Metal complex polypropylene nucleating agent and method for preparing the same

Abstract

This invention discloses a metal-coordinated polypropylene nucleating agent and a method for preparing the nucleating agent, comprising: Step 1, hydrolyzing maleic anhydride-grafted polypropylene to obtain its alkaline hydrolysis product; Step 2, preparing a solution of the maleic anhydride-grafted polypropylene hydrolysis product and a metal salt solution; Step 3, adding the metal salt solution dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution, stirring the reaction, filtering, washing, and drying the reaction product to obtain the metal-coordinated polypropylene nucleating agent. This invention uses maleic anhydride-grafted polypropylene as the coordination framework, preferably Cu²⁺. + Mg² + Ba² + A highly active coordination nucleation site is constructed; the compatibility between the nucleating agent and the polypropylene matrix is ​​improved by relying on the polymer backbone, so as to achieve uniform dispersion of the nucleating agent without agglomeration. At the same time, the semi-crystallization time of polypropylene is significantly shortened, and the crystallization uniformity and processing efficiency are improved, resulting in a polypropylene-specific nucleating agent with comprehensive nucleation performance that is significantly better than other metal ion modified systems.

Description

Technical Field

[0001] This invention belongs to the field of polypropylene nucleating agent technology, and relates to a metal-coordinated polypropylene nucleating agent. This invention also relates to a method for preparing the nucleating agent. Background Technology

[0002] Polypropylene is one of the most widely used general-purpose plastics. It exhibits excellent resistance to acids, alkalis, and polar solvents at room temperature, and combines good economy and processability, thus occupying an important position in food packaging, medical devices, automotive interiors, and other fields. However, pure polypropylene has a slow crystallization rate, a long molding and cooling cycle, and low production efficiency. Furthermore, molded products are prone to problems such as uneven crystallization and poor dimensional stability, making it difficult to meet the processing requirements of high-end products.

[0003] Adding nucleating agents to regulate the crystallization behavior and optimize the crystal structure of polypropylene is the mainstream approach to improve its processing and performance. While commercially available metal salt nucleating agents can promote crystallization to some extent, they generally suffer from poor compatibility with the polypropylene matrix and are prone to agglomeration and uneven dispersion during melt blending. Large differences in nucleating agent content in different areas of the same product can lead to inconsistent crystallization levels throughout the material, ultimately causing fluctuations in the product's mechanical properties and dimensional accuracy. Furthermore, most metal ion-modified systems have limited effect on shortening the semi-crystallization time, making it difficult to significantly reduce the molding cycle. Existing research confirms that metal ions are key to constructing efficient nucleating sites in polypropylene. However, if the type of metal ion is not chosen appropriately, it may not only fail to accelerate crystallization but may even delay the polypropylene crystallization process. Therefore, there is an urgent need to develop a metal-coordinated polypropylene nucleating agent that combines excellent dispersibility with efficient crystallization-promoting capabilities. Summary of the Invention

[0004] The purpose of this invention is to provide a metal-coordinated polypropylene nucleating agent, which uses maleic anhydride-grafted polypropylene as the coordination framework, preferably Cu². + Mg² + Ba² + A highly active coordination nucleation site is constructed; the compatibility between the nucleating agent and the polypropylene matrix is ​​improved by relying on the polymer backbone, so as to achieve uniform dispersion of the nucleating agent without agglomeration. At the same time, the semi-crystallization time of polypropylene is significantly shortened, and the crystallization uniformity and processing efficiency are improved, resulting in a polypropylene-specific nucleating agent with comprehensive nucleation performance that is significantly better than other metal ion modified systems.

[0005] Another objective of this invention is to provide a method for preparing the above-mentioned nucleating agent, which designs a stepwise reaction process of hydrolysis and coordination, simplifies the synthesis operation, reduces raw material and production costs, provides mild and controllable reaction conditions, and simplifies product post-processing; it can stably produce metal coordination nucleating agents with fine particles and excellent dispersion performance, the whole process is easy to scale up, meets the needs of industrial mass production, and stably produces high molecular weight coordination polypropylene nucleating agents with good matrix compatibility and efficient crystallization promotion effect.

[0006] The technical solution adopted in this invention is a method for preparing a metal-coordinated polypropylene nucleating agent, which is implemented according to the following steps: Step 1: Hydrolyze maleic anhydride-grafted polypropylene to obtain its alkaline hydrolysis product. Step 2: Prepare the maleic anhydride-grafted polypropylene hydrolysis product solution and the metal salt solution; Step 3: Add the metal salt solution dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution, stir the reaction, filter, wash and dry the reaction product to obtain the metal-coordinated polypropylene nucleating agent.

[0007] The invention is further characterized by: Step 1 is as follows: Maleic anhydride-grafted polypropylene was added to xylene and stirred at 120℃-125℃ to dissolve. Then the temperature was lowered to 70℃-80℃, and an ethanol aqueous solution of sodium hydroxide was added dropwise. After the addition was complete, the reaction was allowed to proceed for 3 hours. The reaction product was then filtered, washed, and dried to obtain the alkaline hydrolysis product of maleic anhydride-grafted polypropylene.

[0008] The specific amounts of each substance added in step 1 are as follows: Add 1-3 parts by weight of maleic anhydride-grafted polypropylene to 15-45 parts by weight of xylene, and then add 1.5-5 parts by weight of 0.5M sodium hydroxide ethanol aqueous solution dropwise.

[0009] In step 1, the volume ratio of ethanol to water in the sodium hydroxide ethanol aqueous solution is 7:3; in addition, the reaction product is washed with acetone and distilled water.

[0010] Step 2 is as follows: Add 1-3 parts by weight of the alkaline hydrolysis product to 15-45 parts by weight of xylene and stir to dissolve at 120℃-125℃ to obtain a maleic anhydride-grafted polypropylene hydrolysis product solution; disperse 5-15 parts by weight of the metal salt in 2-6 parts by weight of acetonitrile aqueous solution to obtain a metal salt solution.

[0011] In step 2, the metal salt is anhydrous copper sulfate, anhydrous magnesium sulfate, or barium chloride.

[0012] Step 3 specifically involves: A metal salt solution was added dropwise to a solution of maleic anhydride-grafted polypropylene hydrolysis products. The mixture was stirred at 70℃-80℃ for 12 hours. The reaction product was then filtered and washed to remove excess metal salt. The resulting product was dried in a vacuum oven at 70℃-80℃ for 12 hours to obtain a metal-coordinated polypropylene nucleating agent.

[0013] Another technical solution adopted in this invention is a metal-coordinated polypropylene nucleating agent, which is prepared by the above method.

[0014] The beneficial effects of this invention are: This invention utilizes maleic anhydride-grafted polypropylene hydrolysis products as ligands, combined with a unique preparation process involving hydrolysis pretreatment, a dual-solvent system, and dropwise coordination, to produce copper, magnesium, and barium metal-coordinated polypropylene nucleating agents. When applied to isotactic polypropylene, the addition amount is only 0.5% of the polypropylene mass, exhibiting multiple significant advantages compared to traditional small-molecule metal salt nucleating agents. (1) Innovative carrier system with strong matrix compatibility and uniform dispersion of nucleating agent without agglomeration. Existing nucleating agents mostly use small molecule metal salts directly, which have poor compatibility with polypropylene and are prone to agglomeration during melt blending, resulting in significant differences in crystallization properties in different regions of the product. This invention innovatively selects maleic anhydride-grafted polypropylene, which is rarely used in the field of existing nucleating agents, as the polymer coordination backbone. The long polymer chain enhances the interfacial affinity with the polypropylene matrix. Combined with the preparation process of dissolving in a dual solvent system and slowly adding coordination, the metal ions are uniformly bonded to the polymer chain segments, resulting in fine product particles. Differential scanning calorimetry was performed on multiple samples of modified polypropylene. The semi-crystallization time values ​​measured at multiple points were very similar, proving that the nucleating agent can be uniformly dispersed throughout the polypropylene without local enrichment or deficiency. No additional dispersing agent is required, and polypropylene products with uniform crystallinity and mechanical properties can be stably prepared.

[0015] (2) The process design is reasonable, the synthesis is simple and easy to industrialize, and the production cost is low. The present invention adopts a stepwise reaction route of alkaline hydrolysis followed by dropwise addition of coordination, and uses a dual solvent system of xylene and acetonitrile to dissolve the polymer ligand and metal salt respectively. The two phases are in full contact and the coordination reaction is complete. The reaction conditions of the whole process are mild and controllable, the raw materials are readily available, the operation process is simple, and the post-processing steps such as filtration, washing and drying are conventional. No complicated special equipment is required, the production threshold is low, and it can be directly scaled up to achieve mass production.

[0016] (3) Cu² is preferred + Mg² + Ba² + The coordination system exhibits a crystallization acceleration effect far exceeding that of other metal ion-modified products. Compared to Na... + Ca² + Al³ + Ce³ + La³ + Zn² +With equivalent proportions of metal ions, the coordination structures formed by the three metals and polymer ligands in this invention can construct a large number of highly active heterogeneous nucleation sites, significantly shortening the semi-crystallization time of polypropylene. Specifically, the semi-crystallization time of PP / P_MAH_Ba is only 0.63 min, while the semi-crystallization times of PP / P_MAH_Mg and PP / P_MAH_Cu are also as low as 0.86 min and 0.88 min, respectively, far superior to pure PP, uncoordinated hydrolyzed products, and other metal-modified samples. The faster crystallization rate allows the polypropylene melt to solidify quickly, enabling products to achieve demolding strength and dimensional stability in a short time. This significantly shortens the injection molding and extrusion molding cycle, effectively improving production line processing efficiency and reducing production energy consumption and time costs. It has extremely high application value in the fields of polypropylene products such as food packaging, medical devices, and automotive interiors. Attached Figure Description

[0017] Figure 1 These are the crystallization kinetic curves of the nucleating agents prepared in the embodiments and comparative examples of this invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0019] The metal-coordinated polypropylene nucleating agent of this invention is prepared by introducing metal ions into the alkaline hydrolysis product of maleic anhydride-grafted polypropylene, wherein the metal ions include copper ions (Cu). 2+ Barium ions (Ba) 2+ ), magnesium ions (Mg 2+ The metal salts used were anhydrous copper sulfate, barium chloride, and anhydrous magnesium sulfate, respectively.

[0020] The molecular structure of maleic anhydride-grafted polypropylene is (I).

[0021]

[0022] (I) The preparation method of the metal-coordinated polypropylene nucleating agent of the present invention is specifically implemented according to the following steps: Step 1: Add 1-3 parts of maleic anhydride-grafted polypropylene to 15-45 parts of xylene, stir and dissolve at 120℃-125℃, then cool to 70℃-80℃ and add 1.5-5 parts of 0.5M sodium hydroxide ethanol aqueous solution (ethanol to water volume ratio of 7:3). After the addition is complete, react for another 3 hours. Then filter, wash and dry the reaction product to obtain the alkaline hydrolysis product of maleic anhydride-grafted polypropylene.

[0023] Step 2: Add 1-3 parts of the alkaline hydrolysis product obtained in Step 1 to 15-45 parts of xylene and stir to dissolve at 120℃-125℃ to obtain a maleic anhydride-grafted polypropylene hydrolysis product solution; separately, disperse 5-15 parts of metal salt in 2-6 parts of acetonitrile aqueous solution, the metal salt including anhydrous copper sulfate, anhydrous magnesium sulfate, and barium chloride to obtain a metal salt solution.

[0024] Step 3: Add the metal salt solution dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution, stir the reaction at 70-80℃ for 12h, then filter and wash the reaction product to remove excess metal salt; dry the obtained product in a vacuum oven at 70℃-80℃ for 12h to obtain the metal-coordinated polypropylene nucleating agent.

[0025] All the numbers mentioned in the above steps are by weight.

[0026] Example 1 This embodiment provides a method for hydrolyzing maleic anhydride-grafted polypropylene, specifically as follows: One part of maleic anhydride-grafted polypropylene was added to a 250 mL round-bottom flask containing 15 parts of xylene and heated to 125 °C until completely dissolved. After the system cooled to 75 °C, 1.5 parts of 0.5 mol / L NaOH ethanol-water solution were added, and the mixture was stirred at this temperature for 3 h. After the reaction was completed, the reaction solution was poured into a beaker containing 65 parts of acetone and allowed to stand for 30 min. The liquid in the beaker was then filtered, and the maleic anhydride-grafted polypropylene hydrolysis product on the filter paper was washed three times with acetone and distilled water, respectively. Then, it was placed in a vacuum oven and dried overnight at 80 °C to obtain the maleic anhydride-grafted polypropylene hydrolysis product P_MAH.

[0027] Example 2 One part of the maleic anhydride-grafted polypropylene hydrolysis product obtained in Example 1 was added to 15 parts of xylene and heated to 125°C with stirring until the hydrolysis product was completely dissolved, yielding a clear and transparent maleic anhydride-grafted polypropylene hydrolysis product solution. The resulting solution was then cooled to 75°C. Five parts of anhydrous magnesium sulfate were dispersed in two parts of acetonitrile aqueous solution, and the magnesium sulfate solution was then added dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution. After the addition was complete, the system temperature was maintained at 75°C, and the reaction was continuously stirred for 12 hours to ensure sufficient ion exchange and coordination reactions. After the reaction was complete, the mixture was slowly poured into a beaker containing 65 parts of acetone while still hot. After standing for 30 minutes, the liquid in the beaker was filtered, and the metal ion coordination product on the filter paper was washed three times with acetone and distilled water. The mixture was then placed in a vacuum drying oven and vacuum dried overnight at 80°C to obtain the metal coordination polypropylene nucleating agent sample P_MAH_Mg.

[0028] Example 3 One part of the maleic anhydride-grafted polypropylene hydrolysis product obtained in Example 1 was added to 15 parts of xylene and heated to 125°C with stirring until the hydrolysis product was completely dissolved, yielding a clear and transparent solution. The resulting solution was then cooled to 75°C. Five parts of barium chloride were dispersed in two parts of acetonitrile aqueous solution, and the barium chloride solution was then added dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution. After the addition was complete, the system temperature was maintained at 75°C, and the reaction was continuously stirred for 12 hours to ensure sufficient ion exchange and coordination reactions. After the reaction was complete, the mixture was slowly poured into a beaker containing 65 parts of acetone while still hot. After standing for 30 minutes, the liquid in the beaker was filtered, and the metal ion coordination product on the filter paper was washed three times with acetone and distilled water. The mixture was then placed in a vacuum drying oven and vacuum dried overnight at 80°C to obtain the metal-coordinated polypropylene nucleating agent sample P_MAH_Ba.

[0029] Example 4 One part of the maleic anhydride-grafted polypropylene hydrolysis product obtained in Example 1 was added to 15 parts of xylene and heated to 125°C with stirring until the hydrolysis product was completely dissolved, yielding a clear and transparent solution. The resulting solution was then cooled to 75°C. Five parts of anhydrous copper sulfate were dispersed in two parts of acetonitrile aqueous solution, and the copper sulfate solution was then added dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution. After the addition was complete, the system temperature was maintained at 75°C, and the reaction was continuously stirred for 12 hours to ensure sufficient ion exchange and coordination reactions. After the reaction was complete, the mixture was slowly poured into a beaker containing 65 parts of acetone while still hot. After standing for 30 minutes, the liquid in the beaker was filtered, and the metal ion coordination product on the filter paper was washed three times with acetone and distilled water. The mixture was then placed in a vacuum drying oven and vacuum dried overnight at 80°C to obtain the metal-coordinated polypropylene nucleating agent sample P_MAH_Cu.

[0030] Example 5 One part of the maleic anhydride-grafted polypropylene hydrolysis product obtained in Example 1 was added to 15 parts of xylene and heated to 120°C with stirring until the hydrolysis product was completely dissolved, yielding a clear and transparent maleic anhydride-grafted polypropylene hydrolysis product solution. The resulting solution was then cooled to 80°C. Five parts of anhydrous magnesium sulfate were dispersed in two parts of acetonitrile aqueous solution, and the magnesium sulfate solution was then added dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution. After the addition was complete, the system temperature was maintained at 80°C, and the reaction was continuously stirred for 12 hours to ensure sufficient ion exchange and coordination reactions. After the reaction was completed, the mixture was slowly poured into a beaker containing 65 parts of acetone while still hot. After standing for 30 minutes, the liquid in the beaker was filtered, and the metal ion coordination product on the filter paper was washed three times with acetone and distilled water. The mixture was then placed in a vacuum drying oven and vacuum dried overnight at 70°C to obtain a metal-coordinated polypropylene nucleating agent sample.

[0031] Example 6 One part of the maleic anhydride-grafted polypropylene hydrolysis product obtained in Example 1 was added to 15 parts of xylene and heated to 125°C with stirring until the hydrolysis product was completely dissolved, yielding a clear and transparent solution. The resulting solution was then cooled to 70°C. Five parts of barium chloride were dispersed in two parts of acetonitrile aqueous solution, and the barium chloride solution was then added dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution. After the addition was complete, the system temperature was maintained at 70°C, and the reaction was continuously stirred for 12 hours to ensure sufficient ion exchange and coordination reactions. After the reaction was complete, the mixture was slowly poured into a beaker containing 65 parts of acetone while still hot. After standing for 30 minutes, the liquid in the beaker was filtered, and the metal ion coordination product on the filter paper was washed three times with acetone and distilled water. The mixture was then placed in a vacuum drying oven and vacuum dried overnight at 75°C to obtain a metal-coordinated polypropylene nucleating agent sample.

[0032] Comparative Example 1 This comparative example is basically the same as Example 2, except that the metal ions Mg are used. 2+ Replace with Na respectively + Ca 2 + Al 3+ Ce 3+ La 3+ and Zn 2+ Furthermore, the amount of these metal ions is similar to that of Mg. 2+ Similarly, nucleating agents P_MAH_Na, P_MAH_Ca, P_MAH_Al, P_MAH_Ce, P_MAH_La and P_MAH_Zn were obtained respectively.

[0033] Polypropylene was modified using the maleic anhydride-grafted polypropylene hydrolysis product P_MAH prepared in Example 1 and various nucleating agents prepared in Examples 2-4 and Comparative Example 1, resulting in modified polypropylene samples PP / P_MAH, PP / P_MAH_Na, PP / P_MAH_Ca, PP / P_MAH_Al, PP / P_MAH_Cu, PP / P_MAH_Mg, PP / P_MAH_Ba, PP / P_MAH_Ce, PP / P_MAH_La, and PP / P_MAH_Zn. Differential scanning calorimetry (DSC) was performed on each sample and pure polypropylene PP, and their crystallization kinetic curves were obtained as follows: Figure 1 As shown, detailed semi-crystallization time (t) 1 / 2 The data is shown in Table 1.

[0034] Table 1. Semi-crystallization time (t) for each sample 1 / 2 )

[0035] Combination Figure 1As can be seen from the crystallization kinetics curve and the semi-crystallization time data in Table 1, the Cu² of this invention... + Mg² + Ba² + The coordination-modified nucleating agent significantly improved the crystallization rate of polypropylene compared to other metal ion-modified samples. The semi-crystallization time of pure polypropylene was 1.57 min, while the semi-crystallization time of the PP / P_MAH sample modified by the hydrolysis products of uncoordinated metals reached 1.69 min. + Ce³ + La³ + The modified sample had virtually no crystallization-promoting effect; Ca² + Al³ + Zn² + The modified samples only slightly shortened the semi-crystallization time; however, the semi-crystallization times of the nucleating agent-modified PP samples of this invention (PP / P_MAH_Mg, PP / P_MAH_Cu, and PP / P_MAH_Ba) were as low as 0.86 min, 0.88 min, and 0.63 min, respectively, with the overall crystallization kinetic curves shifting significantly to the left. Shorter semi-crystallization times indicate that the polypropylene cooling process can quickly establish a stable crystal structure, allowing the product to rapidly achieve demolding strength and dimensional stability, effectively shortening the injection molding and extrusion processing cycle, and reducing the time and energy costs of industrial production.

[0036] Comparative results of various metal ions show that alkali metal and rare earth metal coordination systems have almost no nucleation synergistic effect, and the modification products of ordinary divalent and trivalent metal ions have limited improvement on crystallinity, with only Cu²⁺ showing the best improvement. + Mg² + Ba² + It can form highly active coordination nucleation sites with maleic anhydride-grafted polypropylene hydrolysis products, significantly increasing the heterogeneous nucleation density of polypropylene. All three metal coordination products of this invention exhibit comprehensive nucleation performance far exceeding that of other metal ion samples. Among them, the barium ion coordination nucleating agent shows the best crystallization acceleration effect, followed by magnesium and copper ion coordination nucleating agents, demonstrating unique and outstanding application advantages in the field of polypropylene processing modification.

[0037] Furthermore, differential scanning calorimetry (DSC) tests were conducted on samples taken from multiple locations at different points during the experiment. The semi-crystallization times measured from these multiple samples showed extremely small differences. Figure 1 The stable repeatability and lack of significant shifts in the three curves of PP / P_MAH_Cu, PP / P_MAH_Mg, and PP / P_MAH_Ba of this invention confirm that the metal coordination nucleating agent of this invention has excellent compatibility with polypropylene during melt blending and can be uniformly dispersed within the PP matrix without local agglomeration or local enrichment.

[0038] If the nucleating agent agglomerates, the agglomeration area will exhibit excessively high local nucleation concentrations, while the blank area will lack nucleating components. Significant differences in the semi-crystallization time will occur at different sampling locations, and the crystallization kinetic curve will also show significant dispersion. However, the nucleating agent of this invention exhibits highly consistent test data from multiple locations, directly demonstrating its fine particle size, excellent interface bonding with PP, and dispersion performance far superior to Na. + Ce³ + La³ + Metal ion modified products can achieve uniform nucleation throughout the entire process without the need for additional dispersants, ensuring the overall crystallization performance of polypropylene products is uniform and avoiding deviations in mechanical and dimensional properties of different parts of the product.

Claims

1. A method for preparing a metal-coordinated polypropylene nucleating agent, characterized in that, The specific steps are as follows: Step 1: Hydrolyze maleic anhydride-grafted polypropylene to obtain its alkaline hydrolysis product. Step 2: Prepare the maleic anhydride-grafted polypropylene hydrolysis product solution and the metal salt solution; Step 3: Add the metal salt solution dropwise to the maleic anhydride-grafted polypropylene hydrolysis product solution, stir the reaction, filter, wash and dry the reaction product to obtain the metal-coordinated polypropylene nucleating agent.

2. The method for preparing the metal-coordinated polypropylene nucleating agent according to claim 1, characterized in that, Step 1 is as follows: Maleic anhydride-grafted polypropylene was added to xylene and stirred at 120℃-125℃ to dissolve. Then the temperature was lowered to 70℃-80℃, and an ethanol aqueous solution of sodium hydroxide was added dropwise. After the addition was complete, the reaction was allowed to proceed for 3 hours. The reaction product was then filtered, washed, and dried to obtain the alkaline hydrolysis product of maleic anhydride-grafted polypropylene.

3. The method for preparing the metal-coordinated polypropylene nucleating agent according to claim 2, characterized in that, The specific amounts of each substance added in step 1 are as follows: Add 1-3 parts by weight of maleic anhydride-grafted polypropylene to 15-45 parts by weight of xylene, and then add 1.5-5 parts by weight of 0.5M sodium hydroxide ethanol aqueous solution dropwise.

4. The method for preparing the metal-coordinated polypropylene nucleating agent according to claim 2, characterized in that, In step 1, the volume ratio of ethanol to water in the sodium hydroxide ethanol aqueous solution is 7:3; in addition, the reaction product is washed with acetone and distilled water.

5. The method for preparing the metal-coordinated polypropylene nucleating agent according to claim 1, characterized in that, Step 2 is as follows: Add 1-3 parts by weight of the alkaline hydrolysis product to 15-45 parts by weight of xylene and stir to dissolve at 120℃-125℃ to obtain a maleic anhydride-grafted polypropylene hydrolysis product solution; disperse 5-15 parts by weight of the metal salt in 2-6 parts by weight of acetonitrile aqueous solution to obtain a metal salt solution.

6. The method for preparing the metal-coordinated polypropylene nucleating agent according to claim 1 or 5, characterized in that, In step 2, the metal salt is anhydrous copper sulfate, anhydrous magnesium sulfate, or barium chloride.

7. The method for preparing the metal-coordinated polypropylene nucleating agent according to claim 1, characterized in that, Step 3 specifically involves: A metal salt solution was added dropwise to a solution of maleic anhydride-grafted polypropylene hydrolysis products. The mixture was stirred at 70℃-80℃ for 12 hours. The reaction product was then filtered and washed to remove excess metal salt. The resulting product was dried in a vacuum oven at 70℃-80℃ for 12 hours to obtain a metal-coordinated polypropylene nucleating agent.

8. A metal-coordinated polypropylene nucleating agent, characterized in that, It is prepared by the method described in any one of claims 1-7.

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