Propylene polymer and preparation method therefor and polypropylene composition

Abstract

The present invention relates to the technical field of polypropylene preparation, and in particular to a propylene polymer and a preparation method therefor and a polypropylene composition. The propylene polymer is characterized by: (1) comprising a matrix having a content greater than or equal to 99 wt%, the matrix being selected from a propylene homopolymer, a propylene copolymer or a propylene homopolymer and propylene copolymer; (2) comprising a polymer nucleating agent having a mass content of 1-1,000 ppm; (3) the matrix comprising 0.1-10.0 wt% of an ultra-high molecular weight component having a molecular weight M greater than or equal to 10 million; and (4) the propylene polymer having Mz+1 greater than or equal to 6,000×103 and less than or equal to 100,000×103, and Mz+1 / Mn being greater than or equal to 100 and less than or equal to 1,000. The propylene polymer of the present invention has both processability and mechanical properties, and has significantly improved rigidity and toughness in terms of mechanical properties. In addition, the propylene polymer has excellent transparency.

Description

Propylene polymers, their preparation methods, and polypropylene compositions Technical Field

[0001] This invention belongs to the field of polypropylene preparation technology, and particularly relates to a propylene polymer, its preparation method, and a polypropylene composition. Background Technology

[0002] Polypropylene often exists as a semi-crystalline polymer, which typically has good rigidity, but improving its toughness often requires modification through various methods.

[0003] Propylene copolymers are often used to manufacture pipes and various packaging materials, and their toughness and strength are often very important performance parameters. It is well known that the comonomer units in propylene polymers are beneficial to toughness, but at the same time, they often reduce the strength of the material. According to the papers Prog. Polym. Sci. 2003, 28, 1643 and Macromol. Mater. Eng. 2005, 290, 621, the molecular weight of the polymer and the orientation of the polymer molecular chains are important parameters that determine its strength. Therefore, if ultra-high molecular weight components can be introduced into polypropylene, the ultra-high molecular weight components should be beneficial to the improvement of the strength of propylene polymer materials. However, the use or introduction of ultra-high molecular weight components is limited by two aspects: (1) polypropylene containing ultra-high molecular weight components is difficult to obtain and prepare; (2) polymers containing ultra-high molecular weight components are difficult to blend with polymers with higher melt indexes to achieve sufficient mixing.

[0004] Among existing modification methods, there are cases of obtaining polypropylene containing ultra-high molecular weight components through hydrogen-free polymerization. However, the proportion of components with a molecular weight exceeding 10 million produced by hydrogen-free polymerization is usually less than 0.1 wt%, which limits the improvement of material properties. For example, Sinopec's patent document US9068030B2 discloses that hydrogen-free polymerization can obtain components with a molecular weight greater than 5 million, accounting for approximately 1.86 wt%; however, the final product's molecular weight... z The highest is only 282.9×10 4 M z+1 Only 511.0×10 4 The performance improvement of the final product is limited.

[0005] In existing technologies, copolymers can be blended with a polypropylene matrix to lower the brittle-ductile transition temperature of polypropylene. For example, Montecatini's patent document US3036987A discloses that blending polypropylene with a nearly amorphous ethylene-propylene copolymer can lower the embrittlement temperature of polypropylene from 6°C to -7°C. Besides ethylene as a comonomer, other olefin monomers (especially α-olefins) are also commonly used to copolymerize with propylene to obtain copolymers. For instance, DuPont's patent document US3888949A discloses that blending polypropylene with a propylene / 1-hexene copolymer can also significantly improve the impact strength of the final material.

[0006] Lustiger et al. (J. Polym. Sci. B Polym. Phys. 1998, 36, 2047) argued that copolymers and other components enhance the bonding between polypropylene spherulites, thereby improving its toughness. However, the blending of copolymer elastomers often compromises the transparency of the material, and improvements have been made in this area to mitigate this problem. For example, Asahi Kasei Corporation's patent document US9115279B2 discloses that incorporating some SEBS elastomer can not only further improve the toughness of the material but also reduce its haze. Similarly, Hercules Corporation's patent document US3262992A discloses that blending polypropylene with products obtained from alternating sequential polymerization of ethylene / propylene can also improve the impact strength of the material.

[0007] Direct in-reactor generation of multiphase propylene copolymers has become a classic method for toughening polypropylene. This typically involves sequential generation in two or more reactors. The upstream reactor produces a crystalline polypropylene matrix, which can be a homopolymer or a copolymer; the downstream reactor produces a toughening component, primarily composed of a rubber phase, through copolymerization. Numerous existing technologies exist in this area. However, multiphase propylene copolymers often have relatively low moduli, frequently necessitating alternative techniques to improve their rigidity and achieve a balance between stiffness and toughness.

[0008] Nucleating agents are commonly used to alter the crystallization behavior of polypropylene to achieve higher crystallization temperatures, higher rigidity, and / or higher transparency. For example, Shell's patent document US5362782A discloses that adding sodium benzoate as a nucleating agent to multiphase copolymers can improve both the material's rigidity and impact strength. Borealis' patent US10920055B2 discloses adding a second nucleating agent to multiphase copolymers already containing polymer nucleating agents to further improve the material's rigidity-toughness balance. However, due to the inherent incompatibility between the rubber and plastic phases in multiphase copolymers, there are still insurmountable defects in transparency and other properties, limiting their applications.

[0009] Therefore, how to prepare polyolefins with good processing performance, significantly improved rigidity and toughness while simplifying the process is a direction worth exploring. Summary of the Invention

[0010] The purpose of this invention is to address some technical problems existing in the propylene polymerization process by providing a propylene polymer, its preparation method, and a polypropylene composition. The obtained propylene polymer has both processing performance and mechanical properties, and in terms of mechanical properties, it achieves simultaneous improvement in rigidity and toughness. At the same time, the propylene polymer has excellent transparency.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] In the first aspect, a propylene polymer is provided that is directly obtained from a polymerization reactor, the propylene polymer having the following characteristics:

[0013] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​selected from propylene homopolymer, propylene copolymer or propylene homopolymer and propylene copolymer;

[0014] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0015] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0016] (4) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000.

[0017] In the propylene polymer, the matrix content (when both propylene homopolymer and propylene copolymer are used as the matrix, it refers to the total content of the two) can be 99.00wt%-99.99wt%, 99.20wt%-99.90wt%, 99.30wt%-99.80wt%, or 99.41wt%-99.80wt%, for example, 99.10wt%, 99.20wt%, 99.30wt%, 99.40wt%, 99.50wt%, 99.60wt%, 99.80wt%, 99.90wt%, 99.91wt%, 99.92wt%, 99.94wt%, 99.95wt%, 99.96wt%, 99.98wt%, or 99.99wt%.

[0018] The mass content of the polymer nucleating agent in the propylene polymer can be 1-1000 ppm, 3-900 ppm, 10-800 ppm, or 30-600 ppm, for example, 2 ppm, 4 ppm, 5 ppm, 8 ppm, 10 ppm, 15 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 80 ppm, 100 ppm, 150 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 800 ppm, or 900 ppm.

[0019] In the propylene polymer matrix, the content of ultra-high molecular weight components with a molecular weight M ≥ 10 million can be 0.1wt%-10.0wt%, 0.2wt%-5.0wt%, or 0.3wt%-2.0wt%, for example, 0.15wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.5wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, 9.0wt%, or 9.5wt%.

[0020] The M of the propylene polymer z+1 It can be 6000×10 3 -100000×10 3 It can also be 6500×10 3 -50000×10 3 It can be 7000×10 3 -20000×10 3 For example, it can be 6200×10 3 6500×10 3 7000×10 3 7500×10 3 8000×10 3 9000×10 3 9500×10 3 10000×10 3 11000×10 3 12000×10 3 15000×10 3 , etc.; and M z+1 / M nIt can be 100-1000, 101-500, or 102-300. For example, it can be 105, 110, 120, 125, 130, 140, 150, 160, 180, 200, 220, 240, 250, 280, 310, 320, 340, 350, 380, 400, 450, 500, 520, 540, 550, 560, 580, 600, 620, 640, 650, 680, 700, 750, 800, 820, 850, 880, 900, 910, 930, 950, 960, 980, 990, etc.

[0021] According to the propylene polymer provided by the present invention, in some embodiments, the propylene polymer has the following characteristics:

[0022] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer;

[0023] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0024] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0025] (4) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000.

[0026] According to the propylene polymer provided by the present invention, in some embodiments, the propylene polymer has the following characteristics:

[0027] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer;

[0028] (2) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a.

[0029] Wherein, NIS is the notched impact strength, with units of kJ / m². -2FlexMod is the bending modulus, measured in MPa, with a value range of 800-2500 (e.g., 820, 840, 850, 860, 880, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2100, 2200, 2400). 'a' is a constant with a value range of 7.4690-9.0000 (e.g., 7.5, 7.55, 7.6, 7.8, 7.9, 8.0, 8.1, 8.2, 8.4, 8.5, 8.6, 8.8, 8.9).

[0030] In some embodiments, the propylene polymer has the following characteristics:

[0031] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer;

[0032] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0033] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0034] (4) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000;

[0035] (5) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a.

[0036] Wherein, NIS is the notched impact strength, with units of kJ / m². -2 FlexMod is the bending modulus, measured in MPa, with a value range of 800-2500. a is a constant with a value range of 7.4690-9.0000.

[0037] According to the propylene polymer provided by the present invention, in some embodiments, the propylene polymer has the following characteristics:

[0038] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer;

[0039] (2) The unnotched impact strength UNIS of the propylene polymer is 1 / (-0.009425+1.1850×10⁻⁶). -5×FlexMod+0.003876×ln(MFR))+b,

[0040] UNIS is the unnotched impact strength, measured in kJ / m³. -2 FlexMod is the flexural modulus, measured in MPa, with a value range of 800-2500 (e.g., 820, 840, 850, 860, 880, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2100, 2200, 2400). ln represents the natural logarithm, and MFR is the melt flow index, measured in g / 10min. -1 b is a constant with a value range of 30-110 (e.g., 32, 33, 34, 35, 38, 40, 45, 50, 52, 54, 55, 56, 58, 60, 62, 65, 70, 74, 75, 80, 85, 90, 95, 100, 105, 108).

[0041] In some embodiments, the propylene polymer has the following characteristics:

[0042] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer;

[0043] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0044] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0045] (4) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000;

[0046] (5) The unnotched impact strength UNIS of the propylene polymer is 1 / (-0.009425+1.1850×10⁻⁶). -5 ×FlexMod+0.003876×ln(MFR))+b,

[0047] UNIS is the unnotched impact strength, measured in kJ / m³. -2 FlexMod is the flexural modulus, measured in MPa, with a value ranging from 800 to 2500. ln represents the natural logarithm, and MFR is the melt flow index, measured in g / 10min. -1b is a constant with a value range of 30-110.

[0048] According to the propylene polymer provided by the present invention, in some embodiments, the propylene polymer has the following characteristics:

[0049] (1) Contains a matrix, wherein the matrix is ​​a propylene homopolymer and a propylene copolymer; the total content of the propylene homopolymer and the propylene copolymer as the matrix is ​​greater than or equal to 99 wt%;

[0050] (2) In the propylene polymer, the content of comonomer in the low molecular weight component with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomer in the high molecular weight component with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component is 0.01-1.00.

[0051] The propylene polymer may contain low molecular weight components with a molecular weight <1 million and high molecular weight components with a molecular weight ≥1 million. The content of comonomers in the low molecular weight components with a molecular weight <1 million may be 0.05-5.00 wt%, 0.05-4.00 wt%, or 0.05-3.00 wt%, for example, 0.15 wt%, 0.20 wt%, 0.40 wt%, 0.50 wt%, 0.80 wt%, 1.00 wt%, 1.50 wt%, 2.00 wt%, 2.50 wt%, 3.00 wt%, 3.50 wt%, 4.00 wt%, or 4.50 wt%. The content of comonomers in the high molecular weight components with a molecular weight ≥1 million may be 0.10-5.00 wt%, 0.20-4.00 wt%, or 0.30-3.00 wt%, for example... For example, the content of comonomers can be 0.15wt%, 0.20wt%, 0.40wt%, 0.50wt%, 0.80wt%, 1.00wt%, 1.50wt%, 2.00wt%, 2.50wt%, 3.00wt%, 3.50wt%, 4.00wt%, or 4.50wt%. The ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component can be 0.01-1.00, 0.02-0.95, or 0.03-0.90, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.10, 0.20, 0.40, 0.50, 0.60, 0.80, 0.90, or 0.95.

[0052] That is, in some embodiments, the propylene polymer has the following characteristics:

[0053] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer and a propylene copolymer;

[0054] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0055] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0056] (4) The content of comonomers in low molecular weight components with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomers in high molecular weight components with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of low molecular weight components to the comonomer content of high molecular weight components is 0.01-1.00.

[0057] (5) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000.

[0058] According to the propylene polymer provided by the present invention, in some embodiments, the propylene polymer has the following characteristics:

[0059] (1) Contains propylene homopolymer and propylene copolymer as matrix, wherein the total content of propylene homopolymer and propylene copolymer is greater than or equal to 99 wt%;

[0060] (2) The content of comonomers in low molecular weight components with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomers in high molecular weight components with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of low molecular weight components to the comonomer content of high molecular weight components is 0.01-1.00.

[0061] (3) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a.

[0062] Wherein, NIS is the notched impact strength, with units of kJ / m². -2FlexMod is the bending modulus, measured in MPa, with a value range of 800-2500 (e.g., 820, 840, 850, 860, 880, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2100, 2200, 2400). 'a' is a constant with a value range of 7.4690-11.0000 (e.g., 7.5, 7.6, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.8, 9.0, 9.2, 9.4, 9.5, 9.6, 9.8, 9.9, 10.0, 10.2, 10.4, 10.5, 10.6, 10.8).

[0063] In some embodiments, the propylene polymer has the following characteristics:

[0064] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer and a propylene copolymer;

[0065] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0066] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0067] (4) The content of comonomers in low molecular weight components with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomers in high molecular weight components with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of low molecular weight components to the comonomer content of high molecular weight components is 0.01-1.00.

[0068] (5) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000;

[0069] (6) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a.

[0070] Wherein, NIS is the notched impact strength, with units of kJ / m². -2 FlexMod is the bending modulus, measured in MPa, with a value range of 800-2500. a is a constant with a value range of 7.4690-11.0000.

[0071] In this invention, the propylene homopolymer can be understood as a polymer obtained by polymerization reaction using only propylene as the polymerization monomer in the presence of a polymerization catalyst.

[0072] In some embodiments of the propylene polymer provided by the present invention, the propylene copolymer is a polymer obtained by copolymerization of propylene and a comonomer. The comonomer is selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene; preferably selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene.

[0073] In some embodiments, the content of comonomer units in the propylene copolymer is 0.05-25.00 wt% (e.g., 0.06 wt%, 0.1 wt%, 0.15 wt%, 0.20 wt%, 0.30 wt%, 0.40 wt%, 0.50 wt%, 1.00 wt%, 2.00 wt%, 4.00 wt%, 6.00 wt%, 8.00 wt%, 10.00 wt%, 12.00 wt%, 14.00 wt%, 15.00 wt%, 18.00 wt%, 20.00 wt%, 23.00 wt%), preferably 0.05-10.00 wt%, more preferably 0.05-5.00 wt%.

[0074] According to the propylene polymer provided by the present invention, in some embodiments, the propylene polymer has the following characteristics:

[0075] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene copolymer;

[0076] (2) The comonomer content in the low molecular weight component with a molecular weight <1 million is 0.10-8.00 wt%, and the comonomer content in the high molecular weight component with a molecular weight ≥1 million is 0.10-8.00 wt%, and the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component is 1.00-2.30.

[0077] The propylene polymer may contain low molecular weight components with a molecular weight <1 million and high molecular weight components with a molecular weight ≥1 million. The content of comonomers in the low molecular weight components with a molecular weight <1 million may be 0.01-8.00 wt%, 0.02-7.00 wt%, or 0.03-6.00 wt%, for example, 0.01 wt%, 0.05 wt%, 0.10 wt%, 0.20 wt%, 0.40 wt%, 0.50 wt%, 0.80 wt%, 1.00 wt%, 1.50 wt%, 2.00 wt%, 2.50 wt%, 3.00 wt%, 3.50 wt%, 4.00 wt%, 5.00 wt%, 6.00 wt%, or 7.50 wt%. The content of comonomers in the high molecular weight components with a molecular weight ≥1 million may be 0.01-8.00 wt% or 0.02-7.00 wt%. It can also be 0.03-6.00 wt%, for example, 0.01 wt%, 0.05 wt%, 0.10 wt%, 0.20 wt%, 0.40 wt%, 0.50 wt%, 0.80 wt%, 1.00 wt%, 1.50 wt%, 2.00 wt%, 2.50 wt%, 3.00 wt%, 3.50 wt%, 4.00 wt%, 5.00 wt%, 6.00 wt%, 7.50 wt%; the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component can be 1.00-2.30, 1.00-2.00, or 1.00-1.80, for example, 1.10, 1.20, 1.40, 1.50, 1.80, 2.00, 2.10, 2.20.

[0078] That is, in some embodiments, the propylene polymer has the following characteristics:

[0079] (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene copolymer;

[0080] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0081] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0082] (4) The comonomer content in the low molecular weight component with a molecular weight < 1 million is 0.10-8.00 wt%, and the comonomer content in the high molecular weight component with a molecular weight ≥ 1 million is 0.10-8.00 wt%, and the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component is 1.00-2.30.

[0083] (5) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000.

[0084] In some embodiments, the propylene copolymer is a polymer obtained by copolymerizing propylene with a comonomer. The comonomer is selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene, preferably selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene.

[0085] In some embodiments, the content of comonomer units in the propylene copolymer is 0.10-20.00 wt% (e.g., 0.15 wt%, 0.20 wt%, 0.40 wt%, 0.50 wt%, 1.00 wt%, 2.00 wt%, 4.00 wt%, 8.00 wt%, 12.00 wt%, 14.00 wt%, 15.00 wt%, 18.00 wt%), more preferably 0.10-10.00 wt%, and even more preferably 0.10-8.00 wt%.

[0086] According to the propylene polymer provided by the present invention, in some embodiments, the polymer nucleating agent is a polymer generated by a double bond addition reaction of a compound represented by general formula I as a nucleating agent monomer:

[0087] In the formula, R 1 and R 2 Together with the carbon atoms to which they are attached, they form substituted or unsubstituted saturated or unsaturated or aromatic rings or fused rings, wherein the rings or fused rings contain 4 to 20 carbon atoms, preferably R 1 and R 2 Together with the carbon atoms they are attached to, they form saturated or unsaturated or aromatic 5- to 12-membered rings or fused rings, or R... 1 and R 2 Each is independently an alkyl group containing 0 to 4 carbon atoms, or R 1 and R 2 Each is an alkyl group containing 0 to 4 carbon atoms and substituted with silicon atoms.

[0088] The nucleating agent monomer is selected from one or more of vinylcycloalkanes (such as vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane, vinylnorbornene), 3-methyl-1-butene, 3-ethyl-1-hexene, styrene, p-methylstyrene, allyltrimethylsilane, 3-methyl-1-pentene, and 4-methyl-1-pentene, preferably selected from one or more of vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene, styrene, allyltrimethylsilane, 3-methyl-1-pentene, and 4-methyl-1-pentene.

[0089] The polymer nucleating agent can be added to the propylene polymer through blending.

[0090] In some embodiments, the polymer nucleating agent can be generated in situ in a propylene polymerization catalyst during the prepolymerization process using a compound of general formula I as a nucleating agent monomer. This in-situ polymerization to generate the polymer nucleating agent can be carried out in any inert solvent, preferably in mineral oil with a viscosity <100 cSt (40°C); the reaction temperature for in-situ polymerization to generate the polymer nucleating agent is typically 30-110°C (e.g., 40°C, 50°C, 70°C, 80°C, 100°C), preferably 60-95°C; the reaction time is typically 0.2-100 hours (e.g., 1 hour, 2 hours, 4 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 80 hours), preferably 0.5-24 hours.

[0091] In the embodiment employing the in-situ generation of polymer nucleating agents during the pre-polymerization process as described above, the conversion rate of the nucleating agent monomer is >30%, and the in-situ polymerization generates a modified polymerization catalyst (containing the polymer nucleating agent). The mass ratio of the polymer nucleating agent to the initial pre-catalyst (i.e., the pre-catalyst contained in the propylene polymerization catalyst before in-situ polymerization) is typically 0.1-10.0, preferably 0.5-5.0, and more preferably 0.5-3.0. The content of the polymer nucleating agent can be adjusted by the amount of added nucleating agent monomer. After sufficient reaction time, the nucleating agent monomer is converted into the polymer nucleating agent.

[0092] The content of polymer nucleating agent can be obtained by taking a sample, washing away mineral oil and residual catalyst with an acidified ethanol / hexane mixed solvent, drying and weighing.

[0093] In embodiments employing the in-situ generation of polymer nucleating agents during prepolymerization as described above, in certain cases, a chlorinating agent may be used as a terminator to terminate the reaction after prepolymerization; the chlorinating agent is a compound containing an E-Cl bond (E being a metal atom, B, C, Al, or Si), and may be selected from, but not limited to, one or more of (CH3)3SiCl, (CH3)2SiCl2, CH3SiCl3, SiCl4, C2H5AlCl2, and AlCl3.

[0094] The prepolymerization process, as described above, refers to the polymerization reaction carried out prior to propylene polymerization.

[0095] As mentioned above, in-situ generated polymer nucleating agents refer to polymer nucleating agents that are formed and retained in the propylene polymerization catalyst system. In-situ generated polymer nucleating agents can be separated from the solvent for use, or they can be used in subsequent polymerization reactions without separation.

[0096] In a second aspect, a method for preparing a propylene polymer is provided, comprising the following steps:

[0097] (1) The propylene polymerization catalyst is contacted with the nucleating agent monomer and a polymerization reaction is carried out to obtain the modified polymerization catalyst;

[0098] (2) In the presence of hydrogen and the modified polymerization catalyst, propylene is added to carry out a polymerization reaction for 0.1-10 hours (e.g., 0.2 hours, 0.5 hours, 1 hour, 2 hours, 4 hours, 5 hours, 6 hours, 8 hours, 9 hours) with or without the presence of comonomer.

[0099] (3) Add a hydrogenation catalyst to the polymerization system obtained in step (2) and continue the polymerization reaction for 0.1-10 hours (e.g., 0.2 hours, 0.5 hours, 1 hour, 2 hours, 4 hours, 5 hours, 6 hours, 8 hours, 9 hours) with or without the presence of comonomer.

[0100] In some embodiments, the method for preparing the propylene polymer includes the following steps:

[0101] (1) The propylene polymerization catalyst is contacted with the nucleating agent monomer and a polymerization reaction is carried out to obtain the modified polymerization catalyst;

[0102] (2) In the presence of hydrogen and the modified polymerization catalyst, propylene is added to carry out a polymerization reaction for 0.1-10 hours;

[0103] (3) Add hydrogenation catalyst to the polymerization system obtained in step (2) and then continue polymerization for 0.1-10 hours.

[0104] In some embodiments, the method for preparing the propylene polymer includes the following steps:

[0105] (1) The propylene polymerization catalyst is contacted with the nucleating agent monomer and a polymerization reaction is carried out to obtain the modified polymerization catalyst;

[0106] (2) In the presence of hydrogen and the modified polymerization catalyst, propylene is added to carry out a polymerization reaction for 0.1-10 hours, with or without the presence of comonomers.

[0107] (3) Add a hydrogenation catalyst to the polymerization system obtained in step (2) and continue the polymerization reaction for 0.1-10 hours in the presence of the comonomer.

[0108] In some embodiments, the method for preparing the propylene polymer includes the following steps:

[0109] (1) The propylene polymerization catalyst is contacted with the nucleating agent monomer and a polymerization reaction is carried out to obtain the modified polymerization catalyst;

[0110] (2) In the presence of hydrogen and the modified polymerization catalyst, the comonomer is contacted with propylene and subjected to polymerization for 0.1-10 hours;

[0111] (3) Add a hydrogenation catalyst to the polymerization system obtained in step (2) and continue the polymerization reaction for 0.1-10 hours in the presence of the comonomer.

[0112] According to the preparation method provided by the present invention, the polymer nucleating agent in step (1) is generated in situ in a propylene polymerization catalyst during the prepolymerization process by using a compound represented by general formula I as a nucleating agent monomer. The process of generating the polymer nucleating agent by in-situ polymerization can be carried out in any inert solvent, preferably in mineral oil with a viscosity <100 cSt (40°C); the reaction temperature for generating the polymer nucleating agent by in-situ polymerization is typically 30-110°C (e.g., 40°C, 50°C, 70°C, 80°C, 100°C), preferably 60-95°C; the reaction time is typically 0.2-100 hours (e.g., 1 hour, 2 hours, 4 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 80 hours), preferably 0.5-24 hours.

[0113] In some embodiments, the conversion rate of the nucleating agent monomer in step (1) is >30%, and in the in-situ polymerization to generate the modified polymerization catalyst, the mass ratio of the polymer nucleating agent to the initial catalyst (propylene polymerization catalyst) is typically 0.1-10.0 (e.g., 0.5, 1.0, 2.0, 4.0, 5.5, 6.0, 8.0), preferably 0.5-5.0, and more preferably 0.5-3.0. The content of the polymer nucleating agent can be adjusted by the amount of nucleating agent monomer added.

[0114] According to the preparation method provided by the present invention, in some embodiments, in step (1), the propylene polymerization catalyst is selected from Ziegler-Natta catalysts and / or metallocene catalysts.

[0115] In some embodiments, the Ziegler-Natta catalyst comprises a pre-catalyst (solid active component), a co-catalyst i, and an optional external electron donor, wherein:

[0116] The concept of a precatalyst is well known in the industry; it typically includes magnesium, titanium, chlorine, and an internal electron donor. A typical precatalyst can be obtained by reacting a catalyst precursor with titanium tetrachloride in the presence of an internal electron donor.

[0117] The catalyst precursor may be a magnesium chloride / alcohol complex, an alkoxy magnesium, an alkyl magnesium, or a Grignard reagent.

[0118] The internal electron donor is selected from ethyl benzoate, ethyl p-ethoxybenzoate, di-n-butyl phthalate, diisobutyl phthalate, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2-ethyl-2-butyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, and 9,9-di(methoxymethyl) Fluorene, diethyl 2,3-diisopropylsuccinate, di-n-butyl 2,3-diisopropylsuccinate, diisobutyl 2,3-diisopropylsuccinate, di(2-ethylhexyl)citronitrate, dimethyl benzenemethylene malonate, diethyl benzenemethylene malonate, 2,4-pentanediol dibenzoate, 1,3-propanediol dibenzoate, 3-methyl-2,4-pentanediol dibenzoate, 3-methyl-5-tert-butyl-1,2-benzenediol dibenzoate, 4-tert-butyl-1,2-benzenediol dibenzoate Phenolic dibenzoate, 3,6-dimethyl-1,2-benzenediol dibenzoate, 1,8-naphthol dibenzoate, 2,4-pentanediol di(4-methylbenzoic acid) ester, 1,3-propanediol di(4-methylbenzoic acid) ester, 3-methyl-2,4-pentanediol di(4-methylbenzoic acid) ester, 3-methyl-5-tert-butyl-1,2-benzenediol di(4-methylbenzoic acid) ester, 4-tert-butyl-1,2-benzenediol di(4-methylbenzoic acid) ester, 3,6-dimethyl ... One or more of the following: 1,2-benzenediol di(4-methylbenzoic acid) ester, 1,8-naphthol di(4-methylbenzoic acid) ester, 1,2-cyclohexanoic acid diisobutyl ester, 1,2,3,6-tetrahydrophthalic acid diethyl ester, N-(3-benzylcarboxy-1-methylbutyl)benzamide, N-[2-benzylcarboxy-4-tert-butyl-6-methylphenyl]benzamide, and N-[3-(4-butylbenzylcarboxy)-2,2-dimethylpropyl]-4-butylbenzamide. One or more of the following: ester, 1,8-naphthol di(4-methylbenzoic acid) ester, 1,2-cyclohexanoic acid diisobutyl ester, 1,2,3,6-tetrahydrophthalic acid diethyl ester, N-(3-benzylcarboxy-1-methylbutyl)benzamide, N-[2-benzylcarboxy-4-tert-butyl-6-methylphenyl]benzamide, and N-[3-(4-butylbenzylcarboxy)-2,2-dimethylpropyl]-4-butylbenzamide.

[0119] The cocatalyst i can be a hydrocarbon-based aluminum compound, preferably selected from one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trihexylaluminum, and alkylaluminoxanes.

[0120] The external electron donor can be of the general formula R. 3 m R 4 n Si(OR 5) 4-m-n The organosilicon compound shown has the following formula:

[0121] R 3 R 4 Each group is independently selected from C1-C12 straight-chain, branched, or cyclic aliphatic groups, or C3-C12 nitrogen-containing straight-chain, branched, or cyclic organic groups; R 5 Selected from C1-C4 straight-chain or branched aliphatic groups;

[0122] m and n are both natural numbers, and their values ​​satisfy 0 ≤ (m + n) ≤ 2.

[0123] The external electron donor may be, for example, but not limited to, dimethyldimethoxysilane, diphenyldimethoxysilane, methylcyclopentyldimethoxysilane, methylcyclohexyldimethoxysilane, methyl(3,3,3-trifluoropropyl)dimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, di-n-propyldimethoxysilane, di-n-butyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, isopropylisopentyldimethoxysilane, methylcyclopentyldiethoxysilane, methylcyclohexyldiethoxysilane, methyl(3,3,3-trifluoropropyl)diethoxysilane, dicyclopentyldiethoxysilane, dicyclohexyldiethoxysilane, di-n-propyldiethoxysilane, di-n-butyldiethoxysilane, and diisopropyldiethoxysilane. One or more of the following: diisobutyldiethoxysilane, isopropylisopentyldiethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isopentyltrimethoxysilane, cyclopentyltrimethoxysilane, cyclohexyltrimethoxysilane, allyltrimethoxysilane, vinyltrimethoxysilane, diethylaminotrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, isopentyltriethoxysilane, cyclopentyltriethoxysilane, cyclohexyltriethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, diethylaminotriethoxysilane, bis(perhydroisoquinoline)dimethoxysilane, tetramethoxysilane, and tetraethoxysilane.

[0124] Taking the propylene polymerization catalyst selected from Ziegler-Natta catalysts as an example, the ratio of the amount of the pre-catalyst component to the amount of organoaluminum compound can be determined by the Ti / Al molar ratio, for example, it can be 1:2 to 1:400 (e.g., 1:3, 1:4, 1:5, 1:10, 1:50, 1:120, 1:200, 1:300); the amount of the external electron donor component can be conventionally selected in the art, and will not be elaborated here.

[0125] In some embodiments, the metallocene catalyst includes a support, a metallocene coordination compound, and a co-catalyst; wherein:

[0126] The carrier can be selected from particulate silica or layered silicates.

[0127] The metallocene coordination compound can be selected from bridged C2-symmetrical compounds containing a group IV metal and an indenyl group, such as, but not limited to, rac-dimethylsilyl-bis(2-methyl-4-phenylindenyl)zirconia, rac-dimethylsilyl-bis[2-methyl-4-(4'-tert-butylphenyl)indenyl]zirconia, rac-methyl(cyclohexyl)silyl-bis[2-methyl-4-(4'-tert-butylphenyl)indenyl]zirconia, rac-dimethylsilyl-bis(2-methyl-4-carbazoleindenyl)zirconia, rac-dimethylsilyl-bis[2-methyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindenyl] ... Alkyl-bis[2-methyl-4-phenyl-5-methoxy-6-tert-butylindene]zirconium dichloride, rac-dimethylsilyl-bis(2-isopropyl-4-phenylindene)zirconium dichloride, rac-dimethylsilyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indene]zirconium dichloride, rac-methyl(cyclohexyl)silyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indene]zirconium dichloride, rac-dimethylsilyl-bis(2-isopropyl-4-carbazolylindene)zirconium dichloride, rac-dimethylsilyl-bis[2-isopropyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindene]zirconium dichloride, and compounds thereof with alkyl-substituted chlorine.

[0128] The co-catalyst ii can be selected from methylaluminoxane or modified methylaluminoxane.

[0129] In some embodiments, the metallocene catalyst includes an active support and a metallocene coordination compound as described above; wherein the active support refers to silica, aluminosilicate, or layered silicate modified by sulfation, fluorination, or chlorination.

[0130] For example, the metallocene catalyst comprises silica, a metallocene coordination compound, and methylaluminoxane; wherein the metallocene coordination compound is selected from rac-dimethylsilyl-bis(2-methyl-4-phenylindenyl)zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-(4'-tert-butylphenyl)indenyl]zirconia dichloride, rac-methyl(cyclohexyl)silyl-bis[2-methyl-4-(4'-tert-butylphenyl)indenyl]zirconia dichloride, rac-dimethylsilyl-bis(2-methyl-4-carbazoleindenyl)zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindenyl] ... One or more of the following: alkyl-bis[2-methyl-4-phenyl-5-methoxy-6-tert-butylindene]zirconium chloride, rac-dimethylsilyl-bis(2-isopropyl-4-phenylindene)zirconium chloride, rac-dimethylsilyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indene]zirconium chloride, rac-methyl(cyclohexyl)silyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indene]zirconium chloride, rac-dimethylsilyl-bis(2-isopropyl-4-carbazolylindene)zirconium chloride, and rac-dimethylsilyl-bis[2-isopropyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindene]zirconium chloride, as well as compounds thereof with alkyl-substituted chlorine.

[0131] The proportions of each component in the metallocene catalyst can be conventionally chosen in the field and will not be elaborated here.

[0132] According to the preparation method provided by the present invention, in some embodiments, in step (1), the nucleating agent monomer is selected from one or more of vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane, vinylnorbornene, 3-methyl-1-butene, 3-ethyl-1-hexene, styrene, p-methylstyrene, allyltrimethylsilane, 3-methyl-1-pentene, and 4-methyl-1-pentene.

[0133] According to the preparation method provided by the present invention, in some embodiments, in step (2), the amount of hydrogen added is 1:10-100000 by mass ratio of the amount of polymer monomers used, for example, 1:15, 1:20, 1:40, 1:50, 1:80, 1:100, 1:150, 1:200, 1:500, 1:1000, 1:2000, 1:5000, 1:10000, 1:50000, 1:80000.

[0134] In some implementations, in step (2), the ratio of the mass of the added comonomer to the mass of the initial propylene monomer is 1:10-1000, for example, 1:15, 1:20, 1:50, 1:100, 1:200, 1:400, 1:500, 1:800, 1:900.

[0135] In some embodiments, the mass ratio of the polymer nucleating agent contained in the modified polymerization catalyst to the titanium contained in the hydrogenation catalyst can be 0.5-8000, for example 1.0, 2.0, 4.0, 5.0, 8.0, 10, 20, 40, 50, 100, 200, 500, 1000, 2000, 3000, 4000, 4500, 5000, 6000, 7000.

[0136] Ultra-high molecular weight components with a molecular weight M ≥ 10 million are produced after adding a highly efficient hydrogenation catalyst during the propylene polymerization process.

[0137] Typically, the concentration of comonomers in the polymerization reactor is increased during or after the addition of a hydrogenation catalyst to obtain ultra-high molecular weight components with a high content of comonomer units.

[0138] The step of adding a highly efficient hydrogenation catalyst can be carried out in the same reactor as the step without the hydrogenation catalyst, or it can be carried out in another reactor through a system isolated from outside air, where the material to be polymerized is introduced. Alternatively, it can be carried out in any container or pipeline containing propylene monomer that is isolated from outside air. For example, the hydrogenation catalyst can be added outside a single reactor or in the outlet pipeline outside multiple reactors in series, using the outlet pipeline as an additional polymerization reaction site. This allows the feed stream containing polypropylene and other components discharged from the reactor in the first polymerization stage to contact the hydrogenation catalyst, followed by catalyst deactivation and degassing to obtain the propylene polymer product.

[0139] The hydrogenation catalyst can be added continuously or in a pulse.

[0140] In some embodiments, in step (3), the hydrogenation catalyst is a mixture of an organometallic compound of general formula R(R')-MX(X') and an alkylaluminum;

[0141] In this general formula, R and R' are each independently an alkyl group (such as methyl, ethyl, propyl, butyl, cycloalkyl, etc.), or an unsaturated hydrocarbon group (such as cyclopentadienyl, indenyl, fluorenyl, etc.), or a heteroatom-substituted unsaturated hydrocarbon group (analogous to which the carbon atom of the unsaturated hydrocarbon group is replaced by a heteroatom), preferably cyclopentadienyl and its derivatives, heteroatom-substituted cyclopentadienyl and its derivatives; M is a transition metal element (such as Fe, Ti, Cr, Mn, etc.); X and X' are each independently a halogen atom, alkyl or alkoxy group.

[0142] In some embodiments, the molar ratio of the organometallic compound (based on metal element) to the alkylaluminum (based on aluminum) in the mixture is 1:3 to 1:10 (e.g., 1:4, 1:6, 1:7, 1:9), preferably 1:5 to 1:8.

[0143] According to the preparation method provided by the present invention, the molar ratio of the hydrogenation catalyst to hydrogen in the system is 1:1000 to 1:1000000 (e.g., 1:1500, 1:2000, 1:4000, 1:5000, 1:10000, 1:20000, 1:50000, 1:80000, 1:100000, 1:200000, 1:500000, 1:80000), preferably 1:10000 to 1:1000000. The amount of hydrogen here can be understood as the initial amount of hydrogen or the amount of hydrogen in the system before the addition of the hydrogenation catalyst; during the polymerization process, the consumption of hydrogen is negligible when no hydrogenation catalyst is used.

[0144] According to the preparation method provided by the present invention, in some embodiments, the process conditions of the polymerization reaction in step (1) include: a reaction temperature of 30-110℃ (e.g., 50℃, 60℃, 80℃, 100℃, 105℃) and a reaction time of 0.1-48.0 hours (e.g., 0.5 hours, 1 hour, 2 hours, 5 hours, 10 hours, 12 hours, 18 hours, 24 hours, 30 hours, 36 hours, 42 hours).

[0145] In some embodiments, the polymerization reaction in step (2) is carried out at a temperature of 40-120°C (e.g., 50°C, 60°C, 80°C, 100°C, 110°C).

[0146] In some embodiments, the polymerization reaction in step (3) is carried out at a temperature of 40-120°C (e.g., 50°C, 60°C, 80°C, 100°C, 110°C).

[0147] In some implementations, in step (3), the ratio of the mass of the added comonomer to the mass of the initial propylene monomer is 1:10-1000, for example, 1:15, 1:20, 1:50, 1:100, 1:200, 1:400, 1:500, 1:800, 1:900.

[0148] According to the preparation method provided by the present invention, in some embodiments, the obtained propylene polymer comprises a propylene homopolymer with a content ≥99wt% as a matrix, and a polymer nucleating agent with a mass content of 1-1000ppm. The matrix of the propylene polymer contains 0.1wt%-10.0wt% of an ultra-high molecular weight component with a molecular weight M ≥10 million. The M of the propylene polymer... z+1 ≥6000×10 3 And M z+1 / M n ≥100.

[0149] According to the preparation method provided by the present invention, in some embodiments, a propylene polymer having the following characteristics can be obtained:

[0150] (1) Contains propylene homopolymer and propylene copolymer as matrix, wherein the total content of propylene homopolymer and propylene copolymer is greater than or equal to 99 wt%;

[0151] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0152] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M≥10 million;

[0153] (4) The content of comonomers in low molecular weight components with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomers in high molecular weight components with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of low molecular weight components to the comonomer content of high molecular weight components is 0.01-1.00.

[0154] (5) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And M z+1 / M n Greater than or equal to 100.

[0155] In some embodiments, the preparation method provided by this invention can obtain a propylene polymer with the following characteristics:

[0156] (1) Contains a propylene copolymer as a matrix, the content of which is greater than or equal to 99 wt%;

[0157] (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm;

[0158] (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million;

[0159] (4) The comonomer content in the low molecular weight component with a molecular weight < 1 million is 0.10-8.00 wt%, and the comonomer content in the high molecular weight component with a molecular weight greater than or equal to 1 million is 0.10-8.00 wt%, and the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component is 1.00-2.30.

[0160] (5) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And M z+1 / M n Greater than or equal to 100.

[0161] In a third aspect, a polypropylene composition is provided, comprising, based on a total weight of 100 wt% of the composition:

[0162] 80.0-99.9 wt% (e.g., 82 wt%, 84 wt%, 85 wt%, 86 wt%, 90 wt%, 95 wt%, 98 wt%) of the propylene polymer as described above or the propylene polymer prepared by the method described above, and

[0163] Additives in the range of 0.1-20.0 wt% (e.g., 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 14 wt%, 15 wt%, 18 wt%).

[0164] The additives are selected from one or more of the following: additives, fillers, and reinforcing agents.

[0165] In some embodiments, the additive is selected from one or more of antioxidants, deacidifiers, antistatic agents, flame retardants, light stabilizers, nucleating agents, and colorants.

[0166] In some embodiments, the filler is selected from one or more of mica, calcium carbonate, talc, and wollastonite.

[0167] In some embodiments, the reinforcing agent is selected from short glass fibers, long glass fibers, carbon fibers, steel fibers, and cellulose fibers.

[0168] In existing methods for preparing propylene polymers, the proportion of components with a molecular weight exceeding 10 million generated through hydrogen-free polymerization is typically less than 0.1 wt%, which limits the performance improvement of the final polyolefin material. The inventors unexpectedly discovered that the propylene polymer with the features of this invention can possess both processability and mechanical properties, and in terms of mechanical properties, it achieves a significant improvement in both rigidity and toughness, while simultaneously enhancing the transparency of the material.

[0169] In addition, the preparation method also overcomes the limitation of the preparation method using a dual reactor, which makes it difficult to obtain products with low content of ultra-high molecular weight components.

[0170] Compared with the prior art, the beneficial effects of the technical solution of the present invention are at least as follows:

[0171] (1) The obtained propylene polymer can simultaneously improve processing performance and mechanical properties. At the same time, it also improves modulus and impact strength in terms of mechanical properties. Under the premise that the rigidity of the propylene polymer is not significantly reduced, its impact toughness is significantly improved, achieving an excellent balance between rigidity and toughness.

[0172] (2) The obtained propylene polymer also has good transparency. Attached Figure Description

[0173] Figure 1 shows a schematic diagram of the molecular weight distribution of the products obtained in Example L1 and Comparative Example L1;

[0174] Figure 2 shows a schematic diagram of the molecular weight distribution of the products obtained in Examples L2-L6 and Comparative Example L2;

[0175] Figure 3 shows a schematic diagram comparing the stiffness-toughness balance properties of the products obtained in Examples L1-L6 and Comparative Examples L1-L2 with several commercially available finished materials.

[0176] Figure 4 shows a schematic diagram comparing the unnotched impact properties of the products obtained in Examples L1-L6 and Comparative Examples L1-L2 with several commercially available finished materials.

[0177] In Figures 3 and 4, the commercially available finished materials are a series of propylene homopolymer commercial products with different melt flow rates (MFR = 1.8-70 g / 10 min), including the following grades: PP 1024, T98D, F401, LHP456J, T30S, PPH-MS12, PPH-MN15, PPH-MM20, LHP565S, LHA801U, PPH-M70, and 8 batches of S1003 powder and granules from the State Energy Group.

[0178] In Figure 3, the horizontal axis (flexmod) represents the flexural modulus, and the vertical axis (NIS) represents the notched impact strength; the solid circles in the figure represent various commercially available finished materials, the solid squares represent comparative examples, and the hollow circles represent specific examples.

[0179] In Figure 4, the horizontal axis represents the fitting equation for the unnotched impact strength of commercially available finished materials (with flexural modulus and melt flow index MFR as variables), and the vertical axis (UNIS) represents the unnotched impact strength; the solid circles in the figure represent various commercially available finished materials, the solid squares represent comparative examples, and the hollow circles represent examples.

[0180] Figure 5 shows the molecular weight distribution and short branch content distribution of the products obtained in Examples M1-M4 and Comparative Example M1 as a function of molecular weight.

[0181] Figure 6 shows a schematic diagram comparing the stiffness-toughness balance properties of the products obtained in Examples M1-M4, Comparative Example M1, and several commercially available finished materials.

[0182] In Figure 5, the vertical axis on the right represents the number of short branches per thousand carbon atoms.

[0183] In Figure 6, the commercially available finished materials are a series of propylene homopolymer commercial products with different melt flow rates (MFR = 1.8-70 g / 10 min), including the following grades: PP 1024, T98D, F401, LHP456J, T30S, PPH-MS12, PPH-MN15, PPH-MM20, LHP565S, LHA801U, PPH-M70, and 8 batches of S1003 powder and granules produced by the State Energy Group.

[0184] In Figure 6, the horizontal axis (flexmod) represents the flexural modulus, and the vertical axis (NIS) represents the notched impact strength; the solid circles in the figure represent various commercially available finished materials, the solid squares represent comparative examples, and the hollow circles represent specific examples.

[0185] Figure 7 shows a schematic diagram of the molecular weight distribution and short branch content of the products obtained in each embodiment and comparative example N1 as a function of molecular weight.

[0186] In Figure 7, the vertical axis on the right represents the number of short branches per thousand carbon atoms. Detailed Implementation

[0187] To provide a detailed understanding of the technical features and content of this invention, preferred embodiments will be described in more detail below. While preferred embodiments are described in the examples, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply.

[0188] In the following examples and comparative examples, the sources of some reagents or raw materials used, unless otherwise specified, are all conventional products that can be purchased commercially.

[0189] <Source of Raw Materials>

[0190] Pre-catalyst A is a Ziegler-Natta catalyst with phthalate as the internal electron donor, prepared according to patent document CN101054424A. The titanium content in pre-catalyst A is 2.9 wt%.

[0191] Triisobutylaluminum (1.0M hexane solution), purchased from Bailingwei.

[0192] Triethylaluminum (1.0M hexane solution), purchased from Bailingwei.

[0193] Di(cyclopentadienyl)titanium dichloride, purchased from Sigma-Aldrich.

[0194] Dicyclopentyldimethoxysilane (97 wt%), purchased from ABCR.

[0195] Vinylcyclohexane (97 wt%) was purchased from Sigma-Aldrich.

[0196] n-Heptane (99 wt%, ultra-dry), purchased from Bailingwei.

[0197] Drakeol 35 mineral oil, purchased from Calumet-Penreco.

[0198] Silicon tetrachloride, purchased from Inokai.

[0199] <Testing Methods>

[0200] Polymer molecular weight and molecular weight distribution:

[0201] A PolymerChar GPC-IR6 high-temperature gel permeation chromatography (HT-GPC) system, equipped with a Wyatt 8-angle laser light scattering detector and a PolymerChar four-bridge capillary viscometer, was used. 1,2,4-trichlorobenzene (TCB, chromatographic grade) was used as the solvent, with 3% (wt%) of antioxidant (BHT) added. The flow rate was 1.0 mL / min, the injection volume was 200 μL, and one PLgel Olexis Guard (50 × 7.5 mm) and three PLgel Olexis columns (300 × 7.5 mm) were used. The sample concentration ranged from 1.0 to 2.0 mg / mL. Under nitrogen protection, the sample dissolution temperature was 160 °C, the dissolution time was 180 min, and the detector temperature was 150 °C. The internal standard (flow marker) was a 3% (v%) mixture of n-hexane and TCB. Data processing was performed using PolymerChar GPC One software. The plate count (including the pre-column and three analytical columns) measured using n-hexane was no less than 15,000. Third-order polynomial fitting was performed on the column using polystyrene standards (PS, a mixed red-yellow-blue-green standard). An IR-6 concentration detector was used to calculate the molecular weight distribution. The molecular weight of polypropylene was obtained from the molecular weight of polystyrene (PS) using the following Mark-Houwink coefficient: K PP =1.901×10 -4 ; ɑ PP=0.725; K PS =1.016×10 -4 ; ɑ PS =0.722.

[0202] Based on GPC data, this paper defines the following: low molecular weight components refer to components with a molecular weight M less than 1 million (i.e., logM less than 6), high molecular weight components refer to components with a molecular weight M greater than or equal to 1 million (i.e., logM ≥ 6), and ultra-high molecular weight components refer to components with a molecular weight M greater than or equal to 10 million (i.e., logM ≥ 7).

[0203] The content of ultra-high molecular weight components was calculated from GPC data using the following Equation 1:

[0204] In the formula, A UH y represents the mass content of ultra-high molecular weight components with a molecular weight greater than or equal to 10 million, and y is the mass distribution density of the component with a molecular weight of logM = x. In GPC data, x and y are represented as the x-axis and y-axis data of the mass distribution data, respectively. logM is the commonly used logarithm of molecular weight, and the integral sign means that the value is integraled in a trapezoidal shape.

[0205] Melt flow index test: The melt flow index of the sample was measured using CEAST's MF30 according to the GB / T 3682-2018 test standard.

[0206] Flexural modulus test: The flexural modulus was measured using an Instron 9650 universal testing machine at a rate of 2 mm min⁻¹ according to the GB / T9341-2008 test standard.

[0207] Impact strength test: The cantilever beam impact test was performed on the test samples using the CEAST 9050 pendulum impact testing machine according to the GB / T 1843-2008 test standard, including notched test and unnotched test.

[0208] Transmittance and haze testing: The haze / transmittance tester of 1 mm thick standard test piece was used to test the sample according to the test standard GB / T 2410-2008.

[0209] Ethylene content in components with a molecular weight greater than or equal to 1 million (high molecular weight components):

[0210] First, the average number of methyl groups per thousand carbons (SCB) of this component was calculated using the GPC test results through the following Equation 2. h :

[0211] In the formula, SCBh SCB is the number of short branches per thousand carbon atoms for components with a molecular weight greater than or equal to 1 million. x It represents the number of methyl groups per thousand carbons corresponding to the component with logM = x. The integral sign indicates that the numerical value is integrally represented by a trapezoidal shape.

[0212] Then, the ethylene mass percentage of this component can be calculated using Equation 3:

[0213] In the formula, w h It represents the percentage of ethylene by mass in components with a molecular weight greater than or equal to 1 million.

[0214] The ethylene content in components with a molecular weight of less than 1 million (low molecular weight components) is calculated in a similar way to the ethylene content in high molecular weight components, except that the integration interval in Equation 2 is changed from UL to 6 to LL to 6.

[0215] The above UL and LL represent the upper and lower limits of the logM data corresponding to the 1,000 methyl group data, respectively. These two values ​​are determined by the threshold of 10% set when the GPC data is exported in this paper.

[0216] Example 1 of hydrogenation catalyst preparation:

[0217] Take 249.0 mg (1.0 mmol) of bis(cyclopentadienyl)titanium chloride, then add 6.0 mL of triethylaluminum (1.0 M hexane solution) to dissolve it. Then dilute the resulting solution (i.e., the molar ratio of bis(cyclopentadienyl)titanium chloride to triethylaluminum in the solution is 1:6) to 200 mL (concentration is 5.0 mM) to obtain hydrogenation catalyst-1, which is ready for use.

[0218] Example 2 of hydrogenation catalyst preparation:

[0219] Take 249.0 mg (1.0 mmol) of bis(cyclopentadienyl)titanium chloride, then add 2.0 mL of triethylaluminum (1.0 M hexane solution) and mix. Then add dry hexane to dilute to 200 mL to obtain hydrogenation catalyst-2. In this case, bis(cyclopentadienyl)titanium chloride cannot be completely dissolved and cannot form a homogeneous mixed solution, making it difficult to accurately measure and use.

[0220] Example L1

[0221] The preparation process of propylene polymers includes the following steps:

[0222] (1) In-situ generation of polymer nucleating agents:

[0223] A mixed solution of 0.96 mL of triisobutylaluminum (1.0 M hexane solution) and 0.96 mL of dicyclopentyldimethoxysilane (0.2 M n-heptane solution) was injected into 15 mL of mineral oil slurry (33 mg / mL) containing pre-catalyst A, followed by the injection of 2.0 g of vinylcyclohexane. After reacting at 75 °C for 1 h, 0.11 mL of silicon tetrachloride was injected into the system to obtain a modified polymerization catalyst (containing a polymer nucleating agent), wherein the mass ratio of the polymer nucleating agent to pre-catalyst A was 1.43.

[0224] The modified polymerization catalyst was prepared into a catalyst slurry using mineral oil and shaken well for later use; the concentration of the slurry (based on the original catalyst A) was 10 mg / mL.

[0225] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0226] 1.1 kg of liquid propylene was added to a 5 L stainless steel reactor, 0.23 mol of hydrogen gas was introduced, and the temperature was raised to 70 °C; a freshly prepared triethylaluminum / dicyclopentyldimethoxysilane (Al / Si = 5.0) mixed solution was added to the stainless steel reactor.

[0227] Subsequently, 1.0 mL of the catalyst slurry obtained in step (1) was mixed with 10 mL of fresh refined n-hexane and transferred to a feeding tank to prepare a catalyst slurry for later use; then, the catalyst slurry prepared in the feeding tank was injected into a stainless steel reactor (Al / Ti = 300) with high-pressure hexane to initiate a polymerization reaction, which lasted for 1 hour.

[0228] (3) The reaction continues to polymerize:

[0229] Subsequently, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and the reaction continued for 1 hour.

[0230] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product. The mass content of the polymer nucleating agent was measured to be 39 ppm. The obtained product was tested, and the results are shown in Table 1.

[0231] Comparative Example L1

[0232] The preparation process of propylene polymers includes the following steps:

[0233] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L1;

[0234] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L1;

[0235] (3) Continued polymerization reaction: Refer to Example L1, except that no hydrogenation catalyst was added to the system obtained in step (2), and polymerization continued for 1 hour.

[0236] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 40 ppm. The obtained product was tested, and the results are shown in Table 1.

[0237] Example L2

[0238] The preparation process of propylene polymers includes the following steps:

[0239] (1) In-situ generation of polymer nucleating agents:

[0240] A mixed solution of 0.96 mL of triisobutylaluminum (1.0 M hexane solution) and 0.96 mL of dicyclopentyldimethoxysilane (0.2 M n-heptane solution) was injected into 15 mL of mineral oil slurry (33 mg / mL) containing pre-catalyst A. Then, 2.0 g of vinylcyclohexane was injected. After reacting at 60 °C for 1 h, 0.48 mL of silicon tetrachloride in 2.0 M n-heptane solution was injected into the system to obtain a modified polymerization catalyst (containing a polymer nucleating agent), wherein the mass ratio of the polymer nucleating agent to pre-catalyst A was 1.79.

[0241] The modified polymerization catalyst was prepared into a catalyst slurry using mineral oil and shaken well for later use; the concentration of the slurry (based on the original catalyst A) was 10 mg / mL.

[0242] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0243] 1.1 kg of liquid propylene was added to a 5 L stainless steel reactor, 0.23 mol of hydrogen gas was introduced, and the temperature was raised to 70 °C; a freshly prepared triethylaluminum / dicyclopentyldimethoxysilane (Al / Si = 5.0) mixed solution was added to the stainless steel reactor.

[0244] Subsequently, 1.0 mL of the catalyst slurry obtained in step (1) was mixed with 10 mL of fresh refined n-hexane and transferred to a feeding tank to prepare a catalyst slurry for later use; then, the catalyst slurry prepared in the feeding tank was injected into a stainless steel reactor (Al / Ti = 300) with high-pressure hexane to initiate a polymerization reaction, which lasted for 1 hour.

[0245] (3) The reaction continues to polymerize:

[0246] Subsequently, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and the reaction continued for 0.5 h.

[0247] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 42 ppm. The obtained product was tested, and the results are shown in Table 2.

[0248] Example L3

[0249] The preparation process of propylene polymers includes the following steps:

[0250] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L2;

[0251] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L1;

[0252] (3) Continued polymerization reaction: Refer to Example L1, except that after adding 4.5 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction continued for 0.75 h.

[0253] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 41 ppm. The obtained product was tested, and the results are shown in Table 2.

[0254] Example L4

[0255] The preparation process of propylene polymers includes the following steps:

[0256] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L2;

[0257] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L1;

[0258] (3) Continued polymerization reaction: Refer to Example L1, except that after adding 1.0 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction was continued for 1 h.

[0259] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 41 ppm. The obtained product was tested, and the results are shown in Table 2.

[0260] Example L5

[0261] The preparation process of propylene polymers includes the following steps:

[0262] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L2;

[0263] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L1;

[0264] (3) Continued polymerization reaction: Refer to Example L1, except that after adding 10.0 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction was continued for 1 h.

[0265] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 36 ppm. The obtained product was tested, and the results are shown in Table 2.

[0266] Example L6

[0267] The preparation process of propylene polymers includes the following steps:

[0268] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L2;

[0269] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L1;

[0270] (3) Continued polymerization reaction: Refer to Example L1, except that after adding 4.5 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction was continued for 2 h.

[0271] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 38 ppm. The results of the tests are shown in Table 2.

[0272] Comparative Example L2

[0273] The preparation process of propylene polymers includes the following steps:

[0274] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L2;

[0275] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L2;

[0276] (3) Continued polymerization reaction: Refer to Example L2, except that no hydrogenation catalyst was added to the system obtained in step (2), and polymerization continued for 1 hour.

[0277] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 45 ppm. The obtained product was tested, and the results are shown in Table 2.

[0278] Comparative Example L3

[0279] The preparation process of propylene polymers includes the following steps:

[0280] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example L1;

[0281] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example L1;

[0282] (3) Continued polymerization reaction: Refer to Example L1, except that hydrogenation catalyst-2 was added to the system obtained in step (2). During the experiment, it was found that the prepared hydrogenation catalyst-2 solution could not completely dissolve bis(cyclopentadienyl)titanium chloride, and the solution could not be used in the polymerization reaction of this step.

[0283] Table 1. Experimental conditions and performance tests of the obtained polymers.

[0284] In Table 1, A UH The content of ultra-high molecular weight components with a molecular weight M ≥ 10 million. The increase in notched impact strength, the increase in unnotched impact strength, and the decrease in haze are all relative to comparative example L1.

[0285] Table 2 Experimental conditions and performance tests of the obtained polymers

[0286] In Table 2, A UH The content of ultra-high molecular weight components with a molecular weight M ≥ 10 million. The increase in notched impact strength, the increase in unnotched impact strength, and the decrease in haze are all relative to the comparative example 2L.

[0287] As can be seen from the results in Tables 1 and 2, compared with Comparative Example L1, the product obtained in Example L1 showed significant improvements in notched impact strength, unnotched impact strength, and flexural modulus, while its haze was reduced; similarly, compared with Comparative Example L2, the products obtained in Examples L2-L6 showed significant improvements in notched impact strength, unnotched impact strength, and flexural modulus, while their haze was reduced.

[0288] As shown in Figures 1 and 2, the polypropylene obtained in each embodiment exhibits a significant enhancement in the high molecular weight fraction, which occurs during the polymerization stage following the addition of the hydrogenation catalyst. Figures 3 and 4 show that the notched and unnotched impact strengths of the polypropylene obtained in each embodiment are significantly higher than those of the commercially available finished product and the comparative example, demonstrating the effectiveness of the present invention in improving the impact strength of polypropylene.

[0289] As can be seen, by adding a small amount of hydrogenation catalyst to the product stream obtained in the first polymerization stage, the present invention can quickly remove hydrogen from the system, allowing propylene monomer to continue to polymerize and generate a small amount of ultra-high molecular weight component with a molecular weight M ≥ 10 million; and by adjusting the polymerization reaction time and the amount of hydrogenation catalyst in the reaction site of the material in the second polymerization stage, the amount of ultra-high molecular weight polypropylene component generated can be flexibly controlled and kept within a low content range (e.g., 0.1-10 wt%), which can avoid the negative impact of excessive ultra-high molecular weight component content on the processability of the material, while significantly improving the mechanical properties of polypropylene products.

[0290] Example M1

[0291] The preparation process of propylene polymers includes the following steps:

[0292] (1) In-situ generation of polymer nucleating agents:

[0293] A mixed solution of 0.96 mL of triisobutylaluminum (1.0 M hexane solution) and 0.96 mL of dicyclopentyldimethoxysilane (0.2 M n-heptane solution) was injected into 15 mL of mineral oil slurry (33 mg / mL) containing pre-catalyst A, followed by the injection of 2.0 g of vinylcyclohexane. After reacting at 75 °C for 1.25 hours, 0.11 mL of silicon tetrachloride was injected into the system to obtain a modified polymerization catalyst (containing a polymer nucleating agent), wherein the mass ratio of the polymer nucleating agent to pre-catalyst A was 1.71.

[0294] The modified polymerization catalyst was prepared into a catalyst slurry using mineral oil and shaken well for later use; the concentration of the slurry (based on the original catalyst A) was 10 mg / mL.

[0295] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0296] 1.1 kg of liquid propylene was added to a 5 L stainless steel reactor, 0.23 mol of hydrogen gas was introduced, and the temperature was raised to 70 °C; a freshly prepared triethylaluminum / dicyclopentyldimethoxysilane (Al / Si = 5.0) mixed solution was added to the stainless steel reactor.

[0297] Subsequently, 1.0 mL of the catalyst slurry obtained in step (1) was mixed with 10 mL of fresh refined n-hexane and transferred to a feeding tank to prepare a catalyst slurry for later use; then, the catalyst slurry prepared in the feeding tank was injected into a stainless steel reactor (Al / Ti = 300) with high-pressure hexane to initiate a polymerization reaction, which lasted for 1 hour.

[0298] (3) The reaction continues to polymerize:

[0299] Subsequently, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and after 6 min, 7.0 g of ethylene was added to the reactor at a rate of 500 g / h, and the reaction continued for 1 h.

[0300] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 52 ppm. The obtained product was tested, and the results are shown in Table 3.

[0301] Example M2

[0302] The preparation process of propylene polymers includes the following steps:

[0303] (1) In-situ generation of polymer nucleating agents:

[0304] A mixture of 0.96 mL of triisobutylaluminum (1.0 M hexane solution) and 0.96 mL of dicyclopentyldimethoxysilane (0.2 M n-heptane solution) was injected into 15 mL of mineral oil slurry (33 mg / mL) containing pre-catalyst A, followed by the injection of 2.0 g of vinylcyclohexane. After reacting at 60 °C for 24 hours, 0.48 mL of silicon tetrachloride in 2.0 M n-heptane solution was injected into the system to obtain a modified polymerization catalyst (containing a polymer nucleating agent), wherein the mass ratio of the polymer nucleating agent to pre-catalyst A was 2.44.

[0305] The modified polymerization catalyst was prepared into a catalyst slurry using mineral oil and shaken well for later use; the concentration of the slurry (based on the original catalyst) was 10 mg / mL.

[0306] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0307] 1.1 kg of liquid propylene was added to a 5 L stainless steel reactor, 0.23 mol of hydrogen gas was introduced, and the temperature was raised to 70 °C; a freshly prepared triethylaluminum / dicyclopentyldimethoxysilane (Al / Si = 5.0) mixed solution was added to the stainless steel reactor.

[0308] Subsequently, 1.0 mL of the catalyst slurry obtained in step (1) was mixed with 10 mL of fresh refined n-hexane and transferred to a feeding tank to prepare a catalyst slurry for later use; then, the catalyst slurry prepared in the feeding tank was injected into a stainless steel reactor (Al / Ti = 300) with high-pressure hexane to initiate a polymerization reaction, which lasted for 1 hour.

[0309] (3) The reaction continues to polymerize:

[0310] Subsequently, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and after 6 min, 7.0 g of ethylene was added to the reactor at a rate of 500 g / h, and the reaction continued for 2 h.

[0311] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 63 ppm. The obtained product was tested, and the results are shown in Table 3.

[0312] Example M3

[0313] The preparation process of propylene polymers includes the following steps:

[0314] (1) In-situ generation of polymer nucleating agent: Same as in Example M2;

[0315] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system: the same as in Example M2;

[0316] (3) Continued polymerization reaction: Refer to Example M2, except that 1.0 mL of hydrogenation catalyst-1 was added, and after 6 min, 7.0 g of ethylene was added to the reactor at a rate of 500 g / h and the polymerization reaction continued for 1 h.

[0317] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 70 ppm. The obtained product was tested, and the results are shown in Table 3.

[0318] Example M4

[0319] The preparation process of propylene polymers includes the following steps:

[0320] (1) In-situ generation of polymer nucleating agent: Same as in Example M2;

[0321] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system: the same as in Example M2;

[0322] (3) Continued polymerization reaction: Refer to Example M2, except that 10.0 mL of hydrogenation catalyst-1 was added, and after 6 min, 7.0 g of ethylene was added to the reactor at a rate of 500 g / h and the polymerization reaction continued for 1 h.

[0323] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 60 ppm. The obtained product was tested, and the results are shown in Table 3.

[0324] Comparative Example M1

[0325] The preparation process of propylene polymers includes the following steps:

[0326] (1) In-situ generation of polymer nucleating agent: Same as in Example M2;

[0327] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system: the same as in Example M2;

[0328] (3) Continued polymerization reaction: Refer to Example M2, except that no hydrogenation catalyst or ethylene was added to the polymerization system obtained in step (2), and polymerization continued for 1 hour.

[0329] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 70 ppm. The obtained product was tested, and the results are shown in Table 3.

[0330] Comparative example M2

[0331] The preparation process of propylene polymers includes the following steps:

[0332] (1) In-situ generation of polymer nucleating agent: Same as in Example M1;

[0333] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system: the same as in Example M1;

[0334] (3) Continued polymerization reaction: Refer to Example M1, except that hydrogenation catalyst-2 is added; During the experiment, it was found that the titanium di(cyclopentadienyl)dichloride in hydrogenation catalyst-2 could not be completely dissolved, and the solution could not be used in the polymerization reaction.

[0335] Table 3 Experimental conditions and product performance tests

[0336] *NB indicates that the test specimen did not break during the unnotched impact test.

[0337] **W l It refers to the mass percentage of copolymer monomers in components with a molecular weight of less than 1 million.

[0338] ***W h It is the mass percentage of copolymer monomers in components with a molecular weight greater than or equal to 1 million.

[0339] A UH This refers to the content of ultra-high molecular weight components with a molecular weight M ≥ 10 million.

[0340] As can be seen from the results in Table 3, compared with Comparative Example M1, the products obtained in Examples M1-M4 have significantly improved in terms of notched impact strength and unnotched impact strength, and the haze has also decreased significantly, while the flexural modulus has decreased slightly, achieving an excellent balance between stiffness and toughness.

[0341] In Comparative Example M2, the molar ratio of bis(cyclopentadienyl)titanium chloride to triethylaluminum in hydrogenation catalyst-2 is less than 1:3, and the bis(cyclopentadienyl)titanium chloride cannot be completely dissolved. Therefore, this hydrogenation catalyst solution cannot be used for polymerization reaction.

[0342] As can be seen from Figure 5, the polypropylene obtained in each embodiment is significantly enhanced in the high molecular weight portion, and the number of short branches per thousand carbon atoms is reduced. This component is generated in the polymerization stage after the addition of the hydrogenation catalyst, indicating that the component generated in this stage is a high molecular weight copolymer. As can be seen from Figure 6, the notched impact strength of the polypropylene obtained in each embodiment is significantly higher than that of the commercially available finished product and the comparative example, indicating the improvement effect of the technical solution of the present invention on the notched impact strength of polypropylene.

[0343] As can be seen, by adding a small amount of hydrogenation catalyst to the product stream obtained in the first polymerization stage, the present invention can quickly remove hydrogen from the system, allowing propylene monomer to continue polymerizing to generate a small amount of ultra-high molecular weight component with a molecular weight M ≥ 10 million; and by adding the hydrogenation catalyst simultaneously or afterward, the concentration of comonomer in the polymerization reactor can be increased to obtain an ultra-high molecular weight component with a high content of comonomer units; furthermore, by controlling the amount of hydrogenation catalyst and the reaction time of the second polymerization stage, the molecular weight (so that M reaches 10 million or above) and the content of the ultra-high molecular weight component can be controlled; the final product achieves an excellent balance of rigidity and toughness while maintaining good transparency.

[0344] Example N1

[0345] The preparation process of propylene polymers includes the following steps:

[0346] (1) In-situ generation of polymer nucleating agents:

[0347] A mixture of 0.96 mL of triisobutylaluminum (1.0 M hexane solution) and 0.96 mL of dicyclopentyldimethoxysilane (0.2 M n-heptane solution) was injected into 15 mL of mineral oil slurry (33 mg / mL) containing pre-catalyst A, followed by the injection of 2.0 g of vinylcyclohexane. After reacting at 75 °C for 1 hour, 0.11 mL of silicon tetrachloride was injected to obtain a modified polymerization catalyst (containing a polymer nucleating agent), wherein the mass ratio of the polymer nucleating agent to pre-catalyst A was 1.43.

[0348] The modified polymerization catalyst was prepared into a catalyst slurry using mineral oil and shaken well for later use; the concentration of the slurry (based on the original catalyst A) was 10 mg / mL.

[0349] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0350] 1.1 kg of liquid propylene was added to a 5 L stainless steel reactor, 0.23 mol of hydrogen gas was introduced, 7.0 g of ethylene was added, and the temperature was raised to 70 °C; a freshly prepared triethylaluminum / dicyclopentyldimethoxysilane (Al / Si = 5.0) mixed solution was added to the stainless steel reactor.

[0351] Subsequently, 1.0 mL of the catalyst slurry obtained in step (1) was mixed with 10 mL of freshly refined n-hexane and transferred to a feeding tank to prepare a catalyst slurry for later use; then, the catalyst slurry prepared in the feeding tank was injected into a stainless steel reactor (Al / Ti = 300) with high-pressure hexane to initiate the polymerization reaction. During the polymerization reaction, ethylene was continuously added at a rate of 15 g / h and reacted for 1 h.

[0352] (3) The reaction continues to polymerize:

[0353] Then, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and the reaction continued for 1 hour with the addition of ethylene.

[0354] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 24 ppm. The obtained product was tested, and the results are shown in Table 4.

[0355] Example N2

[0356] The preparation process of propylene polymers includes the following steps:

[0357] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example N1;

[0358] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example N1;

[0359] (3) Continued polymerization reaction: Refer to Example N1, except that after adding 4.5 mL of hydrogenation catalyst-1 to the system obtained in step (2), the ethylene pathway is closed (i.e., the addition of ethylene is stopped, and a certain amount of ethylene still exists in the system), and polymerization continues for 1 h.

[0360] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 59 ppm. The obtained product was tested, and the results are shown in Table 4.

[0361] Example N3

[0362] The preparation process of propylene polymers includes the following steps:

[0363] (1) In-situ generation of polymer nucleating agents:

[0364] A mixture of 0.96 mL of triisobutylaluminum (1.0 M hexane solution) and 0.96 mL of dicyclopentyldimethoxysilane (0.2 M n-heptane solution) was injected into 15 mL of mineral oil slurry (33 mg / mL) containing pre-catalyst A, followed by the injection of 2.0 g of vinylcyclohexane. After reacting at 60 °C for 24 hours, 0.11 mL of silicon tetrachloride was injected to obtain a modified polymerization catalyst (containing a polymer nucleating agent), wherein the mass ratio of the polymer nucleating agent to pre-catalyst A was 2.44.

[0365] The modified polymerization catalyst was prepared into a catalyst slurry using mineral oil and shaken well for later use; the concentration of the slurry (based on the original catalyst A) was 10 mg / mL.

[0366] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0367] 1.1 kg of liquid propylene was added to a 5 L stainless steel reactor, 0.23 mol of hydrogen gas was introduced, 7.0 g of ethylene was added, and the temperature was raised to 70 °C; a freshly prepared triethylaluminum / dicyclopentyldimethoxysilane (Al / Si = 5.0) mixed solution was added to the stainless steel reactor.

[0368] Subsequently, 1.0 mL of the catalyst slurry obtained in step (1) was mixed with 10 mL of freshly refined n-hexane and transferred to a feeding tank to prepare a catalyst slurry for later use; then, the catalyst slurry prepared in the feeding tank was injected into a stainless steel reactor (Al / Ti = 300) with high-pressure hexane to initiate the polymerization reaction. During the polymerization reaction, ethylene was continuously added at a rate of 15 g / h and reacted for 1 h.

[0369] (3) The reaction continues to polymerize:

[0370] Then, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and the reaction continued for 0.25 h with the addition of ethylene.

[0371] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 70 ppm. The obtained product was tested, and the results are shown in Table 4.

[0372] Example N4

[0373] The preparation process of propylene polymers includes the following steps:

[0374] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example N3;

[0375] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example N3;

[0376] (3) Continued polymerization reaction: Refer to Example N3, except that after adding 4.5 mL of hydrogenation catalyst-1 to the system obtained in step (2), polymerization continued for 0.5 h.

[0377] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 66 ppm. The obtained product was tested, and the results are shown in Table 4.

[0378] Comparative Example N1

[0379] The preparation process of propylene polymers includes the following steps:

[0380] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example N3;

[0381] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example N3;

[0382] (3) Continued polymerization reaction: Refer to Example N3, except that no hydrogenation catalyst was added to the system obtained in step (2), and polymerization continued for 1 hour.

[0383] After the reaction was complete, the material in the reactor was discharged into a receiving tank to obtain propylene polymer product, in which the mass content of polymer nucleating agent was 79 ppm. The obtained product was tested, and the results are shown in Table 4.

[0384] Comparative Example N2

[0385] The propylene polymer is propylene copolymer B4801 (MFR = 1.5 g / 10 min) produced by the National Energy Group.

[0386] Comparative Example N3

[0387] The preparation process of propylene polymers includes the following steps:

[0388] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example N3;

[0389] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example N3;

[0390] (3) Continued polymerization reaction: Refer to Example N3, except that hydrogenation catalyst-2 is added to the system obtained in step (2); During the experiment, it was found that the di(cyclopentadienyl)titanium chloride in hydrogenation catalyst-2 could not be completely dissolved, and the hydrogenation catalyst-2 solution could not be used in the polymerization reaction.

[0391] Table 4 Experimental conditions and performance tests of the obtained products

[0392] *W l It is the mass percentage of comonomers in components with a molecular weight of less than 1 million.

[0393] **W h It is the mass percentage of comonomers in components with a molecular weight greater than or equal to 1 million.

[0394] A UH This refers to the content of ultra-high molecular weight components with a molecular weight M ≥ 10 million.

[0395] As can be seen from the results in Table 4, the content of ultra-high molecular weight components in the products prepared in each embodiment is greater than 0.1 wt%, the content of comonomers of components with molecular weight less than 1 million is closer to that of components with molecular weight greater than or equal to 1 million, and the tensile strength of propylene polymers is significantly improved while maintaining good transparency and toughness.

[0396] In Comparative Example N1, because no hydrogenation catalyst was added in the second polymerization stage, the content of ultra-high molecular weight components in the polymer was less than 0.1 wt%, and the M of the propylene polymer was... z+1 Below 6000×10 3 And M z+1 / M n The content of comonomers in components with a molecular weight less than 100 (below 1 million) differs significantly from that in components with a molecular weight greater than or equal to 1 million, resulting in a lower strength of the final propylene polymer. The polypropylene product provided in Comparative Example N2 also lacks the characteristics of the propylene polymer obtained in this invention, and its tensile strength is also low. In Comparative Example N3, the molar ratio of bis(cyclopentadienyl)dichloride to triethylaluminum in hydrogenation catalyst-2 is less than 1:3, meaning that bis(cyclopentadienyl)dichloride cannot be completely dissolved, thus this hydrogenation catalyst solution cannot be used for the polymerization reaction.

[0397] As can be seen from Figure 7, the polypropylene obtained in each embodiment is significantly enhanced in the high molecular weight portion, and the number of short branches per thousand carbon atoms is reduced. This component is generated in the polymerization stage after the addition of the hydrogenation catalyst, indicating that the component generated in this stage is a high molecular weight copolymer.

[0398] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the spirit of the invention.

Claims

1. A propylene polymer directly obtained from a polymerization reactor, characterized in that, The propylene polymer has the following characteristics: (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​selected from propylene homopolymer, propylene copolymer or propylene homopolymer and propylene copolymer; (2) Contains a polymer nucleating agent, the mass content of which is 1-1000 ppm; (3) The matrix contains 0.1wt%-10.0wt% of ultra-high molecular weight components with a molecular weight M greater than or equal to 10 million; (4) M of the propylene polymer z+1 Greater than or equal to 6000 × 10 3 And less than or equal to 100000 × 10 3 And M z+1 / M n Greater than or equal to 100 and less than or equal to 1000.

2. The propylene polymer according to claim 1, characterized in that, The propylene polymer has the following characteristics: (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer; (2) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a. Wherein, NIS is the notched impact strength, with units of kJ / m². -2 FlexMod is the bending modulus, measured in MPa, with a value range of 800-2500. a is a constant with a value range of 7.4690-9.0000.

3. The propylene polymer according to claim 1, characterized in that, The propylene polymer has the following characteristics: (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene homopolymer; (2) The unnotched impact strength UNIS of the propylene polymer is 1 / (-0.009425+1.1850×10⁻⁶). -5 ×FlexMod+0.003876×ln(MFR))+b, UNIS is the unnotched impact strength, measured in kJ / m³. -2 FlexMod is the flexural modulus, measured in MPa, with a value ranging from 800 to 2500. ln represents the natural logarithm, and MFR is the melt flow index, measured in g / 10min. -1 b is a constant with a value range of 30-110.

4. The propylene polymer according to claim 1, characterized in that, The propylene polymer has the following characteristics: (1) Contains a matrix, wherein the matrix is ​​a propylene homopolymer and a propylene copolymer; the total content of the propylene homopolymer and the propylene copolymer as the matrix is ​​greater than or equal to 99 wt%; (2) In the propylene polymer, the content of comonomer in the low molecular weight component with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomer in the high molecular weight component with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component is 0.01-1.

00.

5. The propylene polymer according to claim 1, characterized in that, The propylene polymer has the following characteristics: (1) Contains propylene homopolymer and propylene copolymer as matrix, wherein the total content of propylene homopolymer and propylene copolymer is greater than or equal to 99 wt%; (2) The content of comonomers in low molecular weight components with a molecular weight <1 million is 0.05-5.00 wt%, and the content of comonomers in high molecular weight components with a molecular weight ≥1 million is 0.10-5.00 wt%; and the ratio of the comonomer content of low molecular weight components to the comonomer content of high molecular weight components is 0.01-1.

00. (3) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a. Wherein, NIS is the notched impact strength, with units of kJ / m². -2 FlexMod is the bending modulus, measured in MPa, with a value range of 800-2500. a is a constant with a value range of 7.4690-11.0000.

6. The propylene polymer according to claim 4 or 5, characterized in that, The propylene copolymer is a polymer obtained by copolymerization of propylene and comonomer; The comonomer is selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene; preferably selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. The content of comonomer units in the propylene copolymer is 0.05-25.00 wt%, preferably 0.05-10.00 wt%, and more preferably 0.05-5.00 wt%.

7. The propylene polymer according to claim 1, characterized in that, The propylene polymer has the following characteristics: (1) Contains a matrix, the content of which is greater than or equal to 99 wt%; the matrix is ​​a propylene copolymer; (2) The comonomer content in the low molecular weight component with a molecular weight < 1 million is 0.10-8.00 wt%, and the comonomer content in the high molecular weight component with a molecular weight ≥ 1 million is 0.10-8.00 wt%, and the ratio of the comonomer content of the low molecular weight component to the comonomer content of the high molecular weight component is 1.00-2.30; Preferably, the propylene copolymer is a polymer obtained by copolymerizing propylene with a comonomer; Preferably, the comonomer is selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene, and more preferably from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene; Preferably, the content of comonomer units in the propylene copolymer is 0.10-20.00 wt%, more preferably 0.10-10.00 wt%, and even more preferably 0.10-8.00 wt%.

8. The propylene polymer according to any one of claims 1-7, characterized in that, The polymer nucleating agent is a polymer generated by a double bond addition reaction of a compound represented by the following general formula I as a nucleating agent monomer: In the formula, R 1 and R 2 Together with the carbon atoms to which they are attached, they form substituted or unsubstituted saturated or unsaturated or aromatic rings or fused rings, wherein the rings or fused rings contain 4 to 20 carbon atoms, preferably R 1 and R 2 Together with the carbon atoms they are attached to, they form saturated or unsaturated or aromatic 5- to 12-membered rings or fused rings, or R... 1 and R 2 Each is independently an alkyl group containing 0 to 4 carbon atoms, or R 1 and R 2 Each is an alkyl group containing 0 to 4 carbon atoms and substituted with silicon atoms.

9. The propylene polymer according to claim 8, characterized in that, The nucleating agent monomer is selected from one or more of vinylcycloalkanes, 3-methyl-1-butene, 3-ethyl-1-hexene, styrene, p-methylstyrene, allyltrimethylsilane, 3-methyl-1-pentene, and 4-methyl-1-pentene.

10. A method for preparing a propylene polymer, characterized in that, Includes the following steps: (1) The propylene polymerization catalyst is contacted with the nucleating agent monomer and a polymerization reaction is carried out to obtain the modified polymerization catalyst; (2) In the presence of hydrogen and the modified polymerization catalyst, propylene is added to carry out a polymerization reaction for 0.1-10 hours, with or without the presence of comonomers. (3) Add a hydrogenation catalyst to the polymerization system obtained in step (2) and continue the polymerization reaction for 0.1-10 hours with or without the presence of comonomer.

11. The preparation method according to claim 10, characterized in that, In step (1), the propylene polymerization catalyst is selected from Ziegler-Natta catalysts and / or metallocene catalysts; In step (3), the hydrogenation catalyst is a mixture of organometallic compounds of the general formula R(R')-MX(X') and alkylaluminum; In this general formula, R and R' are each independently an alkyl group, or an unsaturated hydrocarbon group, or a heteroatom-substituted unsaturated hydrocarbon group, preferably cyclopentadienyl and its derivatives, heteroatom-substituted cyclopentadienyl and its derivatives; M is a transition metal element; X and X' are each independently a halogen atom, an alkyl group, or an alkoxy group; In the mixture, the molar ratio of organometallic compound (calculated as metal element) to alkylaluminum (calculated as aluminum) is 1:3 to 1:10, preferably 1:5 to 1:

8.

12. The preparation method according to claim 10, characterized in that, The molar ratio of the hydrogenation catalyst to hydrogen in the system is 1:1000 to 1:1000000, preferably 1:10000 to 1:1000000.

13. The preparation method according to claim 10, characterized in that, The process conditions for the polymerization reaction in step (1) include: a reaction temperature of 30-110℃ and a reaction time of 0.1-48.0 hours; The polymerization reaction in step (2) is carried out at a temperature of 40-120℃; The polymerization reaction in step (3) is carried out at a temperature of 40-120℃.

14. A polypropylene composition, characterized in that, Based on a total weight of 100 wt%, the composition comprises: 80.0-99.9 wt% of the propylene polymer as described in any one of claims 1-9 or the propylene polymer prepared by the method as described in any one of claims 10-13, and 0.1-20.0 wt% of additives; The additive is selected from one or more of additives, fillers, and reinforcing agents; Preferably, the additive is selected from one or more of antioxidants, deacidifying agents, antistatic agents, flame retardants, light stabilizers, nucleating agents, and colorants; Preferably, the filler is selected from one or more of mica, calcium carbonate, talc, and wollastonite; Preferably, the reinforcing agent is selected from short glass fibers, long glass fibers, carbon fibers, steel fibers, and cellulose fibers.

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