent, its apparent viscosity is superior to commercially available toughening agents, mitigating the problem of a sharp decrease in melt flowability of the composite material upon addition of the toughening agent. Finally, the outward-spreading "pom-pom" structure of the molecular chains can entangle with the polypropylene matrix at multiple points, enhancing the interfacial bonding between the two, significantly reducing the possibility of interfacial failure, and ensuring the long-term stability of the polypropylene composite material.

[0037] The thin-walled plastic parts polypropylene composite material provided by this invention has high mechanical properties, melt flowability and long-term stability, and is suitable for the design and application of thin-walled plastic parts.

[0038] Example 1: The preparation of a composite material of a macromolecular pompon structure toughening agent and a thin-walled plastic part includes the following steps: Weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE were dried in an oven at 80°C for 12 hours. Three parts by weight of pentaerythritol were placed in a reactor, the temperature was raised to 135°C, nitrogen gas was introduced, and mechanical stirring was performed. 52 parts by weight of maleic anhydride-grafted SEBS were added, and the reaction was maintained at this temperature for 1.5 hours. The reactor temperature was raised to 150°C, and 6 parts by weight of 2,2-dihydroxymethylpropionic acid and 0.2 parts by weight of p-toluenesulfonic acid were added in batches, maintaining the reaction temperature for 1 hour. The reactor temperature was lowered to 130°C, and 160 parts by weight of maleic anhydride-grafted POE were added, maintaining the reaction temperature for 2 hours. The reaction temperature was raised to 150°C, and 24 parts by weight of fatty alcohol were added, maintaining the reaction temperature for 1 hour. Nitrogen gas was stopped, and the reaction was continued under reduced pressure and vacuum for 1 hour. Stop heating and wait for the reactor to cool down before removing the solid reactants. Granulate the solid reactants to obtain a macromolecular pom-pom toughening agent.

[0039] Talc powder was dried in a vacuum drying oven at 80°C for 12 hours. Hyperbranched polyester was ground into fine powder. Three parts of hyperbranched polyester powder and 30 parts of talc powder were immersed in dimethylformamide solution and ultrasonically dispersed for 1 hour using an ultrasonic vibrating head. Then, the mixture was allowed to stand and precipitate for 24 hours. The solvent on the precipitate was removed, and the precipitate was then taken out and dried in a vacuum drying oven at 90°C to obtain hyperbranched polyester modified inorganic filler.

[0040] 50 parts of polypropylene, 30 parts of hyperbranched polyester-modified talc, 20 parts of macromolecular pom-pom toughening agent, 0.2 parts of antioxidant, and 0.1 parts of nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a thin-walled polypropylene composite material for plastic parts was obtained.

[0041] Example 2: The preparation of a composite material of a macromolecular pompon structure toughening agent and a thin-walled plastic part includes the following steps: Weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE were dried in an oven at 80°C for 12 hours. Five parts by weight of pentaerythritol were placed in a reactor, heated to 135°C, nitrogen was introduced, and mechanical stirring was performed. Sixty-two parts by weight of maleic anhydride-grafted SEBS were added, and the reaction was maintained at this temperature for 2 hours. The reactor temperature was raised to 150°C, and ten parts by weight of 2,2-dihydroxymethylpropionic acid and 0.2 parts by weight of p-toluenesulfonic acid were added in batches, maintaining the reaction for 1 hour. The reactor temperature was lowered to 130°C, and 175 parts by weight of maleic anhydride-grafted POE were added, maintaining the reaction for 2 hours. The reaction temperature was raised to 150°C, and 30 parts by weight of fatty alcohol were added, maintaining the reaction for 1 hour. Nitrogen introduction was stopped, and the reaction was continued under reduced pressure and vacuum for 1 hour. Heating was stopped, and after the reactor cooled, the solid reactant was removed and granulated to obtain a macromolecular pom-pom toughening agent.

[0042] Talc powder was dried in a vacuum drying oven at 80°C for 12 hours. Hyperbranched polyester was ground into fine powder. Three parts of hyperbranched polyester powder and 30 parts of talc powder were immersed in dimethylformamide solution and ultrasonically dispersed for 1 hour using an ultrasonic vibrating head. Then, the mixture was allowed to stand and precipitate for 24 hours. The solvent on the precipitate was removed, and the precipitate was then taken out and dried in a vacuum drying oven at 90°C to obtain hyperbranched polyester modified inorganic filler.

[0043] 50 parts of polypropylene, 30 parts of hyperbranched polyester-modified talc, 20 parts of macromolecular pom-pom toughening agent, 0.2 parts of antioxidant, and 0.1 parts of nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a thin-walled polypropylene composite material for plastic parts was obtained.

[0044] Example 3: The preparation of a composite material of a macromolecular pompon structure toughening agent and a thin-walled plastic part includes the following steps: Weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE were dried in an oven at 80°C for 12 hours. Eight parts by weight of pentaerythritol were placed in a reactor, heated to 135°C, nitrogen was introduced, and mechanical stirring was performed. Seventy-two parts by weight of maleic anhydride-grafted SEBS were added, and the reaction was maintained at this temperature for 1 hour. The reactor temperature was raised to 150°C, and 16 parts by weight of 2,2-dihydroxymethylpropionic acid and 0.2 parts by weight of p-toluenesulfonic acid were added in batches, maintaining the reaction for 1 hour. The reactor temperature was lowered to 130°C, and 192 parts by weight of maleic anhydride-grafted POE were added, maintaining the reaction for 1 hour. The reaction temperature was raised to 150°C, and 36 parts by weight of fatty alcohol were added, maintaining the reaction for 1 hour. Nitrogen introduction was stopped, and the reaction was continued under reduced pressure and vacuum for 1 hour. Heating was stopped, and after the reactor cooled, the solid reactant was removed and granulated to obtain a macromolecular pom-pom toughening agent.

[0045] Talc powder was dried in a vacuum drying oven at 80°C for 12 hours. Hyperbranched polyester was ground into fine powder. Three parts of hyperbranched polyester powder and 30 parts of talc powder were immersed in dimethylformamide solution and ultrasonically dispersed for 1 hour using an ultrasonic vibrating head. Then, the mixture was allowed to stand and precipitate for 24 hours. The solvent on the precipitate was removed, and the precipitate was then taken out and dried in a vacuum drying oven at 90°C to obtain hyperbranched polyester modified inorganic filler.

[0046] 50 parts of polypropylene, 30 parts of hyperbranched polyester-modified talc, 20 parts of macromolecular pom-pom toughening agent, 0.2 parts of antioxidant, and 0.1 parts of nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a thin-walled polypropylene composite material for plastic parts was obtained.

[0047] Example 4: The preparation of a composite material of a macromolecular pompon structure toughening agent and a thin-walled plastic part includes the following steps: Weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE were dried in an oven at 80°C for 12 hours. Three parts by weight of pentaerythritol were placed in a reactor, heated to 135°C, nitrogen was introduced, and mechanical stirring was performed. 52 parts by weight of maleic anhydride-grafted SEBS were added, and the reaction was maintained at this temperature for 1 hour. The reactor temperature was raised to 150°C, and 6 parts by weight of 2,2-dihydroxymethylpropionic acid and 0.2 parts by weight of p-toluenesulfonic acid were added in batches, maintaining the reaction for 1 hour. The reactor temperature was lowered to 130°C, and 160 parts by weight of maleic anhydride-grafted POE were added, maintaining the reaction for 1 hour. The reaction temperature was raised to 150°C, and 24 parts by weight of fatty alcohol were added, maintaining the reaction for 1 hour. Nitrogen introduction was stopped, and the reaction was continued under reduced pressure and vacuum for 1 hour. Heating was stopped, and after the reactor cooled, the solid reactant was removed and granulated to obtain a macromolecular pom-pom toughening agent.

[0048] Talc powder was dried in a vacuum drying oven at 80°C for 12 hours. Hyperbranched polyester was ground into fine powder. Five parts of hyperbranched polyester powder and 35 parts of talc powder were immersed in dimethylformamide solution and ultrasonically dispersed for 1 hour using an ultrasonic vibrating head. Then, the mixture was allowed to stand and precipitate for 24 hours. The solvent on the precipitate was removed, and the precipitate was then taken out and dried in a vacuum drying oven at 90°C to obtain hyperbranched polyester modified inorganic filler.

[0049] 50 parts of polypropylene, 35 parts of hyperbranched polyester-modified talc, 15 parts of macromolecular pom-pom toughening agent, 0.2 parts of antioxidant, and 0.1 parts of nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a thin-walled polypropylene composite material for plastic parts was obtained.

[0050] Example 5: The preparation of a composite material of a macromolecular pompon structure toughening agent and a thin-walled plastic part includes the following steps: Weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE were dried in an oven at 80°C for 12 hours. Three parts by weight of pentaerythritol were placed in a reactor, heated to 135°C, nitrogen was introduced, and mechanical stirring was performed. 52 parts by weight of maleic anhydride-grafted SEBS were added, and the reaction was maintained at this temperature for 1 hour. The reactor temperature was raised to 150°C, and 6 parts by weight of 2,2-dihydroxymethylpropionic acid and 0.2 parts by weight of p-toluenesulfonic acid were added in batches, maintaining the reaction for 1 hour. The reactor temperature was lowered to 130°C, and 160 parts by weight of maleic anhydride-grafted POE were added, maintaining the reaction for 1 hour. The reaction temperature was raised to 150°C, and 24 parts by weight of fatty alcohol were added, maintaining the reaction for 1 hour. Nitrogen introduction was stopped, and the reaction was continued under reduced pressure and vacuum for 1 hour. Heating was stopped, and after the reactor cooled, the solid reactant was removed and granulated to obtain a macromolecular pom-pom toughening agent.

[0051] Talc powder was dried in a vacuum drying oven at 80°C for 12 hours. Hyperbranched polyester was ground into fine powder. Three parts of hyperbranched polyester powder and 25 parts of talc powder were immersed in dimethylformamide solution and ultrasonically dispersed for 1 hour using an ultrasonic vibrating head. Then, the mixture was allowed to stand and precipitate for 24 hours. The solvent on the precipitate was removed, and the precipitate was then taken out and dried in a vacuum drying oven at 90°C to obtain hyperbranched polyester modified inorganic filler.

[0052] 50 parts of polypropylene, 25 parts of hyperbranched polyester-modified talc, 25 parts of macromolecular pom-pom toughening agent, 0.2 parts of antioxidant, and 0.1 parts of nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a thin-walled polypropylene composite material for plastic parts was obtained.

[0053] Comparative Example 1: 50 parts polypropylene, 30 parts talc, 20 parts POE, 0.2 parts antioxidant, and 0.1 parts nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a polypropylene composite material was obtained.

[0054] Comparative Example 2: 50 parts polypropylene, 30 parts talc, 20 parts SEBS, 0.2 parts antioxidant, and 0.1 parts nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder for melt blending. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a polypropylene composite material was obtained.

[0055] Comparative Example 3: The preparation of a composite material of a macromolecular pompon structure toughening agent and a thin-walled plastic part includes the following steps: Weighed maleic anhydride-grafted SEBS and maleic anhydride-grafted POE were dried in an oven at 80°C for 12 hours. Three parts by weight of pentaerythritol were placed in a reactor, the temperature was raised to 135°C, nitrogen gas was introduced, and mechanical stirring was performed. 52 parts by weight of maleic anhydride-grafted SEBS were added, and the reaction was maintained at this temperature for 1.5 hours. The reactor temperature was raised to 150°C, and 6 parts by weight of 2,2-dihydroxymethylpropionic acid and 0.2 parts by weight of p-toluenesulfonic acid were added in batches, maintaining the reaction temperature for 1 hour. The reactor temperature was lowered to 130°C, and 160 parts by weight of maleic anhydride-grafted POE were added, maintaining the reaction temperature for 2 hours. The reaction temperature was raised to 150°C, and 24 parts by weight of fatty alcohol were added, maintaining the reaction temperature for 1 hour. Nitrogen gas was stopped, and the reaction was continued under reduced pressure and vacuum for 1 hour. Stop heating and wait for the reactor to cool down before removing the solid reactants. Granulate the solid reactants to obtain a macromolecular pom-pom toughening agent.

[0056] 50 parts polypropylene, 30 parts talc, 20 parts macromolecular pom-pom toughening agent, 0.2 parts antioxidant, and 0.1 parts nucleating agent were mixed in a high-speed mixer for 5 minutes. The mixture was then fed into the feed port of a twin-screw extruder and melt-blended. The extruder temperature zones were set as follows: Zone 1 160-180℃, Zone 2 175-195℃, Zone 3 200-215℃, Zone 4 225-235℃, Zone 5 230-220℃, and Zone 6 215-200℃. After cooling and granulation, a polypropylene composite material was obtained.

[0057] Performance evaluation and implementation standards: The flexural modulus test of polypropylene composite thin-walled plastic parts was conducted according to GB / T 9341-2008 standard. A rectangular specimen with dimensions of 80 mm × 10 mm × 4 mm was prepared, the span was set to 60 mm, and the bending rate was 2 mm / min.

[0058] The impact strength test of polypropylene composite materials for thin-walled plastic parts was conducted according to GB / T 1043.1-2008 standard, using long... LIt is 80 mm wide. b It is 8 mm thick. h The sample was 4 mm thick with a notch depth of 2 mm. The pendulum energy was 2.75 J, and the test temperature was room temperature (25℃).

[0059] The melt flow rate (MFR) of polypropylene composite thin-walled plastic parts was measured by applying a 2.16 kg load at 230 °C for 10 s, cutting 5 samples each time.

[0060] The test results of mechanical properties and melt flow properties of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1. Table 1. Product performance tests obtained from the examples and comparative examples.

[0061] The test results above show that, compared with single POE and SEBS toughening agents, macromolecular pom-pom structure toughening agent not only has a better toughening effect on polypropylene, but also improves melt flow to a certain extent; after the inorganic filler is modified by hyperbranched polyester, it is more uniformly dispersed in the composite material, thus exhibiting a stronger flexural modulus than the untreated composite material.

[0062] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A macromolecular pom-pom structure toughening agent, characterized in that, Using pentaerythritol as the core, the core is grafted with SEBS chain, POE chain and fatty alcohol chain in sequence through a multi-step esterification reaction to form a fluffy molecular structure with the molecular chains diverging outward; in the preparation process of the toughening agent, a half ester carboxylic acid structure is formed in sequence, the hydroxyl groups of the core are expanded, and finally the grafting of each molecular chain is achieved through an esterification reaction.

2. The macromolecular pom-pom structure toughening agent according to claim 1, characterized in that, The SEBS chain is grafted onto the globular core via a ring-opening esterification reaction involving maleic anhydride grafting of SEBS and some of the hydroxyl groups of pentaerythritol, the ring-opening esterification reaction generating a half-ester carboxylic acid structure; the hydroxyl amplification of the globular core is achieved by reacting 2,2-dihydroxymethylpropionic acid with the remaining hydroxyl groups of pentaerythritol, the remaining hydroxyl groups being the hydroxyl groups that have not reacted with the maleic anhydride grafted SEBS.

3. The macromolecular pom-pom structure toughening agent according to claim 1, characterized in that, The POE chain is grafted onto the globular core via an esterification reaction between maleic anhydride-grafted POE and all the amplified hydroxyl groups, and the esterification reaction generates a half-ester carboxylic acid structure; the fatty alcohol chain is grafted onto the globular core via an esterification reaction between the fatty alcohol and the half-ester carboxylic acid structure, and the half-ester carboxylic acid structure is the half-ester carboxylic acid structure generated by the reaction of maleic anhydride-grafted POE and the amplified hydroxyl groups.

4. A method for preparing the macromolecular pom-pom structure toughening agent according to claim 1, characterized in that, Includes the following steps: S1. Place maleic anhydride-grafted SEBS and maleic anhydride-grafted POE in an oven and dry them. S2. Place 3-8 parts by weight of pentaerythritol in a reaction vessel, heat to 130-135℃, introduce nitrogen gas, stir mechanically, add 52-72 parts by weight of maleic anhydride grafted SEBS, and keep the reaction at the temperature for 1-2 hours. S3. Control the temperature of the reactor to rise to 150-160℃, add 6-16 parts by weight of 2,2-dihydroxymethylpropionic acid in batches, add esterification catalyst, and keep the reaction at the temperature for 1-1.5h. S4. Control the temperature of the reactor to 130-135℃, add 160-192 parts by weight of maleic anhydride-grafted POE, and keep the reaction at the temperature for 1-2 hours. S5. Control the reaction temperature to 150-160℃, add 24-36 parts by weight of fatty alcohol, keep the reaction at this temperature for 1.5-2 hours, stop the nitrogen gas supply, reduce the pressure and continue the reaction under vacuum for 1-2 hours. S6. Stop heating and wait for the reactor to cool down before taking out the solid reactants. Granulate the solid reactants to obtain a macromolecular pom-pom toughening agent.

5. The preparation method of the macromolecular pom-pom structure toughening agent according to claim 4, characterized in that, The catalyst is one of p-toluenesulfonic acid, stannous octoate, and butyl titanate, and the amount added is 0.1wt%-0.3wt% of the total reactant mass.

6. The method for preparing the macromolecular pom-pom structure toughening agent according to claim 4, characterized in that, The grafting rate of maleic anhydride to POE is 1%-1.5%, and the grafting rate of maleic anhydride to SEBS is 1.4%-2.0%.

7. The preparation method of the macromolecular pom-pom structure toughening agent according to claim 4, characterized in that, The fatty alcohol is one or more of lauryl alcohol, myristol, cetyl alcohol, and stearyl alcohol.

8. A thin-walled plastic part made of polypropylene composite material, characterized in that, By weight, its components include: 45-60 parts of polypropylene, 20-35 parts of hyperbranched polyester modified inorganic filler, 15-20 parts of the macromolecular pom-pom structure toughening agent as described in any one of claims 1-3, 0.2-0.8 parts of antioxidant, and 0.1-0.3 parts of nucleating agent.

9. The thin-walled polypropylene composite material for plastic parts according to claim 8, characterized in that, The preparation process of the hyperbranched polyester modified inorganic filler is as follows: The inorganic filler was dried in a vacuum drying oven. The hyperbranched polyester was ground into fine powder. The hyperbranched polyester powder and the inorganic filler were immersed in a dimethylformamide solution and ultrasonically dispersed using an ultrasonic vibrating head. The mixture was then allowed to settle and the solvent on top of the precipitate was removed. The precipitate was then removed and placed in a vacuum drying oven to dry, thus obtaining the hyperbranched polyester modified inorganic filler.

10. A method for preparing the thin-walled polypropylene composite material of claim 8, characterized in that, Includes the following steps: S1. Weigh out polypropylene, hyperbranched polyester modified inorganic filler, macromolecular pom-pom toughening agent, antioxidant, and nucleating agent according to the proportion, and put them into a high-speed mixer and mix for 3-5 minutes. S2. Add the above mixture to the feed port of the twin-screw extruder, melt-blend the mixture, extrude, cool, and granulate.

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