Ziegler-Natta catalyst

Abstract

The invention relates to a solid Ziegler-Natta catalyst which specifically comprises the following components in percentage by weight: (a) a catalytic component containing 10-25% of magnesium, 1-10% of titanium, 40-60% of halogen and 1-30% of at least one maleate selected from a general formula (I); (b) an aluminum alkyl compound; (c) optionally, an external electron donor; as the compound which has a special structure and contains a thiophene structure is used as an internal electron donor, the synthesized Ziegler-Natta catalyst shows very high catalytic activity in propylene (co) polymerization, and the obtained polymer has high stereospecificity. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a Ziegler-Natta catalyst for propylene (co)polymerization. Background Art

[0002] Supported Ziegler-Natta catalyst is a solid titanium catalyst with magnesium, titanium, halogen and electron donor as basic components. It is particularly suitable for the polymerization of α-olefins with 3 or more carbon atoms. The obtained olefin polymer has a high yield and stereoregularity. Electron donor is one of the essential components of supported Ziegler-Natta catalyst, which can effectively improve the activity and isotacticity of the catalyst. Polyolefin catalysts are constantly updated with the development of electron donor compounds.

[0003] Researchers use a variety of electron donor compounds to improve the activity and isotacticity of Ziegler-Natta catalysts. Commonly used are mono- or poly-carboxylic acid esters, anhydrides, ketones, mono- or poly-ethers, amines, and their derivatives. Currently, di-aromatic carboxylic acid esters are more commonly used in industry, such as diisobutyl phthalate (PM Trivedi, et al. J. Polym. Res., 2021, 28, Article number: 45). Supported Ziegler-Natta catalysts with 1,3-diether compounds as electron donors are recognized as a new generation of electron donor compounds with high activity and isotacticity, such as 9,9-di(methoxymethyl)fluorene recently disclosed by CN1090194C, CN00103538, and CN1137155C. In addition, researchers have recently tried to use other compounds as electron donors in olefin polymerization catalyst components, such as 1,8-naphthalene diphenol esters reported by Chang et al. of BASF (WO2011084691A2 and US20110213106A1) and 1,2-benzenediphenol esters (US20190338054A1 and CN102325808A) structures disclosed by Dow. These electron donor-loaded catalysts have high activity and isotacticity.

[0004] Although phthalate compounds are relatively active and isotactic in the synthesis of Ziegler-Natta catalysts as internal electron donors, and they are cheap and easy to obtain. However, it is a plasticizer that is harmful to the human body. Studies have shown that its toxicity comes from the aromatic rings in its structure (Y.Hu., et al. Ind. Eng. Chem. Res. 2020, 59, 7367-7374). The development of non-phthalate internal electron donors has always been a hot topic in the field of Ziegler-Natta catalyst synthesis. For example, cyclohexane diacid ester compounds disclosed in patent WO2017117439 can be used as effective internal electron donors for Ziegler-Natta catalysts; the catalysts supported by a monocyclic structure in which the substituents on the 2nd and 3rd carbon atoms of maleate are connected to form a ring disclosed in patents JP2014201602A and WO2006077945 show very high propylene polymerization activity and isotacticity; in addition, internal electron donors containing bio-based furans have also been reported (patents CN101423566A and CN101671408A). Summary of the invention

[0005] The present invention aims to provide a Ziegler-Natta catalyst for CH2=CHR olefin polymerization, wherein R is hydrogen or a hydrocarbon group having 1 to 12 carbon atoms. Another object of the present invention is to provide a catalytic component of the catalyst.

[0006] The Ziegler-Natta catalyst components proposed by the present invention specifically include:

[0007] (a) a main catalyst: a catalyst component containing, by weight percentage, 10% to 25% magnesium, 1% to 10% titanium, 40% to 60% halogen and 1% to 30% of at least one maleate selected from the general formula (I);

[0008]

[0009] (b) an alkylaluminum compound;

[0010] (c) optionally, an external electron donor component;

[0011] Wherein, the groups R1 and R2 in the general formula (I) are the same or different from each other and are C1 to C 20 a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; the groups R3 to R6 are identical or different from each other and are hydrogen or C1-C 20 A linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms, and two or more groups in R3-R6 can be bonded to each other to form one or more condensed ring structures.

[0012] Based on the molar ratio of titanium:aluminum:external electron donor compound, the dosage ratio between the components in the catalyst is 1:5 to 1000:0 to 500.

[0013] Further, in the above technical solution, in the above general formula (I) of the compound, R1 and R2 are C1-C 10 alkyl, cycloalkyl or arylalkyl, preferably C1-C 10 alkyl, particularly preferably isopropyl, n-butyl, isobutyl or neopentyl alcohol group.

[0014] Further, in the above technical solution, in the above general formula (I) of the compound, it is preferred that at least one group of R3 and R4, R5 and R6 is hydrogen, and more preferably, both R3 and R4 are hydrogen.

[0015] Further, in the above technical solution, in the above general formula (I) of the compound, R5 and R6 are not simultaneously hydrogen or C1-C 20 linear or branched alkyl.

[0016] Further, in the above technical solution, the above general formula (I) of the compound includes but is not limited to: dimethyl 3,4-thiophenedicarboxylate, diethyl 2-methyl-3,4-thiophenedicarboxylate, diisopropyl 2,5-dimethyl-3,4-thiophenedicarboxylate, dibenzyl 3,4-thiophenedicarboxylate, di-n-butyl 2-methyl-3,4-thiophenedicarboxylate, diisobutyl 2,5-diformyl-3,4-thiophenedicarboxylate, diisobutyl 2-phenyl-3,4-thiophenedicarboxylate, dineopentyl 2,5-diphenyl-3,4-thiophenedicarboxylate.

[0017] Further, in the above technical solution, the synthesis of the above general formula (I) of the compound can be prepared by the esterification reaction of the corresponding thiophene dicarboxylic acid (anhydride), as shown below, which is simple and easy to synthesize. In the following synthesis route, the definitions of the substituents R1-R4 in the structural formula are the same as R1-R4 in formula (I).

[0018]

[0019] Further, in the above technical solution, the particle size distribution of magnesium in the catalyst is 20 to 250 μm, and it is provided by the magnesium alkoxide of the general formula Mg(OR') m M (2-m) ·nROH, where R' is C1-C 20 alkyl, arylalkyl or aryl; M is a halogen; m is an integer of 0 ≤ m ≤ 2; n is a decimal or integer of 0 < n < 6; R is C1-C 20 alkyl or arylalkyl.

[0020] Mg(OR')mM(2-m)+nROH → Mg(OR′)m M (2-m) ·nROH

[0021] Furthermore, in the above technical scheme, the magnesium halide in the magnesium halide alcoholate is selected from one of magnesium dichloride, magnesium dibromide, chloromethoxymagnesium or chloroethoxymagnesium; the alcohol in the magnesium halide alcoholate is one of ethanol, n-propanol, isopropanol, n-butanol or isobutanol, preferably ethanol.

[0022] Further, in the above technical scheme, the magnesium halide alcoholate is synthesized according to the literature report (US4399054), and the synthesis of the ethanolate of magnesium chloride is taken as an example. The specific synthesis method is as follows: 24g of anhydrous MgCl2, 390mL of vaseline oil, 50mL of anhydrous ethanol, 10mL of silicone oil and 2mL of Siban are added to a high-pressure reactor at room temperature, and stirred and heated to 130°C for 3 hours under nitrogen protection to completely dissolve the solid. After that, nitrogen is continuously charged into the kettle and the pressure of 1MPa is maintained, and the discharge valve is opened to pass the mixture in the kettle through a capillary tube with a diameter of 1.2mm and a length of 3.54 meters, and washed with hexane 5 times, and dried at room temperature to obtain a spherical MgCl2 ethanolate carrier.

[0023] Furthermore, in the above technical solution, the titanium in the catalytic component is of the general formula TiA n (OR”) 4-n The compound is provided, wherein R" is a hydrocarbon group having 1 to 20 carbon atoms; A is a halogen; and n=1 to 4. Specific compounds include: titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tetrabutoxytitanium, tetraethoxytitanium, monochlorotriethoxytitanium, dichlorodiethoxytitanium or trichloroethoxytitanium, preferably titanium tetrachloride.

[0024] The present invention provides a preparation method of a catalytic component a, comprising: (1) adding a spherical magnesium halide alcoholate to a titanium compound at -40 to 10°C, reacting for 1 to 4 hours, wherein the molar ratio of magnesium to titanium is 1:5 to 1:50; (2) heating the temperature to 30 to 80°C, adding an inner electron compound, wherein the molar ratio of magnesium to the inner electron donor compound is 2:1 to 15:1; (3) heating the temperature to 100 to 150°C, reacting for 1 to 4 hours; (4) filtering, then adding the same amount of titanium compound as in step (1), reacting at 110 to 130°C for 1 to 4 hours, and filtering, washing, and drying to obtain the catalyst.

[0025] Furthermore, in the above technical solution, the alkylaluminum compound is a trialkylaluminum compound, such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, a mixture of trialkylaluminum and alkylaluminum halide or alkylaluminum hydride, or an alkylaluminumoxane.

[0026] The external electron donor can be selectively added as needed. For olefin polymers that need to have very high stereoregularity (eg, isotactic index greater than 99%), it is recommended to add an external electron donor compound.

[0027] The external electron donor may be a 1,3-diether compound of the general formula (II):

[0028]

[0029] Among them, R5-R 12 may be the same or different and are hydrogen or a hydrocarbon group having 1 to 18 carbon atoms, and R5-R 12 One or more of the groups may be linked to form a ring. 11 and R 12 is a C1-C4 alkyl group, R5 and R6 form an unsaturated condensed ring, R9, R 10 , R7 and R8 are all hydrogen. Particularly preferably, 9,9-bis(methoxymethyl)fluorene is used.

[0030] The usage ratio of the components in the catalyst is preferably 1:25-100-25-300, calculated on the molar ratio of titanium:aluminum:external electron donor compound.

[0031] The catalyst of the present invention can be used for olefin polymerization, especially homopolymerization of propylene or copolymerization of propylene with other olefins to obtain polymers with very high isotactic index. At the same time, it is not excluded that the catalyst is suitable for the production of polyethylene and copolymerization of ethylene with α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene or 1-octene.

[0032] When used for propylene polymerization, various methods in the prior art can be used, which can be carried out in liquid phase or gas phase, or in a combination of liquid phase and gas phase polymerization stages. The polymerization is usually carried out at 0 to 150°C, preferably 40 to 90°C. The polymerization pressure is 0.01 to 10 MPa. Hydrogen or other compounds that can act as chain transfer agents can be used to control the molecular weight of the polymer.

[0033] Since the present invention adopts a maleate compound with a special unsaturated heterocyclic structure as an internal electron donor, its unique electronic effect makes the catalyst have excellent comprehensive performance. When used for propylene (co)polymerization, a satisfactory polymerization yield can be obtained, and the stereospecificity of the polymer is high. At the same time, the catalyst has good hydrogen adjustment sensitivity. DETAILED DESCRIPTION

[0034] The following embodiments are used to further illustrate the present invention, but not to limit the present invention.

[0035] 1. Synthesis of internal electron donors

[0036] The compound of the general formula (I) of the present invention can be obtained by esterification reaction of the corresponding thiophene diacid (anhydride). Diisobutyl phthalate (99%) was purchased from TCI (Shanghai).

[0037] Example 1

[0038] Synthesis of dimethyl 3,4-thiophenedicarboxylate. Add 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylate into a 150 mL flask and stir under reflux overnight. Column chromatography was performed to obtain 39.9 g of dimethyl 3,4-thiophenedicarboxylate, a colorless and transparent liquid product, with a yield of 99%. 1 The H NMR results are shown in Table 1.

[0039] Example 2

[0040] Synthesis of diethyl 2-methyl-3,4-thiophenedicarboxylate The synthesis method is the same as that of Example 1, except that 40 mL of ethanol and 37.2 g of 2-methyl-3,4-thiophenedicarboxylic acid are used instead of 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylic acid, and the yield is 99%. 1 The HNMR results are shown in Table 1.

[0041] Example 3

[0042] Synthesis of diisopropyl 2,5-dimethyl-3,4-thiophenedicarboxylate. The synthesis method is the same as that of Example 1, except that 53 mL of isopropanol and 40.0 g of 2,5-dimethyl-3,4-thiophenedicarboxylate replace 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylate, with a yield of 99%. 1 The H NMR results are shown in Table 1.

[0043] Example 4

[0044] Synthesis of dibenzyl 3,4-thiophene dicarboxylate The synthesis method is the same as that of Example 1, except that 76.0 g of benzyl alcohol and 34.4 g of 3,4-thiophene dicarboxylic acid are used to replace 28 mL of methanol and 34.4 g of 3,4-thiophene dicarboxylic acid, and the yield is 81%. 1 The H NMR results are shown in Table 1.

[0045] Example 5

[0046] Synthesis of 2-methyl-3,4-thiophenedicarboxylic acid di-n-butyl ester. The synthesis method is the same as that of Example 1, except that 65.0 mL of n-butanol and 37.2 g of 2-methyl-3,4-thiophenedicarboxylic acid replace 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylic acid, and the yield is 99%. 1 The H NMR results are shown in Table 1.

[0047] Example 6

[0048] Synthesis of 2,5-dialdehyde-3,4-thiophenedicarboxylic acid diisobutyl ester. The synthesis method is the same as that of Example 1, except that 65.0 mL of isobutyl alcohol and 40.0 g of 2,5-dialdehyde-3,4-thiophenedicarboxylic acid are used to replace 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylic acid, and the yield is 99%. 1 The H NMR results are shown in Table 1.

[0049] Example 7

[0050] Synthesis of 2-phenyl-3,4-thiophenedicarboxylic acid diisobutyl ester. The synthesis method is the same as that of Example 1, except that 65.0 mL of isobutyl alcohol and 49.7 g of 2-phenyl-3,4-thiophenedicarboxylic acid replace 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylic acid, and the yield is 75%. 1 The H NMR results are shown in Table 1.

[0051] Example 8

[0052] Synthesis of dineopentyl 2,5-diphenyl-3,4-thiophenedicarboxylate The synthesis method is the same as that of Example 1, except that 62.0 g of neopentyl alcohol and 64.9 g of 2,5-diphenyl-3,4-thiophenedicarboxylate replace 28 mL of methanol and 34.4 g of 3,4-thiophenedicarboxylate, with a yield of 99%. 1 The H NMR results are shown in Table 1.

[0053] Table 1. 1H NMR results of internal electron donors.

[0054]

[0055]

[0056] 2. Preparation of main catalyst

[0057] TiCl4 was added to a dry glass reactor protected by nitrogen and cooled to -20°C. Microspherical magnesium chloride alcoholate (magnesium alcohol ratio of 2.9:1) carrier was added under stirring. The carrier and TiCl4 were mixed in a ratio of 1g:20mL. The reaction mixture was heated uniformly from -20°C to 0°C, and then to 70°C. The internal electron donor was added to the reactor, and the reaction mixture was heated to 110°C and continued to react for 2h. Filtered, fresh equal amount of TiCl4 was added again, heated to 120°C and continued to react for 2h, filtered, washed the filter cake with hexane, and vacuum dried to obtain the catalyst component. The loading amount of the internal electron donor was determined by Angent 8890A gas chromatograph; the titanium loading amount was determined according to the spectrophotometer.

[0058] 3. Propylene polymerization

[0059] 0.25 mL of external electron donor diphenyldimethoxysilane, 10.0 mL of a hexane solution of a co-catalyst triethylaluminum with a concentration of 1 mol / L, and 0.01 mmol (calculated as titanium) of the catalyst component a prepared by the present invention were added to a 5 L autoclave in sequence, 3 MPa of propylene and 0.2 MPa of hydrogen were added, stirred and mixed uniformly at room temperature, heated to 70° C., stirred for reaction for 2 h, the autoclave was opened and polypropylene was taken out, the polymer was cooled to room temperature, and the propylene was completely volatilized before being weighed, the activity of the catalyst was calculated, and the isotacticity, bulk density, melt index, particle size distribution, molecular weight distribution and other properties of the polypropylene were measured.

[0060] Examples 9-16 used the Ziegler-Natta catalyst synthesized by the internal electron donor in Examples 1-8 and then carried out propylene polymerization using the above-mentioned polymerization steps. The polymerization results are shown in Table 2.

[0061] Table 2. Aggregation results

[0062]

[0063] From the above results, it can be seen that the activity and isotacticity of the synthesized catalyst with thiophene diacid ester as internal electron donor are significantly better than those of the commercial diisobutyl phthalate catalyst.

Claims

1. A solid Ziegler-Natta catalyst, specifically comprising: (a) a main catalyst: a catalyst component containing, by weight percentage, 10% to 25% magnesium, 1% to 10% titanium, 40% to 60% halogen and 1% to 30% of at least one vicinal diester selected from the internal electron donor of general formula (I); (b) an alkylaluminum compound; (c) optionally, an external electron donor component; Wherein, the groups R1 and R2 in the general formula (I) are the same or different from each other and are selected from C1 to C 20 a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; the groups R3 and R4 are identical or different from each other and are selected from hydrogen or C1 to C 20 A linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms, and R3 and R4 may be bonded to each other to form a condensed ring structure. Calculated by the molar ratio of titanium:aluminum:external electron donor compound, the dosage ratio of each component in the catalyst is 1:5-1000:0-500.

2. The catalyst according to claim 1, characterized in that In the general formula (I) of the internal electron donor compound, R1 and R2 are C1 to C 10 The alkyl, cycloalkyl or arylalkyl groups are selected from the group consisting of:

3. The main catalyst according to claim 1, characterized in that In the general formula (I) of the internal electron donor compound, R1 and R2 are isopropyl, n-butyl, isobutyl or neopentyl.

4. The main catalyst according to claim 1, characterized in that The internal electron donor compound of general formula (I) includes dimethyl 3,4-thiophene dicarboxylate, diethyl 2-methyl-3,4-thiophene dicarboxylate, diisopropyl 2,5-dimethyl-3,4-thiophene dicarboxylate, dibenzyl 3,4-thiophene dicarboxylate, di-n-butyl 2-methyl-3,4-thiophene dicarboxylate, diisobutyl 2,5-dialdo-3,4-thiophene dicarboxylate, diisobutyl 2-phenyl-3,4-thiophene dicarboxylate, and dineopentyl 2,5-diphenyl-3,4-thiophene dicarboxylate.

5. The catalyst according to claim 1, characterized in that The particle size distribution of magnesium in the catalyst component is 20 to 250 μm, and the general formula is Mg(OR') m M (2-m) ·nROH is provided by a magnesium halide alcoholate, wherein R' is C1~C 20 alkyl, arylalkyl or aryl; M is halogen; m is an integer where 0 ≤ m ≤ 2; n is a decimal or an integer where 0 < n < 6; R is an alkyl or arylalkyl having C1 to C 20 alkyl; The titanium in the catalytic component is represented by the general formula TiA n (OR”) 4-n A compound is provided, wherein R" is a hydrocarbon group having 1 to 20 carbon atoms; A is a halogen; and n=1 to 4.

6. The catalyst according to claim 5, characterized in that A magnesium halide alcoholate of magnesium is provided, wherein the magnesium halide is one of magnesium dichloride, magnesium dibromide, chloromethoxymagnesium or chloroethoxymagnesium; and the alcohol in the magnesium halide alcoholate is one of ethanol, n-propanol, isopropanol, n-butanol or isobutanol; The titanium in the catalytic component is provided by titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxide, titanium tetraethoxide, titanium triethoxide monochloride, titanium diethoxide dichloride or titanium triethoxide monochloride.

7. The catalyst according to claim 1, characterized in that The alkylaluminum compound is a trialkylaluminum compound; The external electron donor is a 1,3-diether compound of the general formula (II). Among them, R5-R 12 may be the same or different and are hydrogen or a hydrocarbon group having 1 to 18 carbon atoms, and R5-R 12 One or more of the groups may be linked to form a ring.

8. The catalyst according to claim 7, characterized in that The alkylaluminum compound is triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, a mixture of a trialkylaluminum and an alkylaluminum halide or an alkylaluminum hydride, or an alkylaluminumoxane; The compound of general formula (II) is characterized in that R 11 and R 12 is a C1-C4 alkyl group, R5 and R6 form an unsaturated condensed ring, R9, R 10 , R7 and R8 are all hydrogen.

9. The catalyst according to claim 7, characterized in that The external electron donor is 9,9-bis(methoxymethyl)fluorene.

10. The catalyst according to claim 1, characterized in that Calculated by the molar ratio of titanium:aluminum:external electron donor compound, the dosage ratio of each component in the catalyst is 1:25-100:25-300.

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