Catalyst and catalyst system for olefin polymerization

Abstract

The present invention proposes a catalyst component for olefin polymerization and its catalyst. The present invention uses cyclohexanecarboxylic acid monoester compounds and other internal electron donor compounds (phthalate compounds, 1,3-diethers, glycol ester compounds) as the catalyst for olefin polymerization prepared by internal electron donor compounds. The polymerization activity is greater than 53kgPP / gcat, the polymerization activity is extremely high, and the cyclohexanecarboxylic acid monoester compounds are easier to synthesize, the raw material price is low and easy to obtain, the post-processing process is simple, does not involve the generation of waste water, and the production cost is low. The catalyst contains the catalyst system in CH2=CHR olefin polymerization, wherein R is hydrogen or an alkyl or aryl group with a carbon number of 1-6, particularly in the application of propylene polymerization, which can make the polypropylene production cost low, improve the quality and stability of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of olefin polymerization, and in particular to a catalyst and a catalyst system for olefin polymerization reaction. Background Art

[0002] At present, the most widely used catalyst in domestic polypropylene industrial equipment is still the Ziegler-Natta propylene polymerization catalyst (ZN catalyst for short). The brand with the largest production capacity is the general homopolymer and copolymer brand. With the continuous increase in domestic polypropylene production capacity, market competition will become increasingly fierce. For domestic polypropylene manufacturers, reducing the production cost of general materials and improving product quality and production stability have become urgent tasks.

[0003] To reduce the production cost of polypropylene and improve the polymerization activity of polypropylene catalysts, reducing the production cost of catalysts is the only way. At the same time, the improvement of catalyst polymerization activity will also reduce the amount of co-catalyst used in the polymerization process, thereby reducing the ash content in the final product and improving product quality. A lot of research has been conducted in academia and industry to improve the polymerization activity of catalysts. The most effective way is to develop and use new internal electron donors. After repeated experiments, the inventor unexpectedly found that the use of cyclohexanecarboxylic acid monoester compounds and other different types of internal electron donors (phthalates, 1,3-diethers, glycol esters) as internal electron donors has extremely high polymerization activity and is particularly suitable for CH2=CHR olefin polymerization, where R is hydrogen or an alkyl or aryl group with 1-6 carbon atoms, especially propylene polymerization. In addition, cyclohexanecarboxylic acid monoester compounds are relatively easy to synthesize, the raw materials are cheap and easy to obtain, the post-treatment process is simple, no wastewater is involved, and the production cost is low.

[0004] Therefore, the present invention aims to provide a ZN catalyst active component using two or more compounds of specific structures as internal electron donors, and a ZN catalyst containing the component. The catalyst has high activity, good stereospecificity and hydrogen regulation performance when used for olefin polymerization, and is very suitable for preparing general polypropylene grades. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention provides a catalyst and a catalyst system for olefin polymerization reaction.

[0006] In a first aspect, the present invention provides a catalyst for olefin polymerization, characterized in that its components include titanium, magnesium, halogen, and an internal electron donor compound;

[0007] The internal electron donor compound includes a first internal electron donor compound and a second internal electron donor compound;

[0008] The first internal electron donor compound is a cyclohexanecarboxylic acid monoester compound, and its general structural formula is shown in formula (I):

[0009]

[0010] Wherein, R1 is a straight-chain alkane having 1 to 20 carbon atoms, a branched alkyl or cycloalkyl having 3 to 20 carbon atoms, an aromatic hydrocarbon having 6 to 20 carbon atoms, an alkaryl having 7 to 20 carbon atoms, or an aralkyl having 7 to 20 carbon atoms, and R1 is connected to the cyclohexyl group in any manner to form a ring;

[0011] More preferably, R1 is a straight-chain alkyl group having 1 to 6 carbon atoms or a branched-chain alkyl group having 1 to 6 carbon atoms, selected from at least one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, cyclopentyl and phenyl.

[0012] As a specific embodiment of the present invention, the cyclohexanecarboxylic acid monoester compound is selected from at least one of methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, n-propyl cyclohexanecarboxylate, isopropyl cyclohexanecarboxylate, n-butyl cyclohexanecarboxylate, isobutyl cyclohexanecarboxylate, tert-butyl cyclohexanecarboxylate, n-pentyl cyclohexanecarboxylate, isopentyl cyclohexanecarboxylate, tert-pentyl cyclohexanecarboxylate, cyclopentyl cyclohexanecarboxylate, and phenyl cyclohexanecarboxylate.

[0013] Preferably, it is selected from at least one of: methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, n-propyl cyclohexanecarboxylate, isopropyl cyclohexanecarboxylate, n-butyl cyclohexanecarboxylate, isobutyl cyclohexanecarboxylate, tert-butyl cyclohexanecarboxylate, n-pentyl cyclohexanecarboxylate, isopentyl cyclohexanecarboxylate and tert-pentyl cyclohexanecarboxylate.

[0014] More preferably, it is selected from at least one of: methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, n-propyl cyclohexanecarboxylate, isopropyl cyclohexanecarboxylate, n-butyl cyclohexanecarboxylate, isobutyl cyclohexanecarboxylate, n-pentyl cyclohexanecarboxylate, and isopentyl cyclohexanecarboxylate.

[0015] The second internal electron donor is at least one of phthalate, 1,3-diether and diol ester compounds;

[0016] The general structural formula of the phthalate ester is shown in formula (II):

[0017]

[0018] In the formula, R2 and R3 may be the same or different, representing a straight-chain alkane with 1-20 carbon atoms, a branched alkyl with 3-20 carbon atoms or a cycloalkyl with 3-20 carbon atoms, an aromatic hydrocarbon with 6-20 carbon atoms, an alkaryl with 7-20 carbon atoms or an aralkyl with 7-20 carbon atoms, wherein the hydrogen atoms on the carbon in the alkyl, cycloalkyl, aryl, alkaryl or aralkyl may be optionally replaced by halogen (hetero) atoms, alkyl or alkoxy, and the carbon atoms on the main chain may be optionally replaced by heteroatoms; R2 and R3 may be connected to form a ring in any manner, and the skeleton of the formed ring may contain double bonds or heteroatoms. The heteroatoms are N, P, S or O.

[0019] Preferably, the R2 and R3 groups are selected from a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an aryl group having 6 to 10 carbon atoms. More preferably, the R2 and R3 groups are linear alkyl groups having 1 to 6 carbon atoms or branched alkyl groups having 1 to 6 carbon atoms, and are selected from at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, tert-pentyl and phenyl.

[0020] As a specific embodiment of the present invention, the phthalate is selected from at least one of dimethyl phthalate, diethyl phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-n-pentyl phthalate and diisopentyl phthalate.

[0021] Preferably, it is at least one selected from diethyl phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate and diisobutyl phthalate.

[0022] More preferably, it is selected from at least one of diethyl phthalate, di-n-butyl phthalate and diisobutyl phthalate.

[0023] The 1,3-diether structural formula is shown in formula (III):

[0024]

[0025] The 1,3-diether compound is 2-isopentyl-2-isopropyl-1,3-dimethyl ether.

[0026] The general structural formula of the diol ester compound is shown in formula (IV):

[0027]

[0028] In the formula, R4 and R5 are the same or different and are selected from a straight chain alkyl group having 1 to 10 carbon atoms, a branched chain alkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0029] Preferably, R4 and R5 are straight-chain alkyl groups having 1 to 6 carbon atoms or branched-chain alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl; and n is 1 or 2.

[0030] As a specific embodiment of the present invention, the diol ester compound is preferably at least one of 2,4-pentanediol benzoic acid diester and 3,5-heptanediol benzoic acid diester.

[0031] As a specific embodiment of the present invention, the mass ratio of the titanium element, the magnesium element, the halogen, and the internal electron donor compound is 1-8:10-70:20-90:2-30; preferably, 1.6-6:15-40:30-85:3-20.

[0032] As a specific embodiment of the present invention, in the internal electron donor compound, the molar ratio of the first internal electron donor compound to the second internal electron donor compound is (0.1:1) to (1:0.1); preferably, (0.2:1) to (1:0.2); more preferably, (0.3:1) to (1:0.3).

[0033] The catalyst for olefin polymerization according to the present invention can be prepared by contacting a magnesium compound, a titanium compound and an internal electron donor compound under certain conditions. The amounts of the titanium compound, the magnesium compound and the internal electron donor compound used to prepare the olefin polymerization catalyst component are not particularly limited and can be conventional substances and amounts in the art, respectively.

[0034] As a specific embodiment of the present invention, the magnesium element is in the form of a magnesium compound; in particular, the magnesium compound is at least one of a magnesium compound represented by formula (V), a hydrate of a magnesium compound represented by formula (VI), and an alcohol adduct of a magnesium compound represented by formula (VII).

[0035] The magnesium compound represented by the formula (V):

[0036] MgR6R7 Formula (V)

[0037] Among them, R6 and R7 are the same or different, and are each independently at least one of halogen, a straight-chain alkoxy group having 1 to 5 carbon atoms, a branched-chain alkoxy group having 3 to 5 carbon atoms, a straight-chain alkyl group having 1 to 5 carbon atoms, and a branched-chain alkyl group having 3 to 5 carbon atoms.

[0038] The hydrate of the magnesium compound represented by the formula (VI):

[0039] MgR6R7·qH2O Formula (VI)

[0040] wherein R6 and R7 are the same or different and are each independently at least one of halogen, a linear alkoxy group having 1 to 5 carbon atoms, a branched alkoxy group having 3 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms;

[0041] q is in the range of 0.1-6.

[0042] The alcohol adduct of the magnesium compound represented by the formula (VII):

[0043] MgR6R7·pR8OH Formula (VII)

[0044] wherein R6 and R7 are the same or different and are each independently at least one of halogen, a linear alkoxy group having 1 to 5 carbon atoms, a branched alkoxy group having 3 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms;

[0045] R8 is a hydrocarbon group having 1 to 18 carbon atoms;

[0046] p is 0.1-6, preferably 2-3.5.

[0047] Preferably, the magnesium compound is at least one of dimethoxymagnesium, diethoxymagnesium, dipropoxymagnesium, diisopropoxymagnesium, dibutoxymagnesium, diisobutoxymagnesium, dipentoxymagnesium, dihexylmagnesium, di(2-methyl)hexylmagnesium, methoxymagnesium chloride, methoxymagnesium bromide, methoxymagnesium iodide, ethoxymagnesium chloride, ethoxymagnesium bromide, ethoxymagnesium iodide, propoxymagnesium chloride, propoxymagnesium bromide, propoxymagnesium iodide, butoxymagnesium chloride, butoxymagnesium bromide, butoxymagnesium iodide, magnesium dichloride, magnesium dibromide, magnesium diiodide, an alcohol adduct of magnesium dichloride, an alcohol adduct of magnesium dibromide, and an alcohol adduct of magnesium diiodide. Most preferably, the magnesium compound is at least one of diethoxymagnesium or magnesium dichloride.

[0048] As a specific embodiment of the present invention, the titanium element is in the form of a titanium compound.

[0049] The titanium compound may be a compound represented by formula (VIII);

[0050] TiX m (OR9)4-m Formula (VIII);

[0051] Wherein, X is a halogen, and the halogen is one of chlorine, bromine, and iodine; R9 is a hydrocarbon group having 1 to 20 carbon atoms, and m is an integer between 0 and 4;

[0052] Preferably, R9 is an alkyl group having 1 to 5 carbon atoms.

[0053] Preferably, the titanium compound is at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxide, titanium tetraethoxide, titanium triethoxide monochloride, titanium diethoxide dichloride and titanium triethoxide monochloride.

[0054] More preferably, the titanium compound is titanium tetrachloride.

[0055] The catalyst for olefin polymerization according to the present invention can be prepared by contacting a magnesium compound, a titanium compound and an internal electron donor compound under certain conditions. The amounts of the titanium compound, the magnesium compound and the internal electron donor compound used to prepare the catalyst for olefin polymerization are not particularly limited and can be conventional substances and amounts in the art, respectively.

[0056] As a specific embodiment of the present invention, the method for preparing the catalyst for olefin polymerization of the present invention by reacting a titanium compound, a magnesium compound and an internal electron donor compound can be carried out by a conventional method for preparing olefin catalysts in the art. For example, the catalyst for olefin polymerization of the present invention can be prepared by the following method.

[0057] Method 1, referring to the method of CN102453150B, the catalyst component is prepared according to the following steps: (1) an alkoxy magnesium or alkoxy magnesium halide compound is contacted with a titanium compound and an internal electron donor compound represented by formula (I) in the presence of an inert diluent; (2) the solid obtained in step (1) is washed with an inert solvent to obtain a solid catalyst.

[0058] Specific examples of the above-mentioned magnesium alkoxides include dimethoxymagnesium, diethoxymagnesium, dipropoxymagnesium, diisopropoxymagnesium, dibutoxymagnesium, diisobutoxymagnesium, dipentoxymagnesium, dihexoxymagnesium, di(2-methyl)hexoxymagnesium, etc. or mixtures thereof, preferably diethoxymagnesium or a mixture of diethoxymagnesium and other magnesium alkoxides. The preparation method of the magnesium alkoxide compound can be prepared by a method known in the art, such as preparing the compound by reacting metallic magnesium with a fatty alcohol in the presence of a small amount of iodine.

[0059] As specific examples of the above-mentioned alkoxy magnesium halide, methoxy magnesium chloride, ethoxy magnesium chloride, propoxy magnesium chloride, butoxy magnesium chloride, etc. can be cited, preferably ethoxy magnesium chloride. The preparation method of the alkoxy magnesium halide compound can be prepared by a method well known in the art, such as mixing the Grignard reagent butyl magnesium chloride with tetraethoxy titanium and tetraethoxy silicon to prepare ethoxy magnesium chloride.

[0060] In step (1), the inert diluent is selected from at least one of alkanes or aromatic hydrocarbons having 6 to 10 carbon atoms. Specific examples of the inert diluent include hexane, heptane, octane, decane, benzene, toluene, xylene, or a mixture thereof; toluene is preferred in the present invention. There is no particular limitation on the order of contacting. For example, the components may be contacted in the presence of an inert diluent, or the components may be contacted by diluting the components with an inert solvent in advance. There is no particular limitation on the number of contacts. The components may be contacted once or multiple times.

[0061] The solid catalyst component obtained by the above contact reaction can be washed with an inert solvent, such as a hydrocarbon compound. Specific examples of the inert solvent can be selected from hexane, heptane, octane, decane, benzene, toluene, xylene, or a mixture thereof. Hexane is preferred in the present invention.

[0062] As a specific embodiment of the present invention, there is no particular limitation on the washing method, and decantation, filtration and the like are preferred. The amount of the inert solvent used, the washing time, and the number of washing times are not particularly limited. Usually 1 to 1000 moles, preferably 10 to 500 moles of solvent are used relative to 1 mole of the magnesium compound, and the washing is usually performed for 1 to 24 hours, preferably 10 to 6 hours. In addition, from the perspective of washing uniformity and washing efficiency, stirring is preferably performed during the washing operation. It should be noted that the obtained solid catalyst can be stored in a dry state or in an inert solvent.

[0063] The amount of each component used in method 1 is calculated per mole of magnesium. The amount of titanium compound used is 0.5-100 moles, preferably 1-50 moles; the amount of inert diluent used is usually 0.5-100 moles, preferably 1-50 moles; the total amount of electron donor compound is usually 0.005-10 moles, preferably 0.01-1 mole.

[0064] The contact temperature of the components is usually -40 to 200°C, preferably -20 to 150°C; the contact time is usually 1 minute to 20 hours, preferably 5 minutes to 8 hours.

[0065] Method 2, referring to the method of patent CN85100997, magnesium dihalide is dissolved in a solvent system consisting of an organic epoxy compound, an organic phosphorus compound and an inert diluent to form a uniform solution, which is then mixed with a titanium compound, and a solid is precipitated in the presence of a precipitation aid; then the solid is contacted with an internal electron donor to attach it to the solid to obtain a solid catalyst.

[0066] The precipitation aid used in method 2 may be at least one of an organic anhydride, an organic acid, an ether and a ketone. A specific example of the organic anhydride may be at least one of acetic anhydride, phthalic anhydride, succinic anhydride and maleic anhydride, a specific example of the organic acid may be at least one of acetic acid, propionic acid, butyric acid, acrylic acid and methacrylic acid, a specific example of the ether may be at least one of methyl ether, ethyl ether, propyl ether, butyl ether and amyl ether, and the ketone may be at least one of acetone, methyl ethyl ketone and benzophenone.

[0067] The organic epoxy compound used in the second method can be at least one selected from ethylene oxide, propylene oxide, butylene oxide, butadiene oxide, butadiene dioxide, epichlorohydrin, methyl glycidyl ether and diglycidyl ether, preferably epichlorohydrin.

[0068] The organophosphorus compound used in method 2 can be a hydrocarbon ester or a halogenated hydrocarbon ester of orthophosphoric acid or phosphorous acid. Specific examples of the organophosphorus compound include: trimethyl orthophosphate, triethyl orthophosphate, tributyl orthophosphate, triphenyl orthophosphate, trimethyl phosphite, triethyl phosphite, tributyl phosphite or benzyl phosphite, etc., preferably tributyl orthophosphate.

[0069] The inert diluent used in the second method can be at least one of hexane, heptane, octane, decane, benzene, toluene and xylene.

[0070] The amount of each component used in method 2, calculated per mole of magnesium halide, can be 0.2-10 moles of organic epoxy compound, preferably 0.5-4 moles; the organic phosphorus compound can be 0.1-3 moles, preferably 0.3-1.5 moles; the titanium compound can be 0.5-20 moles, preferably 5-15 moles; the precipitation-aiding component can be 0.01-0.3 moles, preferably 0.02-0.08 moles; the total amount of electron donor compounds can be 0-10 moles, preferably 0.02-0.3 moles.

[0071] Method three, prepare the catalyst with reference to the preparation method of CN1091748. Magnesium chloride alcoholate melt is dispersed in a dispersion system of white oil and silicone oil by high-speed stirring to form an emulsion, which is then unloaded into a coolant and rapidly cooled and shaped to form magnesium chloride alcoholate microspheres. The coolant is an inert hydrocarbon solvent with a low boiling point, such as petroleum ether, pentane, hexane, heptane, etc. The obtained magnesium chloride alcoholate microspheres are washed and dried to form a spherical carrier, and the molar ratio of alcohol to magnesium chloride is 2-3, preferably 2-2.5. The carrier particle size is 10-300 microns, preferably 30-150 microns.

[0072] The spherical carrier is treated with excess titanium tetrachloride at low temperature, and the temperature is gradually increased. An electron donor is added during the treatment process, and after the treatment, it is washed with an inert solvent for multiple times, and a solid powdery spherical catalyst is obtained after drying. The molar ratio of titanium tetrachloride to magnesium chloride is 20-200, preferably 30-60; the initial treatment temperature is -30-0°C, preferably -25--20°C; the final treatment temperature is 80-136°C, preferably 100-130°C.

[0073] The obtained spherical catalyst has the following characteristics: titanium content (by weight) 1.5-3.5%, ester content 6.0-20.0%, chlorine content 52-60%, magnesium content 10-20%, inert solvent content 1-6%.

[0074] Method 4: Prepare the catalyst with reference to the method disclosed in CN1506384. First, a magnesium compound and an organic alcohol compound are mixed with an inert solvent at a molar ratio of 2-5, and the temperature is raised to 120-150°C to form a uniform solution, and phthalic anhydride, a silicon-containing compound or other auxiliary agents that are conducive to obtaining good particles are selectively added as precipitation aids; then, the alcoholate is contacted with the titanium compound at a titanium / magnesium molar ratio of 20-50 for reaction for 2-10 hours, the reaction temperature is -15 to -40°C, and the temperature is raised to 90-110°C in the presence of a precipitation aid; the electron donor compound of the present invention is added at a magnesium / ester molar ratio of 2-10, and the reaction is carried out at 100-130°C for 1-3 hours, and the solid particles are separated by filtration; then (optionally repeated 2-3 times) the solid particles are contacted with the titanium compound at a titanium / magnesium molar ratio of 20-50 for reaction at 100-130°C for 1.5-3 hours, and the solid particles are separated by filtration; finally, the solid particles are washed with an inert solvent at 50-80°C, and the catalyst is obtained after drying.

[0075] In any of the above four methods for preparing the catalyst for olefin polymerization of the present invention, the internal electron donor may be used alone or in combination of two or more.

[0076] In any of the above four methods for preparing the olefin polymerization catalyst of the present invention, the internal electron donor compound can also be added before or during the contact between the magnesium compound and the titanium compound. For example, in method one, the internal electron donor compound is first added to a suspension of alkoxymagnesium or alkoxymagnesium halide in an inert diluent, and then mixed with the titanium compound to prepare the olefin polymerization catalyst; in method two, the internal electron donor compound is added to the magnesium halide solution before the magnesium halide solution contacts the titanium compound.

[0077] In the preparation of the above-mentioned olefin polymerization catalyst, the molar ratio of the sum of the amounts of the first internal electron donor compound and the second internal electron donor compound to the magnesium atom is usually 0.01-3, preferably 0.02-0.3.

[0078] The catalyst provided by the present invention preferably contains 1-3.5wt% titanium, 10-20wt% magnesium, 50-70wt% chlorine, and 6-20wt% internal electron donor compounds based on the total amount of the catalyst, and more preferably contains 1.8-3.2wt% titanium, 15-20wt% magnesium, 52-60wt% chlorine, and 7-11wt% internal electron donor compounds based on the total amount of the catalyst components. In the total internal electron donor, the molar ratio of the first internal electron donor compound represented by formula (I) to the second internal electron donor compound represented by formulas (II) to (IV) is (0.1:1) to (1:0.1); preferably, (0.2:1) to (1:0.2); more preferably, (0.3:1) to (1:0.3).

[0079] As a specific embodiment of the present invention, the olefin polymerization catalyst system is used for the polymerization reaction of olefins represented by the general formula CH2=CHR, wherein R is hydrogen or an alkyl group with 1 to 6 carbon atoms.

[0080] In a second aspect, the present invention provides a catalyst system for olefin polymerization reaction, wherein the catalyst system comprises the catalyst for olefin polymerization reaction, an alkyl aluminum compound and an external electron donor compound.

[0081] As a specific embodiment of the present invention, the molar ratio of the alkyl aluminum compound to the catalyst for olefin polymerization reaction is 5-5000:1; the molar ratio of the alkyl aluminum compound to the catalyst for olefin polymerization reaction is 50-500:1.

[0082] As a specific embodiment of the present invention, the alkyl aluminum compound is a compound represented by formula (IX);

[0083] AlR'nX'3-n' formula (IX);

[0084] In formula (IX), R' is hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, X' is a halogen, and n' is an integer between 1 and 3;

[0085] The alkyl aluminum compound is at least one of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trioctylaluminum, diethyl aluminum monohydrogenate, diisobutyl aluminum monohydrogenate, diethyl aluminum monochloride, diisobutyl aluminum monochloride, sesquiethyl aluminum chloride and ethyl aluminum dichloride.

[0086] As a specific embodiment of the present invention, in the catalyst system for olefin polymerization, the type and content of the external electron donor compound are not particularly limited. Preferably, the molar ratio of the alkyl aluminum compound to the external electron donor compound is 0.1-500:1, preferably 1-300:1, and more preferably 3-100:1.

[0087] As a specific embodiment of the present invention, the external electron donor compound is a co-catalyst of a Ziegler-Natta type catalyst;

[0088] The external electron donor compound is an organosilicon compound represented by formula (X);

[0089] R 1″ m″ R 2″ n″ Si(OR 3″ ) 4-m″-n″ Formula (X);

[0090] Among them, R 1″ and R 2″ are the same or different, and are each one of halogen, hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a haloalkyl group having 1 to 20 carbon atoms;

[0091] R 3″ is one of an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a haloalkyl group having 1 to 20 carbon atoms;

[0092] m″ and n″ are integers of 0-3 respectively, and m″+n″<4.

[0093] The external electron donor compound is trimethylmethoxysilane, trimethylethoxysilane, trimethylphenoxytriethylmethoxysilane, triethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, ethylisopropyldimethoxysilane, propylisopropyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, isopropylisobutyldimethoxysilane, di-tert-butyldimethoxysilane, tert-butylmethyldimethoxysilane, tert-butylethyldimethoxysilane, tert-butylpropyldimethoxysilane, tert-butylisopropyldimethoxysilane, tert-butylbutyldimethoxysilane. dimethoxysilane, tert-butylisobutyldimethoxysilane, tert-butyl(sec-butyl)dimethoxysilane, tert-butylpentyldimethoxysilane, tert-butylnonyldimethoxysilane, tert-butylhexyldimethoxysilane, tert-butylheptyldimethoxysilane, tert-butyloctyldimethoxysilane, tert-butyldecyldimethoxysilane, tert-butylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane, cyclohexylpropyldimethoxysilane, cyclohexylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexyltert-butyldimethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentylethyl trimethoxysilane, cyclopentylpropyl trimethoxysilane, cyclopentyl tert-butyl dimethoxysilane, dicyclopentyl dimethoxysilane, cyclopentyl cyclohexyl dimethoxysilane, bis (2-methylcyclopentyl) dimethoxysilane, diphenyl dimethoxysilane, diphenyl diethoxysilane, phenyl triethoxysilane, methyl trimethoxysilane, methyl triethoxysilane, ethyl trimethoxysilane, ethyl triethoxysilane, propyl trimethoxysilane, isopropyl trimethoxysilane, butyl trimethoxysilane, butyl triethoxysilane, isobutyl trimethoxysilane, tert-butyl trimethoxysilane, sec-butyl trimethoxysilane The external electron donor compound may be at least one of dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, cyclohexyl trimethoxysilane, diphenyl dimethoxysilane, diphenyl diethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane, n-propyl trimethoxysilane, vinyl trimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, 2-ethylpiperidinyl-2-tert-butyl dimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyl dimethoxysilane and (1,1,1-trifluoro-2-propyl)-methyl dimethoxysilane. More preferably, the external electron donor compound may be at least one of dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, cyclohexyl methyl dimethoxysilane, methyl tert-butyl dimethoxysilane and tetramethoxysilane.

[0094] In a third aspect, the present invention provides a method for polymerizing polyolefins, comprising contacting one or more olefins with a catalyst system for olefin polymerization reaction under olefin polymerization conditions,

[0095] At least one of the olefins is an olefin represented by the general formula CH2=CHR, wherein R is hydrogen or an alkyl group having 1 to 6 carbon atoms. Preferably, R1 is a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0096] As a specific embodiment of the present invention, the present invention provides a polymerization method for polyolefins, which can be used for homopolymerization of olefins, and can also be used for copolymerization of multiple olefins. The olefin includes 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 can be at least one of ethylene, propylene, 1-n-butene, 4-methyl-1-pentene and 1-n-hexene; preferably, the olefin is propylene.

[0097] As a specific embodiment of the present invention, the catalyst is used in the preparation of polyolefins, and the components of the catalyst system for preparing olefin polymerization reactions, that is, the catalyst provided by the present invention, the organic aluminum compound as a co-catalyst, and the compound as an external electron donor can be contacted before contacting the olefin monomer, which is called "pre-contact" or "pre-complexation" in the industry; or the three components can be added to the olefin monomer separately before the polymerization reaction, that is, no "pre-contact" is implemented. According to the olefin polymerization method provided by the present invention, it is preferred that the components in the olefin polymerization catalyst system adopt the "pre-contact" method. The time of "pre-contact" is 0.1-30 minutes, preferably 1-10 minutes; the temperature of "pre-contact" is -20°C to 80°C, preferably 10-50°C.

[0098] As a specific embodiment of the present invention, the catalyst system is first polymerized to a certain extent in the presence of a small amount of olefin monomer to obtain a prepolymerized catalyst, and then the prepolymerized catalyst is further contacted with the olefin monomer to react to obtain an olefin polymer. This technology is called the "prepolymerization" process in the industry, which helps to improve the polymerization activity of the catalyst and the bulk density of the polymer. According to the olefin polymerization method provided by the present invention, the "prepolymerization" process may be adopted or not, and the "prepolymerization" process is preferably adopted. The "prepolymerization" ratio is 5-1000gPP / gcat, preferably 10-500gPP / g·cat when the olefin monomer is propylene; the temperature of the "prepolymerization" is -20°C to 80°C, preferably 10-50°C.

[0099] According to the polymerization method for preparing polyolefin of the present invention, the polymerization conditions may be conventional conditions in the art, and the amount of catalyst used may be the amount of various catalysts used in the prior art.

[0100] The above raw materials in the present invention can be prepared in-house or commercially available, and the present invention is not particularly limited thereto.

[0101] Compared with the prior art, the present invention has the following beneficial effects:

[0102] 1. The catalyst for olefin polymerization of the present invention, which is prepared by using cyclohexanecarboxylic acid monoester compounds and other internal electron donor compounds (phthalate compounds, 1,3-diethers, glycol ester compounds) as internal electron donor compounds, has a polymerization activity greater than 53 kgPP / gcat and a bulk density of 0.40 to 0.44 g / cm 3 , the melt index is 20.7-33.8 g / 10 min, and the isotacticity is greater than 95%; in particular, the polymerization activity is extremely high, and the cyclohexanecarboxylic acid monoester compounds are relatively easy to synthesize, the raw materials are cheap and easy to obtain, the post-treatment process is simple, does not involve the generation of wastewater, and the production cost is low.

[0103] 2. The present invention provides a catalyst and a catalyst system containing an internal electron donor compound of a specific structure. The catalyst is prepared by compounding a cyclohexanecarboxylic acid monoester compound with other internal electron donors, namely, phthalate compounds, 1,3-diethers, and glycol ester compounds as internal electron donors. The catalyst system containing the catalyst is used in CH2=CHR olefin polymerization, wherein R is hydrogen or an alkyl or aromatic group having 1 to 6 carbon atoms, especially in propylene polymerization reactions, which can reduce the production cost of polypropylene and improve the quality and stability of the product. BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION

[0104] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0105] In each embodiment of the present invention, the purity of the internal electron donor compound used is measured by gas chromatography.

[0106] In each embodiment of the present invention, the melt index (MI) of the polymer used is measured according to GB / T3682-2000.

[0107] In each embodiment of the present invention, the isotacticity index (II) of the propylene polymer used is determined by the heptane extraction method: 2 g of dried polymer sample is placed in an extractor and extracted with boiling heptane for 6 hours. The residue is dried to constant weight, and the ratio of the polymer weight (g) to 2 (g) is the isotacticity.

[0108] In each embodiment of the present invention, the activity calculation used is: catalyst activity = (mass of prepared polyolefin) / (mass of catalyst solid component) g / g.

[0109] In each embodiment of the present invention, the bulk density is determined by dropping the prepared polymer powder from a height of 10 cm into a 100 mL container in a funnel, and weighing the polymer powder in the container as Mg. The bulk density of the polymer is M / 100 g / cm 3 .

[0110] Preparation Example 1-7

[0111] Preparation Examples 1-7 provide synthesis examples of seven electron-donating compounds, ABCDEFG, with the details as follows:

[0112] Compound A: Ethyl cyclohexanecarboxylate

[0113] 75.2g of ethanol and 113.0g of anhydrous pyridine were mixed, stirred evenly, and then dripped into a mixture of 200.0g of cyclohexanecarbonyl chloride and 800mL of toluene. After the dropwise addition was completed, the temperature was raised to 80°C, and the reaction was continued for two hours, and the temperature was continued to be raised to reflux for reaction for 8 hours. After the reaction was completed, the mixture was cooled, the solid was filtered to remove the solid, the solvent was removed by spinning, and the crude product was subjected to vacuum distillation to obtain 166.6g of the final product, ethyl cyclohexanecarboxylate, with a purity of 99.1% (GC).

[0114] Compound B: cyclohexanecarboxylic acid n-propyl ester

[0115] Using a synthetic method similar to compound A, 84.1 g of n-propyl cyclohexanecarboxylate was prepared by replacing ethanol with n-propanol with a purity of 99.0% (GC).

[0116] Compound C: Isopropyl cyclohexanecarboxylate

[0117] Using a synthetic method similar to compound A, 81.7 g of isopropyl cyclohexanecarboxylate was prepared by replacing ethanol with isopropanol with a purity of 99.6% (GC).

[0118] Compound D: n-Butyl cyclohexanecarboxylate

[0119] Using a synthetic method similar to compound A, 84.3 g of n-butyl cyclohexanecarboxylate was prepared by replacing ethanol with n-butanol with a purity of 99.3% (GC).

[0120] Compound E: Isobutyl Cyclohexanecarboxylate

[0121] Using a synthetic method similar to compound A, 79.9 g of isobutyl cyclohexanecarboxylate was prepared by replacing ethanol with isobutyl alcohol with a purity of 99.2% (GC).

[0122] Compound F: Cyclohexanecarboxylic acid n-pentyl ester

[0123] Using a synthetic method similar to compound A, 81.3 g of n-pentyl cyclohexanecarboxylate was prepared by replacing ethanol with n-pentanol with a purity of 99.0% (GC).

[0124] Compound G: Isoamyl cyclohexanecarboxylate

[0125] Using a synthetic method similar to compound A, 84.1 g of isopentyl cyclohexanecarboxylate was prepared by replacing ethanol with isopentyl alcohol with a purity of 99.0% (GC).

[0126] Example 1

[0127] This embodiment provides a method for preparing a catalyst for olefin polymerization reaction, and the specific details are as follows:

[0128] Step 1 Preparation of alkoxymagnesium:

[0129] In a 1L reactor equipped with a stirrer, a reflux condenser, a thermometer and a burette, after fully replacing with nitrogen, add 550mL of ethanol, 10mL of isopropanol and 0.68g of iodine to the reactor to dissolve. After stirring, heat up until the reflux temperature of the reaction system is reached. Then add 32g of magnesium powder in succession; react until no more hydrogen is discharged. Then wash, filter and dry to obtain 147g of alkoxy magnesium carrier.

[0130] Step 2 Preparation of catalyst for olefin polymerization:

[0131] Take 10g of the alkoxy magnesium carrier prepared above, 50mL of toluene, 3.0g of a mixture of compound A and di-n-butyl phthalate (mass ratio is 1:2), and prepare a suspension; in a 300mL reactor repeatedly replaced with high-purity nitrogen, heat it to 65°C, keep it constant for 0.5 hours, and then continue to heat it to 115°C, keep it constant for 1.5 hours, and filter the liquid clean. Add 90mL of toluene and 60mL of titanium tetrachloride to a mixed solution and heat it to 110°C and stir it for 1 hour, filter the liquid clean, then add 120mL of toluene and 30mL of titanium tetrachloride to a mixed solution and heat it to 110°C and stir it for 1 hour, filter the liquid, and wash the solid with 150mL of n-hexane 3 times at 55°C, wash it once with n-hexane at room temperature, filter the liquid and dry it, and the catalyst for olefin polymerization of the present invention is obtained.

[0132] Example 2

[0133] The same preparation method as in Example 1 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with 3.0 g of a mixture of compound B and di-n-butyl phthalate (mass ratio of 1:2).

[0134] Example 3

[0135] The same preparation method as in Example 1 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with 3.0 g of a mixture of compound C and di-n-butyl phthalate (mass ratio of 1:2).

[0136] Example 4

[0137] The same preparation method as in Example 1 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 3.0 g of compound D and di-n-butyl phthalate (mass ratio of 1:2).

[0138] Example 5

[0139] The same preparation method as in Example 1 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with 3.0 g of a mixture of compound E and di-n-butyl phthalate (mass ratio of 1:2).

[0140] Comparative Example 1

[0141] The same preparation method as in Example 1 was used to prepare a catalyst for olefin polymerization reaction by replacing the internal electron donor compound with 3.0 g of di-n-butyl phthalate.

[0142] Example 6

[0143] (1) Preparation of alcoholate solution

[0144] In a reactor that has been repeatedly replaced with high-purity nitrogen, 20 g of anhydrous magnesium chloride, 80 mL of toluene, and 80 mL of isooctyl alcohol were added in sequence. The reaction was carried out at a stirring speed of 300 rpm and a temperature of 110°C for 3.0 hours. 3.0 mL of tetrabutyl titanate was added, and the reaction was continued for 1.5 hours. 120 mL of toluene was added to obtain a stable and uniform alcohol complex solution.

[0145] (2) Preparation of catalysts for olefin polymerization

[0146] 75 mL of the alcoholate solution and 2.4 g of 2,4-pentanediol benzoate were added dropwise into a reactor fully replaced with nitrogen and equipped with 60 mL of titanium tetrachloride and 40 mL of toluene. The mixture was stirred and fully contacted at -25 ° C for 1.5 hours, and then heated to 110 ° C for 3.5 hours. After 1 hour of constant temperature, 108 mL of toluene and 12 mL of titanium tetrachloride were added, stirred for 1 hour, cooled and filtered, and then 12 mL of titanium tetrachloride and 108 mL of toluene were added. The temperature was raised to 100 ° C, and a mixture of 1.5 g of compound A and diisobutyl phthalate (mass ratio of 1:2) was added, and the temperature was kept constant for 1 hour. The temperature was raised to 110 ° C, 96 mL of toluene and 24 mL of titanium tetrachloride were added, stirred for 1 hour, and the liquid was removed by filtering, and repeated twice. 108 mL of toluene and 12 mL of titanium tetrachloride were added and stirred for 1 hour. After filtering, the solid obtained was washed 4 times with 150 mL of hexane. The catalyst for olefin polymerization is obtained by filter pressing, transfer and drying.

[0147] Example 7

[0148] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound D and diisobutyl phthalate (mass ratio of 1:2).

[0149] Example 8

[0150] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound E and diisobutyl phthalate (mass ratio of 1:2).

[0151] Example 9

[0152] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound F and diisobutyl phthalate (mass ratio of 1:2).

[0153] Example 10

[0154] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound G and diisobutyl phthalate (mass ratio of 1:2).

[0155] Comparative Example 2

[0156] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction by replacing the internal electron donor compound with 1.5 g of diisobutyl phthalate.

[0157] Embodiment 11

[0158] (1) Preparation of magnesium chloride solution:

[0159] In a reactor that has been repeatedly replaced with high-purity nitrogen, 20g of anhydrous magnesium chloride, 80mL of toluene, 32mL of epichlorohydrin, and 36mL of tributyl phosphate were added in sequence at room temperature, the temperature was raised to 50°C, and the mixture was reacted for 5 hours to dissolve all of them. A uniform magnesium chloride solution was formed, 80mL of toluene was added dropwise, and then stirred at 50°C for 1 hour.

[0160] (2) Preparation of catalyst components:

[0161] 60mL of titanium tetrachloride and 60mL of toluene are mixed and cooled to -28°C. 60mL of the above-mentioned magnesium chloride solution and 0.64g of 2,4-pentanediol dibenzoate are added dropwise into the mixed solution for 1 hour. After the addition is completed, it is stirred to fully contact at -28°C for 0.5 hour, and then the temperature is raised to 85°C after 4.5 hours. After the temperature is kept constant for 1 hour, the liquid is removed by filter pressing, and 120mL of toluene is added for washing, and the washing is repeated twice. 24mL of titanium tetrachloride and 96mL of toluene, 1.5g of a mixture of compound A and di-n-butyl phthalate (mass ratio is 1:2) are added (mass ratio is 1:2), the temperature is raised to 100°C and stirred for 1 hour. 72mL of toluene and 48mL of titanium tetrachloride are added, stirred for 1 hour, and the liquid is removed by filter pressing, and repeated three times. The solid obtained after the liquid is removed by filter pressing is washed 4 times with 150mL of hexane. Filter pressing, transfer and dry to obtain a catalyst for olefin polymerization reaction.

[0162] Example 12

[0163] The same preparation method as in Example 11 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound B and di-n-butyl phthalate (mass ratio of 1:2).

[0164] Example 13

[0165] The same preparation method as in Example 11 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound C and di-n-butyl phthalate (mass ratio of 1:2).

[0166] Embodiment 14

[0167] The same preparation method as in Example 11 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound D and di-n-butyl phthalate (mass ratio of 1:2).

[0168] Embodiment 15

[0169] The same preparation method as in Example 11 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound E and di-n-butyl phthalate (mass ratio of 1:2).

[0170] Comparative Example 3

[0171] The same preparation method as in Example 11 was used to prepare a catalyst for olefin polymerization reaction by replacing the internal electron donor compound with 1.5 g of di-n-butyl phthalate.

[0172] Example 16

[0173] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound A and 2-isopentyl-2-isopropyl-1,3-dimethyl ether (mass ratio of 1:2).

[0174] Embodiment 17

[0175] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound D and 2-isopentyl-2-isopropyl-1,3-dimethyl ether (mass ratio of 1:2).

[0176] Embodiment 18

[0177] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound A and 2,4-pentanediol benzoic acid diester (mass ratio of 1:2).

[0178] Embodiment 19

[0179] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound E and 2,4-pentanediol benzoic acid diester (mass ratio of 1:2).

[0180] Embodiment 20

[0181] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound A and 3,5-heptanediol benzoic acid diester (mass ratio of 1:2).

[0182] Embodiment 21

[0183] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound D and 3,5-heptanediol benzoic acid diester (mass ratio of 1:2).

[0184] Embodiment 22

[0185] The same preparation method as in Example 6 was used to prepare a catalyst for olefin polymerization reaction, except that the internal electron donor compound was replaced with a mixture of 1.5 g of compound E and 3,5-heptanediol benzoic acid diester (mass ratio of 1:2).

[0186] Test Case

[0187] The catalysts prepared in Examples 1 to 22 and the catalysts prepared in Comparative Examples 1 to 3 were respectively combined with triethylaluminum and cyclohexylmethyldimethoxysilane to form different catalyst systems, and propylene polymerization was carried out. The specific details are as follows:

[0188] In a 5L autoclave, after sufficient replacement of gaseous propylene, 5mL of triethylaluminum hexane solution (the concentration of triethylaluminum is 0.5mmol / mL), 1mL of cyclohexylmethyldimethoxysilane (CHMMS) hexane solution (the concentration of CHMMS is 0.10mmol / mL), 10mL of anhydrous hexane and 10mg of catalyst were added at room temperature. The autoclave was closed, and a certain amount of hydrogen and 1.2kg of liquid propylene were introduced. The amount of hydrogen added was 4.5L, the polymerization temperature was 70℃, and the material was discharged after the polymerization time of 1 hour.

[0189] The solid catalysts prepared in Examples 1-22 and Comparative Examples 1-3 were tested respectively, and their performance data are shown in Table 1:

[0190] Table 1. Performance of catalysts prepared in Examples 1-22 and Comparative Examples 1-3

[0191]

[0192]

[0193] From the data in Table 1, it can be seen that the ZN catalyst prepared by compounding the cyclohexanecarboxylic acid monoester compound with phthalate compound, 1,3-diether and diol ester compound as internal electron donors has high activity, and the catalyst has excellent hydrogen regulation performance and high stereospecific ability. Therefore, the polypropylene catalyst prepared by compounding these types of internal electron donors provided by the present invention is very suitable for preparing general polypropylene grades.

[0194] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0195] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A catalyst for olefin polymerization, characterized in that: Including titanium, magnesium, halogens, and internal electron donor compounds; The electron donor compound includes a first internal electron donor compound and a second internal electron donor compound; The first internal electron donor compound is a cyclohexanecarboxylic acid monoester compound, and its general structural formula is shown in formula (I): Wherein, R1 is a straight-chain alkane having 1 to 20 carbon atoms, a branched-chain alkyl or cycloalkyl having 3 to 20 carbon atoms, or an aralkyl having 7 to 20 carbon atoms; The second internal electron donor is at least one of phthalate, 1,3-diether, and glycol ester compounds; The general structural formula of the phthalate ester is shown in formula (II): In the formula, RR2 and R3 are the same or different, and represent a straight-chain alkane having 1 to 20 carbon atoms, a branched-chain alkyl having 3 to 20 carbon atoms, a cycloalkyl having 3 to 20 carbon atoms, or an aralkyl having 7 to 20 carbon atoms, wherein the hydrogen atoms on the carbon in the alkyl, cycloalkyl or aralkyl are optionally substituted by heteroatoms, alkyl or alkoxy groups, and / or the carbon atoms on the main chain thereof are optionally substituted by heteroatoms; The 1,3-diether structural formula is shown in formula (III): The 1,3-diether compound is 2-isopentyl-2-isopropyl-1,3-dimethyl ether; The general structural formula of the diol ester compound is shown in formula (IV): In the formula, R4 and R5 are the same or different and are selected from a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or a cycloalkyl group; Among the internal electron donor compounds, the molar ratio of the first internal electron donor compound to the second internal electron donor compound is (0.1:1) to (1:0.1).

2. The catalyst for olefin polymerization according to claim 1, characterized in that The cyclohexanecarboxylic acid monoester compound is selected from at least one of methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, n-propyl cyclohexanecarboxylate, isopropyl cyclohexanecarboxylate, n-butyl cyclohexanecarboxylate, isobutyl cyclohexanecarboxylate, tert-butyl cyclohexanecarboxylate, n-pentyl cyclohexanecarboxylate, isopentyl cyclohexanecarboxylate, tert-pentyl cyclohexanecarboxylate and cyclopentyl cyclohexanecarboxylate.

3. The catalyst for olefin polymerization according to claim 1, characterized in that The phthalate compound is selected from at least one of dimethyl phthalate, diethyl phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-n-pentyl phthalate and diisopentyl phthalate.

4. The catalyst for olefin polymerization according to claim 1, characterized in that The diol ester compound is at least one of 2,4-pentanediol benzoic acid diester and 3,5-heptanediol benzoic acid diester.

5. The catalyst for olefin polymerization according to any one of claims 1 to 4, characterized in that in, The mass ratio of the titanium element, the magnesium element, the halogen, and the internal electron donor compound is 1-8:10-70:20-90:2-30; and / or In the internal electron donor compound, the molar ratio of the first internal electron donor compound to the second internal electron donor compound is (0.2:1) to (1:0.2).

6. The catalyst for olefin polymerization according to claim 5, characterized in that in, The mass ratio of the titanium element, the magnesium element, the halogen, and the internal electron donor compound is 1.6-6:15-40:30-85:3-20; and / or In the internal electron donor compound, the molar ratio of the first internal electron donor compound to the second internal electron donor compound is (0.3:1) to (1:0.3).

7. The catalyst for olefin polymerization according to any one of claims 1 to 4, characterized in that The magnesium element is in the form of a magnesium compound; The magnesium compound is at least one of a magnesium compound represented by formula (V), a hydrate of a magnesium compound represented by formula (VI), and an alcohol adduct of a magnesium compound represented by formula (VII); The magnesium compound represented by the formula (V): MgR6R7 Formula (V) wherein R6 and R7 are the same or different and are each independently at least one of halogen, a linear alkoxy group having 1 to 5 carbon atoms, a branched alkoxy group having 3 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms; The hydrate of the magnesium compound represented by the formula (VI): MgR6R7·qH2O Formula (VI) wherein R6 and R7 are the same or different and are each independently at least one of halogen, a linear alkoxy group having 1 to 5 carbon atoms, a branched alkoxy group having 3 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms; q is in the range of 0.1-6; The alcohol adduct of the magnesium compound represented by the formula (VII): MgR6R7·pR8OH Formula (VII) wherein R6 and R7 are the same or different and are each independently at least one of halogen, a linear alkoxy group having 1 to 5 carbon atoms, a branched alkoxy group having 3 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms; R8 is a hydrocarbon group having 1 to 18 carbon atoms; p is 0.1-6.

8. The catalyst for olefin polymerization according to claim 7, characterized in that: p is 2-3.

5.

9. The catalyst for olefin polymerization according to any one of claims 1 to 4, characterized in that The titanium element is in the form of a titanium compound; The titanium compound is a compound represented by formula (VIII); TiX m (OR9) 4-m Formula (VIII) Wherein, X is a halogen, and the halogen is one of chlorine, bromine, and iodine; R9 is a hydrocarbon group having 1 to 20 carbon atoms, and m is an integer between 0 and 4.

10. A catalyst system for olefin polymerization, characterized in that: The catalyst system comprises the catalyst for olefin polymerization according to any one of claims 1 to 9, an alkyl aluminum compound and an external electron donor compound.

11. The catalyst system for olefin polymerization according to claim 10, characterized in that: The molar ratio of the alkyl aluminum compound to the catalyst for olefin polymerization is 5-5000:

1.

12. The catalyst system for olefin polymerization according to claim 11, characterized in that: The molar ratio of the alkyl aluminum compound to the catalyst for olefin polymerization is 50-500:

1.

13. The catalyst system for olefin polymerization according to any one of claims 10 to 12, characterized in that: The alkyl aluminum compound is a compound represented by formula (IX); AlR' n X' 3-n Formula (IX); In formula (IX), R' is hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, X' is a halogen, and n is an integer between 1 and 3; The external electron donor compound is a co-catalyst for a Ziegler-Natta type catalyst.

14. The catalyst system for olefin polymerization according to claim 13, characterized in that: The external electron donor compound is an organosilicon compound represented by formula (X); R 1” m” R 2” n” Si(OR 3” ) 4-m”-n” Formula (X); Among them, R 1” and R 2” are the same or different, and are each one of halogen, hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a haloalkyl group having 1 to 20 carbon atoms; R 3” is one of an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a haloalkyl group having 1 to 20 carbon atoms; m" and n" are integers of 0-3 respectively, and m"+n"<4.

15. A method for polymerizing polyolefins, characterized in that: Under olefin polymerization conditions, one or more olefins are contacted with the catalyst system for olefin polymerization according to any one of claims 10 to 14, wherein at least one of the olefins is an olefin represented by the general formula CH2=CHR, wherein R is hydrogen or an alkyl group having 1 to 6 carbon atoms.

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