Homopolypropylene as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of olefin polymerization, and relates to homo-polypropylene as well as a preparation method and application thereof. The isotactic index of the homo-polypropylene is 50-75%, and the crystallinity of the homo-polypropylene is 30-42%. The preparation method comprises the following step: in the presence of a catalyst, polymerizing propylene to obtain the homo-polypropylene, wherein the catalyst contains a catalyst component, an aluminum alkyl compound and an optional external electron donor compound; the catalyst component comprises reaction products of the following components: a magnesium source, a titanium source and an internal electron donor, wherein the internal electron donor comprises a succinic acid monoester compound. Compared with the existing low isotactic polymer, the homopolymer provided by the invention has the advantages of higher isotacticity, larger weight-average molecular weight and favorable mechanical properties, and meets the application requirements of low isotactic polypropylene.

Description

Technical Field

[0001] The invention belongs to the technical field of olefin polymerization, and more specifically, relates to homopolypropylene and a preparation method and application thereof. Background Art

[0002] Low isotactic polypropylene has good application prospects due to its good adhesion, excellent hydrophobicity, chemical resistance, electrical insulation, bonding and good compatibility. Low isotactic polypropylene has different forms and uses according to its isotacticity and molecular weight. Products with lower isotacticity and smaller molecular weight are usually amorphous and can be used in hot melt adhesives, improved asphalt waterproofing materials, building sealants and rubber and plastic material performance improvers. Products with higher isotacticity and larger molecular weight can be used as thermoplastic elastomers for films, filaments, fibers, sheets and other uses requiring elasticity.

[0003] The isotacticity of homopolymer polypropylene resins currently produced in industrial devices is mostly 95-99%, and its mechanical properties are good, but it cannot meet the application requirements of low-isotactic polypropylene.

[0004] The production of low isotactic polypropylene in the early stage was separated from the polypropylene product, which was complicated and costly. At present, existing patents disclose a catalyst preparation method for directly synthesizing low isotactic polypropylene, such as WO1988009348 discloses a catalyst preparation method, wherein chlorine or hydrogen chloride reacts with an alkyl magnesium compound to form a carrier, and then reacts with titanium tetrachloride to prepare a catalyst, and the isotacticity of polypropylene obtained by using the catalyst is about 30%. CN1146461A discloses a catalyst preparation method, wherein aluminum chloride and a toluene solution of an organosilicon compound react with a chlorobenzene suspension of Mg(OC2H5)2 to form a carrier, and then the carrier is loaded with titanium to form a catalyst, and the isotacticity of polypropylene obtained by using the catalyst is about 16%-30%. CN1124740 discloses a catalyst preparation method, wherein a suspension of magnesium chloride alcohol solution and silicon dioxide is treated with alkyl aluminum to obtain a carrier, and then reacted with titanium tetrachloride to obtain a catalyst, and the isotacticity of polypropylene obtained by using the catalyst is about 30%. CN1262283A discloses a method for preparing a catalyst, wherein a suspension of magnesium halide alcohol solution and clay is treated with alkyl aluminum to obtain a carrier, which is then reacted with titanium tetrachloride to obtain a catalyst, and the catalyst is used for propylene polymerization to obtain a polypropylene with an isotacticity of about 25-40%. CN1693316A discloses a method for preparing a catalyst, wherein magnesium chloride and aluminum chloride are co-grinded, and then reacted with titanium tetrachloride to obtain a catalyst, and the catalyst is used for propylene polymerization to obtain a polypropylene with an isotacticity of about 25-40%.

[0005] The isotacticity of the polymers provided in the above patents is lower than 40% and the molecular weight is low, so their application is subject to many restrictions and it is difficult to meet the application requirements of low-isotactic polypropylene with higher isotacticity and larger molecular weight. Summary of the invention

[0006] The inventors of the present invention unexpectedly discovered during their research work that by using a catalyst with a special composition, a low-isotactic and low-crystallinity polypropylene resin can be directly obtained through a polymerization reaction, and the resin can also have a larger weight-average molecular weight.

[0007] In order to achieve the purpose of the present invention, the first aspect of the present invention provides a homopolypropylene, wherein the isotactic index of the homopolypropylene is 50-75% and the crystallinity is 30-42%.

[0008] A second aspect of the present invention provides a method for preparing homopolypropylene, comprising the following steps:

[0009] In the presence of a catalyst, polymerizing propylene to obtain the homopolypropylene;

[0010] The catalyst contains a catalyst component, an alkyl aluminum compound and an optional external electron donor compound; the catalyst component comprises a reaction product of the following components: a magnesium source, a titanium source and an internal electron donor, and the internal electron donor comprises a succinic acid monoester compound.

[0011] The third aspect of the present invention provides homopolypropylene obtained by the preparation method.

[0012] The fourth aspect of the present invention provides the use of the homopolypropylene in the fields of thermoplastic elastomers, building sealants and rubber and plastic material performance improvers.

[0013] Compared with the existing low-isotactic polymers, the homopolymer provided by the present invention has higher isotacticity and larger weight-average molecular weight, good mechanical properties, and meets the application requirements of low-isotactic polypropylene.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0016] In order to achieve the purpose of the present invention, the first aspect of the present invention provides a homopolypropylene, wherein the isotactic index of the homopolypropylene is 50-75% and the crystallinity is 30-42%.

[0017] According to the present invention, preferably, the homopolypropylene has an isotactic index of 55-72% and a crystallinity of 35-40%.

[0018] According to the present invention, preferably, the weight average molecular weight of the homopolymer polypropylene is 5×10 4 -25×10 4 , preferably 8×10 4 -22×10 4 , more preferably 10×10 4 -18×10 4 .

[0019] According to the present invention, preferably, the homopolypropylene is directly prepared via a one-step polymerization reaction.

[0020] In the present invention, homopolypropylene is directly prepared through a one-step polymerization reaction without the need for complicated separation steps, and the preparation method is simple and has better industrial prospects.

[0021] A second aspect of the present invention provides a method for preparing homopolypropylene, comprising the following steps:

[0022] In the presence of a catalyst, polymerizing propylene to obtain the homopolypropylene;

[0023] The catalyst contains a catalyst component, an alkyl aluminum compound and an optional external electron donor compound; the catalyst component comprises a reaction product of the following components: a magnesium source, a titanium source and an internal electron donor, and the internal electron donor comprises a succinic acid monoester compound.

[0024] According to the present invention, based on the total weight of the internal electron donor, the total content of the succinic acid monoester compound is 80-100 weight %, preferably 90-100 weight %.

[0025] In the present invention, the succinic acid monoester compound may be any succinic acid monoester compound that can be used as an electron donor in a catalyst for olefin polymerization. Preferably, the succinic acid monoester compound is selected from at least one of the compounds represented by formula (1):

[0026]

[0027] In formula (1), R1 is C1-C 20 A straight or branched alkyl, cycloalkyl, aryl, aralkyl or alkaryl group, R2 to R5 are each independently selected from hydrogen, C1-C 20 The straight chain or branched chain alkyl, cycloalkyl, aryl, aralkyl or alkaryl group may contain heteroatoms, and R2 to R5 attached to the same carbon atom may be bonded to form a ring.

[0028] Preferably, R1 is C1-C10 Straight chain alkyl, C3-C 10 Branched alkyl, C3-C 10 Cycloalkyl, C6-C 10 Aryl, C7-C 10 Alkyl or C7-C 10 R2 to R5 are each independently selected from hydrogen, C1-C 10 Straight chain alkyl, C3-C 10 Branched alkyl, C3-C 10 Cycloalkyl, C6-C 10 Aryl, C7-C 10 Alkyl or C7-C 10 The aralkyl group may contain a heteroatom, and R2 to R5 bonded to the same carbon atom may be bonded to form a ring.

[0029] Further preferably, the succinic acid monoester compound is selected from at least one of 4-methoxy-4-oxobutyric acid, 4-ethoxy-4-oxobutyric acid, 4-propoxy-4-oxobutyric acid, 4-tert-butoxy-4-oxobutyric acid, and 4-benzyl-4-oxobutyric acid; more preferably, the succinic acid monoester compound is 4-tert-butoxy-4-oxobutyric acid.

[0030] In the present invention, the magnesium source can be various magnesium-containing compounds that can be used for olefin polymerization catalysts, for example, the magnesium source can be a magnesium halide, an alcoholate of magnesium, a halogenated alcoholate of magnesium, or a magnesium halide adduct carrier, etc. The magnesium halide can be, for example, magnesium chloride and / or magnesium bromide. The alcoholate of magnesium can be, for example, diethoxymagnesium. The halogenated alcoholate of magnesium can be, for example, ethoxymagnesium chloride. The types of the magnesium halide adduct carrier are well known to those skilled in the art, for example, the magnesium halide adduct carriers disclosed in patent documents CN1091748, CN101050245, CN101486722, CN102796132B, CN102796129B and CN102796128B, and the relevant contents disclosed in these patent documents are all introduced into the present invention as a reference.

[0031] According to the present invention, the titanium source can be a conventional choice in the art, for example, the titanium source can be a titanium source having a general formula of Ti(OR′) 3-a Z a and / or Ti(OR′) 4-b Z b A titanium compound wherein R′ is C1-C 20alkyl, Z is F, Cl, Br or I, a is an integer of 1 to 3, and b is an integer of 1 to 4. Preferably, the titanium source is one or more of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tributoxytitanium chloride, dibutoxytitanium dichloride, butoxytitanium trichloride, triethoxytitanium chloride, diethoxytitanium dichloride, ethoxytitanium trichloride and titanium trichloride.

[0032] The catalyst component for olefin polymerization of the present invention can be prepared by conventional methods. For example, the preparation method of the catalyst component comprises: contacting a magnesium source with a titanium source, and adding an internal electron donor in one or more time periods before, during and after the contacting reaction of the magnesium source with the titanium source, wherein the internal electron donor comprises a succinic acid monoester compound.

[0033] Preferably, the reaction of the magnesium source and the titanium source can be carried out in the following manner: the titanium source is cooled to below 0°C (preferably -5 to -25°C), and then the magnesium source is added and stirred and mixed at this temperature, preferably for 15-60 minutes, and then the temperature is gradually raised to the reaction temperature (i.e., about 60-130°C), and maintained at the reaction temperature for 0.2-10 hours, preferably 0.5-6 hours. In the preparation method of the catalyst component for olefin polymerization, the internal electron donor is added in one or more time periods before, during or after the reaction of the magnesium source and the titanium source. The time period before the reaction of the magnesium source and the titanium source refers to the time period after the magnesium source is added to the reactor and before the temperature is raised to the reaction temperature.

[0034] In the present invention, the amounts of magnesium source, titanium source and internal electron donor can be conventional amounts in the prior art, for example, the molar ratio of the amount of magnesium source calculated as magnesium element, the amount of titanium source calculated as titanium element and the amount of internal electron donor can be 1:10-180:0.1-1. Preferably, the molar ratio of the amount of magnesium source calculated as magnesium element, the amount of titanium source calculated as titanium element and the amount of internal electron donor is 1:15-150:0.2-0.9.

[0035] According to the present invention, the catalyst comprises the reaction product of:

[0036] (i) the above-mentioned catalyst components;

[0037] (ii) at least one alkylaluminum compound; and

[0038] (iii) Optional external electron donor.

[0039] In the present invention, the alkyl aluminum compound may be any of various alkyl aluminum compounds commonly used in the art. For example, the general formula of the alkyl aluminum may be AlR 16 R 16 ′R 16 ″, where, where, R16 , R 16 ′ and R 16 "each independently represents a C1-C8 alkyl group or a halogen group, but they are not halogen groups at the same time, and the hydrogen atoms on the alkyl group are optionally replaced by halogen atoms.

[0040] Specific examples of the C1-C8 alkyl group may include, but are not limited to, methyl, ethyl, propyl, n-butyl, isobutyl, pentyl, hexyl, n-heptyl, and n-octyl, and the halogen may include fluorine, chlorine, bromine, and iodine.

[0041] Specifically, the alkylaluminum compound can be selected from one or more of triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, di-n-butylaluminum monochloride, di-n-hexylaluminum monochloride, monoethylaluminum dichloride, monoisobutylaluminum dichloride, mono-n-butylaluminum dichloride and mono-n-hexylaluminum dichloride.

[0042] According to the present invention, the molar ratio of aluminum in the alkyl aluminum compound to titanium in the catalyst component may be 20-2000:1, preferably 100-800:1, and more preferably 150-600:1.

[0043] In the present invention, the external electron donor can be any external electron donor commonly used in the art. For example, the external electron donor can be selected from carboxylic acids, carboxylic anhydrides, carboxylates, ketones, ethers, alcohols, lactones, organophosphorus compounds and organosilicon compounds.

[0044] Preferably, the external electron donor is selected from a group containing at least one Si-OR 19 bond, and the general formula is (R 17 ) x (R 18 ) y Si(OR 19 ) z Silicon compounds, where R 17 , R 18 and R 19 C1-C 18 The hydrocarbon group optionally contains heteroatoms, x and y are each independently an integer of 0-2, z is an integer of 1-3, and the sum of x, y, and z is 4. 17 , R 18 Preferably C3-C 10 The alkyl or cycloalkyl group may contain heteroatoms; R 19 Preferably C1-C 10 The alkyl group may contain a heteroatom.

[0045] Specifically, the external electron donor can be selected from at least one of cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane and (1,1,1-, trifluoro-2-propyl)-methyldimethoxysilane.

[0046] According to the present invention, the amount of the external electron donor can be a conventional amount in the art. The molar ratio of the external electron donor to the aluminum in the alkyl aluminum compound can be 1:2-500, preferably 1:10-100.

[0047] According to the present invention, in the preparation process of the catalyst for olefin polymerization, the alkyl aluminum compound and the optional external electron donor can be mixed with the catalyst component for propylene polymerization separately and then reacted, or the alkyl aluminum compound and the optional external electron donor can be mixed first and then mixed with the catalyst component for propylene polymerization and reacted.

[0048] According to the present invention, the catalyst components, the alkyl aluminum compound and the optional external electron donor compound are preferably subjected to a pre-complexation reaction before the polymerization reaction. The pre-complexation reaction temperature may be -10°C to 30°C, preferably 0-25°C.

[0049] According to the present invention, after the pre-complexation reaction and before the polymerization reaction, the catalyst is preferably subjected to a pre-polymerization reaction with propylene and / or other α-olefin monomers. The pre-polymerization reaction temperature may be 10-40°C, preferably 15-30°C.

[0050] According to the present invention, the polymerization temperature may be 50-90°C, preferably 60-80°C.

[0051] According to the present invention, the polymerization reaction is carried out in a liquid phase monomer, a solvent or in a gas phase under the protection of an inert gas. The pressure of the polymerization reaction is 0.01-8MPa, preferably 1.5-5MPa. The pressure in the present invention refers to the gauge pressure. The polymerization time of propylene and the catalyst is preferably 0.3-6h, more preferably 1-3h. During the polymerization process, hydrogen can be used as a polymer molecular weight regulator and added to the reaction system to adjust the molecular weight and melt index of the polymer.

[0052] In addition, during the polymerization reaction of propylene, the types and amounts of the inert gas and solvent are well known to those skilled in the art and will not be described in detail herein.

[0053] The third aspect of the present invention provides homopolypropylene obtained by the preparation method.

[0054] The fourth aspect of the present invention provides the application of the homopolypropylene in the fields of thermoplastic elastomers, building sealants and rubber and plastic material performance improvers.

[0055] The present invention will be further described below in conjunction with embodiments, but the scope of the present invention is not limited to these embodiments.

[0056] The isotactic index of the polymer in the present invention is determined by the heptane extraction method (heptane boiling extraction for 6 hours), that is, 2 g of a dry polymer sample is taken, placed in an extractor and extracted with boiling heptane for 6 hours, then the residue is dried to constant weight, and the ratio of the obtained polymer weight (g) to 2 is the isotactic index.

[0057] The crystallinity of polypropylene in the present invention is tested by differential scanning calorimetry DSC, specifically, a PEdiamond DSC differential scanning calorimeter can be used, and the sample amount is 4-5 mg; the specific steps are firstly heating the sample to 200°C at a rate of 10°C / min, maintaining it for 5 minutes to eliminate the thermal history, then cooling it to 50°C at a rate of 10°C / min, maintaining it at 50°C for 1 minute, and then heating it again to 200°C at a rate of 10°C / min, and determining the melting temperature and melting enthalpy from the DSC curve recorded by the reheating. The crystallinity Xc is calculated according to formula (1), and the results are shown in Table 1.

[0058]

[0059] Where ΔHm is the melting enthalpy per unit mass of the sample, ΔH α θ is the melting enthalpy of 100% crystalline polypropylene, ΔH α θ Take it as 209J / g.

[0060] The weight average molecular weight of polypropylene was tested by PL-GPC220 gel permeation chromatograph, with trichlorobenzene as solvent, test temperature of 150° C., polystyrene as standard sample, and flow rate of 1.0 mL / min.

[0061] Examples 1 to 4 are used to illustrate the catalyst component and catalyst for olefin polymerization and their application according to the present invention.

[0062] Example 1

[0063] (1) Preparation of catalyst components

[0064] In a 300mL glass reaction bottle, add 80mL of titanium tetrachloride and cool to -20°C, add 33mmol of a magnesium halide carrier (prepared according to the method disclosed in Example 1 of CN1267508C) in terms of magnesium element, then heat to 108°C, and add 9.1mmol of 4-tert-butoxy-4-oxobutanoic acid during the heating process. After maintaining at 110°C for 30min, filter out the liquid, wash with titanium tetrachloride, then wash with hexane, and vacuum dry to obtain the catalyst component Cat-1 for olefin polymerization.

[0065] (2) Propylene liquid phase bulk polymerization

[0066] The bulk polymerization of propylene in liquid phase was carried out in a 5L stainless steel autoclave. Under nitrogen protection, 2mL of triethylaluminum hexane solution (concentration of 0.5mmol / mL), 0.4mL of cyclohexylmethyldimethoxysilane (CHMMS) hexane solution (concentration of 0.1mmol / mL) and 9mg of the above-mentioned catalyst component Cat-1 for olefin polymerization were added to the reactor in sequence. The autoclave was closed, and 1.5NL of hydrogen and 2.3L of liquid propylene were added. The temperature was raised to 70°C, and after reacting for 1 hour, the temperature was lowered, the pressure was released, and the material was discharged. The obtained propylene homopolymer was dried, weighed and analyzed. The results are shown in Table 1.

[0067] Example 2

[0068] The catalyst components were prepared and propylene liquid phase bulk polymerization was carried out according to the method of Example 1, except that 2.0 NL of hydrogen was added.

[0069] The obtained propylene homopolymer was dried, weighed and analyzed. The results are shown in Table 1.

[0070] Example 3

[0071] The catalyst component was prepared and propylene liquid phase bulk polymerization was carried out according to the method of Example 1, except that the amount of 4-tert-butoxy-4-oxobutanoic acid added during the heating process was 7 mmol, to obtain a catalyst component Cat-2 for olefin polymerization.

[0072] The obtained propylene homopolymer was dried, weighed and analyzed. The results are shown in Table 1.

[0073] Example 4

[0074] The catalyst components were prepared and propylene liquid phase bulk polymerization was carried out according to the method of Example 3, except that 1.0 NL of hydrogen was added.

[0075] The obtained propylene homopolymer was dried, weighed and analyzed. The results are shown in Table 1.

[0076] Comparative Example 1

[0077] The commercial DQC catalyst (produced by Beijing Aoda Branch) was used to carry out liquid phase bulk polymerization of propylene according to the method of Example 1; the obtained propylene homopolymer was dried, weighed and analyzed. The results are shown in Table 1.

[0078] Table 1

[0079]

[0080] As can be seen from Table 1, the polymer of the present invention has a significantly lower isotactic index and a lower crystallinity than conventional polymers, and has a moderate weight average molecular weight. Compared with low isotactic polymers in the literature, it has a higher isotacticity, better mechanical properties and thermal properties, and can meet the application requirements of low isotactic polypropylene with higher isotacticity and larger molecular weight. In addition, the preparation method of the polymer is simple and has a better industrialization prospect.

[0081] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0082] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A homopolymer polypropylene, characterized in that: The homopolymer polypropylene has an isotactic index of 50-75% and a crystallinity of 30-42%.

2. The homopolypropylene according to claim 1, wherein The homopolymer polypropylene has an isotactic index of 55-72% and a crystallinity of 35-40%.

3. The homopolypropylene according to claim 1, wherein The weight average molecular weight of the homopolymer polypropylene is 5×10 4 -25×10 4 , preferably 8×10 4 -22×10 4 , more preferably 10×10 4 -18×10 4 .

4. The homopolypropylene according to claim 1, wherein The homopolypropylene is directly prepared via a one-step polymerization reaction.

5. A method for preparing homopolypropylene, characterized in that: The steps include: In the presence of a catalyst, polymerizing propylene to obtain the homopolypropylene; The catalyst contains a catalyst component, an alkyl aluminum compound and an optional external electron donor compound; the catalyst component comprises a reaction product of the following components: a magnesium source, a titanium source and an internal electron donor, and the internal electron donor comprises a succinic acid monoester compound.

6. The preparation method according to claim 5, wherein: Based on the total weight of the internal electron donor, the total amount of the succinic acid monoester compound is 80-100 weight %, preferably 90-100 weight %.

7. The preparation method according to claim 5, wherein: The succinic acid monoester compound is selected from at least one of the succinic acid monoester compounds shown in formula (1), In formula (1), R1 is C1-C 20 Straight chain alkyl, C3-C 20 Branched alkyl, C3-C 20 Cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkyl or C7-C 20 R2 to R5 are each independently selected from hydrogen, C1-C 20 Straight chain alkyl, C3-C 20 Branched alkyl, C3-C 20 Cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkyl or C7-C 20 The aralkyl group may contain a heteroatom, and R2 to R5 attached to the same carbon atom may be bonded to form a ring; Preferably, R1 is C1-C 10 Straight chain alkyl, C3-C 10 Branched alkyl, C3-C 10 Cycloalkyl, C6-C 10 Aryl, C7-C 10 Alkyl or C7-C 10 R2 to R5 are each independently selected from hydrogen, C1-C 10 Straight chain alkyl, C3-C 10 Branched alkyl, C3-C 10 Cycloalkyl, C6-C 10 Aryl, C7-C 10 Alkyl or C7-C 10 The aralkyl group may contain a heteroatom, and R2 to R5 attached to the same carbon atom may be bonded to form a ring; Further preferably, the succinic acid monoester compound is at least one selected from 4-methoxy-4-oxobutyric acid, 4-ethoxy-4-oxobutyric acid, 4-propoxy-4-oxobutyric acid, 4-tert-butoxy-4-oxobutyric acid and 4-benzyl-4-oxobutyric acid; More preferably, the succinic acid monoester compound is 4-tert-butoxy-4-oxobutanoic acid.

8. The preparation method according to claim 5, wherein The magnesium source is at least one of a magnesium halide, a magnesium alcoholate or a halogenated alcoholate and a magnesium halide adduct carrier; The titanium source is of the general formula Ti(OR′) 3-a Z a and Ti(OR′) 4-b Z b At least one of the compounds shown, wherein R′ is C1-C 20 The alkyl group is preferably C1-C 12 alkyl, more preferably a C1-C6 alkyl, Z is a halogen, a is an integer of 1-3, and b is an integer of 1-4; preferably, the titanium source is at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tributoxytitanium chloride, dibutoxytitanium dichloride, butoxytitanium trichloride, triethoxytitanium chloride, diethoxytitanium dichloride, ethoxytitanium trichloride and titanium trichloride.

9. The preparation method according to claim 5, wherein: The molar ratio of the magnesium source calculated as magnesium element, the titanium source calculated as titanium element and the internal electron donor is 1:10-180:0.1-1, preferably 1:15-150:0.2-0.

9.

10. The preparation method according to claim 5, wherein: The preparation method of the catalyst component comprises the following steps: A magnesium source is contacted with a titanium source for reaction, and an internal electron donor is added in one or more time periods before, during and after the contact reaction of the magnesium source and the titanium source, and then the titanium source is treated once or multiple times, and then washed with an inert solvent to obtain the solid catalyst component.

11. The preparation method according to claim 5, wherein: The alkyl aluminum compound is selected from the general formula AlR 16 R 16 ′R 16 At least one of the compounds shown in ″, wherein R 16 , R 16 ′ and R 16 "each independently represents a C1-C8 alkyl group or a halogen group, and they are not halogen groups at the same time, and the hydrogen atoms on the alkyl group are optionally replaced by halogen atoms; Preferably, the alkylaluminum compound is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, di-n-butylaluminum monochloride, di-n-hexylaluminum monochloride, monoethylaluminum dichloride, monoisobutylaluminum dichloride, mono-n-butylaluminum dichloride and mono-n-hexylaluminum dichloride.

12. The preparation method according to claim 5, wherein: The external electron donor is selected from at least one of carboxylic acid, carboxylic anhydride, carboxylic ester, ketone, ether, alcohol, lactone, organophosphorus compound and organosilicon compound; preferably, the external electron donor is selected from at least one Si-OR 19 bond, and the general formula is (R 17 ) x (R 18 ) y Si(OR 19 ) z Silicon compounds, where R 17 , R 18 and R 19 C1-C 18 A hydrocarbon group optionally containing heteroatoms, x and y are each independently an integer of 0-2, z is an integer of 1-3, and the sum of x, y, and z is 4, R 17 , R 18 Preferably C3-C 10 The alkyl or cycloalkyl group may contain heteroatoms; R 19 Preferably C1-C 10 An alkyl group optionally containing heteroatoms; Preferably, the external electron donor is selected from at least one of cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane and (1,1,1-, trifluoro-2-propyl)-methyldimethoxysilane.

13. The preparation method according to claim 5, wherein: The molar ratio of the solid catalyst component calculated as titanium element to the alkyl aluminum compound calculated as aluminum element is 1:1-2000, preferably 1:50-800, more preferably 1:100-500; The molar ratio of the external electron donor to the alkyl aluminum compound calculated as aluminum element is 1:5-500, preferably 1:20-200.

14. The preparation method according to claim 5, wherein: The polymerization conditions include: temperature of 50-90°C, preferably 60-80°C, pressure of 0.01-8MPa, preferably 1.5-5MPa, time of 0.3-6h, more preferably 1-3h.

15. Homopolypropylene obtained by the preparation method according to any one of claims 5 to 14.

16. Use of the homopolypropylene according to any one of claims 1 to 4 and 15 in the fields of thermoplastic elastomers, building sealants and rubber and plastic material performance improvers.

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