A catalyst system for producing a broad molecular weight distribution high melt strength polypropylene and its use

Abstract

The application provides a catalyst system for preparing a wide-molecular-weight-distribution high-melt-strength polyolefin and application thereof, and belongs to the technical field of olefin polymerization. The catalyst system comprises the following components and reaction products thereof: A, a catalyst component; B, an organic aluminum compound; and C, an external electron donor compound; the external electron donor compound comprises a silane external electron donor compound, a cyano acid ester external electron donor compound and a diol ester external electron donor compound. The application uses a specific catalyst component containing a cyano acid ester and a diol ester electron donor compound, adds a silane external electron donor and uses the cyano acid ester and the diol ester external electron donor in cooperation to form the catalyst system, and the prepared polymer has a wide molecular weight distribution and a high proportion of ultralarge molecules through a special preparation process. The method provided by the application is simple, easy to industrialize and capable of preparing a high-performance product, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to a catalyst system for preparing a wide molecular weight distribution high melt strength polypropylene and its application, belonging to the technical field of olefin polymerization. BACKGROUND

[0002] The conventional linear isotactic polypropylene (iPP) with semi-crystalline type has a relatively narrow molecular weight distribution and low melt strength, which is difficult to be hot formed and has limited application fields. The high melt strength polypropylene has been widely used in hot forming, foaming, extrusion coating and other fields due to its high melt strength, yield strength, bending modulus, heat distortion temperature, melting point, crystallization temperature and short crystallization time. In these applications, the high melt strength polypropylene can be used for hot forming to make the product demold at a higher temperature, shorten the forming cycle and improve the yield; in the foaming process, it can resist the rupture of the microcell wall, improve the foaming ratio, reduce the density and improve the closed cell rate; in the extrusion coating process, it shows a faster coating speed and smaller necking. Therefore, the high melt strength polypropylene is the research focus of the polypropylene production technology innovation and the technical bottleneck of the expansion and high performance of the polypropylene application field.

[0003] Currently, the conventional methods for improving the melt strength of polypropylene include polymerization technology, reactive extrusion and irradiation modification. The polymerization technology includes one-step method, two-step method, copolymerization method and in-situ polymerization method. The foreign patent technology uses the CGC (constrained geometry catalysts) constrained geometry catalyst of Chisso Company to make the long chain branching of the polymer in US 6225432B1; the Chinese invention patents CN200710179266.7 and CN 201010147765.X graft copolymerize propylene with α, ω-non-conjugated diene, styrene and substituted styrene monomers (T-type monomers) to form long chain branching. The polymerization technology method can accurately control the length of the branch and the distribution of the branching structure in the main chain of the polymer. In the preparation of high melt strength polypropylene with Ziegler-Natta catalyst, the introduction of other monomers, or the increase of more reactors and the change of the material types of different reactors increase the reaction raw materials, increase the treatment processes such as recovery and purification, and complicate the process. The practicability of the long chain branching structure based on the metallocene catalyst system still needs to be improved.

[0004] The reactive extrusion method produces high melt strength polypropylene by adding peroxide and other multifunctional reactive monomers to polypropylene. That is, peroxide and tertiary monomers are added to polypropylene powder, and long-chain branched polypropylene is generated after reaction, thereby improving the melt strength of polypropylene. The method of reactive extrusion for producing high melt strength polypropylene requires the addition of various chemical components, which increases production costs and also causes fluctuations in product quality due to the control of the amount added. More importantly, the additives exist in the polymer for a long time, which causes the gradual deterioration of the yellow index and physical properties of the product, and some added compounds are toxic and cannot be used for food and drug contact. Many research institutions at home and abroad use this method to produce high melt strength polypropylene with long-chain branched structure.

[0005] Radiation modification is to irradiate polypropylene with a suitable radiation source and dose to crosslink the polypropylene molecular chain to produce long-chain branched structure, thereby improving the melt strength of polypropylene. In the selection of radiation source, electron beams generated by electron accelerators or gamma rays generated by 60Co are currently mainly used.

[0006] In summary, it is necessary to develop high-performance high melt strength polypropylene with economic and environmentally friendly production technology. Among them, the catalyst in-situ generation method is the most suitable, environmentally friendly, simple and stable industrial production method with the best product performance. This method is to prepare polypropylene with wide molecular weight distribution by using a specific catalyst reactor, and to realize the high melt strength of the final polymer. It usually selectively adds hydrogen-sensitive external electron donors at different polymerization stages, and adjusts the hydrogen concentration in different reactors to control the molecular weight, so as to prepare polypropylene containing both high molecular weight fraction and low molecular weight fraction, wherein the high molecular weight fraction ensures the melt strength of the final polymer, and the wide molecular weight distribution ensures the good processing performance. SUMMARY

[0007] In order to solve the problems in the prior art, the present application provides a catalyst system for preparing polypropylene with wide molecular weight distribution and high melt strength and its application. The present application adopts a Ziegler-Natta catalyst component containing internal electron donors of cyano acid ester and diol ester and / or other types of compounds. When the catalyst is composed, by reasonably compounding three different types of external electron donors of silane, cyano acid ester and diol ester, a special catalyst system is formed. The method of direct polymerization in the reactor obtains polypropylene with wide molecular weight distribution and containing more ultra-high molecular weight fraction, and the polymer has ultra-high melt strength.

[0008] The Ziegler-Natta catalyst component used according to the present application contains 1.0 wt% to 5.0 wt% of titanium element, 0.5 wt% to 10.0 wt% of diol ester type internal electron donor compound, 3.0 wt% to 20.0 wt% of cyano acid ester type internal electron donor compound, and the molar ratio of the diol ester type internal electron donor compound to the cyano acid ester type internal electron donor compound is 0.025:1 to 0.8:1, based on the total weight of the catalyst component; preferably, 1.3 wt% to 4.0 wt% of titanium element, 0.8 wt% to 6 wt% of diol ester type internal electron donor compound, 5 wt% to 15 wt% of cyano acid ester type internal electron donor compound, and the molar ratio of the diol ester type internal electron donor compound to the cyano acid ester type internal electron donor compound is (0.05 to 0.6):1, based on the total weight of the catalyst component.

[0009] Optionally, the cyano acid ester type internal electron donor compound has the structure shown in general formula (I):

[0010]

[0011] In general formula (I), R 1 and R 2 are independently selected from linear C1-C4 alkyl, branched C1-C4 alkyl; R 3 and R 4 are independently selected from C3-C6 isoalkyl, C3-C6 secondary alkyl and C3-C6 cycloalkyl.

[0012] Optionally, the cyano acid ester type internal electron donor compound is selected from cyano butanedioic acid ester compounds, preferably 2,3-di-non-linear alkyl-2-cyano butanedioic acid diester compounds, more preferably 2,3-diisopropyl-2-dicyano butanedioic acid dimethyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid diethyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid di-n-propyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid diisopropyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid di-n-butyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid diisobutyl ester, 2,3-diisopropyl-2-cyano butanedioic acid-1-methyl-4-ethyl ester (R 1 = methyl, R 2 = ethyl), 2,3-diisopropyl-2-cyano butanedioic acid-1-ethyl-4-methyl ester (R 1 = ethyl, R 2 = methyl), 2,3-diisopropyl-2-cyano butanedioic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2= ethyl), 2,3-diisopropyl-2-cyanosuccinic acid 1-ethyl-4-n-butyl ester (R 1 = ethyl, R 2 = n-butyl), 2,3-diisobutyl-2-dicyanosuccinic acid dimethyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid diethyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid diisopropyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid di-n-butyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid diisobutyl ester, 2,3-diisobutyl-2-cyanosuccinic acid 1-methyl-4-ethyl ester (R 1 = methyl, R 2 = ethyl), 2,3-diisobutyl-2-cyanosuccinic acid 1-ethyl-4-methyl ester (R 1 = ethyl, R 2 = methyl), 2,3-diisobutyl-2-cyanosuccinic acid 1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 = ethyl), 2,3-diisobutyl-2-cyanosuccinic acid 1-ethyl-4-n-butyl ester (R 1 = ethyl, R 2 = n-butyl), 2,3-diisobutyl-2-dicyanosuccinic acid dimethyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid diethyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid diisopropyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid di-n-butyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid diisobutyl ester, 2,3-diisobutyl-2-cyanosuccinic acid 1-methyl-4-ethyl ester (R 1 = methyl, R 2 = ethyl), 2,3-diisobutyl-2-cyanosuccinic acid 1-ethyl-4-methyl ester (R 1 = ethyl, R 2 = methyl), 2,3-diisobutyl-2-cyanosuccinic acid 1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 = ethyl), 2,3-diisobutyl-2-cyanosuccinic acid 1-ethyl-4-n-butyl ester (R 1 = ethyl, R 2= n-Butyl), dimethyl 2,3-dicyclopentyl-2-dicyanosuccinate, diethyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclopentyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclopentyl-2-cyanosuccinate (R 1 =Methyl, R 2 =Ethyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 =Methyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-n-butyl ester-4-ethyl ester (R 1 = n-Butyl, R 2 =Ethyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-Butyl), dimethyl 2,3-dicyclohexyl-2-dicyanosuccinate, diethyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclohexyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate (R 1 =Methyl, R 2 =Ethyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 =Methyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-n-butyl ester-4-ethyl ester (R 1 = n-Butyl, R 2 =Ethyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 At least one of (n-butyl). More preferably, diethyl 2,3-diisopropyl-2-dicyanosuccinate, di-n-propyl 2,3-diisopropyl-2-dicyanosuccinate, diisopropyl 2,3-diisopropyl-2-dicyanosuccinate, di-n-butyl 2,3-diisopropyl-2-dicyanosuccinate, and diisobutyl 2,3-diisopropyl-2-dicyanosuccinate. The above-mentioned internal electron-donating compounds can be used alone or in combination.

[0013] Optionally, in the present application, the 2,3-di-non-linear alkyl-2-cyanosuccinic acid diester compound is prepared according to the method disclosed in International Patent Application No. PCT / CN2010 / 000202.

[0014] Optionally, the diol ester internal electron donor compound has a structure shown in general formula (II):

[0015]

[0016] In general formula (II), R1-R6, R 1 ~R 2n are independently selected from hydrogen, halogen, substituted or unsubstituted linear or branched C1-C 20 alkyl, substituted or unsubstituted C3-C 20 cycloalkyl, substituted or unsubstituted C6-C 20 aryl, C7-C 20 alkylaryl, substituted or unsubstituted C7-C 20 aralkyl, substituted or unsubstituted C2-C 10 alkenyl, substituted or unsubstituted C 10 ~C 20 fused ring aryl, or substituted or unsubstituted C 10 ~C 20 ester group.

[0017] Optionally, in general formula (II), R1 and R2 are not hydrogen, R3-R6 and R 1 ~R 2n any one of the groups optionally contains one or several heteroatoms as a substitute for carbon atoms or hydrogen atoms or both, the heteroatoms being selected from nitrogen, oxygen, sulfur, silicon, phosphorus or halogen atoms, R3-R6 and R 1 ~R 2n one or more of the groups optionally form a ring with each other, and n is an integer from 0 to 10.

[0018] In the diol ester internal electron donor compound shown in general formula (II), a compound shown in general formula (III) is preferably contained:

[0019]

[0020] In general formula (III), R1-R6, R 1 ~R 2 are independently selected from hydrogen, halogen atoms, linear or branched C1-C 20 alkyl, C3-C 20 cycloalkyl, C6-C 20 aryl, C7-C 20 alkylaryl, or C7-C 20 aralkyl.

[0021] The internal electron donor compound in the above-mentioned solid catalyst component of the present application is disclosed in Chinese patents CN1436766A and CN1436796A, the relevant contents of which are incorporated herein by reference.

[0022] Alternatively, the diol ester internal electron donor compound of the general formula (III) includes 2-ethyl-1,3-propanediol dibenzoate, 2-propyl-1,3-propanediol dibenzoate, 2-isopropyl-2-isopentyl-1,3-propanediol dibenzoate, 1,3-butanediol dimethylbenzoate, 2-methyl-1,3-butanediol di-m-chlorobenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, 1,3-pentanediol neopentanoate, 2,4-pentanediol dibenzoate, 2-methyl-1,3-pentanediol benzoate cinnamate, 2,2-dimethyl-1,3-pentanediol dibenzoate, 2,4-heptanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, 4-ethyl-3,5-heptanediol dibenzoate, etc., preferably 2,4-pentanediol dibenzoate and 4-ethyl-3,5-heptanediol dibenzoate.

[0023] The present application also relates to a catalyst system for the polymerization of olefins, comprising the following components and the reaction products thereof:

[0024] A. the above-mentioned catalyst component of the present application;

[0025] B. an organic aluminum compound;

[0026] C. an external electron donor compound;

[0027] The external electron donor compound includes silane-based external electron donor compounds, cyano acid ester-based external electron donor compounds and diol ester-based external electron donor compounds.

[0028] Alternatively, the organic aluminum compound has the general formula AlR n X 3-n wherein R is hydrogen or a hydrocarbon group having 1-20 carbon atoms; X is halogen; and n is an integer satisfying 0 < n ≤ 3.

[0029] Alternatively, the organic aluminum compound is selected from the group consisting of trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, ethylaluminum dichloride, etc., preferably triethylaluminum and triisobutylaluminum.

[0030] Alternatively, the ratio of the organic aluminum compound to the catalyst component is 5-5000 in terms of the molar ratio of aluminum to titanium, preferably 20-500.

[0031] Optionally, the silane-based external electron donor compound is selected from at least one of compounds having general formula of R1R2 m Si(OR3) 3-m , R4 n Si(OR5) 4-n and R6R7Si(OR8)2, or a mixture of any two or more thereof in any ratio, wherein m, n are independently an integer from 0 to 2, R1and R2are the same or different C1-C 10 linear or branched or cyclic aliphatic group, R3, R4, R5, R6and R8are the same or different C1-C3linear aliphatic group, and R7is a C3-C6branched or cyclic aliphatic group.

[0032] Optionally, specific examples of the silane-based external electron donor compound include, but are not limited to, tetramethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, n-propyltrimethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, phenyltrimethoxysilane, dicyclopentyldimethoxysilane, and the like.

[0033] Optionally, the molar ratio of aluminum element to silicon element of the organoaluminum compound to the silane-based external electron donor compound is 0.5:1 to 200:1, preferably 1:1 to 100:1.

[0034] Optionally, the cyano acid ester-based external electron donor compound has a structure shown in general formula (I):

[0035]

[0036] In general formula (I), R 1 and R 2 are independently selected from linear C1-C4alkyl, branched C1-C4alkyl; R 3 and R 4 are independently selected from C3-C6isoalkyl, C3-C6secondary alkyl and C3-C6cyclic alkyl.

[0037] Optionally, the cyano acid ester external electron donor compound is selected from the group consisting of cyano succinic acid ester compounds, preferably 2,3-di-nonlinear alkyl-2-cyano succinic acid diester compounds, more preferably 2,3-diisopropyl-2-dicyano succinic acid dimethyl ester, 2,3-diisopropyl-2-dicyano succinic acid diethyl ester, 2,3-diisopropyl-2-dicyano succinic acid di-n-propyl ester, 2,3-diisopropyl-2-dicyano succinic acid diisopropyl ester, 2,3-diisopropyl-2-dicyano succinic acid di-n-butyl ester, 2,3-diisopropyl-2-dicyano succinic acid diisobutyl ester, 2,3-diisopropyl-2-cyano succinic acid-1 -methyl-4-ethyl ester (R 1 = methyl, R 2 = ethyl), 2,3-diisopropyl-2-cyano succinic acid-1 -ethyl-4-methyl ester (R 1 = ethyl, R 2 = methyl), 2,3-diisopropyl-2-cyano succinic acid-1 -n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 = ethyl), 2,3-diisopropyl-2-cyano succinic acid-1 -ethyl-4-n-butyl ester (R 1 = ethyl, R 2 = n-butyl), 2,3-diisobutyl-2-dicyano succinic acid dimethyl ester, 2,3-diisobutyl-2-dicyano succinic acid diethyl ester, 2,3-diisobutyl-2-dicyano succinic acid di-n-propyl ester, 2,3-diisobutyl-2-dicyano succinic acid diisopropyl ester, 2,3-diisobutyl-2-dicyano succinic acid di-n-butyl ester, 2,3-diisobutyl-2-dicyano succinic acid diisobutyl ester, 2,3-diisobutyl-2-cyano succinic acid-1 -methyl-4-ethyl ester (R 1 = methyl, R 2 = ethyl), 2,3-diisobutyl-2-cyano succinic acid-1 -ethyl-4-methyl ester (R 1 = ethyl, R 2 = methyl), 2,3-diisobutyl-2-cyano succinic acid-1 -n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 = ethyl), 2,3-diisobutyl-2-cyano succinic acid-1 -ethyl-4-n-butyl ester (R 1 = ethyl, R 2= n-Butyl), dimethyl 2,3-disec-butyl-2-dicyanosuccinate, diethyl 2,3-disec-butyl-2-dicyanosuccinate, di-n-propyl 2,3-disec-butyl-2-dicyanosuccinate, diisopropyl 2,3-disec-butyl-2-dicyanosuccinate, di-n-butyl 2,3-disec-butyl-2-dicyanosuccinate, diisobutyl 2,3-disec-butyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-disec-butyl-2-cyanosuccinate (R 1 =Methyl, R 2 =Ethyl), 2,3-disec-butyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 =Methyl), 2,3-disec-butyl-2-cyanosuccinic acid-1-n-butyl ester-4-ethyl ester (R 1 = n-Butyl, R 2 =Ethyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 = n-Butyl), dimethyl 2,3-dicyclopentyl-2-dicyanosuccinate, diethyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclopentyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclopentyl-2-cyanosuccinate (R 1 =Methyl, R 2 =Ethyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 =Methyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-n-butyl ester-4-ethyl ester (R 1 = n-Butyl, R 2 =Ethyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-Butyl), dimethyl 2,3-dicyclohexyl-2-dicyanosuccinate, diethyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclohexyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate (R 1 =Methyl, R 2= ethyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester (R 1 = ethyl, R 2 = methyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 = ethyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-ethyl-4-n-butyl ester (R 1 = ethyl, R 2 = n-butyl). Among them, preferably are 2,3-diisopropyl-2-dicyano butanedioic acid diethyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid di-n-propyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid diisopropyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid di-n-butyl ester, 2,3-diisopropyl-2-dicyano butanedioic acid diisobutyl ester. The above-mentioned external electron donor compounds can be used alone or in combination.

[0038] Optionally, in the present application, the 2,3-di-non-linear alkyl-2-cyanosuccinic acid diester compound is prepared by the method disclosed in International Patent Application No. PCT / CN2010 / 000202.

[0039] Optionally, the molar ratio of aluminum element to cyano group of the organic aluminum compound and the cyano acid ester external electron donor compound is 0.5:1-100:1, preferably 1:1-50:1.

[0040] Optionally, the diol ester external electron donor compound has the structure shown in general formula (II):

[0041]

[0042] General formula (II), wherein R1-R6, R 1 ~R 2n are independently selected from hydrogen, halogen, substituted or unsubstituted linear or branched C1-C 20 alkyl, substituted or unsubstituted C3-C 20 cycloalkyl, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C7-C 20 alkylaryl, substituted or unsubstituted C7-C 20 aralkyl, substituted or unsubstituted C2-C 10 alkenyl, substituted or unsubstituted C 10 ~C 20 fused ring aryl or substituted or unsubstituted C 10 ~C 20 ester group.

[0043] Optionally, R1 and R2 are not hydrogen, R3-R6 and R1 ~R 2n optionally containing one or several heteroatoms as a substitute for carbon atoms or hydrogen atoms or both, said heteroatoms being selected from nitrogen, oxygen, sulfur, silicon, phosphorus or halogen atoms, R3~R6and R 1 ~R 2n one or more of the groups optionally form a ring with each other, and n is an integer from 0 to 10.

[0044] In the diol ester external electron donor compound represented by the above general formula (II), a compound represented by the general formula (III) is preferably contained.

[0045]

[0046] In the general formula (III), R1~R6, R 1 ~R 2 are independently selected from hydrogen, halogen atoms, linear or branched C1~C 20 alkyl groups, C3~C 20 cycloalkyl groups, C6~C 20 aryl groups, C7~C 20 alkylaryl groups or C7~C 20 aralkyl groups.

[0047] Alternatively, the above external electron donor compound is disclosed in Chinese patents CN1436766A and CN1436796A, the relevant contents of which are incorporated herein by reference.

[0048] Alternatively, the diol ester external electron donor compound represented by the general formula (III) includes 2-ethyl-1,3-propanediol dibenzoate, 2-propyl-1,3-propanediol dibenzoate, 2-isopropyl-2-isopentyl-1,3-propanediol dibenzoate, 1,3-butanediol dimethylbenzoate, 2-methyl-1,3-butanediol di-m-chlorobenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, 1,3-pentanediol neopentanoate, 2,4-pentanediol dibenzoate, 2-methyl-1,3-pentanediol benzoate cinnamate, 2,2-dimethyl-1,3-pentanediol dibenzoate, 2,4-heptanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, 4-ethyl-3,5-heptanediol dibenzoate, etc., preferably 2,4-pentanediol dibenzoate and 4-ethyl-3,5-heptanediol dibenzoate.

[0049] Alternatively, the diol ester external electron donor compound is added in an amount of 0.5:1~100:1, preferably 1:1~50:1, in terms of the molar ratio of the organoaluminum compound / diol ester external electron donor.

[0050] Optionally, the ratio of the three external electron donor compounds, i.e. the silane-based external electron donor compound, the cyano acid ester-based external electron donor compound and the diol ester-based external electron donor compound, is 1:0.01-100:0.01-100 in terms of molar ratio, preferably 1:0.02-50:0.02-50.

[0051] The present application also provides a method for polymerizing a polyolefin, which comprises contacting one or more olefins, at least one of which is an olefin represented by the general formula CH2=CHR, wherein R is hydrogen or a C1-C6 alkyl group, with the catalyst system provided by the present application under olefin polymerization conditions. The method for polymerizing a polyolefin provided by the present application can be used for homopolymerization of an olefin, or for copolymerization of a plurality of olefins.

[0052] Specific examples of the olefin include, but are not limited to, at least one of ethylene, propylene, 1-n-butene, 1-n-pentene, 1-n-hexene, 1-n-octene and 4-methyl-1-pentene; preferably, the olefin is at least one of ethylene, propylene, 1-n-butene, 4-methyl-1-pentene and 1-n-hexene; more preferably, the olefin is propylene.

[0053] According to the present application, the catalyst solid component, the organoaluminum compound as a cocatalyst and the external electron donor compound can be contacted before contacting the olefin monomer, which is referred to as "precontacting" or "precomplexing" in the industry; or the three components can be added to the olefin monomer separately and then subjected to a polymerization reaction, i.e. without "precontacting". According to the method for polymerizing an olefin provided by the present application, the components in the olefin polymerization catalyst system preferably are subjected to "precontacting". The "precontacting" time is 0.1-60 minutes, preferably 1-40 minutes; the "precontacting" temperature is -20°C-80°C, preferably 0°C-60°C.

[0054] The catalyst system is first subjected to a certain degree of polymerization in the presence of a small amount of olefin monomer to obtain a prepolymerization catalyst, and then the prepolymerization catalyst is further contacted with the olefin monomer to obtain an olefin polymer. This technique is referred to as "prepolymerization" process in the industry, which is helpful to the improvement of catalyst polymerization activity and polymer bulk density, etc. According to the method for polymerizing an olefin provided by the present application, the "prepolymerization" process can be used or not used, and the "prepolymerization" process is preferred. The "prepolymerization" ratio is 1-1000 gPP / gCat when the olefin monomer is propylene, preferably 2-500 gPP / gCat; the "prepolymerization" temperature is -20°C-80°C, preferably 0°C-50°C.

[0055] The polymerization conditions according to the present application for preparing the polyolefin with high melt strength can be conventional conditions in the art. The amount of the catalyst used can be the amount of various catalysts in the prior art.

[0056] The present application also provides a polypropylene with wide molecular weight distribution and high melt strength, wherein the molecular weight distribution Mw / Mn of the polypropylene is 7.0-20.0, and the melt strength of the polypropylene is 0.15-0.70 N.

[0057] The method for preparing the polypropylene comprises contacting propylene monomers with a catalyst system; the catalyst system is selected from at least one of the catalyst systems described above. DETAILED DESCRIPTION

[0058] The present application is specifically illustrated by the following examples, but the present application is not limited to the following examples.

[0059] The test method involved in the present application is as follows:

[0060] (1) Titanium content in the catalyst: tested by 721 spectrophotometer.

[0061] (2) Melt index (MI) of the polymer: determined according to the test standard GB / T 3682-2000.

[0062] (3) Content of internal electron donor (cyano acid ester content) in the catalyst component: determined by Waters 600E liquid chromatograph.

[0063] (4) Activity: catalyst activity = (mass of the prepared polyolefin) g / (mass of the solid component of the catalyst) g.

[0064] (5) Molecular weight distribution MWD (MWD = Mw / Mn) of the polymer: determined by PL-GPC220 with trichlorobenzene as the solvent at 150°C (standard sample: polystyrene, flow rate: 1.0 ml / min, column: 3xPlgel 10um MlxED-B 300x7.5 nm).

[0065] (6) Melt strength: determined by Rheoten melt strength tester produced by Geottfert Werkstoff Pruefmaschinen Company in Germany. The instrument comprises a pair of rollers rotating in opposite directions, and the polymer melt is extruded from a capillary, stretched vertically through the rollers, and the stretching force is determined by a measuring element.

[0066] Example 1

[0067] (1) Preparation of the catalyst component

[0068] The catalyst component was prepared in the manner of patent CN201510707980.3, the titanium content was 3.0%, the 3,5-heptanediol dibenzoate (abbreviated as "S") content was 2.5%, and the 2,3-diisopropyl-2-dicyanobutane diethyl ester (abbreviated as "JS1") content was 13.4%.

[0069] (2) Olefin polymerization

[0070] Using propylene as the olefin, the polymerization was carried out in the following steps:

[0071] In a 5-liter stainless steel autoclave with a stirrer, after replacement with nitrogen, a hexane solution of triethylaluminum (the concentration of triethylaluminum was 0.5 mmol / ml) 5 ml, a hexane solution of the first external electron donor S (the concentration of 3,5-heptanediol dibenzoate was 0.02 mmol / ml) 2.0 ml, anhydrous hexane 10 ml, and solid catalyst component 10 mg were introduced at room temperature in a nitrogen stream, pre-contacted at 6°C for 5 min; a hexane solution of the second external electron donor JS1 (the concentration of JS1 was 0.02 mmol / ml) 3.0 ml was added, pre-contacted at 6°C for 5 min; a hexane solution of the third external electron donor cyclohexyl methyl dimethoxysilane (CHMMS) (the concentration of CHMMS was 0.10 mmol / ml) 1.0 ml was added, pre-contacted at 10°C for 8 min. The autoclave was closed, 1.8 L (standard state) of hydrogen and 2.0 L of liquid propylene were introduced; the stirring was started, the temperature was raised to 70°C in 10 min after pre-polymerization at 10°C for 20 min. After polymerization at 70°C for 2 hours, the stirring was stopped, the un-polymerized propylene monomer was removed, and the polymer was collected.

[0072] Example 2

[0073] (1) Preparation of catalyst component

[0074] The same as example 1.

[0075] (2) Olefin polymerization

[0076] Except that cyclohexyl methyl dimethoxysilane (CHMMS) was replaced by 2,2-diisobutyl-1,3-dimethoxysilane (DIBMP), the rest was the same as example 1.

[0077] Example 3

[0078] (1) Preparation of catalyst component

[0079] The same as example 1.

[0080] (2) Olefin polymerization

[0081] Example 1 except that the cyclohexylmethyldimethoxysilane (CHMMS) was changed to a hexane solution of 2.0 ml and the other conditions were the same as Example 1.

[0082] Example 4

[0083] (1) Preparation of Catalyst Component

[0084] Example 1.

[0085] (2) Olefin Polymerization

[0086] Example 1 except that the first external donor hexane solution was changed from 2.0 ml to 3.0 ml and the second external donor hexane solution was changed from 3.0 ml to 5.0 ml and the other conditions were the same as Example 1.

[0087] Example 5

[0088] (1) Preparation of Catalyst Component

[0089] Example 1.

[0090] (2) Olefin Polymerization

[0091] Example 1 except that the first external donor hexane solution was changed from 2.0 ml to 1.0 ml and the second external donor hexane solution was changed from 3.0 ml to 1.0 ml and the other conditions were the same as Example 1.

[0092] Example 6

[0093] (1) Preparation of Catalyst Component

[0094] Example 1.

[0095] (2) Olefin Polymerization

[0096] Example 1 except that the precontacting time after addition of the first external donor was changed from 5 min to 1 min, the precontacting time after addition of the second external donor was changed from 5 min to 2 min and the precontacting time after addition of the silane was changed from 8 min to 3 min and the other conditions were the same as Example 1.

[0097] Example 7

[0098] (1) Preparation of Catalyst Component

[0099] Example 1.

[0100] (2) Olefin Polymerization

[0101] Example 1 except that the precontacting time after addition of the first external donor was changed from 5 min to 8 min, the precontacting time after addition of the second external donor was changed from 5 min to 10 min and the precontacting time after addition of the third external donor was changed from 8 min to 15 min and the other conditions were the same as Example 1.

[0102] Example 8

[0103] (1) Preparation of catalyst component

[0104] The same as Example 1.

[0105] (2) Polymerization of olefin

[0106] Using propylene as the olefin, polymerization was carried out in the following steps:

[0107] The same as Example 1 except that the prepolymerization time was changed from 20 min to 2 min.

[0108] Example 9

[0109] (1) Preparation of catalyst component

[0110] The same as Example 1.

[0111] (2) Polymerization of olefin

[0112] The same as Example 1 except that the first external electron donor was changed from 3,5-heptanediol dibenzoate (abbreviated as "S") to 2,4-pentanediol dibenzoate (abbreviated as "F").

[0113] Comparative Example 1

[0114] (1) Preparation of catalyst component

[0115] A suspension was prepared from 10 g of alkoxy magnesium and 50 ml of toluene, and 2.5 ml of di-n-butyl phthalate (abbreviated as "DNBP") of the same specifications as in Example 1; in a 300 ml reactor repeatedly purged with high-purity nitrogen, 10 ml of toluene and 90 ml of titanium tetrachloride were added, and the temperature was raised to 80°C, then the prepared suspension was added to the reactor, and after constant temperature for 1 hour, the temperature was raised to 112°C, and constant temperature was maintained for 2 hours, then the liquid was filtered dry. Then 120 ml of toluene and 30 ml of titanium tetrachloride were added and stirred at 110°C for 1 hour, and this process was repeated 3 times, the liquid was filtered off, the obtained solid was washed 4 times with 150 ml of hexane, the liquid was filtered off and dried, and a solid catalyst component was obtained. The titanium content was 2.5%, and the di-n-butyl phthalate content was 13.89%.

[0116] (2) Polymerization of olefin

[0117] Using propylene as the olefin, polymerization was carried out in the following steps:

[0118] In a 5 liter stainless steel autoclave with stirrer, after purging with nitrogen, introduce into the autoclave at room temperature under nitrogen flow, a hexane solution of triethylaluminum (0.5 mmol / ml), 5 ml, a hexane solution of cyclohexylmethyl dimethoxysilane (CHMMS) (0.10 mmol / ml), 1.0 ml, anhydrous hexane, 10 ml, and solid catalyst component, 10 mg, precontact for 8 min at 10°C. Close the autoclave, introduce hydrogen, 1.8 L (standard state) and liquid propylene, 2.0 L; start stirring, after pre-polymerization for 20 min at 10°C, increase the temperature to 70°C within 10 min. After polymerization for 2 hours at 70°C, stop stirring, remove the un-polymerized propylene monomer, and collect the polymer.

[0119] Table 1 Electron donor composition of catalyst system

[0120]

[0121]

[0122] Table 2 Propylene polymerization data

[0123]

[0124]

[0125] From the comparison of the data in the above table, it can be seen that the polymer obtained by using the catalyst system described in the present application has a wide molecular weight distribution, large molecules, and high melt strength.

[0126] In the present application, a Ziegler-Natta catalyst component containing internal electron donors including cyano acid esters and diol esters and / or other types of compounds is used, and by rational compounding of three different types of external electron donors, silanes, cyano acid esters and diol esters, a unique catalyst system is formed, and the polypropylene prepared by using the catalyst system has a wide molecular weight distribution and a high proportion of ultra-large molecules. The ultra-high molecular weight fraction ensures high melt strength, and the wide molecular weight distribution ensures good processing performance of the polymer. The method provided in the present application is simple, easy to industrialize, can prepare high-performance products, and has a broad application prospect.

[0127] Any numerical values recited herein include all values from the lower value and up to the upper value. Values that are recited herein also include values that are "framed" by the recited values. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 25%, 30%, and 35% are expressly enumerated. All integer values are used "open ended" such that "50%" really means "50% to 50%". The same principle applies to ranges recited as being "between" two values. Discrete, non-integer values can be assumed within the stated ranges. These are only a few of the specific examples that are given. In the application, all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this application.

[0128] It is to be understood that the embodiments described above are merely illustrative of the application and do not limit the scope of the application. The application has been described with reference to the example embodiments. Modifications and alterations can occur to others upon reading and understanding the preceding detailed description. It is intended to include all alternatives, modifications and alterations within the scope of the application. While the application has been described with reference to the specific methods, materials and examples described herein, the application is not to be limited by the particulars disclosed above. It is recognized that certain components, entities and / or functions equally well for other, similar applications.

Claims

1. A catalyst system for olefin polymerization, comprising the following components and their reaction products: A. Catalyst components; B. Organoaluminum compounds; C. External electron donor compounds; The external electron donor compounds include silane-based external electron donor compounds, cyanate-based external electron donor compounds, and glycol ester-based external electron donor compounds; The silane-based external electron donor compounds are selected from those with the general formula R1R2. m Si(OR3) 3-m R4 n Si(OR5) 4-n At least one of the compounds of R6R7Si(OR8)2, wherein, m and n are independent integers from 0 to 2, and R1 and R2 are the same or different C1~C1~C2 ... 10 Straight-chain, branched, or cyclic aliphatic groups; R3, R4, R5, R6, and R8 are the same or different C1~C3 straight-chain aliphatic groups; R7 is a C3~C6 branched or cyclic aliphatic group. The cyano ester external electron donor compounds have the structure shown in general formula (Ⅰ): （Ⅰ） In general formula (Ⅰ), R 1 and R 2 Independently selected from straight-chain C1-C4 alkyl groups and branched C1-C4 alkyl groups; R 3 and R 4 Independently selected from C3-C6 isoalkyl, C3-C6 secondary alkyl, and C3-C6 cycloalkyl; The diol ester external electron donor compounds have the structure shown in general formula (II): (II) In general formula (II), R1~R6, R 1 ~R 2n Independently selected from hydrogen, halogen, substituted or unsubstituted straight or branched C1~C 20 Alkyl, substituted or unsubstituted C3~C 20 Cycloalkyl, substituted or unsubstituted C6~C 20 aryl, substituted or unsubstituted C7~C 20 Alkyl, substituted or unsubstituted C7~C 20 Aryl, substituted or unsubstituted C2~C 10 olefinic, substituted or unsubstituted C 10 ~C 20 Fused aryl or substituted or unsubstituted C 10 ~C 20 Ester group; The organoaluminum compound and the silane-based external electron donor compound have a molar ratio of aluminum to silicon of 0.5:1 to 200:

1. The organoaluminum compound and the cyano ester external electron donor compound have a molar ratio of aluminum to cyano group of 0.5:1 to 100:

1. The molar ratio of the organoaluminum compound to the glycol ester external electron donor compound is 0.5:1 to 100:1; The catalyst component contains titanium, and the molar ratio of the organoaluminum compound to the catalyst component is 5 to 5000, based on the ratio of aluminum to titanium.

2. The catalyst system according to claim 1, characterized in that, The organoaluminum compound and catalyst components are in a molar ratio of aluminum to titanium of 20 to 500. And / or, the organoaluminum compound and the silane-based external electron donor compound have a molar ratio of aluminum to silicon of 1:1 to 100:1; And / or, the organoaluminum compound and the cyanate ester external electron donor compound are in a molar ratio of aluminum to cyano group of 1:1 to 50:1; And / or, the molar ratio of the organoaluminum compound to the glycol ester external electron donor compound is 1:1 to 50:1; And / or, the molar ratio of the silane-based external electron donor compound, the cyanate-based external electron donor compound, and the glycol ester-based external electron donor compound is 1:0.01~100:0.01~100.

3. The catalyst system according to claim 2, characterized in that, The molar ratio of the silane-based external electron donor compound, the cyanate-based external electron donor compound, and the glycol ester-based external electron donor compound is 1:0.02~50:0.02~50.

4. The catalyst system according to claim 1 or 2, characterized in that, The silane-based external electron donor compound is selected from at least one of tetramethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, n-propyltrimethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, phenyltrimethoxysilane, and dicyclopentyldimethoxysilane.

5. The catalyst system according to claim 1 or 2, characterized in that, The cyano ester external electron donor compound is selected from cyano succinate compounds.

6. The catalyst system according to claim 5, characterized in that, The cyano ester external electron donor compounds are selected from 2,3-dinon-linear alkyl-2-cyanosuccinate diesters.

7. The catalyst system according to claim 6, characterized in that, The cyanoester-based external electron donor compounds are selected from dimethyl 2,3-diisopropyl-2-dicyanosuccinate, diethyl 2,3-diisopropyl-2-dicyanosuccinate, di-n-propyl 2,3-diisopropyl-2-dicyanosuccinate, diisopropyl 2,3-diisopropyl-2-dicyanosuccinate, di-n-butyl 2,3-diisopropyl-2-dicyanosuccinate, diisobutyl 2,3-diisopropyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-diisopropyl-2-cyanosuccinate, 1-ethyl-4-methyl 2,3-diisopropyl-2-cyanosuccinate, 1-n-butyl-4-ethyl 2,3-diisopropyl-2-cyanosuccinate, and 1-ethyl 2,3-diisopropyl-2-cyanosuccinate. -4-n-Butyl ester, dimethyl 2,3-diisobutyl-2-dicyanosuccinate, diethyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-propyl 2,3-diisobutyl-2-dicyanosuccinate, diisopropyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-butyl 2,3-diisobutyl-2-dicyanosuccinate, 2,3-diisobutyl-2 -Diisobutyl dicyanosuccinate, 2,3-diisobutyl-2-cyanosuccinic acid-1-methyl-4-ethyl ester, 2,3-diisobutyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester, 2,3-diisobutyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester, 2,3-diisobutyl-2-cyanosuccinic acid-1-ethyl-4-n-butyl ester, 2,3 -Dimethyl di-sec-butyl-2-dicyanosuccinate, diethyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-propyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisopropyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-butyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisobutyl 2,3-di-sec-butyl-2-dicyanosuccinate Esters, 1-methyl-4-ethyl 2,3-di-sec-butyl-2-cyanosuccinic acid, 1-ethyl-4-methyl 2,3-di-sec-butyl-2-cyanosuccinic acid, 1-n-butyl-4-ethyl 2,3-di-sec-butyl-2-cyanosuccinic acid, 1-ethyl-4-n-butyl 2,3-dicyclopentyl-2-dicyanocyanate Dimethyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclopentyl-2-dicyanosuccinate, 2,3-dicyclopentyl 2-Cyanosuccinic acid-1-methyl-4-ethyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl-4-n-butyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid dimethyl ester, 2,At least one of the following: diethyl 3-dicyclohexyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclohexyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate, 1-ethyl-4-methyl 2,3-dicyclohexyl-2-cyanosuccinate, 1-n-butyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate, and 1-ethyl-4-butyl 2,3-dicyclohexyl-2-cyanosuccinate.

8. The catalyst system according to claim 1 or 2, characterized in that, In general formula (II), R1 and R2 are not hydrogen, and R3~R6 and R 1 ~R 2n Any group may optionally contain one or more heteroatoms as substitutes for carbon or hydrogen atoms or both, said heteroatoms being selected from nitrogen, oxygen, sulfur, silicon, phosphorus or halogen atoms, R3~R6 and R 1 ~R 2n One or more of the groups may optionally form a ring with each other, where n is an integer from 0 to 10.

9. The catalyst system according to claim 8, characterized in that, The diol ester external electron donor compounds include compounds represented by general formula (III): (III) In general formula (III), R1~R6, R 1 ~R 2 Independently selected from hydrogen, halogen atoms, and straight-chain or branched C1~C atoms 20 Alkyl group, C3~C 20 cycloalkyl, C6~C 20 Aryl, C7~C 20 Alkyl or C7~C 20 Aryl group.

10. The catalyst system according to claim 9, characterized in that, The compounds represented by general formula (III) include at least one of 2-ethyl-1,3-propanediol dibenzoate, 2-propyl-1,3-propanediol dibenzoate, 2-isopropyl-2-isopentyl-1,3-propanediol dibenzoate, 1,3-butanediol dimethylbenzoate, 2-methyl-1,3-butanediol di-m-chlorobenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, 1,3-pentanediol neopentyl ester, 2,4-pentanediol dibenzoate, 2-methyl-1,3-pentanediol cinnamic acid ester, 2,2-dimethyl-1,3-pentanediol dibenzoate, 2,4-heptanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, and 4-ethyl-3,5-heptanediol dibenzoate.

11. The catalyst system according to claim 1 or 2, characterized in that, The general formula of the organoaluminum compound is AlR n X 3-n In the formula, R is a hydrocarbon group with 1 to 20 hydrogen and carbon atoms; X is a halogen; and n is an integer with 0 < n ≤ 3.

12. The catalyst system according to claim 11, characterized in that, The organoaluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, diethylaluminum chloride, and diethylaluminum chloride. And / or, the catalyst component contains titanium, glycol ester internal electron donor compounds, and cyano ester internal electron donor compounds.

13. The catalyst system according to claim 12, characterized in that, Based on the total weight of the catalyst components, it contains 1.0 wt% to 5.0 wt% titanium, 0.5 wt% to 10.0 wt% glycol ester internal electron donor compounds, and 3.0 wt% to 20.0 wt% cyano ester internal electron donor compounds, and the molar ratio of glycol ester internal electron donor compounds to cyano ester internal electron donor compounds is 0.025:1 to 0.8:

1.

14. The catalyst system according to claim 13, characterized in that, Based on the total weight of the catalyst components, it contains 1.3 wt% to 4.0 wt% titanium, 0.8 wt% to 6 wt% glycol ester internal electron donor compounds, and 5 wt% to 15 wt% cyanate internal electron donor compounds, and the molar ratio of glycol ester internal electron donor compounds to cyanate internal electron donor compounds is (0.05 to 0.6):1; And / or, the cyanoester-type internal electron-donating compound has the structure shown in general formula (I): （Ⅰ） In general formula (Ⅰ), R 1 and R 2 Independently selected from straight-chain C1-C4 alkyl groups and branched C1-C4 alkyl groups; R 3 and R 4 It is independently selected from C3-C6 isoalkyl, C3-C6 secondary alkyl and C3-C6 cycloalkyl.

15. The catalyst system according to claim 14, characterized in that, The cyanoester internal electron donor compound is selected from cyanosuccinate compounds.

16. The catalyst system according to claim 15, characterized in that, It is a 2,3-dinon-linear alkyl-2-cyanosuccinic acid diester compound.

17. The catalyst system according to claim 16, characterized in that, Dimethyl 2,3-diisopropyl-2-dicyanosuccinate, diethyl 2,3-diisopropyl-2-dicyanosuccinate, di-n-propyl 2,3-diisopropyl-2-dicyanosuccinate, diisopropyl 2,3-diisopropyl-2-dicyanosuccinate, di-n-butyl 2,3-diisopropyl-2-dicyanosuccinate, 2,3-diisopropyl-2-dicyanosuccinate Diisobutyl succinate, 2,3-diisopropyl-2-cyanosuccinate-1-methyl 4-ethyl ester, 2,3-diisopropyl-2-cyanosuccinate-1-ethyl 4-methyl ester, 2,3-diisopropyl-2-cyanosuccinate-1-n-butyl 4-ethyl ester, 2,3-diisopropyl-2-cyanosuccinate-1-ethyl 4-n-butyl ... Dimethyl isobutyl-2-dicyanosuccinate, diethyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-propyl 2,3-diisobutyl-2-dicyanosuccinate, diisopropyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-butyl 2,3-diisobutyl-2-dicyanosuccinate, diisobutyl 2,3-diisobutyl-2-dicyanosuccinate Ester, 1-methyl-4-ethyl 2,3-diisobutyl-2-cyanosuccinic acid, 1-ethyl-4-methyl 2,3-diisobutyl-2-cyanosuccinic acid, 1-n-butyl-4-ethyl 2,3-diisobutyl-2-cyanosuccinic acid, 1-ethyl-4-n-butyl 2,3-diisobutyl-2-cyanosuccinic acid, 1-ethyl-4-n-butyl 2,3-disec-butyl-2- Dimethyl dicyanosuccinate, diethyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-propyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisopropyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-butyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisobutyl 2,3-di-sec-butyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-di-sec-butyl-2-dicyanosuccinate, 1-ethyl-4-methyl 2,3-di-sec-butyl-2-dicyanosuccinate, 1-n-butyl-4-ethyl 2,3-di-sec-butyl-2-dicyanosuccinate, 1-ethyl-4-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinic acid Dimethyl ester, diethyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclopentyl-2-dicyanosuccinate, 2,3-dicyclopentyl-2 - Cyanosuccinic acid-1-methyl-4-ethyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl-4-n-butyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid dimethyl ester, 2,At least one of the following: diethyl 3-dicyclohexyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclohexyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate, 1-ethyl-4-methyl 2,3-dicyclohexyl-2-cyanosuccinate, 1-n-butyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate, 1-n-ethyl-4-butyl 2,3-dicyclohexyl-2-cyanosuccinate; And / or, the diol ester internal electron-donating compound has the structure shown in general formula (II): (II) In general formula (II), R1~R6, R 1 ~R 2n Independently selected from hydrogen, halogen, substituted or unsubstituted straight or branched C1~C 20 Alkyl, substituted or unsubstituted C3~C 20 Cycloalkyl, substituted or unsubstituted C6~C 20 aryl, substituted or unsubstituted C7~C 20 Alkyl, substituted or unsubstituted C7~C 20 Aryl, substituted or unsubstituted C2~C 10 olefinic, substituted or unsubstituted C 10 ~C 20 Fused aryl or substituted or unsubstituted C 10 ~C 20 Ester group.

18. The catalyst system according to claim 17, characterized in that, In general formula (II), R1 and R2 are not hydrogen, and R3~R6 and R 1 ~R 2n Any group may optionally contain one or more heteroatoms as substitutes for carbon or hydrogen atoms or both, wherein the heteroatoms are selected from nitrogen, oxygen, sulfur, silicon, phosphorus or halogen atoms, R3~R6 and R 1 ~R 2n One or more of the groups may optionally form a ring with each other, where n is an integer from 0 to 10.

19. The catalyst system according to claim 18, characterized in that, The diol ester internal electron donor compounds include compounds represented by general formula (III); (III) In general formula (III), R1~R6, R 1 ~R 2 Independently selected from hydrogen, halogen atoms, and straight-chain or branched C1~C atoms 20 Alkyl, C3~C 20 cycloalkyl, C6~C 20 Aryl, C7~C 20 Alkyl or C7~C 20 Aryl group.

20. The catalyst system according to claim 19, characterized in that, The compounds represented by general formula (III) include at least one of 2-ethyl-1,3-propanediol dibenzoate, 2-propyl-1,3-propanediol dibenzoate, 2-isopropyl-2-isopentyl-1,3-propanediol dibenzoate, 1,3-butanediol dimethylbenzoate, 2-methyl-1,3-butanediol di-m-chlorobenzoate, 2,3-dimethyl-1,3-butanediol dibenzoate, 1,3-pentanediol neopentyl ester, 2,4-pentanediol dibenzoate, 2-methyl-1,3-pentanediol cinnamic acid ester, 2,2-dimethyl-1,3-pentanediol dibenzoate, 2,4-heptanediol dibenzoate, 2-methyl-3,5-heptanediol dibenzoate, and 4-ethyl-3,5-heptanediol dibenzoate.

21. A method for polymerizing polyolefins, characterized in that, The polymerization method includes: contacting one or more olefin monomers with a catalyst system under olefin polymerization conditions, wherein at least one of the olefin monomers is an olefin represented by the general formula CH2=CHR, wherein R is hydrogen or a C1~C6 alkyl group; The catalyst system is selected from at least one of the catalyst systems described in any one of claims 1 to 20.

22. The polymerization method according to claim 21, characterized in that, The olefin monomer is selected from at least one of ethylene, propylene, 1-n-butene, 1-n-pentene, 1-n-hexene, 1-n-octene and 4-methyl-1-pentene; And / or, the catalyst component, organoaluminum compound, and external electron donor compound are pre-contaminated before contacting the olefin monomer; the pre-contact time is 0.1 to 60 min; the pre-contact temperature is -20°C to 80°C; And / or, the catalyst system is first prepolymerized in the presence of a small amount of olefin monomer to obtain a prepolymerized catalyst, and then the prepolymerized catalyst is further reacted with the olefin monomer to obtain polyolefin; the prepolymerization temperature is -20℃ to 80℃; the prepolymerization rate is 1 to 1000 gPP / gCat when the olefin monomer is propylene.

23. The polymerization method according to claim 22, characterized in that, The pre-contact time is 1~40 min; the pre-contact temperature is 0℃~60℃; And / or, the prepolymerization temperature is 0℃~50℃; the prepolymerization rate is 2~500gPP / gCat when the olefin monomer is propylene.

24. A polypropylene with a wide molecular weight distribution and high melt strength, characterized in that, The polypropylene has a molecular weight distribution Mw / Mn of 7.0~20.0 and a melt strength of 0.15~0.70 N; The method for preparing polypropylene includes contacting and reacting propylene monomer with a catalyst system; the catalyst system is selected from at least one of the catalyst systems described in any one of claims 1 to 20.

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