Catalyst system for the preparation of olefin polymers and use thereof

Abstract

This invention relates to the field of olefin polymerization technology and discloses a catalyst system for preparing olefin polymers and its application. The catalyst system comprises the following components: (1) a solid catalyst component containing Mg, Ti, and an internal electron donor; (2) an alkylaluminum compound; and (3) an external electron donor; wherein the internal electron donor is selected from at least one self-chain asymmetric glycol ester compound; and the external electron donor is selected from at least one diether compound. When the catalyst system of this invention is used for olefin polymerization, especially propylene polymerization, the solid catalyst component exhibits high activity, improved hydrogen sensitivity, and a narrowed molecular weight distribution, making it suitable for producing fiber spinning materials.

Description

Technical Field

[0001] This invention relates to the field of olefin polymerization technology, and more specifically to a catalyst system for preparing olefin polymers and its application. Background Technology

[0002] As is well known, solid titanium catalysts, with magnesium, titanium, halogen atoms, and electron donors as basic components, can be used in olefin polymerization reactions, especially in the polymerization of α-olefins with three or more carbon atoms, yielding polymers with high yields and high stereoregularity. Internal electron donor compounds are an essential component of solid catalysts, and the development of internal electron donor compounds has led to the continuous upgrading of polyolefin catalysts. External electron donors also need to be developed in conjunction with internal electron donors. Currently, a large number of electron donor compounds have been disclosed, including internal electron donors such as carboxylic esters, ketones, ethers, amines, and their derivatives, and external electron donors such as esters, ethers, amines, alkylsiloxanes, aminosilanes, and their derivatives.

[0003] CN1169845C discloses a diol ester compound. Using this diol ester compound as an electron donor in olefin polymerization catalysts yields catalysts with excellent overall performance. However, when used for propylene polymerization, this catalyst produces polymers with a relatively wide molecular weight distribution, predominantly low molecular weight polymers, making it unsuitable for fiber spinning; furthermore, the catalyst's hydrogen sensitivity is not entirely satisfactory. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of the wide molecular weight distribution of polymers in the prior art, and to provide a catalyst system for preparing olefin polymers and its application.

[0005] To achieve the above objectives, a first aspect of the present invention provides a catalyst system for preparing olefin polymers, the catalyst system comprising the following components:

[0006] (1) A solid catalyst component, wherein the solid catalyst component contains Mg, Ti and an internal electron donor;

[0007] (2) Alkyl aluminum compounds; and

[0008] (3) External electron donor;

[0009] The internal electron donor is selected from at least one of the self-chain asymmetric diol ester compounds; the external electron donor is selected from at least one diether compound.

[0010] A second aspect of the present invention provides a prepolymerization catalyst composition for olefin polymerization reactions, the prepolymerization catalyst composition comprising a prepolymer obtained by prepolymerization of an olefin using the catalyst system described above.

[0011] A third aspect of the present invention provides a method for olefin polymerization, characterized in that the method comprises: polymerizing olefins in the presence of the catalyst system described above;

[0012] Alternatively, the olefins may be polymerized in the presence of the aforementioned prepolymerization catalyst composition.

[0013] When the catalyst system of the present invention is used for the polymerization of olefins, especially propylene, the solid catalyst component has high activity, improved hydrogen sensitivity, and narrowed molecular weight distribution, making it suitable for the production of fiber spinning materials. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] In this invention, unless otherwise specified, the halogen atom and halogen can be selected from F, Cl, Br, I, etc. C1-C 10 Straight-chain alkyl groups can be selected from C1, C2, C3, C4, C5, C6, C7, C8, C9, ... 10 Straight-chain alkyl groups. C3-C 10 Branched alkyl groups can be selected from C3, C4, C5, C6, C7, C8, C9, C10, C11, C20, C30, C40, C50, C60, C70, C80, C90, C10, C110, C120, C130, C140, C150, C160, C170, C180, C190, C10 ... 10 Branched alkyl groups. C3-C 10 The cycloalkyl group can be selected from C3, C4, C5, C6, C7, C8, C9, C10, C11, C20, C30, C40, C50, C60, C70, C80, C90, C10, C110, C120, C130, C140, C150, C160, C170, C180, C190, C10 ... 10 Cycloalkyl groups. C6-C 20 The aryl group can be selected from C6, C7, C8, C9, ... 10 C 11 C 12 C 13 C 14 C 15 C 16 C 17 C 18 C 19 C 20 Aryl group. C7-C 20 The alkylaryl group can be selected from C7, C8, C9, C10, C20, C30, C40, C50, C60, C70, C80, C90, C1 ... 10 C 11 C 12 C 13 C 14 C 15C 16 C 17 C 18 C 19 C 20 alkylaryl groups. C7-C 20 Aryl alkyl groups can be selected from C7, C8, C9, and C6. 10 C 11 C 12 C 13 C 14 C 15 C 16 C 17 C 18 C 19 C 20 Aryl groups.

[0016] A first aspect of the present invention provides a catalyst system for preparing olefin polymers, the catalyst system comprising the following components:

[0017] (1) A solid catalyst component, wherein the solid catalyst component contains Mg, Ti and an internal electron donor;

[0018] (2) Alkyl aluminum compounds; and

[0019] (3) External electron donor;

[0020] The internal electron donor is selected from at least one of the self-chain asymmetric diol ester compounds; the external electron donor is selected from at least one diether compound.

[0021] In this invention, the term "main-chain asymmetric diol ester compound" refers to a diol compound used to prepare the diol ester compound that is asymmetric. For example, 2,4-hexanediol dibenzoate is obtained by reacting 1 mol of 2,4-hexanediol with 2 mol of benzoyl chloride, wherein the structure of 2,4-hexanediol is asymmetric.

[0022] According to the present invention, preferably, the internal electron donor is selected from at least one of the main-chain asymmetric diol ester compounds represented by formula (I);

[0023]

[0024] Among them, R1 and R2 may be the same or different, and are each independently selected from halogen atoms, C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl groups;

[0025] R3 and R4 may be the same or different, and each is independently selected from hydrogen, halogen atoms, and C1-C atoms. 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl groups;

[0026] R5 is selected from hydrogen, halogen atoms, and C1-C atoms. 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl group; n is an integer from 1 to 5; where n is the number of substituents on the benzene ring.

[0027] According to the present invention, preferably, R1 and R2 are each independently selected from halogen atoms, C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 Cycloalkyl; more preferably selected from C1-C8 straight-chain alkyl and C3-C8 branched alkyl.

[0028] According to the present invention, preferably, R3 and R4 are each independently selected from hydrogen, halogen atoms, C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl; more preferably selected from hydrogen, C1-C8 straight-chain alkyl, C3-C8 branched alkyl and C7-C 10 Aryl alkyl group.

[0029] According to the present invention, preferably, R5 is selected from hydrogen, halogen atoms, C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl group, where n is an integer from 1 to 3; more preferably selected from hydrogen, halogen atoms, C1-C8 straight-chain alkyl groups, and C3-C8 branched alkyl groups; where n is 1. More preferably, when n = 1, R5 is an ortho- or para-substituent on the benzene ring.

[0030] According to the present invention, preferably, the internal electron donor is selected from 2,4-hexanediol dibenzoate, 2,4-hexanediol di-o-methylbenzoate, 2,4-hexanediol di-m-methylbenzoate, 2,4-hexanediol di-p-methylbenzoate, 2,4-hexanediol di-m-chlorobenzoate, 2,4-hexanediol di-p-chlorobenzoate, 2,4-hexanediol di-p-ethylbenzoate, 2,4-hexanediol di-p-propylbenzoate, 2,4-hexanediol di-p-butylbenzoate, 2,4-hexanediol di-p-tert-butylbenzoate, 3-methyl-2,4-hexanediol dibenzoate, 3-ethyl-2,4-hexanediol dibenzoate, 3-n-propyl-2,4-hexanediol dibenzoate, 3-benzyl-2,4-hexanediol dibenzoate. Ester, 3-methyl-2,4-hexanediol di-p-methylbenzoate, 3-ethyl-2,4-hexanediol di-p-methylbenzoate, 3-ethyl-2,4-hexanediol di-p-ethylbenzoate, 3-ethyl-2,4-hexanediol di-p-n-propylbenzoate, 3-ethyl-2,4-hexanediol di-p-n-butylbenzoate, 3-ethyl-2,4-hexanediol di-p-tert-butylbenzoate, 3-n-butyl-2,4-hexanediol dibenzoate, 2,4-heptanediol dibenzoate, 2,4-heptanediol di-p-methylbenzoate, 2,4-heptanediol di-m-methylbenzoate, 2,4-heptanediol di-o-methylbenzoate, 2,4-heptanediol di-o-chlorobenzoate, 2,4-heptanediol di-m-chlorobenzoate, 2,4-heptanediol di-o-chlorobenzoate, 2,4-heptanediol di-m-chlorobenzoate, 2,4-heptanediol di-o-methylbenzoate, Diol di-p-chlorobenzoate, 2,4-heptanediol di-p-ethylbenzoate, 2,4-heptanediol di-p-propylbenzoate, 2,4-heptanediol di-p-butylbenzoate, 2,4-heptanediol di-p-tert-butylbenzoate, 3-methyl-2,4-heptanediol dibenzoate, 3-ethyl-2,4-heptanediol dibenzoate, 3-n-propyl-2,4-heptanediol dibenzoate, 3-methyl-2,4-heptanediol di-p-methylbenzoate, 3-ethyl-2,4-heptanediol di-p-propylbenzoate, 3-ethyl-2,4-heptanediol di-p-butylbenzoate, 3-ethyl-2,4-heptanediol di-p-tert-butylbenzoate, 6-methyl-2,4-heptanediol dibenzoate, 6-methyl-2,4-heptanediol dibenzoate, 6-methyl-2,4-heptanediol di-p-butylbenzoate, 3-methyl-2,4-heptanediol di-p-propylbenzoate, 3-ethyl-2,4-heptanediol di-p-butylbenzoate, 3-ethyl-2,4-heptanediol di-p-tert-butyl ...-p-butylbenzoate, 6-methyl-2,4-heptanediol di-p-butylbenzoate Diol di-p-methylbenzoate, 6-methyl-2,4-heptanediol di-m-methylbenzoate, 6-methyl-2,4-heptanediol di-o-methylbenzoate, 6-methyl-2,4-heptanediol di-p-ethylbenzoate, 6-methyl-2,4-heptanediol di-p-n-propylbenzoate, 6-methyl-2,4-heptanediol di-p-n-butylbenzoate, 6-methyl-2,4-heptanediol di-p-tert-butylbenzoate, 3-ethyl-6-methyl-2,4-heptanediol dibenzoate, 3-ethyl-6-methyl-2,4-heptanediol di-p-n-propylbenzoate, 3-n-propyl-6-methyl-2,4-heptanediol di-p-n-butylbenzoate, 3-n-butyl-6-methyl-2,4-heptanediol di-p-tert-butylbenzoate, 3...At least one of the following: 5-octanediol dibenzoate, 3,5-octanediol di-p-methylbenzoate, 3,5-octanediol di-m-methylbenzoate, 3,5-octanediol di-o-methylbenzoate, 3,5-octanediol di-p-ethylbenzoate, 3,5-octanediol di-p-n-propylbenzoate, 3,5-octanediol di-p-n-butylbenzoate, 3,5-octanediol di-p-tert-butylbenzoate, 4-methyl-3,5-octanediol dibenzoate, 4-ethyl-3,5-octanediol di-p-n-butylbenzoate, and 4-n-propyl-3,5-octanediol dibenzoate.

[0031] According to the present invention, preferably, the method for preparing the solid catalyst component includes reacting a magnesium compound, a titanium compound, an internal electron donor, a performance modifier, and an optional precipitation aid; wherein the performance modifier is selected from at least one monocarboxylic acid ester compound.

[0032] According to the present invention, preferably, the performance modifier is selected from at least one of the monocarboxylic acid ester compounds represented by formula (II).

[0033]

[0034] In the formula, R6 is C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl and C7-C 15 Aryl groups;

[0035] R7 is C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkyl and C7-C 20 Aryl alkyl group.

[0036] According to the present invention, preferably, R6 is C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 Cycloalkyl; more preferably selected from C1-C8 straight-chain alkyl or C3-C8 branched alkyl.

[0037] According to the present invention, preferably, R7 is C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15Alkyl and C7-C 15 Aryl alkyl; more preferably selected from C1-C8 straight-chain alkyl, C3-C8 branched alkyl, C6-C 12 Aryl, C7-C 12 Alkyl and C7-C 12 Aryl alkyl group.

[0038] According to the present invention, preferably, the performance modifier is selected from ethyl acetate, ethyl propionate, ethyl butyrate, ethyl isobutyrate, ethyl tert-butyrate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, tert-butyl acetate, pentyl acetate, isoamyl acetate, propyl propionate, butyl propionate, pentyl isopropionate, ethyl butyrate, ethyl isobutyrate, isobutyl isobutyrate, propyl tert-butyrate, pentyl butyrate, propyl pentyl butyrate, propyl pentyl butyrate, butyl pentyl butyrate, pentyl isopentyl isovalerate, ethyl 2-methylbenzoate, and methylbenzoic acid. Ethyl benzoate, ethyl 4-methylbenzoate, ethyl 4-ethylbenzoate, ethyl 4-n-propylbenzoate, ethyl 4-isopropylbenzoate, ethyl 4-n-butylbenzoate, ethyl 4-isobutylbenzoate, ethyl 4-tert-butylbenzoate, ethyl 4-n-pentylbenzoate, ethyl 4-isopentylbenzoate, ethyl 2,4-dimethylbenzoate, ethyl 3,4-dimethylbenzoate, ethyl 2,6-dimethylbenzoate, ethyl 2,4,6-trimethylbenzoate, ethyl 4-phenylbenzoate, ethyl 4-benzylmethylbenzoate, and ethyl 2-naphthoate.

[0039] According to the present invention, preferably, the precipitation aid is selected from at least one of organic acid anhydrides, organic acids, ethers and ketones; more preferably, it is selected from at least one of organic acid anhydrides having 4-20 carbon atoms, organic acids having 2-15 carbon atoms, ethers having 2-20 carbon atoms and ketones having 3-20 carbon atoms; and even more preferably, it is selected from at least one of acetic anhydride, phthalic anhydride, succinic anhydride, maleic anhydride, pyromellitic dianhydride, acetic acid, propionic acid, butyric acid, acrylic acid, methacrylic acid, acetone, methyl ethyl ketone, benzophenone, dimethyl ether, diethyl ether, propyl ether, butyl ether and pentyl ether.

[0040] According to the present invention, preferably, the amount of the co-precipitant added relative to each mole of magnesium compound is 0-1 mole (e.g., 0.01 mole, 0.1 mole, 0.15 mole, 0.2 mole, 0.3 mole, 0.4 mole, 0.5 mole, 0.6 mole, 0.7 mole, 0.8 mole, 0.9 mole, 1 mole, and any two of the above, preferably 0.1-2 moles), and the amount of the internal electron donor added is 0.02-0.4 moles (e.g., 0.02 mole, 0.03 mole, 0.04 mole, 0.05 mole, 0.06 mole, 0.07 mole, 0.08 mole, 0.09 ... The amounts of the performance modifier are 1 mol, 0.15 mol, 0.2 mol, 0.25 mol, 0.3 mol, 0.35 mol, 0.4 mol, and any two of the above, preferably 0.05-0.1 mol), and the amount of the performance modifier added is 0.01-0.3 mol (e.g., 0.01 mol, 0.02 mol, 0.03 mol, 0.04 mol, 0.05 mol, 0.06 mol, 0.07 mol, 0.08 mol, 0.09 mol, 0.1 mol, 0.15 mol, 0.2 mol, 0.25 mol, 0.3 mol, and any two of the above, preferably 0.05-0.1 mol).

[0041] According to the present invention, preferably, the amount of titanium compound added is 0.5-150 moles relative to each mole of magnesium compound (e.g., 0.5 moles, 1 mole, 20 moles, 30 moles, 40 moles, 50 moles, 60 moles, 70 moles, 80 moles, 90 moles, 100 moles, 110 moles, 120 moles, 130 moles, 140 moles, 150 moles, and any range of any two of the above).

[0042] According to the present invention, preferably, the method includes: contacting a titanium compound with a solution containing a magnesium compound and a performance modifier in the presence of a precipitation aid to obtain a solid; and then treating the solid with an internal electron donor. More preferably, the solution containing the magnesium compound and the performance modifier further includes a solvent: an organic epoxy compound, an organophosphorus compound, and an inert diluent. More preferably, the method includes: (1) preparing a solution containing a magnesium compound and a performance modifier: dissolving the magnesium compound in a mixture of the performance modifier, the organic epoxy compound, the organophosphorus compound, and the inert diluent to form a homogeneous solution; (2) adding a precipitation aid to the solution obtained in step (1), and then adding a titanium compound dropwise to obtain a solid; (3) treating the solid with an internal electron donor. The treatment can load the internal electron donor onto the solid, and if necessary, the solid can be further treated with titanium tetrahalide and an inert diluent.

[0043] According to the present invention, preferably, the magnesium compound is selected from at least one of magnesium dihalides, magnesium alkoxy compounds, alkyl magnesium compounds, hydrates or alcohols of magnesium dihalides, and derivatives of magnesium dihalides in which the halogen atom is replaced by an alkoxy or haloalkoxy group, more preferably selected from magnesium dihalides and / or magnesium dihalides alcohols; for example, magnesium dichloride, magnesium dibromide, magnesium diiodide, and their alcohols.

[0044] According to the present invention, preferably, the titanium compound has the general formula TiX. m (OR 1) 4-m In the formula R 1 For C1-C 20 The hydrocarbon group, where X is a halogen, and 1 ≤ m ≤ 4. More preferably, the titanium compound is selected from titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxy, titanium tetraethoxy, titanium monochlorotriethoxy, titanium dichlorodiethoxy, titanium trichloromonoethoxy, and titanium tetrachloride, and is even more preferably titanium tetrachloride.

[0045] According to the present invention, preferably, the organic epoxy compound is selected from at least one of aliphatic olefins, dienes, oxides of halogenated aliphatic olefins or dienes, glycidyl ethers and internal ethers having 2-8 carbon atoms; more preferably, the organic epoxy compound is selected from at least one of ethylene oxide, propylene oxide, butane oxide, butadiene oxide, butadiene dioxide, epichlorohydrin, methyl glycidyl ether, diglycidyl ether, and tetrahydrofuran.

[0046] According to the present invention, preferably, the organophosphorus compound is selected from at least one of the following: a hydrocarbon ester or a halohydrocarbon ester of orthophosphoric acid, a hydrocarbon ester or a halohydrocarbon ester of phosphorous acid. More preferably, the organophosphorus compound is selected from at least one of the following: trimethyl orthophosphoric acid, triethyl orthophosphoric acid, tributyl orthophosphoric acid, triphenyl orthophosphoric acid, trimethyl orthophosphoric acid, triethyl orthophosphoric acid, tributyl orthophosphoric acid, and triphenylmethyl orthophosphoric acid.

[0047] According to the present invention, preferably, the inert diluent is selected from at least one of hexadecane, heptane, octane, decane, benzene, toluene and xylene.

[0048] According to the present invention, preferably, the amount of organic epoxy compound added is 0.2-10 moles and the amount of organic phosphorus compound added is 0.1-3 moles per mole of magnesium compound.

[0049] In this invention, the solution containing magnesium compounds and performance regulators may include organic alcohol compounds, wherein the organic alcohol compounds may be monohydric alcohols with 2-8 carbon atoms, such as ethanol, propanol, butanol, pentanol, hexanol, octanol, isooctanol, etc., or mixtures thereof.

[0050] In this invention, the internal electron donor can also be directly mixed with the magnesium compound and then reacted with the titanium compound. Therefore, the solid catalyst component can also be prepared by the following method: forming an emulsion of magnesium compound, performance regulator and internal electron donor in a diluent, then adding titanium compound and precipitation aid to the emulsion to obtain a solid, and then obtaining the solid catalyst component through optional treatment.

[0051] In any preparation method, the desired internal electron donor can be added directly in the form of a compound; or it can be added in other ways, such as by obtaining a suitable precursor of the internal electron donor in situ, which can be converted into the desired internal electron donor through known chemical reactions such as esterification.

[0052] According to the present invention, preferably, the content of magnesium in the solid catalyst component is 3-25 wt%, the content of titanium is 1-6 wt%, and the content of internal electron donor compound is 1-20 wt%; more preferably, the content of magnesium in the solid catalyst component is 10-20 wt%, the content of titanium is 1-5 wt%, and the content of internal electron donor is 5-15 wt%.

[0053] According to the present invention, preferably, the amount of alkyl aluminum compound used is 0.01-100 mmol and the amount of external electron donor is 0.001-10 mmol per 100 mg of solid catalyst component.

[0054] According to the present invention, preferably, the alkylaluminum compound has the general formula AlR 2 j X 3-j In the formula R 2 The alkylaluminum compound is a hydrocarbon group with 1-20 carbon atoms, where X is a halogen and j is an integer from 1 to 3. Preferably, the alkylaluminum compound is selected from at least one of triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-octylaluminum, triisooctylaluminum, diethylaluminum monohydrogen, diisobutylaluminum monohydrogen, diethylaluminum monochloro, diisobutylaluminum monochloro, sesquiethylaluminum chloride, and diethylaluminum dichloro, more preferably triethylaluminum and / or triisobutylaluminum.

[0055] According to the present invention, preferably, the external electron donor is selected from at least one of the diether compounds shown in formula (III).

[0056]

[0057] In the formula, R8 and R9 may be the same or different, and are each independently selected from C1-C2. 15 Straight-chain alkyl, C3-C 15 Branched alkyl, C3-C 15 cycloalkyl, C6-C 20 Aryl, C7-C 20Alkyl and C7-C 20 Aryl alkyl groups, R8 and R9 can be bonded to form rings;

[0058] R 10 For C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl groups, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl alkyl group.

[0059] According to the present invention, preferably, R8 and R9 are each independently selected from C1-C 12 Straight-chain alkyl, C3-C 12 Branched alkyl, C3-C 12 cycloalkyl, C6-C 18 Aryl, C7-C 18 Alkyl and C7-C 18 Aryl alkyl group; more preferably selected from C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C5-C 12 cycloalkyl, C6-C 18 Aryl and C7-C 18 Alkyl aryl.

[0060] According to the present invention, preferably, R 10 It is a C1-C8 straight-chain alkyl, a C3-C8 branched alkyl, or a C3-C8 cycloalkyl; more preferably, it is selected from C1-C4 straight-chain alkyl.

[0061] According to the present invention, preferably, the external electron donor is selected from 2,2-diethyl-1,3-dimethoxypropane, 2,2-di-n-propyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diisopentyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, and 2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane. 2,2-Diphenyl-1,3-dimethoxypropane, 2,2-Dibenzyl-1,3-dimethoxypropane, 2-Methyl-2-ethyl-1,3-dimethoxypropane, 2-Methyl-2-n-propyl-1,3-dimethoxypropane, 2-Methyl-2-isopropyl-1,3-dimethoxypropane, 2-Methyl-2-n-butyl-1,3-dimethoxypropane, 2-Methyl-2-isobutyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-Methyl-2-n-pentyl-1,3-di ... Methoxypropane, 2-methyl-2-isopentyl-1,3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-methyl-2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2-isopropyl-2-(1-methylbutyl)-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclohexyl-1,3-dimethoxypropane, At least one of 3-dimethoxypropane, 2-isopropyl-2-benzyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2-isopropyl-2-phenyl-1,3-dimethoxypropane, 2-isobutyl-2-phenyl-1,3-dimethoxypropane, 2-isobutyl-2-cyclopentyl-1,3-dimethoxypropane, 2-isobutyl-2-cyclohexyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, and 9,9-dimethoxymethylfluorene.

[0062] According to the present invention, preferably, the molar ratio of the solid catalyst component based on Ti, the alkyl aluminum compound based on Al, and the external electron donor is 1:5-1000:0.1-100, more preferably 1:20-250:1-50.

[0063] The catalyst of the present invention can be directly added to the reactor for the polymerization process, or the catalyst can be prepolymerized before the polymerization process. Therefore, a second aspect of the present invention provides a prepolymerization catalyst composition for olefin polymerization, the prepolymerization catalyst composition containing a prepolymer obtained by prepolymerization of an olefin using the catalyst system described above.

[0064] It is understood that the prepolymerization catalyst composition includes the above-mentioned solid catalyst component and the prepolymer obtained by prepolymerization of the solid catalyst component with an olefin.

[0065] In this invention, the term "prepolymerization" refers to polymerization at a lower degree of conversion.

[0066] According to the present invention, preferably, the prepolymerization ratio of the prepolymer is 0.1-1000g olefin polymer / g solid catalyst component, more preferably 0.2-500g olefin polymer / g solid catalyst component.

[0067] According to the present invention, preferably, the olefin has the general formula CH2=CHR, where R is hydrogen or C1-C. 12 The olefin is a hydrocarbon or aryl group, and more preferably, the olefin is ethylene and / or propylene. Particularly preferred is prepolymerization using a mixture of ethylene or propylene and one or more α-olefins in an amount of up to 20 mol%.

[0068] The prepolymerization process can be carried out in a liquid or gas phase at temperatures ranging from -20 to 80°C, preferably from 0 to 50°C. The prepolymerization step can be performed online as part of a continuous polymerization process or independently in a batch operation. For preparing polymers with an olefin polymer content of 0.5-20 g / g solid catalyst component, batch prepolymerization of the catalyst of the present invention with propylene is particularly preferred. The prepolymerization pressure can be 0.01-10 MPa.

[0069] A third aspect of the present invention provides a method for olefin polymerization, characterized in that the method comprises: polymerizing olefins in the presence of the catalyst system described above;

[0070] Alternatively, the olefins may be polymerized in the presence of the aforementioned prepolymerization catalyst composition.

[0071] The catalyst of the present invention can be directly added to the reactor for use in the polymerization process, or the catalyst can be added to the reactor after prepolymerization of the catalyst with olefins to obtain a prepolymerized catalyst composition.

[0072] The olefin polymerization reaction of the present invention is carried out according to known polymerization methods, which can be carried out in the liquid phase or gas phase, or in a combination of liquid phase and gas phase polymerization stages. Conventional techniques such as slurry polymerization and gas-phase fluidized bed polymerization are employed. Preferably, the following reaction conditions are used: polymerization temperature 0-150°C, preferably 60-90°C.

[0073] The olefins described in this invention have the general formula CH2=CHR, where R is hydrogen or C1-C. 12Alkyl or aryl groups. Such as at least one selected from ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Preferably selected from ethylene and / or propylene. Such as homopolymerization of propylene and copolymerization of propylene with other olefins. The method of the present invention is also applicable to homopolymerization of ethylene or copolymerization of ethylene with α-olefins, such as 1-propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene.

[0074] The present invention will be described in detail below through embodiments. In the following embodiments,

[0075] Polymerization activity: The amount of polymer obtained within a certain time (in kg) divided by the amount of solid catalyst component added (in g).

[0076] Examples 1-4

[0077] In a reactor fully purged with high-purity nitrogen, 6.0 g of magnesium chloride, 120 mL of toluene, 5 mL of epichlorohydrin, 15.6 mL of tributyl phosphate (TBP), and 6 mmol of monocarboxylic acid ester compound (II) from Table 1 were added sequentially. The mixture was heated to 50 °C with stirring and maintained for 2.5 hours until the solid completely dissolved. 1.7 g of phthalic anhydride was added, and the temperature was maintained for another hour. The solution was cooled to below -25 °C, and 70 mL of TiCl4 was added dropwise over one hour. The temperature was slowly increased to 80 °C, during which solids gradually precipitated. 6 mmol of the internal electron donor compound from Table 1 was added, and the temperature was maintained for one hour. After filtration, 80 mL of toluene was added, and the mixture was washed twice to obtain a solid precipitate.

[0078] Then add 60 mL of toluene and 40 mL of TiCl4, heat to 100 °C, treat for 2 hours, drain the filtrate, add another 60 mL of toluene and 40 mL of TiCl4, heat to 100 °C, treat for 2 hours, drain the filtrate; add 60 mL of toluene, wash three times in a boiling state, add 60 mL of hexane, wash twice in a boiling state, add 60 mL of hexane, wash twice at room temperature, and obtain the solid catalyst component.

[0079] Comparative Example 1

[0080] The solid catalyst component was prepared according to the method of Example 4, except that the external electron donor was replaced with an equimolar amount of dicyclopentyldimethoxysilane (DCPDMS).

[0081] Comparative Example 2

[0082] The solid catalyst component was prepared according to the method of Example 4, except that the internal electron donor compound was replaced with an equimolar amount of 2,4-pentanediol dibenzoate.

[0083] Test Example 1

[0084] The prepared solid catalyst components were subjected to propylene polymerization. The propylene polymerization procedure was as follows: A 5L stainless steel reactor was fully purged with gaseous propylene, then 2.5 mmol of AlEt3, 0.1 mmol of the external electron donor compound from Table 1, 8-10 mg of the prepared solid catalyst components, and 1.2 NL or 7.2 NL of hydrogen were added. 2.3L of liquid propylene was introduced, and the temperature was raised to 70°C and maintained for 1 hour. The mixture was then cooled and depressurized to obtain PP powder. The polymerization activity results with the addition of 1.2 NL of hydrogen are shown in Table 1.

[0085] Table 1

[0086]

[0087] ID1: 2,4-Hexanediol dibenzoate

[0088] ID2: 2,4-Octadiol di(4-n-propylbenzoate)

[0089] ID3: 2,4-Heptanediol di(4-ethylbenzoate)

[0090] ID4: 4-Methyl-3,5-octanediol dibenzoate

[0091] ID5: 4-Methyl-3,5-heptanediol dibenzoate

[0092] Test Example 2

[0093] The prepared PP powder was tested, and the results are shown in Table 2.

[0094] (1) Melt index of polymer: determined according to test standard GB / T 3682—2000.

[0095] (2) Polymer isotactic index: The isotactic index is determined by the heptane extraction method (boiling heptane extraction for 6 hours): 2g of dry polymer sample is placed in an extractor and extracted with boiling heptane for 6 hours. The polymer weight (g) obtained by drying the residue to constant weight is the ratio of 2g to 2g.

[0096] (3) Polymer molecular weight distribution MWD (MWD = M w / M n Gel permeation chromatography was used, with trichlorobenzene as solvent in a PL-GPC220 column at 150℃ (standard was polystyrene, flow rate was 1.0 mL / min, column was 3xPlgel 10um M1xED-B 300x7.5nm).

[0097] Table 2

[0098]

[0099]

[0100] As shown in Table 2, the polymers obtained using the methods described in Examples 1-4 of this invention exhibit high melt index and isotactic index, as well as a narrow molecular weight distribution. In particular, the melt index of the polymer can be further improved under higher hydrogen concentrations.

[0101] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst system for preparing olefin polymers, characterized in that, The catalyst system comprises the following components: (1) A solid catalyst component, wherein the solid catalyst component contains Mg, Ti and an internal electron donor; (2) Alkyl aluminum compounds; as well as (3) External electron donor; Wherein, the internal electron donor is selected from at least one of the main-chain asymmetric diol ester compounds represented by formula (I); （Ⅰ） Among them, R1 and R2 may be the same or different, and are each independently selected from halogen atoms, C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl alkyl groups; R3 and R4 may be the same or different, and each is independently selected from hydrogen, halogen atoms, and C1-C atoms. 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl alkyl groups; R5 is selected from hydrogen, halogen atoms, and C1-C atoms. 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl group; n is an integer from 1 to 5; where n is the number of substituents on the benzene ring; The external electron donor is selected from at least one of the diether compounds shown in formula (III). （Ⅲ） In the formula, R8 and R9 may be the same or different, and are each independently selected from C1-C2. 15 Straight-chain alkyl, C3-C 15 Branched alkyl, C3-C 15 cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkyl and C7-C 20 Aryl alkyl groups, R8 and R9 can be bonded to form rings; R 10 For C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl groups, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl or C7-C 15 Aryl alkyl group.

2. The catalyst system according to claim 1, wherein, R1 and R2 may be the same or different, and each is independently selected from C1-C8 straight-chain alkyl or C3-C8 branched alkyl. R3 and R4 may be the same or different, and each is independently selected from hydrogen, C1-C8 straight-chain alkyl, C3-C8 branched alkyl, and C7-C4. 10 Aryl alkyl groups; R5 is selected from hydrogen, halogen atoms, C1-C8 straight-chain alkyl, and C3-C8 branched alkyl; n is 1.

3. The catalyst system according to claim 1, wherein, The method for preparing the solid catalyst component includes reacting a magnesium compound, a titanium compound, an internal electron donor, a performance modifier, and an optional precipitation aid; the performance modifier is selected from at least one monocarboxylic acid ester compound.

4. The catalyst system according to claim 3, wherein, The performance modifier is selected from at least one of the monocarboxylic acid ester compounds represented by formula (II). （Ⅱ） In the formula, R6 is C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 15 Aryl, C7-C 15 Alkyl and C7-C 15 Aryl alkyl groups; R7 is C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkyl and C7-C 20 Aryl alkyl group.

5. The catalyst system according to claim 4, wherein, R6 is a C1-C8 straight-chain alkyl or a C3-C8 branched alkyl; R7 is a C1-C8 straight-chain alkyl, C3-C8 branched alkyl, or C6-C8 branched alkyl. 12 Aryl, C7-C 12 Alkyl and C7-C 12 Aryl alkyl group.

6. The catalyst system according to claim 3, wherein, The precipitation aid is selected from at least one of organic acid anhydrides, organic acids, ethers, and ketones.

7. The catalyst system according to claim 6, wherein, The precipitation aid is selected from at least one of the following: organic acid anhydrides with 4-20 carbon atoms, organic acids with 2-15 carbon atoms, ethers with 2-20 carbon atoms, and ketones with 3-20 carbon atoms.

8. The catalyst system according to claim 6, wherein, The precipitation aid is selected from at least one of acetic anhydride, phthalic anhydride, succinic anhydride, maleic anhydride, pyromellitic dianhydride, acetic acid, propionic acid, butyric acid, acrylic acid, methacrylic acid, acetone, methyl ethyl ketone, benzophenone, methyl ether, diethyl ether, propyl ether, butyl ether, and pentyl ether.

9. The catalyst system according to any one of claims 3-8, wherein, For each mole of magnesium compound, the amount of precipitation aid added is 0-1 mole, the amount of titanium compound added is 0.5-150 moles, the amount of internal electron donor added is 0.02-0.4 moles, and the amount of performance modifier added is 0.01-0.3 moles.

10. The catalyst system according to claim 1, wherein, The general formula of the alkylaluminum compound is AlR 2 j X 3-j In the formula R 2 X is a hydrocarbon group with 1-20 hydrogen and carbon atoms, X is a halogen, and j is an integer from 1 to 3.

11. The catalyst system according to claim 10, wherein, The alkylaluminum compound is selected from at least one of triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-octylaluminum, triisooctylaluminum, diethylaluminum monohydrogen, diisobutylaluminum monohydrogen, diethylaluminum monochloro, diisobutylaluminum monochloro, sesquiethylaluminum chloride, and diethylaluminum dichloro.

12. The catalyst system according to claim 11, wherein, The alkylaluminum compound is triethylaluminum and / or triisobutylaluminum.

13. The catalyst system according to claim 1, wherein, R8 and R9 may be the same or different, and each is independently selected from C1-C. 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C5-C 12 cycloalkyl, C6-C 18 Aryl and C7-C 18 Alkyl groups, R8 and R9 can be bonded together to form a ring; R 10 It is a C1-C4 straight-chain alkyl group.

14. The catalyst system according to claim 1, wherein, The molar ratio of solid catalyst components (calculated as Ti), alkylaluminum compounds (calculated as Al), and external electron donors is 1:5-1000:0.1-100.

15. The catalyst system according to claim 14, wherein, The molar ratio of solid catalyst components (calculated as Ti), alkylaluminum compounds (calculated as Al), and external electron donors is 1:20-250:1-50.

16. A prepolymerization catalyst composition for olefin polymerization, characterized in that, The prepolymer catalyst composition contains a prepolymer obtained by prepolymerizing an olefin using the catalyst system described in any one of claims 1-15.

17. The prepolymerization catalyst composition according to claim 16, wherein, The prepolymerization ratio of the prepolymer is 0.1-1000g olefin polymer / gram solid catalyst component.

18. The prepolymerization catalyst composition according to claim 16, wherein, The olefin has the general formula CH2=CHR, where R is hydrogen or C1-C. 12 Hydrocarbon or aryl groups.

19. The prepolymerization catalyst composition according to claim 16, wherein, The olefin is ethylene and / or propylene.

20. A method for olefin polymerization, characterized in that, The method includes: polymerizing olefins in the presence of the catalyst system described in any one of claims 1-15; Alternatively, the olefin may be polymerized in the presence of the prepolymerization catalyst composition according to any one of claims 16-19.

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