Propylene polymer, preparation method thereof and polypropylene composition

Abstract

The invention belongs to the technical field of polypropylene preparation, and particularly relates to a propylene polymer, a preparation method thereof and a polypropylene composition. The propylene polymer is characterized in that the propylene polymer comprises a propylene homopolymer as a matrix, and the content of the propylene homopolymer is greater than or equal to 99 wt%; the composition comprises a polymer nucleating agent, and the mass content of the polymer nucleating agent is 1-1000 ppm; the matrix comprises 0.1 wt%-10.0 wt% of ultra-high molecular weight components with the molecular weight M greater than or equal to 10,000,000; m < z + 1 > of the propylene polymer is greater than or equal to 6000 * 10 < 3 >, and M < z + 1 > / Mn is greater than or equal to 100. The propylene polymer provided by the invention has both processability and mechanical properties, and the rigidity and toughness of the mechanical properties are remarkably improved at the same time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polypropylene preparation, and particularly relates to a propylene polymer, a preparation method thereof, and a polypropylene composition. BACKGROUND

[0002] Polypropylene is a semi-crystalline polymer with high crystallinity, and its thermal, mechanical and optical properties are closely related to its crystallization performance. Nucleating agents are usually used to change the crystallization behavior of polypropylene to obtain higher crystallization temperature, higher rigidity and / or higher transparency. Inorganic salts, organic acid salts, sorbitol acetal, aromatic amides, polymers and other compounds can be used as nucleating agents for polypropylene.

[0003] Currently, the commonly used traditional method is to physically blend the nucleating agent with the polyolefin obtained after polymerization. There are also cases of using in-situ polymerization of nucleating agent monomers to obtain a polymerization catalyst containing a polymer nucleating agent, and then carrying out propylene polymerization to obtain polypropylene containing a nucleating agent.

[0004] If the molecular weight distribution of the polyolefin product presents a bimodal shape, it can have better mechanical properties while retaining good processing properties. This is well known in the industry. Generally, bimodal polypropylene is produced in two series-connected polymerization reactors with different hydrogen concentrations. For example, the Nordic Chemical patent document EP3945112A1 describes synthesizing polypropylene with a molecular weight distribution coefficient of 6.0-20.0 by arranging different hydrogen concentrations in series-connected reactors; in this process, the method of in-situ polymerization of polymer nucleating agents can be used to add nucleating agents to polypropylene. However, the specific distribution of the molecular weight of the polymer product and the influence of these factors on the improvement of product performance are not disclosed and studied in this patent.

[0005] According to the content disclosed in the patent document US6350828B1 of Grand Polymer Co Ltd, by using a two-stage polymerization process (using double reactors), polypropylene with very wide molecular weight distribution can be obtained; in the first stage of polymerization, no hydrogen is added, and a component with an intrinsic viscosity [η] = 8-13 dL g -1 (135℃ in decalin) is obtained, and its corresponding molecular weight range is 1.75-3.42 million, calculated according to the parameters provided by TH.G.Scholte et al. in Journal of Applied Polymer Science 1984, 29, 3763-3782.

[0006] However, when using two reactors to produce polyolefins, the load ratio of the two reactors needs to be maintained within a certain range, usually one of the reactors cannot have a load less than 20% of the total load, if the load ratio is followed, and the components produced in the subsequent reactor are all ultra-high molecular weight components, which will seriously affect the processability of the product.

[0007] In addition, it is an alternative to generate a certain amount of ultra-high molecular weight components in situ during the polymerization of polyolefins to improve the strength of the polymer. According to the disclosure of the patent document US9068030B2 of Sinopec, the components with a molecular weight > 5 million accounted for about 1.86% under hydrogen-free polymerization, the M z The highest is only 282.9 x 10 4 , M z+1 is only 511.0 x 10 4 The performance of the final product is limited.

[0008] Therefore, how to prepare polyolefins with good processability, significantly improved rigidity and toughness while simplifying the process is a direction worth studying. SUMMARY

[0009] The purpose of the present application is to provide a propylene polymer, a preparation method thereof and a polypropylene composition in view of some technical problems existing in the propylene polymerization process. The obtained propylene polymer has both processability and mechanical properties, and the rigidity and toughness are significantly improved at the same time, and at the same time the transparency of the propylene polymer is excellent.

[0010] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0011] In a first aspect, a propylene polymer directly prepared by a polymerization reactor is provided, the propylene polymer has the following characteristics:

[0012] (1) contains a propylene homopolymer as a matrix, the content of which is greater than or equal to 99wt%;

[0013] (2) contains a polymer nucleating agent, the mass content of which is 1-1000ppm;

[0014] (3) the matrix contains 0.1wt%-10.0wt% of an ultra-high molecular weight component with a molecular weight M greater than or equal to 10 million;

[0015] (4) the M z+1 of the propylene polymer is greater than or equal to 6000 x 10 3 and less than or equal to 100000 x 10 3 , and the Mz+1 / M n Greater than or equal to 100 and less than or equal to 1000.

[0016] The content of propylene homopolymer as the matrix in the propylene polymer 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%.

[0017] 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.

[0018] 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%.

[0019] 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 6200×103 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 n It 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, etc.

[0020] 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.

[0021] 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:

[0022]

[0023] 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.

[0024] In some embodiments, the nucleating agent monomer is selected from one or more of vinylcycloalkane (such as vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane or 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.

[0025] In some embodiments, the polymer nucleating agent can be added to the propylene polymer by blending.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The prepolymerization process, as described above, refers to the polymerization reaction carried out prior to propylene polymerization.

[0031] 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.

[0032] In a second aspect, a propylene polymer is provided that is directly obtained from a polymerization reactor, the propylene polymer having the following characteristics:

[0033] (1) Contains a propylene homopolymer as a matrix, the content of which is greater than or equal to 99 wt%;

[0034] (2) The notched impact strength NIS of the propylene polymer is -0.0017 × FlexMod + a.

[0035] 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.

[0036] In a third aspect, a propylene polymer is provided that is directly obtained from a polymerization reactor, the propylene polymer having the following characteristics:

[0037] (1) Contains a propylene homopolymer as a matrix, the content of which is greater than or equal to 99 wt%;

[0038] (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,

[0039] 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.

[0040] In a fourth aspect, a method for preparing a propylene polymer is provided, comprising the following steps:

[0041] (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;

[0042] (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);

[0043] (3) Add a hydrogenation catalyst to the polymerization system obtained in step (2) and then continue polymerization 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).

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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:

[0048] 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.

[0049] The catalyst precursor may be a magnesium chloride / alcohol complex, an alkoxy magnesium, an alkyl magnesium, or a Grignard reagent.

[0050] 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.

[0051] 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.

[0052] 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:

[0053] 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;

[0054] m and n are both natural numbers, and their values ​​satisfy 0 ≤ (m + n) ≤ 2.

[0055] 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. The following are some 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.

[0056] Taking Ziegler-Natta catalyst as an example, the ratio of the amount of the pre-catalyst component to the amount of organoaluminum compound can be expressed 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.

[0057] In some embodiments, the metallocene catalyst includes a support, a metallocene coordination compound, and a co-catalyst; wherein:

[0058] The carrier can be selected from particulate silica or layered silicates.

[0059] 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-carbazolylindenyl)zirconia, rac-dimethylsilyl-bis[2-methyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindenyl]zirconia, rac-dimethylsilyl-bis[2-methyl-4-phenyl-5-methoxy-6-dimethylsilyl]zirconia, etc. One or more of the following: rac-dimethylsilyl-bis(2-isopropyl-4-phenylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-methyl(cyclohexyl)silyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-dimethylsilyl-bis(2-isopropyl-4-carbazolylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindyl]zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-phenyl-5-methoxy-6-tert-butylindyl]zirconia, and compounds thereof with alkyl-substituted chlorine.

[0060] The co-catalyst ii can be selected from methylaluminoxane or modified methylaluminoxane.

[0061] 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.

[0062] 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-phenylindene)zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-(4'-tert-butylphenyl)indene]zirconia dichloride, rac-methyl(cyclohexyl)silyl-bis[2-methyl-4-(4'-tert-butylphenyl)indene]zirconia dichloride, rac-dimethylsilyl-bis(2-methyl-4-carbazoleindene)zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindene]zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-phenyl-5-methoxy-6-methoxyindene]zirconia dichloride, and rac-dimethylsilyl-bis[2-methyl-4-phenyl-5-methoxy-6-methoxyindene]. One or more of the following: rac-dimethylsilyl-bis(2-isopropyl-4-phenylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-methyl(cyclohexyl)silyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-dimethylsilyl-bis(2-isopropyl-4-carbazolylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindyl]zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-phenyl-5-methoxy-6-tert-butylindyl]zirconia, and compounds thereof with alkyl-substituted chlorine.

[0063] The proportions of each component in the metallocene catalyst can be conventionally chosen in the field and will not be elaborated here.

[0064] 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.

[0065] According to the preparation method provided by the present invention, in some embodiments, in step (2), the mass ratio of the amount of hydrogen added to the amount of polymer monomer is 1:10-100000, for example, 1:15, 1:20, 1:50, 1:80, 1:100, 1:150, 1:200, 1:500, 1:1000, 1:2000, 1:4000, 1:5000, 1:10000, 1:50000, 1:80000.

[0066] 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.

[0067] Ultra-high molecular weight components with a molecular weight M ≥ 10 million are produced by adding a hydrogenation catalyst during the propylene polymerization process.

[0068] 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.

[0069] The hydrogenation catalyst can be added continuously or in a pulse.

[0070] In some embodiments, the hydrogenation catalyst is a mixture of an organometallic compound of the general formula R(R')-MX(X') and an alkylaluminum;

[0071] 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, indene, 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.

[0072] In some embodiments, the molar ratio of the organometallic compound (based on metal element) to 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.

[0073] In some embodiments, 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, 1:800000), 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 polymerization, the consumption of hydrogen is negligible when no hydrogenation catalyst is used.

[0074] In some embodiments, the process conditions for the polymerization reaction in step (1) include: a reaction temperature of 30-110°C (e.g., 50°C, 60°C, 80°C, 100°C) 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, 20 hours, 24 hours, 30 hours, 40 hours).

[0075] 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).

[0076] 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).

[0077] According to the preparation method provided by the present invention, 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.

[0078] In a fifth aspect, a polypropylene composition is provided, comprising, based on a total weight of 100 wt% of the composition:

[0079] 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

[0080] 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%).

[0081] The additives are selected from one or more of the following: additives, fillers, and reinforcing agents.

[0082] In some embodiments of the polypropylene composition provided by the present invention, the additive is selected from one or more of antioxidants, acid removers, antistatic agents, flame retardants, light stabilizers, nucleating agents, and colorants.

[0083] In some embodiments of the polypropylene composition provided by the present invention, the filler is selected from one or more of mica, calcium carbonate, talc, and wollastonite.

[0084] In some embodiments of the polypropylene composition provided by the present invention, the reinforcing agent is selected from short glass fibers, long glass fibers, carbon fibers, steel fibers, and cellulose fibers.

[0085] 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 present invention features (e.g., a matrix containing 0.1 wt%-10.0 wt% of ultra-high molecular weight components with a molecular weight M ≥ 10 million; and an average molecular weight of the propylene polymer satisfying 6000 × 10⁻⁶)... 3 ≤M z+1 ≤100000×10 3 And 100≤(M) z+1 / M n Propylene polymers with a strength of ≤1000 can combine both processability and mechanical properties. Moreover, in terms of mechanical properties, they achieve a significant improvement in both rigidity and toughness, while also enhancing the transparency of the material.

[0086] 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.

[0087] Compared with the prior art, the beneficial effects of the technical solution of the present invention are at least as follows:

[0088] (1) The obtained propylene polymer can simultaneously improve processing performance and mechanical properties. In terms of mechanical properties, the modulus and impact strength (especially unnotched impact strength) are significantly improved.

[0089] (2) The obtained propylene polymer also has good transparency. Attached Figure Description

[0090] Figure 1 A schematic diagram of the molecular weight distribution of the products obtained in Example 1 and Comparative Example 1 is shown.

[0091] Figure 2 A schematic diagram of the molecular weight distribution of the products obtained in Examples 2-6 and Comparative Example 2 is shown.

[0092] Figure 3 A schematic diagram comparing the stiffness-toughness balance properties of the products obtained in Examples 1-6 and Comparative Examples 1-2 with those of several commercially available finished materials is shown.

[0093] Figure 4 A schematic diagram showing the comparison of unnotched impact properties of the products obtained in Examples 1-6 and Comparative Examples 1-2 with several commercially available finished materials is presented.

[0094] Figure 3 and Figure 4 The commercially available finished materials consist of a series of homopolymer propylene 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.

[0095] Figure 3 In the figure, the horizontal axis (flexmod) represents the flexural modulus, and the vertical axis (NIS) represents the notched impact strength; the blue solid dots in the figure represent various commercially available finished materials, the red solid dots represent comparative examples, and the hollow dots represent examples.

[0096] Figure 4 In the figure, 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 blue solid dots in the figure represent various commercially available finished materials, the red solid dots represent comparative examples, and the hollow dots represent examples. Detailed Implementation

[0097] 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.

[0098] <Source of Raw Materials>

[0099] 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%.

[0100] Triisobutylaluminum (1.0M hexane solution), purchased from Bailingwei.

[0101] Triethylaluminum (1.0M hexane solution), purchased from Bailingwei.

[0102] Di(cyclopentadienyl)titanium dichloride, purchased from Sigma-Aldrich.

[0103] Dicyclopentyldimethoxysilane (97 wt%), purchased from ABCR.

[0104] Vinylcyclohexane (97 wt%) was purchased from Sigma-Aldrich.

[0105] n-Heptane (99 wt%, ultra-dry), purchased from Bailingwei.

[0106] Drakeol 35 mineral oil, purchased from Calumet-Penreco.

[0107] Silicon tetrachloride, purchased from Inokai.

[0108] <Testing Methods>

[0109] Polymer molecular weight and molecular weight distribution:

[0110] 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 PLgelOlexis Guard (50 × 7.5 mm) and three PLgelOlexis 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. A third-order polynomial was fitted to 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 coefficients:

[0111] K PP =1.901X10 -4 ;

[0112] a PP =0.725;

[0113] K PS =1.016 x 10 -4 ;

[0114] a PS =0.722.

[0115] Based on GPC data, this paper defines components with a molecular weight M ≥ 10 million as ultra-high molecular weight components. The content of ultra-high molecular weight components with a molecular weight M ≥ 10 million is calculated from the GPC data using the following Equation 1:

[0116]

[0117] In the formula, A UHy 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.

[0118] 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.

[0119] Flexural modulus test: An Instron 9650 universal testing machine was used, according to the GB / T9341-2008 test standard, at a minimum bending modulus of 2 mm / min. -1 The rate was measured on the sample to be tested.

[0120] Impact strength test: The cantilever beam impact test was performed on the test samples according to the GB / T1843-2008 test standard using a CEAST 9050 pendulum impact testing machine, including notched test and unnotched test.

[0121] 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.

[0122] <Example>

[0123] Example 1 of hydrogenation catalyst preparation:

[0124] 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.

[0125] Example 2 of hydrogenation catalyst preparation:

[0126] 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.

[0127] Example 1

[0128] The preparation process of propylene polymers includes the following steps:

[0129] (1) In-situ generation of polymer nucleating agents:

[0130] 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.

[0131] 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.

[0132] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0133] 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.

[0134] 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.

[0135] (3) The reaction continues to polymerize:

[0136] Subsequently, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and the reaction continued for 1 hour.

[0137] 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.

[0138] Comparative Example 1

[0139] The preparation process of propylene polymers includes the following steps:

[0140] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 1;

[0141] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 1;

[0142] (3) Continued polymerization reaction: Refer to Example 1, except that no hydrogenation catalyst was added to the system obtained in step (2), and polymerization continued for 1 hour.

[0143] 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.

[0144] Example 2

[0145] The preparation process of propylene polymers includes the following steps:

[0146] (1) In-situ generation of polymer nucleating agents:

[0147] 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.

[0148] 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.

[0149] (2) The modified polymerization catalyst obtained above was used in the propylene polymerization reaction system:

[0150] 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.

[0151] 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.

[0152] (3) The reaction continues to polymerize:

[0153] Subsequently, 4.5 mL of hydrogenation catalyst-1 was added to the stainless steel reactor, and the reaction continued for 0.5 h.

[0154] 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.

[0155] Example 3

[0156] The preparation process of propylene polymers includes the following steps:

[0157] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 2;

[0158] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 1;

[0159] (3) Continued polymerization reaction: Refer to Example 1, except that after adding 4.5 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction continued for 0.75 h.

[0160] 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.

[0161] Example 4

[0162] The preparation process of propylene polymers includes the following steps:

[0163] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 2;

[0164] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 1;

[0165] (3) Continued polymerization reaction: Refer to Example 1, except that after adding 1.0 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction was continued for 1 h.

[0166] 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.

[0167] Example 5

[0168] The preparation process of propylene polymers includes the following steps:

[0169] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 2;

[0170] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 1;

[0171] (3) Continued polymerization reaction: Refer to Example 1, except that after adding 10.0 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction was continued for 1 h.

[0172] 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.

[0173] Example 6

[0174] The preparation process of propylene polymers includes the following steps:

[0175] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 2;

[0176] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 1;

[0177] (3) Continued polymerization reaction: Refer to Example 1, except that after adding 4.5 mL of hydrogenation catalyst-1 to the stainless steel reactor, the polymerization reaction was continued for 2 h.

[0178] 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.

[0179] Comparative Example 2

[0180] The preparation process of propylene polymers includes the following steps:

[0181] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 2;

[0182] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 2;

[0183] (3) Continued polymerization reaction: Refer to Example 2, except that no hydrogenation catalyst was added to the system obtained in step (2), and polymerization continued for 1 hour.

[0184] 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.

[0185] Comparative Example 3

[0186] The preparation process of propylene polymers includes the following steps:

[0187] (1) In-situ generation of polymer nucleating agent: This step is the same as in Example 1;

[0188] (2) The modified polymerization catalyst obtained above is used in the propylene polymerization reaction system: This step is the same as in Example 1;

[0189] (3) Continued polymerization reaction: Refer to Example 1, 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.

[0190] Table 1. Experimental conditions and performance tests of the obtained polymers.

[0191]

[0192] 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 1.

[0193] Table 2 Experimental conditions and performance tests of the obtained polymers

[0194]

[0195]

[0196] 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 Comparative Example 2.

[0197] As can be seen from the results in Tables 1 and 2, compared with Comparative Example 1, the product obtained in Example 1 showed significant improvements in notched impact strength, unnotched impact strength, and flexural modulus, while its haze was reduced; similarly, compared with Comparative Example 2, the products obtained in Examples 2-6 showed significant improvements in notched impact strength, unnotched impact strength, and flexural modulus, while their haze was reduced.

[0198] from Figures 1-2 It can be seen that the polypropylene obtained in each embodiment is significantly enhanced in the high molecular weight fraction, which is due to the polymerization stage after the addition of the hydrogenation catalyst. From Figures 3-4 It can be seen that the notched impact strength and unnotched impact strength of the polypropylene obtained in each embodiment are significantly higher than those of commercially available finished materials and comparative examples, indicating the improvement effect of the technical solution of the present invention on the impact strength of polypropylene.

[0199] 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.

[0200] 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 propylene homopolymer as a matrix, the content of which is greater than or equal to 99 wt%; (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 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.

3. The propylene polymer according to claim 2, 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.

4. A propylene polymer directly obtained from a polymerization reactor, characterized in that, The propylene polymer has the following characteristics: (1) Contains a propylene homopolymer as a matrix, the content of which is greater than or equal to 99 wt%; (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.

5. A propylene polymer directly obtained from a polymerization reactor, characterized in that, The propylene polymer has the following characteristics: (1) Contains a propylene homopolymer as a matrix, the content of which is greater than or equal to 99 wt%; (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.

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

7. The preparation method according to claim 6, characterized in that, In step (1), the propylene polymerization catalyst is selected from Ziegler-Natta catalysts and / or metallocene catalysts.

8. The preparation method according to claim 6, characterized in that, 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.

9. The preparation method according to claim 6, 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.

10. The preparation method according to claim 6, 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℃.

11. 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 1-5 or the propylene polymer prepared by the method as described in any one of claims 6-10, and 0.1-20.0 wt% of additives; The additives are selected from one or more of the following: additives, fillers, and reinforcing agents.

12. The polypropylene composition according to claim 11, characterized in that, The additives are selected from one or more of antioxidants, deacidifiers, antistatic agents, flame retardants, light stabilizers, nucleating agents, and colorants; The filler is selected from one or more of mica, calcium carbonate, talc, and wollastonite; The reinforcing agent is selected from short glass fibers, long glass fibers, carbon fibers, steel fibers, and cellulose fibers.

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