Catalyst for olefin polymerization process, and propylene polymer and production method therefor

Abstract

The present invention belongs to the technical field of propylene polymerization, and in particular relates to a catalyst for olefin polymerization, and a propylene polymer containing an ultrahigh-molecular-weight polypropylene component and having an adjustable isotacticity and a production method therefor. The method comprises: in the presence of hydrogen and a polymerization catalyst, reacting propylene or reacting propylene with one or more optional comonomers; and in the presence of a mixture DH of a hydrogenation catalyst and an external electron donor, continuing to polymerize at least part of the resulting material stream, which contains a polypropylene component I, in a pipeline located outside a reactor or in a subsequent reactor connected thereto in series for 0.05-3.0 h, thereby obtaining a propylene polymer product containing 0.03-15.0 wt% of an ultrahigh-molecular-weight polypropylene component, wherein the molar ratio of the hydrogenation catalyst to the total amount of hydrogen is 1 / 10000 to 1 / 100. In the present invention, a polypropylene product containing a relatively low content of an ultrahigh-molecular-weight component is prepared, and the isotacticity of the ultrahigh-molecular-weight polypropylene component can be flexibly adjusted.

Description

Catalyst for olefin polymerization process, propylene polymer and production method thereof Technical Field

[0001] The present invention belongs to the technical field of propylene polymerization, and in particular relates to a catalyst for olefin polymerization process, a propylene polymer containing an ultra-high molecular weight polypropylene component and with adjustable isotacticity, and a production method thereof. Background Art

[0002] Generally speaking, homopolymer polypropylene has a linear, semi-crystalline molecular chain structure, and common polypropylene has a relatively low molecular weight (approximately several hundred thousand), with its softening point very close to its melting point. Beyond the melting point, its melt strength drops rapidly, leading to uneven container wall thickness during thermoforming, edge curling and shrinkage during extrusion coating and calendering, and cell collapse during extrusion foaming. This makes it difficult to produce large products and high-speed molding, limiting the application of polypropylene.

[0003] The properties of polypropylene are directly related to its overall molecular weight, molecular weight distribution width, molecular chain tacticity, and the type, content, and distribution of comonomers. Furthermore, they are closely related to the isotacticity distribution of the high and low molecular weight components and the comonomer distribution. Research has shown that as the overall molecular weight increases, the rigidity, toughness, and melt strength of polypropylene improve. Adding a small amount of a high molecular weight component to conventional polypropylene can broaden the molecular weight distribution of the polypropylene product, improving crystallization speed and processing performance. However, if the proportion of the high molecular weight component is too high, the material's processability will be rapidly reduced.

[0004] In polypropylene, the high isotacticity of low molecular weight components and the low isotacticity of high molecular weight components are very beneficial for the biaxial stretching of polypropylene film materials.

[0005] US Patent No. 6,875,826 B1 from Borealis discloses a method for producing propylene homopolymers or copolymers by asymmetric hydrogenation in two reactors, i.e., in a series of loop-type gas-phase polymerization reactors, using a Ziegler-Natta catalyst or a metallocene catalyst and an external electron donor (dicyclopentyldimethoxysilane or cyclohexylmethyldimethoxysilane). By varying the amount of hydrogen in each reactor, a broadly distributed polypropylene containing different molecular weight components, such as a high molecular weight component and a low molecular weight component, is produced. The inventors recognized that while it is possible to produce components of different molecular weights in different reactors by varying the amount of hydrogen in each reactor, the hydrogen cannot be removed between the reactors. Therefore, a method is employed in which no hydrogen is added in the first reactor to produce a high molecular weight component with a melt flow rate (MFR) of less than 0.1 g / 10 min, and a method in which an appropriate amount of hydrogen is added in the second reactor to produce medium and low molecular weight components with an MFR of greater than 0.5 g / 10 min, thereby achieving the desired high melt strength characteristic of the resulting polypropylene. Although the patent suggests a load ratio of 5:95 to 95:5 between the two reactors, due to the difficulty of such a design in actual operation, the proportion of high molecular weight components in the examples is not less than 20%.

[0006] Patent documents CN102134291A, CN102816269A and CN105623077A all disclose a method of directly polymerizing a propylene homopolymer or propylene-ethylene copolymer with a wide distribution and high melt strength by using a dual reactor in series, using a traditional Ziegler-Natta catalyst, adopting asymmetric addition of an external electron donor and asymmetric hydrogen regulation technology; that is, first adding a hydrogen-insensitive dicyclopentyldimethoxysilane (D-donor) type external electron donor into the first reactor. The method comprises the following steps: adding a hydrogen-sensitive tetraethoxysilane (TEOS)-type external electron donor in a second reactor to prepare a propylene homopolymer or copolymer with a low molecular weight and high isotacticity under the condition of no hydrogen or low hydrogen; then adding a hydrogen-sensitive tetraethoxysilane (TEOS)-type external electron donor to prepare a low molecular weight propylene homopolymer or copolymer under high hydrogen concentration, and finally obtaining a propylene homopolymer, random copolymer or impact copolymer product with a melt index of 2.0 to 3.0 g / 10 min and a melt strength of 0.8 to 2.0 N; wherein the load ratio of the two reactors is 30:70 to 70:30.

[0007] In the above-disclosed methods, whether using asymmetric hydrogenation or adding an external electron donor, a large amount of hydrogen (sometimes as high as 20,000 ppm) must be added to the second reactor to adjust the product molecular weight. Once this hydrogen returns to the first reactor with the recycle gas, the first reactor will be unable to produce the high-molecular-weight component polyolefin. Therefore, traditional separation methods such as venting or pressure swing adsorption are required to separate or remove the hydrogen. This operation results in a large amount of unreacted monomer loss, prolongs the product brand switching time, generates a large amount of transition material, and increases production costs. Producing the high-molecular-weight component in the first polymerization reactor results in a high content of the high-molecular-weight component and a very small adjustment range due to the reactor's continuous operating load. This results in a narrow melt index adjustment range and poor processing performance in the final product. In addition, using a D-donor to generate the high-molecular-weight component in the first polymerization reactor results in a high isotacticity of the high-molecular-weight component and difficulty in flexible adjustment. Furthermore, the additional introduction of a large amount of external electron donor and hydrogen in the second reactor to produce the low-molecular-weight component significantly reduces polymerization activity, increases production control difficulties, and increases the ash content of the final product.

[0008] Patent documents US10934372B2 and US10544237B2 both propose a method for producing bimodal polyolefins in two or more slurry phase polymerization reactors, wherein hydrogen is normally added to the first reactor to produce a low molecular weight polyolefin component, and all or part of the stream discharged from the first reactor is removed by contacting a hydrogenation catalyst, and the hydrogen is completely or partially removed to form a stream with a low hydrogen concentration and enter the second reactor or return to the first reactor to undergo a polymerization reaction to generate a high molecular weight polyolefin component to produce a polyolefin homopolymer or copolymer with a bimodal molecular weight distribution. As a result, the flash separation unit is omitted, that is, there is no step of emptying the material stream discharged from the first reactor to remove hydrogen. This method adds a hydrogenation catalyst to the stream discharged from the outlet of the first reactor. After the material containing the hydrogenation catalyst enters the second reactor or returns to the first reactor, the reaction activity will be significantly reduced, affecting the control of quality indicators such as the melt index and isotacticity of the polypropylene product, thereby affecting the normal operation of the device.

[0009] For the dual-reactor system, the material obtained from the first polymerization reactor is treated with a hydrogenation catalyst before entering the second reactor. The load adjustment of the two reactors is difficult, the proportion of high molecular weight components is too high, and the isotacticity of the high molecular weight components cannot be adjusted.

[0010] In addition, the various methods mentioned above for producing polypropylene products containing high molecular weight polyolefin components, whether using hydrogenation catalysts for hydrogen removal, asymmetric hydrogen regulation, or asymmetric regulation of external electron donors, also suffer from similar problems. Specifically, if a fixed external electron donor is used and asymmetric hydrogenation is performed in two reactors, the amount of hydrogen used is excessive, the range of adjustment of the molecular weight of the polypropylene product is limited, the reactors are stuck, the operational risk is high, the molecular weight distribution of the resulting polypropylene is not broad enough, the isotacticity of the high molecular weight component cannot be adjusted, and the processing performance is poor. If different types of external electron donors are added to the two reactors separately and asymmetric hydrogenation is performed simultaneously, the amount of external electron donor used is large, the load adjustment of the two reactors is difficult, the proportion of the high molecular weight component is too high (≥30 wt%), the product processing performance is poor, and the ash content in the product is high.

[0011] As can be seen, the above methods have a common drawback: the resulting propylene polymer product contains a high content of high molecular weight components, generally exceeding 15%. This high content of high molecular weight components can affect the material's processability and also makes it difficult to adjust the isotacticity of the high molecular weight components.

[0012] Therefore, the ability to control the isotacticity of the high-molecular-weight component in propylene polymers is beneficial for improving product performance. Simultaneously controlling the proportion of the high-molecular-weight component and flexibly regulating its isotacticity during polymerization is a worthy research direction.

[0013] Summary of the Invention

[0014] In response to some problems existing in the prior art for preparing polypropylene, the present invention aims to provide a catalyst for olefin polymerization, a propylene polymer containing an ultra-high molecular weight polypropylene component and adjustable isotacticity, and a production method thereof. By providing a pipeline or the like outside the reactor at the end of the polymerization reaction as an additional polymerization reaction site and adding a mixture of a hydrogenation catalyst and an external electron donor thereto to continue the polymerization reaction, a polypropylene product containing a relatively low content of the ultra-high molecular weight component is produced. The isotacticity of the ultra-high molecular weight polypropylene component can be flexibly adjusted, and the performance of the polypropylene product (including melt strength, tensile strength, impact strength, flexural strength, etc.) is significantly improved while maintaining good processing performance.

[0015] In order to achieve the above object, the present invention provides the following technical solutions:

[0016] In a first aspect, a catalyst for an olefin polymerization process is provided, wherein the catalyst is a mixture of a transition metal Group IVB metallocene compound, an alkyl aluminum compound, and an external electron donor D1, and the transition metal Group IVB metallocene compound is mixed with at least a portion of the alkyl aluminum compound before contacting the external electron donor D1.

[0017] According to the catalyst provided by the present invention, in some embodiments, the catalyst is a mixture of a hydrogenation catalyst and an external electron donor D1, and the hydrogenation catalyst is a mixture of a transition metal Group IVB metallocene compound and an alkyl aluminum compound.

[0018] According to the catalyst provided by the present invention, in some embodiments, the external electron donor D1 is an alkoxy-substituted silane compound, for example, it can be selected from dicyclopentyldimethoxysilane (D-donor), methylcyclohexyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, tetraethoxysilane (TEOS), diethylaminotriethoxysilane, preferably a dimethoxysilane compound.

[0019] In some embodiments, the transition metal Group IVB metallocene compound has the general formula R(R')-MX(X'), wherein:

[0020] R, R' are each independently an unsubstituted or substituted cyclopentadienyl, indenyl, or fluorenyl group, wherein the substituent is preferably selected from methyl, ethyl, propyl, butyl, or cycloalkyl; R and R' may be bridged by a substituent containing C or Si;

[0021] M is a transition metal element, preferably one or more selected from Ti, Zr and Hf;

[0022] X, X' are each independently a halogen atom, an alkyl group or an alkoxy group;

[0023] More preferably, the transition metal Group IVB metallocene compound is Cp2TiCl2.

[0024] According to the catalyst provided by the present invention, in some embodiments, in the catalyst, the molar ratio of the alkyl aluminum compound to the external electron donor D1 is 0.1:1-50:1 (for example, 0.2:1, 0.5:1, 0.8:1, 1:1, 2:1, 5:1, 8:1, 10:1, 15:1, 20:1, 25:1, 35:1, 40:1, 45:1), preferably 0.1:1-30:1; the molar ratio of aluminum in the alkyl aluminum compound to the transition metal Group IVB metallocene compound is 5.5-100.0:1 (for example, 6:1, 7:1, 8:1, 9:1, 10:1, 25:1, 50:1, 80:1, 90:1), preferably 5.5-10.0:1, more preferably 5.5-8.0:1.

[0025] In a second aspect, a propylene polymer containing an ultra-high molecular weight polypropylene component and adjustable isotacticity is provided, wherein the propylene polymer has a melt flow rate (MFR, 230° C., tested under a load of 2.16 kg) of greater than or equal to 0.01 g / 10 min and less than or equal to 10,000 g / 10 min; for example, 0.05 g / 10 min, 0.1 g / 10 min, 0.2 g / 10 min, 0.5 g / 10 min, 1.0 g / 10 min, 2.0 g / 10 min, 5.0 g / 10 min, 10.0 g / 10 min, 20.0 g / 10 min, 50.0 g / 10 min, 100 g / 10 min, 200 g / 10 min, 500 g / 10 min, 1000 g / 10 min, 2000 g / 10 min, 5000 g / 10 min, or 8000 g / 10 min;

[0026] The propylene polymer contains an ultra-high molecular weight component, wherein the molecular weight MW of the ultra-high molecular weight component is ≥10,000,000; the content of the ultra-high molecular weight component in the propylene polymer is 0.03-15.0 wt% (for example, 0.035 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.8 wt%, 1.0 wt%, 5.0 wt%, 10.0 wt%);

[0027] The ratio of the number average molecular weight Mn of the ultrahigh molecular weight component to the peak molecular weight Mp of the propylene polymer is Mn(MW≥10,000,000) / Mp≥80, for example, 85, 90, 100, 110, 120, 130, 140, or 150.

[0028] According to the propylene polymer provided by the present invention, in some embodiments, the content of the ultra-high molecular weight component in the propylene polymer is 0.03-5.0 wt%.

[0029] In some embodiments, the ratio of the number average molecular weight Mn of the ultrahigh molecular weight component to the peak molecular weight Mp of the propylene polymer is Mn(MW≥10,000,000) / Mp≥100, preferably Mn(MW≥10,000,000) / Mp≥120.

[0030] In some embodiments, the propylene polymer has a melt flow rate (MFR) of greater than or equal to 0.01 g / 10 min and less than or equal to 300 g / 10 min, preferably greater than or equal to 0.1 g / 10 min and less than or equal to 200 g / 10 min.

[0031] In some embodiments, the propylene polymer has a melt strength of 2.0 cN or greater, for example, 2.5 cN, 3.0 cN, 3.5 cN, 4.0 cN, 4.5 cN, 5.0 cN, 6.0 cN.

[0032] In a third aspect, a method for producing a propylene polymer is provided, using two or more polymerization reaction stages arranged in sequence; the production method comprises the following steps:

[0033] (1) in a polymerization reactor, in the presence of hydrogen and a polymerization catalyst, conducting a first stage (co)polymerization reaction of propylene or propylene and one or more optional comonomers for 0.1 to 10 hours (e.g., 0.2 hours, 0.4 hours, 0.5 hours, 1.0 hours, 1.5 hours, 2.0 hours, 3.0 hours, 5 hours, 8 hours) to produce a stream containing a polypropylene component I;

[0034] (2) After the first stage (co)polymerization reaction, at least a portion of the stream containing the polypropylene component I is in a pipeline located outside the polymerization reactor of step (1) or in a second or subsequent polymerization reactor connected in series with the polymerization reactor of step (1), and in a mixture D formed by the hydrogenation catalyst and the external electron donor D1. H , continuing the polymerization reaction for 0.05-3.0 hours (e.g., 0.06 hours, 0.08 hours, 0.1 hours, 0.2 hours, 0.4 hours, 0.5 hours, 0.8 hours, 1.0 hours, 1.5 hours, 2.0 hours, 2.5 hours) in the presence of , to obtain an ultra-high molecular weight polypropylene (UHMWPP) component;

[0035] The reaction is then stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0036] The molar ratio of the hydrogenation catalyst to the total amount of hydrogen in the reactor is 1 / 10000 to 1 / 100 (e.g., 1 / 8000, 1 / 5000, 1 / 4000, 1 / 2000, 1 / 1000, 1 / 800, 1 / 500, 1 / 400, 1 / 200), preferably 1 / 10000 to 1 / 1000.

[0037] The material stream containing the polypropylene component I obtained in step (1) contains at least: unreacted propylene, unreacted hydrogen, the polypropylene component I, and may also contain a small amount of hydrogen, a polymerization catalyst, etc.

[0038] According to the production method provided by the present invention, in some embodiments, in step (1), the polymerization catalyst includes: (a) an active solid catalyst component, preferably a titanium-containing solid catalyst active component; (b) an organic aluminum compound as a co-catalyst component; and, optionally, (3) an external electron donor D2; the polymerization catalyst is preferably a mixture D formed by the active solid catalyst component, the organic aluminum compound and the external electron donor D2.

[0039] In some embodiments, the mixture D H The catalytic strength of the mixture is higher than that of the mixture D.

[0040] The mixture D H The external electron donor D1 in the mixture D and the external electron donor D2 in the mixture D may be the same or different. According to the requirement for the isotacticity of the ultra-high molecular weight polypropylene component, different external electron donors or a combination of two or more different external electron donors may be flexibly selected. When different external electron donors are used, the mixture D H The external electron donor D1 in the mixture D is preferably a compound that has a stronger effect than the external electron donor D2 in the mixture D.

[0041] The "stronger effect" mentioned here means that under the same polymerization reaction conditions, the isotacticity or molecular weight of the polymerization product obtained by using a stronger external electron donor in the polymerization system is higher than that of the polymerization product obtained by using a relatively weaker external electron donor. For example, D-donor has a stronger effect than C-donor and TEOS, and P-donor has a stronger effect than B-donor.

[0042] In the present invention, the catalyst used for propylene (co)polymerization includes but is not limited to Ziegler-Natta type catalysts, which generally include: (a) an active solid catalyst component, such as a titanium-containing solid catalyst active component; (b) an organoaluminum compound as a co-catalyst component; and, optionally, (3) an external electron donor component D2.

[0043] The active solid catalyst component can be a Ziegler-Natta catalyst or a molecular catalyst containing metallocene. Available active main catalyst components include commercially available SUG catalysts, SAL catalysts, or other catalysts containing titanium chloride and magnesium chloride.

[0044] The organoaluminum compound as a co-catalyst component in the catalyst is preferably an alkylaluminum compound, more preferably selected from trialkylaluminum (e.g., triethylaluminum, triisobutylaluminum, tri-n-butylaluminum), methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and the like. The ratio of the active solid catalyst component to the organoaluminum compound, calculated as a Ti / Al molar ratio, is 1:5 to 1:400, preferably 1:25 to 1:200. The amount of the external electron donor component in the polymerization catalyst can be selected as conventionally used in the art and will not be elaborated upon here.

[0045] In some embodiments, the external electron donor D1 and the external electron donor D2 are the same or different, and are each independently an alkoxy-substituted silane compound or a mixture of multiple alkoxy-substituted silane compounds.

[0046] The external electron donor D1 or D2 can be various electron-donating compounds, including alkoxy-substituted silane compounds, whose general formula is SiR n (OR') 4-n , where

[0047] 0≤n≤2,

[0048] R and R' are the same or different and are independently an alkyl group, a cycloalkyl group, an aryl group, a haloalkyl group, etc. R may also be a halogen or a hydrogen atom.

[0049] In some embodiments, the external electron donor may include but is not limited to tetramethoxysilane, tetraethoxysilane (TEOS), dimethyldimethoxysilane, dimethyldiethoxysilane, methyl tert-butyldimethoxysilane, methylisopropyldimethoxysilane, diphenoxydimethoxysilane, vinyltrimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, di-n-propyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, di-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane (D-donor), cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, 1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane, etc., preferably selected from dicyclopentyldimethoxysilane (D-donor), methylcyclohexyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, tetraethoxysilane (TEOS), diethylaminotriethoxysilane.

[0050] In some embodiments, the hydrogenation catalyst is a mixture of a metal organic compound and an alkyl aluminum compound.

[0051] In some embodiments, the metal organic compound has the general formula R(R')-MX(X'), wherein:

[0052] R, R' are each independently an unsubstituted or substituted cyclopentadienyl, indenyl, or fluorenyl group, wherein the substituent is preferably selected from methyl, ethyl, propyl, butyl, or cycloalkyl; R and R' may be bridged by a substituent containing C or Si;

[0053] M is a transition metal element, preferably one or more selected from Ti, Zr and Hf;

[0054] X and X' are each independently a halogen atom, an alkyl group or an alkoxy group.

[0055] In some embodiments, the metal organic compound can be specifically selected from one or more of bis(cyclopentadienyl)titanium dichloride (titanocenes), bis(cyclopentadienyl)titanium dibromide, bis(cyclopentadienyl)methoxytitanium chloride, bis(cyclopentadienyl)ethoxytitanium chloride, bis(cyclopentadienyl)phenoxytitanium chloride, bis(cyclopentadienyl)dimethyltitanium, bis(cyclopentadienyl)diethyltitanium, diindenyltitanium dichloride, diindenyltitanium dibromide, diindenyldimethyltitanium, diindenyldiethyltitanium, bis(cyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)zirconium dibromide, bis(cyclopentadienyl)dimethylzirconium and bis(cyclopentadienyl)diethylzirconium, preferably selected from bis(cyclopentadienyl)titanium dichloride and / or bis(cyclopentadienyl)diethyltitanium.

[0056] In some embodiments, the alkylaluminum compound can be selected from one or more of trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride, methylaluminoxane (MAO) and modified methylaluminoxane (MMAO), preferably selected from triethylaluminum and / or methylaluminoxane.

[0057] In some embodiments, in the hydrogenation catalyst, the molar ratio of aluminum in the alkyl aluminum compound to the metal organic compound is 5.5-100.0:1 (e.g., 6.0:1, 7.0:1, 8.0:1, 9.0:1, 10:1, 25:1, 50:1, 80:1, 90:1), preferably 5.5-10.0:1, and more preferably 5.5-8.0:1.

[0058] In some embodiments, the hydrogenation catalyst is a mixture of Cp2TiCl2 and an alkyl aluminum compound; wherein the molar ratio of aluminum in the alkyl aluminum compound to Cp2TiCl2 is 5.5-100.0:1 (e.g., 6.0:1, 7.0:1, 8.0:1, 9.0:1, 10:1, 25:1, 50:1), preferably 5.5-10.0:1, and more preferably 5.5-8.0:1.

[0059] In some embodiments, the mixture D formed by the hydrogenation catalyst and the external electron donor D1 H In the hydrogenation catalyst, the molar ratio of the alkyl aluminum compound to the external electron donor D1 is 0.1:1-50:1 (for example, 0.2:1, 0.5:1, 0.8:1, 1:1, 2:1, 5:1, 8:1, 10:1, 15:1, 20:1, 25:1, 35:1, 40:1, 45:1), preferably 0.1:1-30:1.

[0060] In the present invention, an outlet pipeline may be provided to the end of a single reactor or a plurality of reactors connected in series (or in parallel).

[0061] In the present invention, the mixture of the hydrogenation catalyst and the external electron donor can be added in a continuous manner or in a pulsed manner.

[0062] In the present invention, there is no step of circulating the material containing the hydrogenation catalyst to the polymerization reactor, which does not affect the normal operation and control of various indicators of the polymerization reactor. In addition, the location for adding the hydrogenation catalyst and the external electron donor mixture is flexible, and can be the powder outlet of the polymerization reactor, or any point on the pipeline provided during the transportation of the polypropylene powder to the silo, or the front end of the inlet of the second or more reactors connected in series with the first polymerization reactor.

[0063] In some embodiments, the length of the pipeline disposed outside the polymerization reactor of step (1) is 0.1 to 50 meters, for example, 0.5 meters, 1 meter, 2 meters, 5 meters, 10 meters, 20 meters, or 40 meters.

[0064] The pipeline may include a pipeline outside a single propylene polymerization reactor or a plurality of reactors connected in series as a polymerization reaction site and a connecting pipeline connected to a subsequent separation device. The material of the pipeline may be any conventional material in the art.

[0065] In some embodiments, the polymerization reaction time of step (i) is 0.2-5 hours, preferably 0.3-3 hours.

[0066] In some embodiments, the polymerization reaction temperature of step (i) is 40-250°C (eg, 50°C, 60°C, 70°C, 80°C, 100°C, 150°C, 220°C), preferably 50-200°C.

[0067] In some embodiments, the polymerization reaction time of step (ii) is 0.08-2.0 hours, preferably 0.1-1.5 hours.

[0068] The polymerization reaction temperature in step (ii) is 0-250°C (e.g., 20°C, 50°C, 60°C, 70°C, 80°C, 100°C, 150°C, 220°C), preferably 20-200°C.

[0069] The polymerization reaction temperature of step (ii) may be equal to or lower than the polymerization reaction temperature of step (i).

[0070] According to the method provided by the present invention, in the polymerization reaction, propylene monomer can be polymerized, or propylene monomer can be copolymerized with one or more comonomers. In some embodiments, the comonomer can be ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-nonene, 1-decene, or a mixture of any two or more of these comonomers.

[0071] According to the production method of the present invention, in some embodiments, the isotacticity of the propylene polymer obtained changes (can be controlled), and its xylene soluble content (XS%) is the same as that of the mixture D formed without the use of a hydrogenation catalyst and an external electron donor D1. H The xylene soluble content of the polymer obtained or the polymer obtained using only the hydrogenation catalyst may vary by 0.02-5%, preferably 0.1-2%.

[0072] According to the production method of the present invention, in some embodiments, the melt mass flow rate (MFR) of the propylene polymer obtained is greater than or equal to 0.01 g / 10 min and less than or equal to 10,000 g / 10 min; for example, 0.05 g / 10 min, 0.1 g / 10 min, 0.2 g / 10 min, 0.5 g / 10 min, 1.0 g / 10 min, 2.0 g / 10 min, 5.0 g / 10 min, 10.0 g / 10 min, 20.0 g / 10 min, 50.0 g / 10 min, 100 g / 10 min, 200 g / 10 min, 500 g / 10 min, 1000 g / 10 min, 2000 g / 10 min, 5000 g / 10 min, 8000 g / 10 min.

[0073] According to the production method of the present invention, in some embodiments, the prepared propylene polymer contains an ultra-high molecular weight component, and the molecular weight MW of the ultra-high molecular weight component is ≥10,000,000, for example, 1,000,000,000 ≥ molecular weight MW ≥10,000,000; in the propylene polymer, the content of the ultra-high molecular weight component is 0.03-15.0 wt% (for example, 0.035 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.8 wt%, 1.0 wt%, 5.0 wt%, 10.0 wt%).

[0074] According to the production method of the present invention, in some embodiments, the ratio of the number average molecular weight Mn of the ultra-high molecular weight component to the peak molecular weight Mp of the propylene polymer is Mn (MW ≥ 10,000,000) / Mp ≥ 80, for example, 85, 90, 100, 110, 120, 130, 140, 150.

[0075] The outlet material of the propylene polymerization reactor contains polypropylene powder, catalyst, optional electron donor, propylene, comonomer, hydrogen, a small amount of propane, a small amount of nitrogen, etc. Usually, such material is still in the conditions that meet the polymerization, the catalyst still has polymerization activity, and there is a certain concentration of polymerization monomer and hydrogen in the environment, so that the polymerization reaction can continue. The present invention utilizes the material outlet pipeline arranged at the end outside the reactor as an additional polymerization reaction site, or the second and subsequent reactors connected in series with the first polymerization reactor or any point on the powder to silo transmission pipeline as an additional polymerization reaction site, so that the product stream discharged from the single reactor or the first polymerization stage reactor in series (parallel) can contact with the mixture of hydrogenation catalyst and external electron donor D1, and enter the gas / solid separator through a 0.1 to 50 meter long connecting pipeline, and then obtain the final product containing ultra-high molecular weight component after catalyst deactivation and degassing.

[0076] During the second-stage polymerization process, adding a certain amount of external electron donor D1 simultaneously with the addition of a hydrogenation catalyst can effectively adjust the aluminum-silicon ratio of the system, further adjusting the isotacticity of the product and further increasing the molecular weight of the product. In the mixture of hydrogenation catalyst and external electron donor, the hydrogenation catalyst is used to remove hydrogen (chain transfer agent) remaining in the product stream (powder) discharged from the first-stage polymerization reactor, allowing propylene to continue to polymerize under near-hydrogen-free conditions to produce an ultrahigh molecular weight polypropylene component (UHWMPP); the external electron donor is used to adjust the isotacticity of the propylene in the continued reaction to produce the ultrahigh molecular weight polypropylene component (UHWMPP) and further increase the product molecular weight. The present invention surprisingly discovered that the introduction of external electron donor D1 did not show any signs of altering the hydrogenation efficiency of the hydrogenation catalyst.

[0077] Compared with the prior art, the beneficial effects of the technical solution of the present invention are at least:

[0078] By adjusting the addition position of the hydrogenation catalyst and external electron donor mixture, the residence time of the material in an additional polymerization reaction site, such as a discharge pipeline, can be flexibly adjusted, and the amount of ultra-high molecular weight polypropylene component produced can be flexibly adjusted, thereby regulating the proportion of the ultra-high molecular weight component in the final polypropylene product and avoiding the negative impact of excessive high molecular weight component content on processability. By adjusting the molar ratio of alkyl aluminum to external electron donor in the hydrogenation catalyst, the aluminum-silicon ratio in the system can be flexibly changed, and the isotacticity of the ultra-high molecular weight polypropylene component can be further flexibly adjusted. By adjusting the amount of hydrogenation catalyst used, the molecular weight of the ultra-high molecular weight polypropylene component can be adjusted to a molecular weight of 10,000,000 or above. Thus, a series of polypropylene products containing ultra-high molecular weight polypropylene components and having different compositions can be prepared.

[0079] Controlling the amount of hydrogenation catalyst and the amount of alkyl aluminum therein within an appropriate range can reduce the effect of alkyl aluminum as a chain transfer agent on the molecular weight of the ultra-high molecular weight component and also reduce catalyst residues in the product;

[0080] High-temperature gel permeation chromatography (GPC) test results show that the final product contains a certain amount of UHWMPP components, and the product molecular weight distribution is slightly broadened; the low content of UHWMPP components can maintain good processing rheological properties, while comprehensively improving the performance of polypropylene products, such as melt strength, tensile strength, impact strength, etc.; the polypropylene products produced by this method can meet the requirements of higher application scenarios and can be expanded to fields such as extrusion foaming, coating, blow molding and thermoforming. DETAILED DESCRIPTION

[0081] In order to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the examples, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Where specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer.

[0082] <Source of raw materials>

[0083] In each embodiment and comparative example, the catalyst A used was prepared according to Example 5 described in patent application CN101054424A, and the Ti content in the catalyst was 3.0 wt%; the catalyst B used was prepared according to Example 3 described in patent application CN101054424A, and the Ti content in the catalyst was 2.4 wt%.

[0084] In each of the Examples and Comparative Examples, the titanocene hydrogenation catalyst used was prepared by mixing titanocene dichloride and triethylaluminum (triethylaluminum was present as a 1.0 mol / L n-hexane solution) at different molar ratios (e.g., 1:5.5 to 1:10) at room temperature for at least 24 hours under a nitrogen atmosphere to prepare multiple mixed solutions, i.e., titanocene hydrogenation catalysts. 1.0 ml of each mixed solution was then taken and diluted with 33 ml of n-hexane for later use.

[0085] Preparation of external electron donor solution: Take different types of external electron donors and prepare 0.50 M hexane solution for later use.

[0086] The hydrogenation catalyst and the external electron donor can be injected into the polymerization reaction device separately and mixed online, or they can be mixed uniformly in proportion and then injected into the polymerization reaction device.

[0087] In each embodiment and comparative example, the polymer was tested for performance by the following test methods:

[0088] (1) Melt flow rate (MFR): tested according to ASTM D1238;

[0089] (2) Xylene soluble matter content XS: Detected using a fully automatic xylene soluble matter analyzer (CRYSTEX QC) from Polymer Char.

[0090] (3) Molecular weight and its distribution: detected using a high-temperature gel permeation chromatograph (GPC-IR6) from Polymer Char.

[0091] (4) Melt strength: tested using a Malvern Instruments RH7-2 capillary rheometer + balance;

[0092] (5) Tensile strength: tested in accordance with GB / T 1040.2-2006;

[0093] (6) Flexural strength: tested in accordance with GB / T 9341-2008;

[0094] (7) Impact test: Test in accordance with GB / T 1843-2008.

[0095] In the following examples and comparative examples, the reaction environment, material concentration, etc. in the reactor after the reaction in step (i) is completed are substantially the same as the reaction environment, material concentration, etc. in the pipeline outside the reactor or in the second or subsequent polymerization reactors connected in series with the first polymerization reactor. Therefore, the experimental process uses a single reactor and is divided into two stages to simulate the polymerization reaction in industrial production after adding a hydrogenation catalyst and an external electron donor to the first polymerization reactor and the discharge pipeline attached to the first polymerization reactor, or the second or subsequent polymerization reactors connected in series with the first polymerization reactor: that is, the first stage polymerization reaction in the single reactor corresponds to the simulation of the normal polymerization reaction in the first reactor in industrial production, and the second stage polymerization reaction in the single reactor corresponds to the simulation of the polymerization reaction after adding a hydrogenation catalyst and an external electron donor to the discharge pipeline attached to the industrial production device or the second or subsequent polymerization reactors connected in series with the first polymerization reactor; and the use of a mixture of the hydrogenation catalyst and the external electron donor in the second stage polymerization reaction in the single reactor simulates the situation of introducing a mixture of the hydrogenation catalyst and the external electron donor into the discharge pipeline outside the industrial production device or the second or subsequent polymerization reactors connected in series with the first polymerization reactor.

[0096] Example 1

[0097] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0098] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.125 mol of hydrogen in sequence at room temperature, and heat to 70°C;

[0099] Before the reactor temperature reached 70° C., 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A were mixed for 5 minutes to form a mixture. When the reactor temperature reached 70° C., the mixture was injected into the reactor through the catalyst feed tube and the reaction timer was started; a first-stage polymerization reaction was carried out to produce a stream containing polypropylene component I;

[0100] (2) After the reaction was carried out for 60 minutes, 25.5 ml (concentration of 4.9×10 -6 mol / ml) titanocene hydrogenation catalyst and 1.5 ml of a 0.50 M external electron donor D-donor mixed solution (in the mixed solution, the molar ratio of the alkyl aluminum contained in the hydrogenation catalyst to the external electron donor is 1:1; the molar ratio of the alkyl aluminum to the titanocene in the hydrogenation catalyst is 6), the temperature is maintained at 70° C., the reaction time is started, and the reaction flow containing the polypropylene component I is simulated to continue to react in the outlet pipeline outside the reactor, or in the second or subsequent reactors connected in series with the polymerization reactor in step (1), and the reaction time is 5 minutes (that is, the situation of simulating the flow containing the polypropylene component I staying in the pipeline outside the polymerization reactor in step (1) or in the second or subsequent polymerization reactors connected in series with the polymerization reactor in step (1) for 5 minutes);

[0101] Then, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0102] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and then the dried polypropylene product was subjected to performance testing. The test results are shown in Table 1.

[0103] Example 2

[0104] The production method of propylene polymer is similar to that of Example 1, except that the polymerization time in step (2) in the presence of a mixed solution of a hydrogenation catalyst and an external electron donor D-donor is changed to 30 minutes.

[0105] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0106] Example 3

[0107] The production method of propylene polymer is similar to that of Example 1, except that the amount of hydrogenation catalyst in step (2) is changed to 2.55 ml (i.e., its amount is one ten-thousandth of the amount of hydrogen), and the amount of external electron donor D-donor is changed to 0.15 ml (the molar ratio of alkyl aluminum in the hydrogenation catalyst to the external electron donor in the mixed solution is 1:1). The polymerization time remains 5 minutes.

[0108] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0109] Comparative Example 1

[0110] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0111] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.12 mol of hydrogen in sequence at room temperature, and heat to 70°C;

[0112] Before the reactor temperature reaches 70°C, 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A are mixed for 5 minutes to form a mixture. When the reactor temperature reaches 70°C, the mixture is injected into the reactor through the catalyst feed tube and the reaction timer is started;

[0113] (2) After 65 minutes of reaction, the unreacted material was vented, the temperature was lowered, and the reaction was stopped;

[0114] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and then the dried polypropylene product was subjected to performance testing. The test results are shown in Table 1.

[0115] Comparative Example 2

[0116] The production method of propylene polymer refers to Comparative Example 1, except that the timing is based on steps (1) and (2), and after 90 minutes of reaction, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped;

[0117] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and then the dried polypropylene product was subjected to performance testing. The test results are shown in Table 1.

[0118] Comparative Example 3

[0119] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0120] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then add 2.2 L of liquid propylene at room temperature without adding hydrogen, and heat to 70°C;

[0121] Before the reactor temperature reaches 70°C, 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A are mixed for 5 min to form a mixture. When the reactor temperature reaches 70°C, the mixture is injected into the reactor through the catalyst feed tube and the reaction timer is started;

[0122] (2) After 60 minutes of reaction, the material was vented, the temperature was lowered, and the reaction was stopped;

[0123] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the dried polypropylene product was tested. The test results are shown in Table 1.

[0124] Example 4:

[0125] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0126] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.125 mol of hydrogen in sequence at room temperature, and heat to 70°C;

[0127] Before the reactor temperature reached 70° C., 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A were mixed for 5 minutes to form a mixture. When the reactor temperature reached 70° C., the mixture was injected into the reactor through the catalyst feed tube and the reaction timer was started; a first-stage polymerization reaction was carried out to produce a stream containing polypropylene component I;

[0128] (2) After the reaction was carried out for 60 minutes, 25.5 ml (concentration of 4.9×10 -6 mol / ml) titanocene hydrogenation catalyst and 15 ml of a 0.50 M external electron donor D-donor mixed solution (in the mixed solution, the molar ratio of the alkyl aluminum contained in the hydrogenation catalyst to the external electron donor is 0.1:1), the temperature is maintained at 70° C., the reaction time is started, and the reaction time is simulated to simulate the stream containing the polypropylene component I continuing to react in the outlet pipeline outside the reactor, or in the second or subsequent reactors connected in series with the polymerization reactor in step (1), and the reaction time is 5 minutes (that is, the situation in which the stream containing the polypropylene component I stays in the pipeline outside the polymerization reactor in step (1) or in the second or subsequent polymerization reactors connected in series with the polymerization reactor in step (1) for 5 minutes is simulated);

[0129] Then, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0130] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the dried polypropylene product was tested. The test results are shown in Table 1.

[0131] Example 5

[0132] The production method of propylene polymer is similar to that of Example 4, except that in the mixed solution of hydrogenation catalyst and external electron donor in step (2), the molar ratio of alkyl aluminum contained in the hydrogenation catalyst to the external electron donor is changed to 10:1. That is, a mixed solution of 25.5 ml of titanocene hydrogenation catalyst and 0.15 ml of 0.50 M external electron donor D-donor is taken, and the reaction is continued for 5 minutes; then, the unreacted material is vented, the temperature is lowered, and the reaction is stopped.

[0133] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 2.

[0134] Example 6

[0135] The production method of the propylene polymer is similar to that of Example 4, except that in the mixed solution of the hydrogenation catalyst and the external electron donor in step (2), the molar ratio of the alkyl aluminum contained in the hydrogenation catalyst to the external electron donor is 50:1, that is, a mixed solution of 25.5 ml of the titanocene hydrogenation catalyst and 0.03 ml of the 0.50 M external electron donor D-donor is used.

[0136] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 2.

[0137] Comparative Example 4:

[0138] The production method of propylene polymer is similar to that of Example 1, except that only a hydrogenation catalyst is added in step (2) without an external electron donor, that is, only 25.5 ml of the titanocene hydrogenation catalyst solution is added, the temperature is maintained at 70° C., and the reaction time is started to simulate the flow containing the polypropylene component I continuing to react in the outlet pipeline outside the reactor or in the second or more reactors connected in series with the polymerization reactor in step (1), and the reaction time is 5 minutes.

[0139] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0140] Table 1

[0141] As can be seen from the data in Table 1, compared to Comparative Examples 1-3, which did not use a mixture of a hydrogenation catalyst and an external electron donor, the use of a hydrogenation catalyst alone without an external electron donor in Comparative Example 4 resulted in improved mechanical properties of the product, with the melt strength increasing to 2.4 cN. The use of a mixture of a hydrogenation catalyst and an external electron donor in Examples 1-3 increased polymerization activity, reduced the xylene soluble content in the product (reflecting increased isotacticity of the ultrahigh molecular weight component), and further improved mechanical properties, with the melt strength increasing to 4.3-5.5 cN.

[0142] Table 2

[0143] The data in Table 2 demonstrate that a lower molar ratio of the alkylaluminum to the external electron donor in the hydrogenation catalyst, i.e., a greater amount of external electron donor, results in a lower xylene-soluble content in the product. Compared to Comparative Example 4, which incorporates only the hydrogenation catalyst without an external electron donor, product performance is significantly improved within a molar ratio of the alkylaluminum to the external electron donor in the hydrogenation catalyst ranging from 0.1 to 50.

[0144] Example 7:

[0145] The copolymerization of propylene and ethylene was carried out in a 5L stainless steel polymerization reactor:

[0146] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.20 mol of hydrogen in sequence at room temperature, and heat to 60°C;

[0147] Before the reactor temperature reached approximately 60° C., ethylene was introduced into the reactor at a flow rate of 20 g / h. Simultaneously, 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A were mixed for 5 minutes to form a mixture. When the reactor temperature reached 60° C., the mixture was injected into the reactor through the catalyst feed tube and the reaction timer was started. A first-stage polymerization reaction was carried out to prepare a stream containing propylene polymer component I.

[0148] (2) After the reaction was carried out for 60 minutes, 4.0 ml (concentration of 4.9×10 -6mol / ml) titanocene hydrogenation catalyst and 0.24 ml of a 0.50M external electron donor D-donor mixed solution (the molar ratio of the alkyl aluminum in the hydrogenation catalyst to the external electron donor in the mixed solution is 1:1; the molar ratio of the alkyl aluminum to titanocene in the hydrogenation catalyst is 6), the temperature is continued to be maintained at 60° C., the reaction time is started, and the stream containing the propylene polymer component I is simulated to continue to react in the outlet pipeline outside the reactor, or in the second or more reactors connected in series with the polymerization reactor of step (1), and the reaction time is 10 minutes (that is, the stream containing the polypropylene component I stays in the pipeline outside the polymerization reactor of step (1) or in the second or more polymerization reactors connected in series with the polymerization reactor of step (1) for 10 minutes);

[0149] Then, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0150] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the dried polypropylene product was tested. The test results are shown in Table 3.

[0151] Example 8:

[0152] The production method of propylene polymer refers to Example 7, except that the time for continuing the reaction in the presence of a mixed solution of the hydrogenation catalyst and the external electron donor D-donor in step (2) is changed to 30 minutes.

[0153] The dried polypropylene product was subjected to performance testing. The test results are shown in Table 3.

[0154] Example 9:

[0155] The production method of propylene polymer is similar to that of Example 7, except that the time for continuing the reaction in the presence of a mixed solution of the hydrogenation catalyst and the external electron donor D-donor in step (2) is changed to 60 minutes.

[0156] The dried polypropylene product was subjected to performance testing. The test results are shown in Table 3.

[0157] Comparative Example 5:

[0158] The copolymerization of propylene and ethylene was carried out in a 5L stainless steel polymerization reactor:

[0159] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.20 mol of hydrogen in sequence at room temperature, and heat to 60°C;

[0160] Before the reactor temperature reached approximately 60°C, ethylene was introduced into the reactor at a flow rate of 20 g / h. Simultaneously, 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A were mixed for 5 minutes to form a mixture. When the reactor temperature reached 60°C, the mixture was injected into the reactor through the catalyst feed tube and the reaction timer was started.

[0161] (2) After the reaction has been carried out for 60 minutes, the unreacted material is vented, the temperature is lowered, and the reaction is stopped;

[0162] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the dried polypropylene product was tested. The test results are shown in Table 3.

[0163] Table 3

[0164] As can be seen from the data in Table 3, compared with Comparative Example 5, when performing propylene-ethylene random copolymerization, when Examples 7-9 use a mixture of a hydrogenation catalyst and an external electron donor, the melt index of the product is lower and the molecular weight is larger; as the polymerization time of the second polymerization stage is prolonged, the content of the generated ultra-high molecular weight polypropylene component also increases.

[0165] Example 10:

[0166] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0167] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.125 mol of hydrogen in sequence at room temperature, and heat to 70°C;

[0168] Before the reactor temperature reached 70° C., 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution, and 8.1 mg of catalyst A were mixed for 5 minutes to form a mixture. When the reactor temperature reached 70° C., the mixture was injected into the reactor through the catalyst feed tube and the reaction timer was started; a first-stage polymerization reaction was carried out to produce a stream containing polypropylene component I;

[0169] (2) After the reaction was carried out for 60 minutes, 2.55 ml (concentration of 4.9×10 -6mol / ml) of a mixed solution of a titanocene hydrogenation catalyst and 0.15 ml of a 0.50 M external electron donor D-donor (in the mixed solution, the molar ratio of the alkyl aluminum contained in the hydrogenation catalyst to the titanocene is 8; the molar ratio of the alkyl aluminum to the external electron donor is 1:1, and the ratio of the molar number of the hydrogenation catalyst to the total hydrogen gas is 1:10000), the temperature is maintained at 70° C., and the reaction time is started to simulate the flow containing the polypropylene component I continuing to react in the outlet pipeline outside the reactor, or in the second or subsequent reactors connected in series with the polymerization reactor of step (1), and the reaction time is 5 minutes (that is, the flow containing the polypropylene component I is simulated to stay in the pipeline outside the polymerization reactor of step (1) or in the second or subsequent polymerization reactors connected in series with the polymerization reactor of step (1) for 5 minutes);

[0170] Then, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0171] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the dried polypropylene product was tested. The test results are shown in Table 4.

[0172] Example 11:

[0173] The method for producing the propylene polymer is similar to that of Example 10, except that in step (2), the molar ratio of the alkyl aluminum to the titanocene in the hydrogenation catalyst is 10.

[0174] The obtained dried polypropylene product was subjected to performance tests. The test results are shown in Table 4.

[0175] Example 12:

[0176] The production method of propylene polymer is similar to that of Example 1, except that in step (2), the amount of hydrogenation catalyst is adjusted to 5.1 ml, and the amount of external electron donor is adjusted to 0.3 ml (ie, the ratio of hydrogenation catalyst to total hydrogen moles is 1:5000).

[0177] The obtained dried polypropylene product was subjected to performance tests. The test results are shown in Table 4.

[0178] Comparative Example 6:

[0179] The production method of the propylene polymer is the same as that of Example 10, except that the molar ratio of the alkyl aluminum to the titanocene in the hydrogenation catalyst is 1.5.

[0180] The obtained dried polypropylene product was subjected to performance tests. The test results are shown in Table 4.

[0181] Comparative Example 7:

[0182] The production method of the propylene polymer is the same as that of Example 10, except that the molar ratio of the alkyl aluminum to the titanocene in the hydrogenation catalyst is 4.

[0183] The obtained dried polypropylene product was subjected to performance tests. The test results are shown in Table 4.

[0184] Table 4

[0185] As can be seen from the data in Table 4, when the molar ratio of the alkyl aluminum to titanocene in the hydrogenation catalyst is less than or equal to 4, the alkyl aluminum cannot completely dissolve the titanocene, and at this time, the titanocene cannot effectively play the hydrogenation effect; when the molar ratio of the alkyl aluminum to titanocene is 1.5, there is obvious precipitation and it cannot be used for polymerization. When the molar ratio of the alkyl aluminum to titanocene in the hydrogenation catalyst is 8 or 10, the alkyl aluminum is slightly excessive, and the product melt index only increases slightly, which can be used to play the role of hydrogenation catalyst. When the hydrogenation catalyst / total hydrogen (mol / mol) molar ratio is 1 / 5000, the hydrogenation effect is better than 1 / 10000, and the resulting polymer product melt index is lower.

[0186] Example 13:

[0187] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0188] (1) First, purge the reactor with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, add 2.2 L of liquid propylene and 0.048 mol of hydrogen in sequence at room temperature, and heat to 70°C;

[0189] Before the reactor temperature reached 70° C., 2.0 ml of a pre-prepared 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M TEOS hexane solution, and 8.1 mg of catalyst B were mixed for 5 minutes to form a mixture. When the reactor temperature reached 70° C., the mixture was injected into the reactor through the catalyst feed tube and the reaction timer was started; a first-stage polymerization reaction was carried out to produce a stream containing polypropylene component I.

[0190] (2) After the reaction was carried out for 60 minutes, 2.55 ml (concentration of 4.9×10 -6mol / ml) titanocene hydrogenation catalyst and 0.15ml of a 0.50M external electron donor D-donor mixed solution (in the mixed solution, the molar ratio of alkyl aluminum to titanocene in the hydrogenation catalyst is 6; the molar ratio of alkyl aluminum to external electron donor is 1:1), the temperature is maintained at 70°C, the reaction time is started, and the reaction time is simulated to continue the reaction of the stream containing the polypropylene component I in the outlet pipeline outside the reactor or in the second or subsequent reactors connected in series with the polymerization reactor in step (1), and the reaction time is 60 minutes (that is, the situation of simulating the stream containing the polypropylene component I staying in the pipeline outside the polymerization reactor in step (1) or in the second or subsequent polymerization reactors connected in series with the polymerization reactor in step (1) for 60 minutes);

[0191] Then, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0192] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and then the performance of the dried polypropylene product was tested. The test results are shown in Table 5.

[0193] Comparative Example 8:

[0194] The production method of propylene polymer refers to Example 13, except that only hydrogenation catalyst is added in step (2) and no external electron donor is added.

[0195] The dried polypropylene product was subjected to performance testing. The test results are shown in Table 5.

[0196] Table 5

[0197] As can be seen from the data in Table 5, compared with Comparative Example 8, in Example 13, using TEOS in the first polymerization stage and using a mixture of a hydrogenation catalyst and an external electron donor D-donor in the second polymerization stage can significantly reduce the xylene soluble content of the product (i.e., reflecting an increase in the isotacticity of the product), which is reduced from 5.38% to 5.02%. This shows that the isotacticity of the ultra-high molecular weight polypropylene component can be adjusted by adding a hydrogenation catalyst and using an external electron donor in the second polymerization stage.

[0198] Therefore, the products of the present invention can significantly improve the performance of polypropylene by including a small amount of ultra-high molecular weight component. The isotacticity of the ultra-high molecular weight polypropylene component can be adjusted by using a mixture of a hydrogenation catalyst and an external electron donor. The average molecular weight Mn (logMW ≥ 7) of the UHMWPP produced in each example is significantly higher than the peak molecular weight Mp of the resulting product, with the Mn (logMW ≥ 7) / Mp ratio exceeding 10.

[0199] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be considered as the scope of protection of the present invention.

Claims

1. A catalyst for olefin polymerization process, characterized in that The catalyst is a mixture of a transition metal IVB group metallocene compound, an alkyl aluminum compound and an external electron donor D1, and the transition metal IVB group metallocene compound is mixed with at least part of the alkyl aluminum compound before contacting the external electron donor D1; Preferably, the catalyst is a mixture of a hydrogenation catalyst and an external electron donor D1, and the hydrogenation catalyst is a mixture of a transition metal IVB group metallocene compound and an alkyl aluminum compound; Preferably, the external electron donor D1 is an alkoxy-substituted silane compound, preferably a dimethoxysilane compound; Preferably, the general formula of the transition metal IVB group metallocene compound is R(R')-MX(X'), wherein: R, R' are each independently an unsubstituted or substituted cyclopentadienyl, indenyl, fluorenyl, wherein the substituent is preferably selected from methyl, ethyl, propyl, butyl, cycloalkyl; R and R' may be bridged by a substituent containing C or Si; M is a transition metal element, preferably one or more selected from Ti, Zr and Hf; X, X' are each independently a halogen atom, an alkyl group or an alkoxy group; More preferably, the transition metal Group IVB metallocene compound is Cp2TiCl2.

2. The catalyst according to claim 1, characterized in that In the catalyst, the molar ratio of the alkyl aluminum compound to the external electron donor D1 is 0.1:1-50:1, preferably 0.1:1-30:1; the molar ratio of aluminum in the alkyl aluminum compound to the transition metal IVB group metallocene compound is 5.5-100.0:1, preferably 5.5-10.0:1, more preferably 5.5-8.0:

1.

3. A propylene polymer containing an ultra-high molecular weight polypropylene component and having adjustable isotacticity, characterized in that: The melt mass flow rate MFR of the propylene polymer is greater than or equal to 0.01 g / 10 min and less than or equal to 10000 g / 10 min; The propylene polymer contains an ultra-high molecular weight component, the molecular weight MW of the ultra-high molecular weight component is ≥ 10,000,000; the content of the ultra-high molecular weight component in the propylene polymer is 0.03-15.0wt%; The ratio of the number average molecular weight Mn of the ultra-high molecular weight component to the peak molecular weight Mp of the propylene polymer is Mn (MW ≥ 10,000,000) / Mp ≥ 80.

4. The propylene polymer according to claim 3, characterized in that In the propylene polymer, the content of the ultra-high molecular weight component is 0.03-5.0wt%; and / or The ratio of the number average molecular weight Mn of the ultra-high molecular weight component to the peak molecular weight Mp of the propylene polymer is Mn(MW≥10,000,000) / Mp≥100, preferably Mn(MW≥10,000,000) / Mp≥120.

5. The propylene polymer according to claim 3 or 4, characterized in that The melt mass flow rate MFR of the propylene polymer is greater than or equal to 0.01 g / 10 min and less than or equal to 300 g / 10 min, preferably greater than or equal to 0.1 g / 10 min and less than or equal to 200 g / 10 min; and / or The melt strength of the propylene polymer is greater than or equal to 2.0 cN.

6. A method for producing a propylene polymer, characterized in that: The production method comprises the following steps: (1) in a polymerization reactor, in the presence of hydrogen and a polymerization catalyst, propylene or propylene and one or more optional comonomers are subjected to a first stage (co)polymerization reaction for 0.1 to 10 hours to prepare a feed stream containing a polypropylene component I; (2) After the first stage (co)polymerization reaction, at least a portion of the stream containing the polypropylene component I is in a pipeline located outside the polymerization reactor of step (1) or in a second or subsequent polymerization reactor connected in series with the polymerization reactor of step (1), and in a mixture D formed by a hydrogenation catalyst and an external electron donor D1. H In the presence of , continuing the polymerization reaction for 0.05-3.0 hours to obtain an ultra-high molecular weight polypropylene (UHMWPP) component; Then, the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component; The molar ratio of the hydrogenation catalyst to the total amount of hydrogen in the reactor is 1 / 10000 to 1 / 100, preferably 1 / 10000 to 1 / 1000.

7. The production method according to claim 6, characterized in that: In step (1), the polymerization catalyst comprises: (a) an active solid catalyst component, preferably a titanium-containing solid catalyst active component; (b) an organoaluminum compound as a co-catalyst component; and, optionally, (3) an external electron donor D2; the polymerization catalyst is preferably a mixture D formed by the active solid catalyst component, the organoaluminum compound and the external electron donor D2; Preferably, the mixture D H The catalytic strength of the mixture D is higher than that of the mixture D; Preferably, the external electron donor D1 and the external electron donor D2 are the same or different, and are each independently an alkoxy-substituted silane compound or a mixture of multiple alkoxy-substituted silane compounds; Preferably, the hydrogenation catalyst is a mixture of a metal organic compound and an alkyl aluminum compound; the general formula of the metal organic compound is R(R')-MX(X'), wherein: R, R' are each independently an unsubstituted or substituted cyclopentadienyl, indenyl, fluorenyl, wherein the substituent is preferably selected from methyl, ethyl, propyl, butyl, cycloalkyl; R and R' may be bridged by a substituent containing C or Si; M is a transition metal element, preferably one or more selected from Ti, Zr and Hf; X, X' are each independently a halogen atom, an alkyl group or an alkoxy group; Preferably, in the hydrogenation catalyst, the molar ratio of aluminum in the alkyl aluminum compound to the metal organic compound is 3.0-100.0:1, preferably 5.5-10.0:1, and more preferably 5.5-8.0:

1.

8. The production method according to claim 6 or 7, characterized in that: The hydrogenation catalyst is a mixture of Cp2TiCl2 and an alkyl aluminum compound; Wherein, the molar ratio of aluminum in the alkyl aluminum compound to Cp2TiCl2 is 5.5-100.0:1, preferably 5.5-10.0:1, and more preferably 5.5-8.0:

1.

9. The production method according to any one of claims 6 to 8, characterized in that: The mixture D formed by the hydrogenation catalyst and the external electron donor D1 H In the hydrogenation catalyst, the molar ratio of the alkyl aluminum compound to the external electron donor D1 is 0.1:1-50:1, preferably 0.1:1-30:

1.

10. The production method according to any one of claims 6 to 9, characterized in that: The length of the pipeline disposed outside the polymerization reactor in step (1) is 0.1 to 50 meters; and / or The polymerization reaction time of step (i) is 0.2-5 hours, preferably 0.3-3 hours; and / or The polymerization temperature of step (i) is 40-250°C, preferably 50-200°C; and / or The polymerization reaction time of step (ii) is 0.08-2.0 hours, preferably 0.1-1.5 hours; and / or The polymerization reaction temperature of step (ii) is 0-250°C, preferably 20-200°C.

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