Polar polypropylene material and preparation method thereof

Abstract

The invention discloses a polar polypropylene material and a preparation method thereof, and belongs to the technical field of polyolefin material preparation. The preparation method comprises the following steps: adding liquid-phase propylene, a solvent, maleic anhydride and a supported metallocene catalyst into a reaction kettle, and carrying out a polymerization reaction, wherein the molar fraction of the maleic anhydride is controlled to be 0.3-2mol% of that of the propylene; according to the supported metallocene catalyst, nano TiO2 modified by a silane coupling agent is used as a carrier, and a Cp2ZrCl2 / MAO metallocene catalyst is supported. According to the invention, the insertion rate of MAH in a polypropylene main chain is obviously improved, so that the material is endowed with excellent polarity, and the adhesive property with a polar material is further improved; and the polypropylene material provided by the invention also has good mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polyolefin material preparation, in particular to a polar polypropylene material and a preparation method thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Polypropylene (PP), a key thermoplastic resin, boasts easy processing, chemical resistance, and excellent electrical insulation, making it widely used in the automotive, electronics, and packaging sectors. However, the symmetrical and non-polar structure of PP molecular chains significantly reduces low-temperature impact strength, making it susceptible to aging due to light, heat, and oxygen. Furthermore, PP exhibits inherent drawbacks such as poor dyeability, difficulty in surface printing, and poor compatibility with polar materials.

[0004] In order to improve the comprehensive performance of polypropylene, it is an important technical direction to modify it by introducing polar monomers to prepare polar polypropylene. At present, the polar modification of polypropylene is mainly achieved through grafting technology. Commonly used grafting monomers include maleic anhydride (MAH), unsaturated monobasic acids (such as acrylic acid, methacrylic acid) and glycidyl methacrylate (GMA). However, grafting modification technology has significant limitations: on the one hand, unlike ethylene, which can directly introduce polar monomers through free radical copolymerization, propylene is difficult to achieve efficient grafting through free radical polymerization due to its molecular structure characteristics; on the other hand, existing grafting modifications mostly use one-step or two-step processes, which have problems such as high investment cost, complex operation process, and unstable grafting effect. In addition, the secondary processing process is prone to cause side reactions such as molecular weight reduction, cross-linking or degradation, which affects the final material performance.

[0005] Therefore, there is an urgent need to develop an efficient and controllable method for preparing polar polypropylene materials, which can achieve precise design of the molecular chain structure while avoiding complex post-processing, thereby taking into account polarity, mechanical properties and processing stability. Summary of the Invention

[0006] In view of this, the present invention provides a polar polypropylene material and a preparation method thereof. The polar polypropylene material provided by the present invention is obtained by copolymerization of propylene and maleic anhydride (MAH), has a significant polarity modification effect, and can obtain a propylene-maleic anhydride copolymer in one step without the need for additional processing steps. The method is simple and the product has good comprehensive performance.

[0007] In a first aspect, the present invention provides a method for preparing a polar polypropylene material, comprising the following steps: Liquid propylene, solvent, maleic anhydride and supported metallocene catalyst are added into a reactor, and polymerization reaction is performed to obtain the product; The molar fraction of maleic anhydride is controlled to be 0.3-2 mol% of propylene; the supported metallocene catalyst uses nano-TiO2 modified by a silane coupling agent as a carrier to load Cp2ZrCl2 / MAO metallocene catalyst.

[0008] Preferably, the solvent is anhydrous toluene.

[0009] Preferably, the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane (KH-560).

[0010] Furthermore, the preparation method of nano-TiO2 modified by silane coupling agent is as follows: nano-TiO2 is added to the hydrolysis solution of silane coupling agent, reacted at 50-70°C for 3-15h after ultrasonication, washed and dried to obtain the product.

[0011] Furthermore, the mass fraction of the silane coupling agent in the nano-TiO2 is 1-5wt%.

[0012] Preferably, the preparation method of the supported metallocene catalyst is as follows: dispersing nano-TiO2 modified with a silane coupling agent in a solvent, adding MAO toluene solution, adding Cp2ZrCl2 after the reaction, heating and stirring, and then purifying to obtain the catalyst.

[0013] Furthermore, the molar ratio of Al in MAO to Zr in Cp2ZrCl2 is controlled to be (800~1200):1; and the loading amount of Zr in Cp2ZrCl2 in the silane coupling agent-modified nano-TiO2 is controlled to be 0.1~0.3wt%.

[0014] Preferably, the polymerization reaction temperature is 50-70° C., and the time is 1-5 hours.

[0015] Preferably, when the supported metallocene catalyst is added, the molar fraction of Zr is controlled to be 5×10 -5 ~2×10 -4 mol%.

[0016] In a second aspect, the present invention provides a polar polypropylene material prepared by the above preparation method.

[0017] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) The present invention uses nano-TiO2 modified with a silane coupling agent as a carrier to load the Cp2ZrCl2 / MAO metallocene catalyst, which effectively alleviates the poisoning effect of maleic anhydride (MAH) on the catalyst and significantly increases the insertion rate of MAH in the polypropylene main chain, thereby giving the material excellent polarity and solving the problem of poor adhesion caused by the non-polar molecular chain of traditional polypropylene.

[0018] (2) The design of the supported metallocene catalyst in the present invention enables the active centers to be evenly dispersed on the support surface, avoiding the problem of easy agglomeration and deactivation of homogeneous catalysts, improving the catalytic activity and stability, and achieving precise control of molecular weight and distribution. The molecular weight distribution is narrow (PDI is about 1.5~2.5), and the mechanical properties of polypropylene materials are improved. The tensile strength can reach more than 25MPa and the impact strength can reach 10kJ / m 2 above. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0020] The present invention provides a method for preparing a polar polypropylene material, comprising the following steps: Liquid propylene, solvent, maleic anhydride and supported metallocene catalyst are added into a reactor, and polymerization reaction is performed to obtain the product; The molar fraction of maleic anhydride is controlled to be 0.3-2 mol% of propylene; the supported metallocene catalyst uses nano-TiO2 modified by a silane coupling agent as a carrier to load Cp2ZrCl2 / MAO metallocene catalyst.

[0021] Traditional polypropylene (PP) has defects such as poor adhesion, weak dyeability, and low compatibility with polar materials due to its highly symmetrical and non-polar molecular chain. By introducing polar monomers (such as maleic anhydride, MAH) and copolymerizing with propylene, polar groups (anhydride groups) can be introduced into the PP backbone, improving its surface polarity and overall performance. However, the carbonyl group (C=O) of MAH is a strong Lewis base and easily reacts with the active center of the catalyst (such as the TiO2 of the Ziegler-Natta). 3+ or homogeneous metallocene Zr 4+ ) coordination, resulting in severe catalyst poisoning and extremely low MAH insertion rates. This invention introduces maleic anhydride (MAH) directly into the polypropylene (PP) molecular chain through in-situ copolymerization. Furthermore, a nano-TiO2-supported metallocene catalyst is modified with a silane coupling agent to produce polypropylene with high activity, a high grafting rate, and controllable polarity.

[0022] The supported metallocene catalyst of the present invention is composed of a silane coupling agent modified nano-TiO2 carrier, MAO (co-catalyst) and Cp2ZrCl2 (main catalyst). Its activation and catalytic process are as follows: ① MAO activation: MAO generates an active center [Cp2ZrCl2] through an alkylation reaction (converting the Zr-Cl bond into a Zr-CH3 bond). + CH3] +, and acts as a weakly coordinated anion to stabilize the highly active species and prevent it from being inactivated due to strong coordination; ② Carrier confinement effect: the active center [Cp2Zr + CH3] + MAO is fixed on the TiO2 surface through the coordination effect between MAO and the carrier, which avoids the agglomeration and deactivation caused by the free movement of active centers in homogeneous catalysts, thereby improving the stability and activity of the catalyst; ③MAH copolymerization mechanism: MAH pre-fixed on the carrier surface is more easily captured by the active center due to the spatial confinement effect, and its double bond (C=C) coordinates to [Cp2Zr + CH3] + The center is then inserted into the polypropylene chain to form a polar copolymer containing anhydride groups.

[0023] In the present invention, the solvent is anhydrous toluene, which can effectively dissolve propylene (non-polar monomer) and maleic anhydride (weakly polar monomer) while preventing water from hydrolyzing and deactivating MAO (methylaluminoxane).

[0024] In this invention, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane (KH-560). KH-560 hydrolyzes to form Si-OH groups, which condense with the hydroxyl groups (Ti-OH) on the surface of nano-TiO2 to form Si-O-Ti covalent bonds, thereby grafting epoxy groups onto the support surface. The introduction of epoxy groups can firstly reduce the surface energy of nano-TiO2 and improve its dispersibility in toluene (preventing aggregation and active site coverage). Secondly, they coordinate with the Al-O bonds of MAO to form a "TiO2-silane-MAO" composite support, providing a stable loading environment for the metallocene catalyst (Cp2ZrCl2). Thirdly, the epoxy groups can undergo an esterification reaction or physical adsorption with the anhydride groups of MAH, pre-fixing MAH on the support surface, reducing its free concentration and mitigating its poisoning of the Zr active sites.

[0025] The present invention provides a method for preparing nano-TiO2 modified with a silane coupling agent as follows: adding nano-TiO2 to a hydrolyzed solution of the silane coupling agent, reacting at 50-70°C for 3-15 hours after ultrasonic treatment, and then washing and drying. The present invention utilizes the cavitation effect of ultrasound to break up nano-TiO2 aggregates, ensuring uniform dispersion in the hydrolyzed solution and increasing the contact area with silane. Furthermore, the mass fraction of the silane coupling agent in the nano-TiO2 is 1-5 wt%.

[0026] In the present invention, the preparation method of the supported metallocene catalyst is as follows: nano-TiO2 modified with a silane coupling agent is dispersed in a solvent, a MAO toluene solution is added, Cp2ZrCl2 is added after the reaction, and the catalyst is heated and stirred before purification. MAO generates an active center [Cp2ZrCl2] by an alkylation reaction (converting the Zr-Cl bond into a Zr-CH3 bond). + CH3]+ In the present invention, after adding the MAO toluene solution, the reaction temperature is 50-70°C, and the reaction time is 1-5 hours; after adding Cp2ZrCl2, the heating and stirring temperature is 50-70°C, and the reaction time is 1-5 hours. The molar ratio of Al in MAO to Zr in Cp2ZrCl2 is controlled to be (800-1200):1; the loading amount of Zr in Cp2ZrCl2 in the silane coupling agent-modified nano-TiO2 is controlled to be 0.1-0.3wt%, ensuring that there are sufficient active centers on the carrier surface, while preventing the active centers from being too dense and causing agglomeration.

[0027] In the present invention, the polymerization reaction temperature is 50-70°C, the time is 1-5 hours, more preferably 1-3 hours, during which the copolymerization of propylene and MAH occurs. The carbonyl group (C=O) of MAH has a strong affinity for Zr + The degree of poisoning of the center is positively correlated with its free concentration. The present invention reduces the effective free concentration of MAH to within the catalyst tolerance range through the carrier pre-fixation effect, avoiding severe deactivation caused by excessive MAH while ensuring sufficient polar group insertion to improve material performance.

[0028] In the present invention, when the supported metallocene catalyst is added, the molar fraction of Zr is controlled to be 5×10 -5 ~2×10 -4 mol% to ensure that there are enough active centers in the unit volume to initiate polymerization and avoid slow reaction rate due to low concentration.

[0029] The present invention also provides a polar polypropylene material prepared by the above-mentioned preparation method. Due to the efficient insertion of MAH, polar groups such as anhydride groups are introduced into the molecular chain, significantly improving the surface hydrophilicity and adhesion to polar materials. Furthermore, its mechanical properties surpass those of conventional polypropylene, making it suitable for applications requiring high polarity and toughness, such as packaging, automotive parts, and electronic devices.

[0030] The technical solution of the present invention is further described below with reference to specific examples. The present invention has no particular limitation on the sources of the reagents used in the following examples, and commercially available products known to those skilled in the art can be used.

[0031] Example 1 This embodiment provides a method for preparing a polar polypropylene material.

[0032] 1. Preparation of silane coupling agent modified nano-TiO2 (m-TiO2): (1) Preparation of modified solution: Add 2 g KH-560 (2 wt% of the mass of TiO2) to 200 mL of ethanol-water mixed solvent (ethanol: water = 9:1, volume ratio), add acetic acid dropwise to adjust the pH to 4-5, and hydrolyze at room temperature for 6 hours to promote the hydrolysis of Si-OCH3 to Si-OH to obtain a modified solution.

[0033] (2) Nano-TiO2 modification: 100 g of nano-TiO2 was added to the modified solution of step (1) and ultrasonically dispersed for 30 minutes (ultrasonic power of 200 W, ice bath temperature control ≤30°C); then refluxed at 60°C for 6 hours to allow Si-OH to condense with the hydroxyl group (Ti-OH) on the surface of TiO2 to form a Si-O-Ti covalent bond; then centrifuged, washed with anhydrous ethanol three times to remove unreacted silane, vacuum dried at 60°C for 24 hours, and ground through a 200-mesh sieve to obtain a modified nano-TiO2 (denoted as m-TiO2) carrier.

[0034] 2. Preparation of supported metallocene catalyst (m-TiO2 / MAO / Zr): (1) MAO preloading: 50 g of m-TiO2 was dispersed in 500 mL of anhydrous toluene, and MAO toluene solution (with an Al mass fraction of approximately 10 wt%) was added. The mixture was stirred at 60 °C for 4 h. During the reaction, the Al-O bond of MAO coordinated with the epoxy group of m-TiO2 to form an "m-TiO2-MAO" carrier.

[0035] (2) Cp2ZrCl2 loading: 0.32 g of Cp2ZrCl2 was added to the above system (control the Al / Zr molar ratio = 1000, and the Zr loading on the m-TiO2 support was about 0.2 wt%), and stirring was continued at 60 °C for 4 h. During this process, Cp2ZrCl2 coordinated with MAO and activated to form the "m-TiO2-MAO-Zr" active center.

[0036] (3) Post-treatment: Filtration and separation, washing with anhydrous toluene three times to remove unloaded MAO and Zr, and vacuum drying at 40 °C for 12 h to obtain a supported metallocene catalyst (denoted as m-TiO2 / MAO / Zr catalyst).

[0037] 3. Preparation of propylene-MAH copolymer (PP-co-MAH): (1) Heat a 5 L autoclave to 60°C and evacuate for 30 min. Then, replace the autoclave with high-purity nitrogen three times to remove oxygen and moisture. Adjust the circulating water temperature to lower the autoclave temperature to room temperature (25 ± 3°C). Add 842 g (20.0 mol) of liquid propylene monomer and 3 L of anhydrous toluene sequentially into the autoclave.

[0038] (2) Dissolve 10 g of MAH (0.1 mol, about 0.5 mol% of propylene molar ratio) in 50 mL of anhydrous toluene and slowly inject it into the reactor through a constant pressure drip pump. The injection is completed within 30 min.

[0039] (3) Add the above-mentioned m-TiO2 / MAO / Zr catalyst, control the mass of Zr after addition to be about 1 mg, start stirring, set the speed to 500 rpm, and react at 60°C for 2 hours.

[0040] (4) 100 mL of ethanol was added to terminate the reaction, and the polymer was separated by filtration. The polymer was then soaked and washed with ethanol several times to remove unreacted monomers, and then vacuum-dried at 80 °C for 24 h to obtain a propylene-MAH copolymer (PP-co-MAH), which is a polar polypropylene material.

[0041] Example 2 The difference between this example and Example 1 is that in the preparation process of PP-co-MAH, the molar ratio of MAH to propylene in this example is about 1.5 mol%, and the amount added is 30 g (0.3 mol). Step (2) of this example is: 30 g of MAH (0.3 mol, accounting for about 1.5 mol% of the molar ratio of propylene) was dissolved in 150 mL of anhydrous toluene and slowly injected into the reactor through a constant pressure drip pump. The injection was completed within 30 min.

[0042] Example 3 The difference between this embodiment and Example 1 is that in this embodiment, the above-mentioned m-TiO2 / MAO / Zr catalyst is added during the preparation of PP-co-MAH, and the mass of Zr after addition is controlled to be about 3 mg.

[0043] Comparative Example 1 This comparative example differs from Example 1 in that a non-supported metallocene catalyst is added during the preparation of PP-co-MAH. The specific steps are as follows: 1. Preparation of metallocene catalyst: MAO toluene solution (Al mass fraction of about 10 wt%) was added to 500 mL of anhydrous toluene, followed by 0.32 g of Cp2ZrCl2 (controlling the Al / Zr molar ratio = 1000), and the mixture was stirred at 60 °C for 4 h for activation.

[0044] 2. Preparation of propylene-MAH copolymer (PP-co-MAH): (1) Heat a 5 L autoclave to 60°C and evacuate for 30 min. Then, replace the autoclave with high-purity nitrogen three times to remove oxygen and moisture. Adjust the circulating water temperature to lower the autoclave temperature to room temperature (25 ± 3°C). Add 842 g (20.0 mol) of liquid propylene monomer and 3 L of anhydrous toluene sequentially into the autoclave.

[0045] (2) Dissolve 10 g of MAH (0.1 mol, about 0.5 mol% of propylene molar ratio) in 50 mL of anhydrous toluene and slowly inject it into the reactor through a constant pressure drip pump. The injection is completed within 30 min.

[0046] (3) Add the above-mentioned metallocene catalyst, control the mass of Zr after addition to be about 1 mg, start stirring, set the speed to 500 rpm, and react at 60°C for 2 hours.

[0047] (4) 100 mL of ethanol was added to terminate the reaction, and the polymer was separated by filtration. The polymer was then soaked and washed with ethanol several times to remove unreacted monomers, and then vacuum-dried at 80 °C for 24 h to obtain a propylene-MAH copolymer (PP-co-MAH), which is a polar polypropylene material.

[0048] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, nano-TiO2 is not modified with a silane coupling agent, and unmodified nano-TiO2 is directly used to prepare the supported metallocene catalyst (TiO2 / MAO / Zr catalyst).

[0049] Comparative Example 3 The difference between this comparative example and Example 1 is that no MAH is added during the preparation of PP-co-MAH in this comparative example.

[0050] Comparative Example 4 The difference between this comparative example and Example 1 is that in the preparation process of PP-co-MAH in this comparative example, the molar ratio of MAH to propylene is about 3 mol%, and the addition amount thereof is 60 g (0.6 mol).

[0051] Comparative Example 5 In this comparative example, a Ziegler-Natta catalyst was used instead of the m-TiO2 / MAO / Zr catalyst.

[0052] 1. Preparation of Ziegler-Natta catalyst (1) Carrier activation: Anhydrous MgCl2 (50 g, particle size 20-50 μm) and dibutyl phthalate (DBP, 5 g) were added to a ball mill and milled for 24 h at 300 rpm to obtain an activated MgCl2 support.

[0053] (2) TiCl4 loading: Activated MgCl2 (20 g) was dispersed in 200 mL of anhydrous toluene, and TiCl4 (10 mL, 0.09 mol) was added and stirred at 80 °C for 4 h (TiCl4 coordinated with the surface defect sites of MgCl2 to form TiCl4 / MgCl2 active centers).

[0054] After filtration, the mixture was washed with anhydrous toluene three times to remove unloaded TiCl4 and dried in vacuum at 60°C for 12 hours to obtain a TiCl4 / MgCl2 catalyst (Ti loading of about 2.5 wt%).

[0055] 2. Preparation of propylene-MAH copolymer (PP-co-MAH): (1) Heat a 5 L autoclave to 60°C and evacuate for 30 min. Then, replace the autoclave with high-purity nitrogen three times to remove oxygen and moisture. Adjust the circulating water temperature to lower the autoclave temperature to room temperature (25 ± 3°C). Add 842 g (20.0 mol) of liquid propylene monomer and 3 L of anhydrous toluene sequentially into the autoclave.

[0056] (2) Dissolve 10 g of MAH (0.1 mol, about 0.5 mol% of propylene molar ratio) in 50 mL of anhydrous toluene and slowly inject it into the reactor through a constant pressure drip pump. The injection is completed within 30 min.

[0057] (3) Add the above-mentioned TiCl4 / MgCl2 catalyst, control the mass of Ti added to be about 2.5 mg, start stirring, set the speed to 500 rpm, and react at 60°C for 2 hours.

[0058] (4) 100 mL of ethanol was added to terminate the reaction, and the polymer was separated by filtration. The polymer was then soaked and washed with ethanol several times to remove unreacted monomers, and then vacuum dried at 80 °C for 24 h to obtain a polymer product.

[0059] Test example 1. Determination of physical parameters: The physical properties of the polymer products of the above examples and comparative examples were measured by nuclear magnetic resonance spectroscopy ( 1 The MAH insertion rate (mol%) was determined by HNMR and calculated. The molecular weight of the polymer was determined by gel permeation chromatography (GPC). The polymer was dissolved in xylene at a concentration of 10 mg / mL and a thin film was prepared by spin coating for water contact angle measurement.

[0060] Table 1 Physical properties of the polymer products of Examples and Comparative Examples

[0061] As can be seen in Table 1, Examples 1, 2, and 3, using supported metallocene catalysts, exhibit high MAH insertion rates, moderate molecular weights, and narrow distributions. The crystallinity is reduced due to MAH insertion, and the water contact angle is small, indicating a significant increase in polarity. Comparative Examples 1 (homogeneous catalyst) and 2 (unmodified support) exhibit low MAH insertion rates, low molecular weights, and wide distributions, large contact angles, and limited polarity enhancement. Comparative Example 3 (no MAH) is a homopolymerized PP with the highest molecular weight, greatest crystallinity, and largest contact angle, but weakest polarity. The polymer products in Comparative Examples 4 and 5 exhibit extremely low MAH insertion rates, low molecular weights, and wide distributions, low crystallinity, and large contact angles, indicating poor copolymerization of propylene and MAH when MAH is too high or when traditional Ziegler-Natta catalysts are used.

[0062] 2. Mechanical properties determination The tensile strength of the polymerized products of the examples and comparative examples was measured according to GB / T 1040.2-2022; the notched impact strength of the polymerized products of the examples and comparative examples was measured according to GB / T 1843-2008. The test results are shown in Table 2.

[0063] Table 2 Mechanical properties of the polymer products of Examples and Comparative Examples

[0064] As can be seen from Table 2, Examples 1 to 3 using supported metallocene catalysts show significant advantages in mechanical properties, with both tensile strength and impact strength being superior to most comparative examples. Example 3 has the best comprehensive mechanical properties due to its higher molecular weight. Example 2 has a slightly increased impact strength but a slightly decreased tensile strength due to the increased MAH insertion rate. Among the comparative examples, Comparative Example 3 without MAH has the highest tensile strength but the lowest impact strength, reflecting the high rigidity and low toughness characteristics of homopolypropylene. Comparative Example 4 with an excessive amount of MAH has the worst tensile and impact strengths due to its extremely low molecular weight. Comparative Examples 1, 2, and 5 using non-supported metallocene catalysts, unmodified TiO2 carriers, and Ziegler-Natta catalysts all have lower performance than the examples, indicating that supported metallocene catalysts with modified TiO2 carriers have greater advantages in balancing rigidity and toughness and improving comprehensive mechanical properties.

[0065] 3. Adhesion performance test The polypropylene materials from the examples and comparative examples were mixed on a two-roll mill at 130°C for 10 minutes. The materials were then hot-pressed with PA6 (nylon 6) sheets (temperature: 180°C, pressure: 5 MPa, time: 5 minutes). The peel strength was measured at a tensile speed of 100 mm / min using a 25 mm sample width. The test results are shown in Table 3.

[0066] Table 3 Peel strength of polypropylene materials of Examples and Comparative Examples

[0067] As shown in Table 3, the polar polypropylene materials prepared in Examples 1-3 exhibit significantly higher peel strengths with PA6 laminates than the comparative examples, demonstrating superior interfacial bonding with PA6. This is primarily due to the supported catalyst's effective control of the MAH insertion rate, which enhances the interaction between the polar groups and PA6. The comparative examples exhibited lower peel strengths with PA6 due to issues such as insufficient polarity or poor interfacial bonding due to improper catalyst type or inappropriate MAH addition (excessive or no MAH), reflecting the limited effectiveness of polar modification.

[0068] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a polar polypropylene material, characterized in that: The steps include: Liquid propylene, solvent, maleic anhydride and supported metallocene catalyst are added into a reactor, and polymerization reaction is performed to obtain the product; The molar fraction of maleic anhydride is controlled to be 0.3-2 mol% of propylene; the supported metallocene catalyst uses nano-TiO2 modified by a silane coupling agent as a carrier to load Cp2ZrCl2 / MAO metallocene catalyst.

2. The preparation method according to claim 1, wherein The solvent is anhydrous toluene.

3. The preparation method according to claim 1, wherein The silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

4. The preparation method according to claim 3, wherein The preparation method of nano-TiO2 modified by silane coupling agent is as follows: nano-TiO2 is added to the hydrolysis solution of silane coupling agent, reacted at 50-70°C for 3-15h after ultrasonication, and then washed and dried to obtain the product.

5. The preparation method according to claim 4, wherein The mass fraction of the silane coupling agent in the nano-TiO2 is 1-5wt%.

6. The preparation method according to claim 1, wherein The preparation method of the supported metallocene catalyst is as follows: dispersing nano-TiO2 modified by a silane coupling agent in a solvent, adding MAO toluene solution, adding Cp2ZrCl2 after reaction, heating and stirring, and then purifying to obtain the catalyst.

7. The preparation method according to claim 6, wherein The molar ratio of Al in MAO to Zr in Cp2ZrCl2 is controlled to be (800~1200):1; the loading amount of Zr in Cp2ZrCl2 in nano-TiO2 modified with silane coupling agent is controlled to be 0.1~0.3wt%.

8. The preparation method according to claim 1, wherein The polymerization reaction temperature is 50-70° C. and the reaction time is 1-5 hours.

9. The preparation method according to any one of claims 1, wherein When the supported metallocene catalyst is added, the molar fraction of Zr is controlled to be 5×10 -5 ~2×10 -4 mol%.

10. The polar polypropylene material prepared by the preparation method according to any one of claims 1 to 9.

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