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

Abstract

The invention belongs to the technical field of propylene polymerization, and particularly relates to a catalyst for olefin polymerization, an isotacticity-adjustable propylene polymer containing an ultra-high molecular weight polypropylene component and a production method of the isotacticity-adjustable propylene polymer, and the method comprises the following steps: in the presence of hydrogen and a polymerization catalyst, propylene or propylene reacts with one or more optional comonomers; at least one part of the obtained material flow containing the polypropylene component I is continuously subjected to polymerization reaction for 0.05-3.0 hours in a pipeline positioned outside the reactor or a subsequent reactor connected with the pipeline in series and in the presence of a mixture DH of a hydrogenation catalyst and an external electron donor; a propylene polymer product containing 0.03 wt%-15.0 wt% of an ultra-high molecular weight polypropylene component is obtained; the molar ratio of the hydrogenation catalyst to the total amount of hydrogen is 1 / 10000 to 1 / 100. According to the invention, the polypropylene product containing the ultra-high molecular weight component with lower content is prepared, and the isotacticity of the ultra-high molecular weight polypropylene component can be flexibly adjusted.

Description

Technical Field

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

[0002] Generally speaking, the molecular chain structure of homopolymer polypropylene is linear and semi-crystalline, and the molecular weight of common polypropylene is relatively small (about hundreds of thousands), and its softening point is very close to the melting point. After exceeding the melting point, its melt strength drops rapidly, resulting in uneven container wall thickness during thermoforming, edge curling and shrinkage during extrusion coating and calendering, and cell collapse during extrusion foaming. It is difficult to produce large products and high-speed molding, which limits the application of polypropylene.

[0003] The performance of polypropylene is directly related to its overall molecular weight, molecular weight distribution width, molecular chain stereoregularity, type, content and distribution of comonomers, and further, it is closely related to the isotactic distribution of high molecular weight components and low molecular weight components and the distribution of comonomers. Studies have shown that with the increase of overall molecular weight, the rigidity, toughness and melt strength of polypropylene will be improved. Adding a small amount of high molecular weight polypropylene component to ordinary polypropylene can widen the molecular weight distribution of polypropylene products, and can improve the crystallization rate and processing performance. However, if the proportion of high molecular weight polypropylene component is too high, the processability of the material will be rapidly reduced.

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

[0005] Patent document US 6875826B1 of BOREALIS discloses a method for producing propylene homopolymer or copolymer, wherein asymmetric hydrogenation is performed in dual reactors, i.e., in a series of loop-gas phase polymerization reactors, a Ziegler-Natta catalyst or a metallocene catalyst and an external electron donor (dicyclopentyldimethoxysilane or cyclohexylmethyldimethoxysilane) are selected, and a wide distribution polypropylene containing different molecular weight components such as high molecular weight components and low molecular weight components is prepared by changing the amount of hydrogen in different reactors. The inventors realize that although components with different molecular weights can be produced in different reactors by changing the amount of hydrogen in different reactors under the condition of using hydrogen, since hydrogen cannot be removed between different reactors, a method without hydrogenation in the first reactor is used to produce a high molecular weight component with MFR<0.1g / 10min, and a method of adding an appropriate amount of hydrogen in the second reactor is used to produce medium and low molecular weight components with MFR>0.5g / 10min; so as to achieve the characteristic of high melt strength of the obtained polypropylene. Although the patent suggests that the load ratio of the two reactors is 5:95 to 95:5, 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 in the reactors to obtain 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, and adopting asymmetric addition of external electron donors and asymmetric hydrogen regulation technology; that is, firstly adding a hydrogen-insensitive dicyclopentyldimethoxysilane (D-donor) type external electron donor in the first reactor; The method comprises the following steps: preparing a propylene homopolymer or copolymer with high molecular weight and high isotacticity under the condition of no hydrogen or little hydrogen; then adding a hydrogen-sensitive tetraethoxysilane (TEOS) type external electron donor to the second reactor to prepare a propylene homopolymer or copolymer with low molecular weight 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 method, whether it is asymmetric hydrogenation or adding an external electron donor, since a large amount of hydrogen (sometimes even up to 20,000 ppm) needs to be added to the second reactor to adjust the product molecular weight, once the hydrogen returns to the first reactor with the circulating gas, the first reactor cannot produce high molecular weight component polyolefin. Therefore, it is necessary to separate or remove hydrogen through traditional separation methods such as venting or pressure swing adsorption. This operation will cause a large amount of unreacted monomer loss, prolong the product grade switching time, produce a large amount of transition materials, and increase production costs. The high molecular weight component is produced by the first polymerization reactor. Due to the limitation of the continuous operation load of the reactor, the composition content of the high molecular weight component is high and the adjustable range is very small, which will lead to a narrow adjustment range of the melt index of the final product and poor processing performance; in addition, the use of D-donor in the first polymerization reactor to generate the high molecular weight component makes the isotacticity of the high molecular weight component very high and difficult to flexibly adjust. At the same time, due to the additional introduction of a large amount of external electron donors and hydrogen in the second reactor to produce low molecular weight components, the polymerization activity will be significantly reduced, the difficulty of production control will increase, and the ash content of the final product will increase.

[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 streams discharged from the first reactor are contacted with a hydrogenation catalyst, and hydrogen is completely or partially removed to form streams with low hydrogen concentrations and enter the second reactor or return to the first reactor for polymerization reaction to generate high molecular weight polyolefin components to produce polyolefin homopolymers or copolymers with bimodal molecular weight distribution. Thus, 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. The 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 to remove hydrogen, or asymmetric hydrogen adjustment or asymmetric regulation of external electron donors, will also have similar problems, that is, if a fixed external electron donor is used, through asymmetric hydrogenation in two reactors, the amount of hydrogen used is too large, the molecular weight adjustment range of the polypropylene product is limited, the reactor is stuck at the edge of the operation, the operation risk is high, the molecular weight distribution of the obtained polypropylene is not wide 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 respectively and asymmetric hydrogenation is performed at the same time, there are problems such as large amount of external electron donor, difficulty in adjusting the load of the two reactors, too high a proportion of high molecular weight components ≥30wt%, poor product processing performance, and high ash content in the product.

[0011] It can be seen that the above methods have a common defect, that is, the content of high molecular weight components in the generated propylene polymer product is relatively high, generally above 15%. Too high content of high molecular weight components will affect the processability of the material; at the same time, the isotacticity of the high molecular weight components is also difficult to adjust.

[0012] In view of this, the controllable isotacticity of the high molecular weight component in propylene polymer is beneficial to the improvement of product performance. How to simultaneously control the proportion of the high molecular weight component and flexibly control the isotacticity of the high molecular weight component in the polymerization process is a direction worthy of research. Summary of the invention

[0013] In view of some problems existing in the prior art for preparing polypropylene, the object of the present invention is to provide a catalyst for olefin polymerization process, a propylene polymer containing an ultra-high molecular weight polypropylene component and adjustable isotacticity and a production method thereof, wherein a pipeline or the like is arranged outside a reactor at the end of the polymerization reaction as an additional polymerization reaction site and a mixture of a hydrogenation catalyst and an external electron donor is added thereto to continue the polymerization reaction, thereby obtaining a polypropylene product containing a relatively low content of an ultra-high molecular weight component, and the isotacticity of the ultra-high molecular weight polypropylene component can be flexibly adjusted, and while maintaining good processing performance, the performance of the polypropylene product (including melt strength, tensile strength, impact strength, bending strength, etc.) is significantly improved.

[0014] In order to achieve the above object, the present invention provides the following technical solutions:

[0015] In a first aspect, a catalyst for olefin polymerization 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 part of the alkyl aluminum compound before contacting the external electron donor D1.

[0016] 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.

[0017] 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.

[0018] In some embodiments, the transition metal Group IVB metallocene compound has the general formula R(R')-MX(X'), wherein:

[0019] 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;

[0020] M is a transition metal element, preferably one or more selected from Ti, Zr and Hf;

[0021] X, X' are each independently a halogen atom, an alkyl group or an alkoxy group;

[0022] More preferably, the transition metal Group IVB metallocene compound is Cp2TiCl2.

[0023] 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 IVB Group 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.

[0024] In a second aspect, a propylene polymer containing an ultra-high molecular weight polypropylene component and having adjustable isotacticity is provided, wherein the melt 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; 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;

[0025] 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; in the propylene polymer, the content of the ultra-high molecular weight component is 0.03-15.0wt% (for example, 0.035wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.08wt%, 0.1wt%, 0.2wt%, 0.4wt%, 0.5wt%, 0.8wt%, 1.0wt%, 5.0wt%, 10.0wt%);

[0026] 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, 150.

[0027] According to the propylene polymer provided by the present invention, in some embodiments, in the propylene polymer, the content of the ultra-high molecular weight component is 0.03-5.0 wt%.

[0028] 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≥100, preferably Mn(MW≥10,000,000) / Mp≥120.

[0029] In some embodiments, the melt 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.

[0030] In some embodiments, the melt strength of the propylene polymer is greater than or equal to 2.0 cN, for example, 2.5 cN, 3.0 cN, 3.5 cN, 4.0 cN, 4.5 cN, 5.0 cN, 6.0 cN.

[0031] 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:

[0032] (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 (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 prepare a stream containing a polypropylene component I;

[0033] (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 , 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;

[0034] Then, the reaction is stopped to obtain a propylene polymer product containing an ultra-high molecular weight polypropylene (UHMWPP) component;

[0035] Wherein, the molar ratio of the hydrogenation catalyst to the total amount of hydrogen present 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.

[0036] 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.

[0037] According to the production method provided by the present invention, in some embodiments, in step (1), the polymerization catalyst comprises: (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 an active solid catalyst component, an organic aluminum compound and an external electron donor D2.

[0038] In some embodiments, the mixture D H The catalytic strength of the mixture is higher than that of the mixture D.

[0039] 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. Different external electron donors or a combination of two or more different external electron donors may be flexibly selected according to the requirement for the isotacticity of the ultra-high molecular weight polypropylene component. 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.

[0040] 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 is stronger than C-donor and TEOS, and P-donor is stronger than B-donor.

[0041] 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 organic aluminum compound as a co-catalyst component; and, optionally, (3) an external electron donor component D2.

[0042] 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.

[0043] The organic aluminum compound as the co-catalyst component in the catalyst is preferably an alkyl aluminum compound, more preferably selected from trialkyl aluminum (such as triethyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum), methyl aluminum oxane (MAO), modified methyl aluminum oxane (MMAO), etc.; wherein the ratio of the active solid catalyst component to the organic aluminum compound is 1:5 to 1:400, preferably 1:25 to 1:200, in terms of Ti / Al molar ratio. In the polymerization catalyst, the amount of the external electron donor component can be selected conventionally in the art, and will not be repeated here.

[0044] 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.

[0045] 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

[0046] 0≤n≤2,

[0047] R and R' are the same or different, and are independently an alkyl group, a cycloalkyl group, an aryl group, a halogenated alkyl group, etc. R may also be a halogen or a hydrogen atom.

[0048] In some embodiments, the external electron donor may include but is not limited to tetramethoxysilane, tetraethoxysilane (TEOS), dimethyldimethoxysilane, dimethyldiethoxysilane, methyltert-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-(1,1,1-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.

[0049] In some embodiments, the hydrogenation catalyst is a mixture of a metal organic compound and an alkyl aluminum compound.

[0050] In some embodiments, the metal organic compound has a general formula of R(R')-MX(X'), wherein:

[0051] 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;

[0052] M is a transition metal element, preferably one or more selected from Ti, Zr and Hf;

[0053] X and X' are each independently a halogen atom, an alkyl group or an alkoxy group.

[0054] In some embodiments, the metal organic compound can be specifically selected from one or more of bis(cyclopentadienyl)titanium dichloride (titanocene), 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.

[0055] In some embodiments, the alkylaluminum compound can be selected from one or more of trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, dimethylaluminum monochloride, diethylaluminum monochloride, dibutylaluminum monochloride, diisobutylaluminum monochloride, methylaluminoxane (MAO) and modified methylaluminoxane (MMAO), preferably selected from triethylaluminum and / or methylaluminoxane.

[0056] 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.

[0057] 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.

[0058] In some embodiments, the mixture D formed by the hydrogenation catalyst and the external electron donor D1 is H In the embodiment, the molar ratio of the alkyl aluminum compound in the hydrogenation catalyst 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.

[0059] In the present invention, an outlet pipeline may be arranged outside a single reactor or outside the terminal of a plurality of series (parallel) reactors.

[0060] 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.

[0061] 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; and the addition position of the hydrogenation catalyst and the external electron donor mixture is flexible, which can be the powder outlet of the polymerization reactor, or any point on the pipeline set in the process of transporting 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.

[0062] 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.

[0063] The pipeline may include a pipeline as a polymerization reaction site outside a single reactor or multiple series reactors for propylene polymerization and a connecting pipeline connected to a subsequent separation device. The material of the pipeline may be a conventional material in the art.

[0064] In some embodiments, the polymerization reaction time of step (i) is 0.2-5 hours, preferably 0.3-3 hours.

[0065] 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.

[0066] In some embodiments, the polymerization reaction time of step (ii) is 0.08-2.0 hours, preferably 0.1-1.5 hours.

[0067] The polymerization reaction temperature of 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.

[0068] The polymerization reaction temperature of step (ii) may be equal to or lower than the polymerization reaction temperature of step (i).

[0069] According to the method provided by the present invention, in the polymerization reaction, propylene monomer can be polymerized, or propylene monomer and one or more comonomers can be copolymerized. In some embodiments, the comonomer can be ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-nonene, 1-decene, etc., or a mixture of any two or more of these comonomers.

[0070] According to the production method of the present invention, in some embodiments, the isotacticity of the propylene polymer obtained is changed (adjustable), and the xylene soluble content (XS%) thereof is the same as that of the mixture D formed without the use of the hydrogenation catalyst and the external electron donor D1. H The xylene soluble content of the obtained polymer or the polymer obtained using only the hydrogenation catalyst may differ by 0.02-5%, preferably 0.1-2%.

[0071] According to the production method of the present invention, in some embodiments, the melt 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 10000 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.

[0072] According to the production method of the present invention, in some embodiments, the prepared propylene polymer contains an ultra-high molecular weight component, 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 0.03-15.0wt% (for example, 0.035wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.08wt%, 0.1wt%, 0.2wt%, 0.4wt%, 0.5wt%, 0.8wt%, 1.0wt%, 5.0wt%, 10.0wt%).

[0073] 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.

[0074] 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 are certain concentrations of polymerization monomers and hydrogen in the environment, so the polymerization reaction can continue. The present invention uses 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 0.1-50 meter long connecting pipeline, and then obtain the final product containing ultra-high molecular weight components after catalyst deactivation and degassing.

[0075] During the second stage polymerization, adding a certain amount of external electron donor D1 while adding the hydrogenation catalyst can effectively adjust the aluminum-silicon ratio of the system, further adjust the isotacticity of the product and further increase the molecular weight of the product. In the mixture of the hydrogenation catalyst and the external electron donor, the hydrogenation catalyst is used to remove the hydrogen (chain transfer agent) remaining in the product stream (powder) discharged from the reactor of the first stage of polymerization, so that propylene continues to polymerize under nearly hydrogen-free conditions to generate an ultra-high molecular weight polypropylene component (UHWMPP); the external electron donor is used to adjust the isotacticity of the propylene continued reaction to generate the ultra-high molecular weight polypropylene component (UHWMPP) and further increase the molecular weight of the product. The present invention unexpectedly found that the introduction of the external electron donor D1 did not show any signs of changing the hydrogenation efficiency of the hydrogenation catalyst.

[0076] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0077] By adjusting the addition position of the hydrogenation catalyst and the external electron donor mixture, the residence time of the material in the additional polymerization reaction place such as the discharge pipeline can be flexibly adjusted, and the generation amount of the ultra-high molecular weight polypropylene component can be flexibly adjusted, so as to control the proportion of the ultra-high molecular weight component in the final polypropylene product, and avoid 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 further the isotacticity of the ultra-high molecular weight polypropylene component can be flexibly adjusted; by adjusting the amount of hydrogenation catalyst, the molecular weight of the ultra-high molecular weight polypropylene component can be adjusted to make its molecular weight MW reach 10,000,000 and above; thus, a series of polypropylene products containing ultra-high molecular weight polypropylene components and having different compositions can be prepared;

[0078] Controlling the amount of hydrogenation catalyst and the amount of alkyl aluminum therein within a suitable 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 the catalyst residue in the product;

[0079] The test results of high-temperature gel permeation chromatography (GPC) show that the final product contains a certain content of UHWMPP component, and the molecular weight distribution of the product is slightly broadened; the UHWMPP component content is low, which 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 extrusion foaming, coating, blow molding and thermoforming. DETAILED DESCRIPTION

[0080] 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 embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. For those who do not specify specific conditions in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer.

[0081] <Source of raw materials>

[0082] 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 3.0wt%; the catalyst B used was prepared according to Example 3 described in patent application CN101054424A, and the Ti content in the catalyst was 2.4wt%.

[0083] In each embodiment and comparative example, the preparation step of the titanocene hydrogenation catalyst used is: under a nitrogen atmosphere, titanocene dichloride and triethylaluminum (triethylaluminum is present in a 1.0 mol / L n-hexane solution) are mixed at different molar ratios (such as 1:5.5 to 1:10) at room temperature for at least 24 hours to prepare multiple groups of mixed liquids, i.e., titanocene hydrogenation catalysts; then, 1.0 ml of each mixed liquid is taken, 33 ml of n-hexane is added to dilute and set aside.

[0084] Preparation of external electron donor solution: Take different types of external electron donors and prepare 0.50 M hexane solutions for later use.

[0085] The hydrogenation catalyst and the external electron donor can be separately injected into the polymerization reaction device and mixed online, or they can be mixed evenly in proportion and then injected into the polymerization reaction device.

[0086] In each embodiment and comparative example, the polymer was tested for performance by the following test methods:

[0087] (1) Melt flow rate (MFR): tested according to ASTM D1238;

[0088] (2) Xylene soluble matter content XS: The content was determined using a fully automatic xylene soluble matter analyzer (CRYSTEX QC) from Polymer Char.

[0089] (3) Molecular weight and its distribution: detected by high temperature gel permeation chromatography (GPC-IR6) of Polymer Char Company;

[0090] (4) Melt strength: tested using RH7-2 capillary rheometer + balance from Malvern Instruments;

[0091] (5) Tensile strength: tested in accordance with GB / T 1040.2-2006;

[0092] (6) Flexural strength: tested in accordance with GB / T 9341-2008;

[0093] (7) Impact test: Tested in accordance with GB / T 1843-2008.

[0094] In the following embodiments 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 and material concentration, etc. in the pipeline outside the reactor or in the second and 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 of reaction to simulate the polymerization reaction in industrial production after adding a hydrogenation catalyst and an external electron donor in the first polymerization reactor and the discharge pipeline attached to the first polymerization reactor, or in the second and subsequent polymerization reactors connected in series with the first polymerization reactor: that is, the first stage polymerization reaction of the single reactor corresponds to the normal polymerization reaction in the first reactor in the simulation of industrial production, and the second stage polymerization reaction of the single reactor corresponds to the polymerization reaction after adding a hydrogenation catalyst and an external electron donor in the discharge pipeline attached to the industrial production device or in the second and subsequent polymerization reactors connected in series with the first polymerization reactor; the situation of introducing a mixture of a hydrogenation catalyst and an external electron donor in the discharge pipeline outside the industrial production device or in the second and subsequent polymerization reaction devices connected in series is simulated by using a mixture of a hydrogenation catalyst and an external electron donor in the second stage polymerization reaction of the single reactor.

[0095] Example 1

[0096] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0097] (1) First, the reactor was purged with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, 2.2 L of liquid propylene and 0.125 mol of hydrogen were added in sequence at room temperature, and the temperature was heated to 70°C;

[0098] Before the temperature of the reactor reaches 70° C., 2.0 ml of a 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 temperature of the reactor reaches 70° C., the mixture is injected into the reactor through a catalyst feed pipe and the reaction timer is started; a first stage polymerization reaction is carried out to prepare a stream containing polypropylene component I;

[0099] (2) After the reaction has been going on for 60 minutes, 25.5 ml (concentration of 4.9×10 -6 mol / ml) of a mixed solution of a titanocene hydrogenation catalyst and 1.5 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 external electron donor is 1:1), the temperature is maintained at 70° C., and the reaction time is started to simulate that the material stream containing the polypropylene component I continues 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 (i.e., the material stream containing the polypropylene component I is simulated to stay in the pipeline outside the polymerization reactor in step (1), or in the second or more polymerization reactors connected in series with the polymerization reactor in step (1) for 5 minutes);

[0100] Then, the unreacted materials are 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;

[0101] (3) After taking out the propylene polymer product, vacuum drying was performed 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.

[0102] Example 2

[0103] The method for producing the 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.

[0104] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0105] Example 3

[0106] 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), and the polymerization time is still 5 minutes.

[0107] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0108] Comparative Example 1

[0109] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0110] (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;

[0111] Before the temperature of the reactor reaches 70°C, 2.0 ml of a 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 temperature of the reactor reaches 70°C, the mixture is injected into the reactor through the catalyst feed tube and the reaction timer is started;

[0112] (2) After 65 minutes of reaction, the unreacted materials were vented, the temperature was lowered, and the reaction was stopped;

[0113] (3) After taking out the propylene polymer product, vacuum drying was performed 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.

[0114] Comparative Example 2

[0115] The production method of propylene polymer is as in Comparative Example 1, except that the timing is set according to step (1) and step (2), and after 90 minutes of reaction, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped;

[0116] (3) After taking out the propylene polymer product, vacuum drying was performed 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.

[0117] Comparative Example 3

[0118] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0119] (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;

[0120] Before the temperature of the reactor reaches 70°C, 2.0 ml of a 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 temperature of the reactor reaches 70°C, the mixture is injected into the reactor through the catalyst feed tube and the reaction timer is started;

[0121] (2) After 60 minutes of reaction, the materials were vented, the temperature was lowered, and the reaction was stopped;

[0122] (3) After taking out the propylene polymer product, vacuum drying was performed at 30°C for 2 hours, and the obtained dried polypropylene product was subjected to performance testing. The test results are shown in Table 1.

[0123] Embodiment 4:

[0124] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0125] (1) First, the reactor was purged with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, 2.2 L of liquid propylene and 0.125 mol of hydrogen were added in sequence at room temperature, and the temperature was heated to 70°C;

[0126] Before the temperature of the reactor reaches 70° C., 2.0 ml of a 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 temperature of the reactor reaches 70° C., the mixture is injected into the reactor through a catalyst feed pipe and the reaction timer is started; a first stage polymerization reaction is carried out to prepare a stream containing polypropylene component I;

[0127] (2) After the reaction has been going on for 60 minutes, 25.5 ml (concentration of 4.9×10 -6 mol / ml) of a mixed solution of a titanocene hydrogenation catalyst and 15 ml of a 0.50M external electron donor D-donor (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., and the reaction time is started to simulate that the stream containing the polypropylene component I continues 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 (i.e., the stream containing the polypropylene component I is simulated to stay in the pipeline outside the polymerization reactor in step (1), or in the second or more polymerization reactors connected in series with the polymerization reactor in step (1) for 5 minutes);

[0128] Then, the unreacted materials are 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;

[0129] (3) After taking out the propylene polymer product, vacuum drying was performed at 30°C for 2 hours, and the obtained dried polypropylene product was subjected to performance testing. The test results are shown in Table 1.

[0130] Example 5

[0131] 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 materials are vented, the temperature is lowered, and the reaction is stopped.

[0132] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 2.

[0133] Example 6

[0134] 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 50:1, that is, a mixed solution of 25.5 ml of titanocene hydrogenation catalyst and 0.03 ml of 0.50 M external electron donor D-donor is used.

[0135] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 2.

[0136] Comparative Example 4:

[0137] The production method of propylene polymer is similar to that of Example 1, except that in step (2), only a hydrogenation catalyst is added and no external electron donor is added, that is, only 25.5 ml of titanocene hydrogenation catalyst solution is added, the temperature is maintained at 70° C., and the reaction time is started to simulate that the material flow containing the polypropylene component I continues 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.

[0138] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0139] Table 1

[0140]

[0141]

[0142]

[0143] It can be seen from the data in Table 1 that, compared with Comparative Examples 1-3 in which no mixture of hydrogenation catalyst and external electron donor was used, the mechanical properties of the product were improved in Comparative Example 4 in which a hydrogenation catalyst was used alone without adding an external electron donor, and the melt strength was increased to 2.4 cN. After the mixture of hydrogenation catalyst and external electron donor was mixed in Examples 1-3, the polymerization activity was improved, the content of xylene solubles in the product was reduced (reflecting the improvement of the isotacticity of the ultrahigh molecular weight component), the mechanical properties were further improved, and the melt strength was increased to 4.3-5.5 cN.

[0144] Table 2

[0145]

[0146]

[0147] It can be seen from the data in Table 2 that the smaller the molar ratio of the alkyl aluminum contained in the hydrogenation catalyst to the external electron donor, that is, the larger the amount of the external electron donor, the lower the xylene soluble content of the product. Compared with Comparative Example 4 in which only the hydrogenation catalyst is added and no external electron donor is used, the performance of the product is significantly improved when the molar ratio of the alkyl aluminum contained in the hydrogenation catalyst to the external electron donor is in the range of 0.1 to 50.

[0148] Embodiment 7:

[0149] The copolymerization of propylene and ethylene was carried out in a 5L stainless steel polymerization reactor:

[0150] (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;

[0151] Before the temperature of the reactor reaches nearly 60° C., ethylene is introduced into the reactor at a flow rate of 20 g / h, and at the same time, 2.0 ml of a 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M D-donor hexane solution and 8.1 mg of a catalyst A prepared in advance are mixed for 5 minutes to form a mixture. When the temperature of the reactor reaches 60° C., the mixture is injected into the reactor through a catalyst feed pipe and a reaction timer is started; a first stage polymerization reaction is carried out to prepare a stream containing a propylene polymer component I;

[0152] (2) After the reaction has been going on for 60 minutes, 4.0 ml (concentration of 4.9×10 -6mol / ml) of a mixed solution of a titanocene hydrogenation catalyst and 0.24 ml of a 0.50M external electron donor D-donor (the molar ratio of the alkyl aluminum in the hydrogenation catalyst to the external electron donor in the mixed solution is 1:1), the temperature is maintained at 60° C., and the reaction timing is started to simulate that the stream containing the propylene polymer component I continues 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 10 minutes (that is, the stream containing the polypropylene component I stays in the pipeline outside the polymerization reactor in step (1), or in the second or more polymerization reactors connected in series with the polymerization reactor in step (1) for 10 minutes);

[0153] Then, the unreacted materials are 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;

[0154] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the obtained dried polypropylene product was tested. The test results are shown in Table 3.

[0155] Embodiment 8:

[0156] The method for producing 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 a hydrogenation catalyst and an external electron donor D-donor in step (2) is changed to 30 minutes.

[0157] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 3.

[0158] Embodiment 9:

[0159] The method for producing the 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.

[0160] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 3.

[0161] Comparative Example 5:

[0162] The copolymerization of propylene and ethylene was carried out in a 5L stainless steel polymerization reactor:

[0163] (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;

[0164] Before the temperature of the reactor reaches nearly 60°C, ethylene is introduced into the reactor at a flow rate of 20 g / h, and at the same time, 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 reaches 60°C, the mixture is injected into the reactor through a catalyst feed pipe and the reaction timer is started;

[0165] (2) After the reaction has been carried out for 60 minutes, the unreacted material is discharged, the temperature is lowered, and the reaction is stopped;

[0166] (3) After taking out the propylene polymer product, it was vacuum dried at 30°C for 2 hours, and the performance of the obtained dried polypropylene product was tested. The test results are shown in Table 3.

[0167] Table 3

[0168]

[0169]

[0170] It can be seen from the data in Table 3 that, compared with Comparative Example 5, when random copolymerization of propylene and ethylene is carried out, 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 accordingly.

[0171] Embodiment 10:

[0172] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0173] (1) First, the reactor was purged with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, 2.2 L of liquid propylene and 0.125 mol of hydrogen were added in sequence at room temperature, and the temperature was heated to 70°C;

[0174] Before the temperature of the reactor reaches 70° C., 2.0 ml of a 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 temperature of the reactor reaches 70° C., the mixture is injected into the reactor through a catalyst feed pipe and the reaction timer is started; a first stage polymerization reaction is carried out to prepare a stream containing polypropylene component I;

[0175] (2) After the reaction has been going on 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 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 more 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 more polymerization reactors connected in series with the polymerization reactor of step (1) for 5 minutes);

[0176] Then, the unreacted materials are 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;

[0177] (3) After taking out the propylene polymer product, vacuum drying was performed at 30° C. for 2 hours, and the performance of the obtained dried polypropylene product was tested. The test results are shown in Table 4.

[0178] Embodiment 11:

[0179] 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.

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

[0181] Embodiment 12:

[0182] The method for producing 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 (i.e., the ratio of hydrogenation catalyst to total hydrogen molar number is 1:5000).

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

[0184] Comparative Example 6:

[0185] The production method of the propylene polymer is the same as that of Example 10, except that the molar ratio of the alkylaluminum to the titanocene in the hydrogenation catalyst is 1.5.

[0186] The obtained dried polypropylene product was subjected to performance tests. The test results are shown in Table 4.

[0187] Comparative Example 7:

[0188] The production method of the propylene polymer is the same as that of Example 10, except that the molar ratio of the alkylaluminum to the titanocene in the hydrogenation catalyst is 4.

[0189] The obtained dried polypropylene product was subjected to performance tests. The test results are shown in Table 4.

[0190] Table 4

[0191]

[0192] As can be seen from the data in Table 4, when the molar ratio of alkyl aluminum to titanocene in the hydrogenation catalyst is less than or equal to 4, alkyl aluminum cannot completely dissolve titanocene, and at this time titanocene cannot effectively play the role of hydrogenation; when the molar ratio of alkyl aluminum to titanocene is 1.5, there is obvious precipitation and it cannot be used for polymerization reaction. When the molar ratio of alkyl aluminum to titanocene in the hydrogenation catalyst is 8 or 10, alkyl aluminum is slightly excessive, and the product melt index is only slightly increased, which can be used to play the role of hydrogenation catalyst. When the molar ratio of hydrogenation catalyst / total hydrogen (mol / mol) is 1 / 5000, the hydrogenation effect is better than 1 / 10000, and the obtained polymer product melt index is lower.

[0193] Embodiment 13:

[0194] The polymerization reaction was carried out in a 5L stainless steel polymerization reactor:

[0195] (1) First, the reactor was purged with purified nitrogen (water <1 ppm, oxygen <1 ppm); then, 2.2 L of liquid propylene and 0.048 mol of hydrogen were added sequentially at room temperature and heated to 70°C;

[0196] Before the temperature of the reactor reaches 70° C., 2.0 ml of a 0.50 M triethylaluminum heptane solution, 0.4 ml of a 0.50 M TEOS hexane solution and 8.1 mg of a catalyst B are mixed for 5 minutes to form a mixture. When the temperature of the reactor reaches 70° C., the mixture is injected into the reactor through a catalyst feed pipe and a reaction timer is started; a first stage polymerization reaction is carried out to prepare a feed stream containing a polypropylene component I;

[0197] (2) After the reaction has been going on 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 0.50M external electron donor D-donor (in the mixed solution, the molar ratio of the alkyl aluminum to the titanocene in the hydrogenation catalyst is 6; the molar ratio of the alkyl aluminum to the external electron donor is 1:1), 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 60 minutes (that is, the flow containing the polypropylene component I is simulated to stay in the pipeline outside the polymerization reactor in step (1) or in the second or more polymerization reactors connected in series with the polymerization reactor in step (1) for 60 minutes);

[0198] Then, the unreacted materials are 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;

[0199] (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.

[0200] Comparative Example 8:

[0201] The method for producing the propylene polymer is similar to that of Example 13, except that only a hydrogenation catalyst is added in step (2) and no external electron donor is added.

[0202] The dried polypropylene product was subjected to performance tests. The test results are shown in Table 5.

[0203] Table 5

[0204]

[0205]

[0206] It can be seen from the data in Table 5 that, compared with Comparative Example 8, in Example 13, TEOS is used in the first polymerization stage, and a mixture of a hydrogenation catalyst and an external electron donor D-donor is used in the second polymerization stage, which can significantly reduce the xylene soluble content of the product (i.e., reflecting the improvement of the isotacticity of the product), which is reduced from 5.38% to 5.02%, indicating that the isotacticity of the ultra-high molecular weight polypropylene component can be adjusted by adding a hydrogenation catalyst in the second polymerization stage while using an external electron donor.

[0207] Therefore, the product of the present invention contains a small amount of ultra-high molecular weight components to significantly improve the performance of polypropylene, and the isotacticity of the ultra-high molecular weight polypropylene component can be adjusted by using a hydrogenation catalyst and an external electron donor mixture. The average molecular weight Mn (logMW ≥ 7) of the UHMWPP produced in each embodiment is much higher than the peak molecular weight Mp of the obtained product, and the ratio of Mn (logMW ≥ 7) / Mp is higher than 10.

[0208] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the spirit 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 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, characterized in that The melt 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, 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 claim 6, 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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