Catalyst for polypropylene for lithium battery separator, propylene polymer and method for producing the same

Abstract

The application discloses a catalyst for polypropylene used for lithium battery diaphragm, a propylene polymer and a preparation method thereof. The catalyst comprises a titanium-containing main catalyst and a cocatalyst. The main catalyst comprises a magnesium halide alcohol compound carrier, titanium halide and an internal electron donor. The internal electron donor is a double phosphine compound with a molecular skeleton of a thiofene structure and a general formula (I). In the formula, R1, R2, R3 and R4 are the same or different, and each is independently selected from a hydrogen atom, a C1-C20 straight chain or branched alkyl group, a C3-C20 cycloalkyl group, a C6-C20 aryl group, a C7-C20 aralkyl group and a C7-C20 alkoxy aryl group. The cocatalyst is a mixture of an aluminoxane modified by a halogenated alkane or a halogenated cycloalkane and an alkyl aluminum compound. The catalyst provided by the application has high catalytic activity under high-temperature polymerization conditions, and in-situ generated polypropylene with a certain beta crystal content.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, in particular to a catalyst for polypropylene used in lithium battery separators, a propylene polymer and a preparation method thereof. BACKGROUND

[0002] The lithium battery separator is a kind of thin film material with microporous structure, the thickness is generally 8-40 μm, and the main function in the battery is to isolate the positive and negative electrodes of the battery to prevent short circuit, and at the same time to ensure the normal passage of lithium ions through the microporous channel in the charging and discharging process to ensure the normal work of the battery. The core process of lithium battery separator preparation is micropore preparation technology. The production process of the separator mainly based on polyolefin is mainly divided into dry process and wet process. Different processes use different raw materials. The raw material corresponding to the dry process is mainly polypropylene.

[0003] The dry process for preparing the separator is also called melt stretching (MSCS) process. The preparation principle is that the polymer melt crystallizes under high stress field to form a lamellar structure perpendicular to the extrusion direction and parallel to the stretching direction. Then, after heat treatment, a hard elastic material is obtained. After re-stretching, the separation between the lamellar structures leads to the formation of a large number of microporous structures. After heat setting, the microporous membrane is obtained. According to the different stretching directions, the dry process is divided into dry unidirectional stretching and dry bidirectional stretching. The dry bidirectional stretching process is a process with independent intellectual property rights developed by the Institute of Chemistry of the Chinese Academy of Sciences in the early 1990s. The dry bidirectional stretching process is to add a β nucleating agent with nucleation effect in polypropylene, and to make polypropylene form micropores through crystal transformation during stretching by using the density difference between different phases of polypropylene. Compared with dry unidirectional stretching, dry bidirectional stretching improves the strength of the separator in the transverse direction, and has the characteristics of good air permeability, good permeability and high absorbency. In addition, the production process of dry bidirectional stretching is continuous and simple, and the production cost is lower than that of dry unidirectional stretching and wet process.

[0004] The dry bidirectional stretching process needs to add a β nucleating agent in the raw material polypropylene to realize the micropore formation during stretching. For example, Chinese patent document CN108346764A discloses a preparation method of a dry bidirectional stretched lithium battery microporous separator. The homopolymer polypropylene and the β crystal nucleating agent are high-temperature blended and extruded through a double-screw extruder, and a cast sheet is obtained by casting. After bidirectional synchronous stretching, the cast sheet is subjected to heat setting treatment to form a separator with microporous structure. However, the addition of β nucleating agent in the homopolymer polypropylene not only increases the production cost, but also increases the ash content introduced by the β nucleating agent. High ash content of the raw material will cause many problems in the production process, such as easy breaking of the membrane, easy aging, and increase of surface crystal points.

[0005] Supported Ziegler-Natta (Z-N) catalyst is one of the most important industrial catalysts for synthesizing propylene polymers. In the polymerization process, Z-N catalyst is usually used as the main catalyst, and alkyl aluminum (such as Et3AL, etc.) is used as the cocatalyst. The propylene polymerization is carried out at a temperature of 70-80℃, and a relatively high polymerization activity can be obtained, and the obtained polymer has a relatively high isotacticity. However, there are two problems: 1. The polypropylene prepared by using the existing Z-N catalyst still needs to add a β nucleating agent to the polypropylene when used for preparing a lithium battery separator; 2. The conventional reaction described above will cause a sharp decrease in the polymerization activity of the catalyst, the isotacticity of the polymer and the molecular weight, etc. when the polymerization temperature is increased. This is because the main role of the cocatalyst alkyl aluminum is to alkylate the active center, but the reduction reaction will also occur at the same time. The increase of the polymerization temperature will promote the reduction reaction, more active centers Ti 3+ are excessively reduced to Ti 2+ , and the deactivation of the active center of the catalyst is accelerated, thereby reducing the polymerization reaction speed, causing the polymerization activity of the system to decrease, the number of oligomers to increase, and the isotacticity of the finally obtained polymer to be low.

[0006] A catalyst is disclosed in Chinese patent document CN1887918A, which introduces a mixture of aluminoxane and alkyl aluminum as a cocatalyst in the polymerization process. The catalyst system has a relatively high activity and stereospecificity, and the isotacticity of the polymer reaches 95% at most when the propylene polymerization temperature is 100℃. However, the polypropylene prepared by using the catalyst still needs to add a β nucleating agent when used for preparing a lithium battery separator, and the polymerization activity and stereospecificity of the catalyst need to be further improved.

[0007] Chinese patent document CN109517099A discloses an external electron donor, an olefin polymerization catalyst system and the application thereof. The olefin polymerization catalyst system comprises a titanium catalyst, an alkyl aluminum compound and an external electron donor. The external electron donor composition comprises a halogenated hydrocarbon, an aliphatic carboxylic acid ester and an alkoxysilane. In this scheme, the halogenated hydrocarbon, the aliphatic carboxylic acid ester and the alkoxysilane are combined to form a composite external electron donor composition. The composition can greatly improve the polymerization activity of propylene at a conventional polymerization temperature under the premise of ensuring low ash content of the olefin polymerization. However, the polymerization activity is low when the temperature is higher than 80℃, and the normalized activity is less than 10.0 kgPP / gCat.h at 100℃ in the examples thereof. Moreover, the polypropylene prepared by using the catalyst still needs to add a β nucleating agent when used for preparing a lithium battery separator. SUMMARY

[0008] In view of the problems in the prior art and the direction for improvement, the present application provides a catalyst for polypropylene used for lithium battery separator, which contains a double phosphine compound with a thiophene molecular skeleton and functional groups in the catalyst composition, and the cocatalyst is a mixture of aluminoxane modified with halogenated alkane and alkyl aluminum compound. The catalyst is used for high temperature polymerization or copolymerization of propylene, which can ensure the catalytic activity and stereoregularity of the catalytic system, and in-situ generate polypropylene with certain beta crystal content, which is used for preparing dry two-way stretched lithium battery separator, solving the problem that the existing dry two-way stretched lithium battery separator needs to add beta nucleating agent in the raw material polypropylene in the production process, reducing the introduction of separator ash and reducing the production cost.

[0009] To achieve the above purpose, the present application provides a catalyst for polypropylene used for lithium battery separator, which comprises a titanium-containing main catalyst and a cocatalyst, wherein:

[0010] The main catalyst is a titanium catalyst supported by halogenated magnesium alcohol compound carrier, which comprises halogenated magnesium alcohol compound carrier, titanium halide and internal electron donor, and the internal electron donor is a double phosphine compound with a thiophene structure with a molecular skeleton of general formula (I):

[0011]

[0012]

[0013] Wherein, R1, R2, R3 and R4 are the same or different, and each is independently selected from hydrogen atom, C1-C20 straight chain or branched alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 aralkyl and C7-C20 alkoxy aryl; P is phosphorus; S is sulfur;

[0014] The cocatalyst is a mixture of aluminoxane modified with halogenated alkane or halogenated cycloalkane and alkyl aluminum compound.

[0015] The present application does not particularly limit the halogenated magnesium alcohol compound carrier, which is selected from at least one of magnesium chloride ethanol adduct carrier, magnesium bromide ethanol adduct carrier, magnesium chloride isopropanol adduct carrier, magnesium chloride n-butanol adduct carrier, chloroethoxy magnesium methanol adduct carrier, preferably magnesium chloride ethanol adduct carrier.

[0016] The present application does not particularly limit the halogenated titanium, which is a liquid compound completely soluble in non-polar solvents at application temperature (such as-50-130℃), selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, chlorotriethoxy titanium, dichlorodiethoxy titanium, trichloroethoxy titanium, titanium trichloride, preferably titanium tetrachloride.

[0017] Optionally, in the catalyst for the polypropylene used for lithium battery separators provided by the application, the internal electron donor is selected from 3,4-bis(dimethylphosphino)-thiophene, 3,4-bis(diethylphosphino)-thiophene, 3,4-bis(di-n-propylphosphino)-thiophene, 3,4-bis(diisopropylphosphino)-thiophene, 3,4-bis(dimethylphosphino)-2-(4-ethylphenyl)thiophene, 3,4-bis(di-n-butylphosphino)-thiophene, 3,4-bis(diisobutylphosphino)-thiophene, 3,4-bis(di-n-pentylphosphino)-thiophene, 3,4-bis(di-cyclopentylphosphino)-thiophene, 3,4-bis(di-n-hexylphosphino)-thiophene, 3,4-bis(di-cyclohexylphosphino)-thiophene, 3,4-bis(diphenylphosphino)-thiophene, 3,4-bis(di-p-tolylphosphino)-thiophene, 3,4-bis(di-m-tolylphosphino)-thiophene, 3,4-bis(di-p-methoxyphenylphosphino)-thiophene, 3,4-bis(di-m-methoxyphenylphosphino)-thiophene, 3,4-bis(di-o-methoxyphenylphosphino)-thiophene, 3,4-bis(dimethylphosphino)-2-methylthiophene, 3,4-bis(diethylphosphino)-2-methylthiophene, 3,4-bis(di-n-propylphosphino)-2-methylthiophene, 3,4-bis(diisopropylphosphino)-2-methylthiophene, 3,4-bis(di-n-butylphosphino)-2-methylthiophene, 3,4-bis(diisobutylphosphino)-2-methylthiophene, 3,4-bis(di-n-pentylphosphino)-2-methylthiophene, 3,4-bis(di-cyclopentylphosphino)-2-methylthiophene, 3,4-bis(di-n-hexylphosphino)-2-methylthiophene, 3,4-bis(di-cyclohexylphosphino)-2-methylthiophene, 3,4-bis(diphenylphosphino)-2-methylthiophene, 3,4-bis(di-p-tolylphosphino)-2-methylthiophene, 3,4-bis(di-m-tolylphosphino)-2-methylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-methylthiophene, 3,4-bis(di-m-methoxyphenylphosphino)-2-methylthiophene, 3,4-bis(di-o-methoxyphenylphosphino)-2-methylthiophene, 3,4-bis(dimethylphosphino)-2-ethylthiophene, 3,4-bis(diethylphosphino)-2-ethylthiophene, 3,4-bis(di-n-propylphosphino)-2-ethylthiophene, 3,4-bis(diisobutylphosphino)-2-ethylthiophene, 3,4-bis(di-cyclopentylphosphino)-2-ethylthiophene, 3,4-bis(di-cyclohexylphosphino)-2-ethylthiophene, 3,4-bis(diphenylphosphino)-2-ethylthiophene, 3,4-bis(di-p-tolylphosphino)-2-ethylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-ethylthiophene, 3,4-bis(dimethylphosphino)-2-isopropylthiophene, 3,4-bis(diethylphosphino)-2-isopropylthiophene, 3,4-bis(di-n-propylphosphino)-2-isopropylthiophene, 3,4-bis(diisobutylphosphino)-2-isopropylthiophene, 3,4-bis(di-cyclopentylphosphino)-2-isopropylthiophene, 3,4-bis(di-cyclohexylphosphino)-2-isopropylthiophene, 3,4-bis(diphenylphosphino)-2-isopropylthiophene, 3,4-bis(di-p-tolylphosphino)-2-isopropylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-isopropylthiophene, 3,4-bis(di-m-methoxyphenylphosphino)-2-isopropylthiophene, 3,4-bis(di-o-methoxyphenylphosphino)-2-isopropylthiophene, 3,4-bis(dimethylphosphino)-2-iso-butylthiophene, 3,4-bis(diethylphosphino)-2-iso-butylthiophene, 3,4-bis(di-n-propylphosphino)-2-iso-butylthiophene, 3,4-bis(diisopropylphosphino)-2-iso-butylthiophene, 3,4-bis(di-n-pentylphosphino)-2-iso-butylthiophene, 3,4-bis(di-cyclopentylphosphino)-2-iso-butylthiophene, 3,4-bis(di-cyclohexylphosphino)-2-iso-butylthiophene, 3,4-bis(diphenylphosphino)-2-iso-butylthiophene, 3,4-bis(di-p-tolylphosphino)-2-iso-butylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-iso-butylthiophene, 3,4-bis(di-m-methoxyphenylphosphino)-2-iso-butylthiophene, 3,4-bis(di-o-methoxyphenylphosphino)-2-iso-butylthiophene, 3,4-bis(dimethylphosphino)-2-iso-pentylthiophene, 3,4-bis(diethylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-n-propylphosphino)-2-iso-pentylthiophene, 3,4-bis(diisopropylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-n-pentylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-cyclopentylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-cyclohexylphosphino)-2-iso-pentylthiophene, 3,4-bis(diphenylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-p-tolylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-m-methoxyphenylphosphino)-2-iso-pentylthiophene, 3,4-bis(di-o-methoxyphenylphosphino)-2-iso-pentylthiophene,4-di(cyclohexylphosphino)-2-isopropylthiophene, 3,4-di(diphenylphosphino)-2- isopropylthiophene, 3,4-di(di-p-tolylphosphino)-2-isopropylthiophene, 3,4-di(di-p- methoxyphenylphosphino)-2-isopropylthiophene, 3,4-di(dimethylphosphino)-2- cyclopentylthiophene, 3,4-di(diethylphosphino)-2-cyclopentylthiophene, 3,4-di(di-n- propylphosphino)-2-cyclopentylthiophene, 3,4-di(diisobutylphosphino)-2- cyclopentylthiophene, 3,4-di(dicyclopentylphosphino)-2-cyclopentylthiophene, 3,4- di(dicyclohexylphosphino)-2-cyclopentylthiophene, 3,4-di(diphenylphosphino)-2- cyclopentylthiophene, 3,4-di(di-p-tolylphosphino)-2-cyclopentylthiophene, 3,4-di- (di-p-methoxyphenylphosphino)-2-cyclopentylthiophene, 3,4-di(dimethylphosphino)- 2-phenylthiophene, 3,4-di(diethylphosphino)-2-phenylthiophene, 3,4-di(di-n- propylphosphino)-2-phenylthiophene, 3,4-di(diisobutylphosphino)-2-phenylthiophene, 3,4-di(dicyclopentylphosphino)-2-phenylthiophene, 3,4-di(dicyclohexylphosphino)- 2-phenylthiophene, 3,4-di(diphenylphosphino)-2-phenylthiophene, 3,4-di(di-p- tolylphosphino)-2-phenylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2- phenylthiophene, 3,4-di(dimethylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4- di(diethylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4-di(di-n-propylphosphino)-2- (4-methoxyphenyl)thiophene, 3,4-di(diisobutylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4-di(dicyclopentylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4- di(dicyclohexylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4-di(diphenylphosphino)- 2-(4-methoxyphenyl)thiophene, 3,4-di(di-p-tolylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4-di(di-p-methoxyphenylphosphino)-2-(4-methoxyphenyl)thiophene, 3,4- di(dimethylphosphino)-2,5-dimethylthiophene, 3,4-di(diethylphosphino)-2,5- dimethylthiophene, 3,4-di(di-n-propylphosphino)-2,5-dimethylthiophene, 3,4-di-4-di(n-propylphosphino)-2,5-diethylthiophene, 3,4-di(diisobutylphosphino)-2,5-diethylthiophene, 3,4-di(dicyclopentylphosphino)-2,5-diethylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-diethylthiophene, 3,4-di(diphenylphosphino)-2,5-diethylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-diethylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diethylthiophene, 3,4-di(dimethylphosphino)-2,5-diisopropylthiophene, 3,4-di(diethylphosphino)-2,5-diisopropylthiophene, 3,4-di(n-propylphosphino)-2,5-diisopropylthiophene, 3,4-di(isobutylphosphino)-2,5-diisopropylthiophene, 3,4-di(dicyclopentylphosphino)-2,5-diisopropylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-diisopropylthiophene, 3,4-di(diphenylphosphino)-2,5-diisopropylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-diisopropylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diisopropylthiophene, 3,4-di(dimethylphosphino)-2,5-di-n-butylthiophene, 3,4-di(diethylphosphino)-2,5-di-n-butylthiophene, 3,4-di(n-propylphosphino)-2,5-di-n-butylthiophene, 3,4-di(isobutylphosphino)-2,5-di-n-butylthiophene, 3,4-di(dicyclopentylphosphino)-2,5-di-n-butylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-di-n-butylthiophene, 3,4-di(diphenylphosphino)-2,5-di-n-butylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-di-n-butylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-di-n-butylthiophene, 3,4-di(dimethylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(diethylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(n-propylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(isobutylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(dicyclopentylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(diphenylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(dimethylphosphino)-2,5-diphenylthiophene, 3,4-di(diethylphosphino)-2,5-diphenylthiophene, 3,4-di(n-propylphosphino)-2,5-diphenylthiophene, 3,4-di(isobutylphosphino)-2,5-diphenylthiophene, 3,4-di(dicyclopentylphosphino)-2,5-diphenylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-diphenylthiophene, 3,4-di(diphenylphosphino)-2,5-diphenylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-diphenylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diphenylthiophene,4-di(diphenylphosphino)-2,5-diphenylthiophene, 3,4-di(di-p-tolylphosphino)-2,5- diphenylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diphenylthiophene, 3,4- di(dimethylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(diethylphosphino)-2,5-di-p- tolylthiophene, 3,4-di(di-n-propylphosphino)-2,5-di-p-tolylthiophene, 3,4- di(diisobutylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(dicyclopentylphosphino)-2,5- di-p-tolylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-di-p-tolylthiophene, 3,4- di(diphenylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-di-p- tolylthiophene, and 3,4-di(di-p-methoxyphenylphosphino)-2,5-di-p-tolylthiophene.

[0018] Preferably, the internal electron donor is selected from at least one of 3,4-di(diphenylphosphino)-2,5-dimethylthiophene, 3,4-di(dimethylphosphino)-2-isopropylthiophene, 3,4-di(diphenylphosphino)-2,5-diethylthiophene, 3,4-di(dicyclohexylphosphino)-2,5- dimethylthiophene, 3,4-di(dimethylphosphino)-2-(4-methoxyphenyl)thiophene, and 3,4- di(dimethylphosphino)-2-(4-ethylphenyl)thiophene.

[0019] The catalyst for the polypropylene used in the lithium battery separator of the present application comprises the following components in the main catalyst:

[0020]

[0021] The present application is not particularly limited to the preparation method of the main catalyst, and the following method can be used: mixing the halogenated magnesium alcohol complex carrier (calculated as magnesium) and the halogenated titanium (calculated as titanium) in a molar ratio of 1:15-60, adding an internal electron donor containing a diphosphine compound with a thiophene molecular skeleton and functional groups, filtering after warming treatment, adding halogenated titanium again, warming treatment, filtering, washing and drying to obtain the catalyst product. The specific steps are as follows: (1) adding spherical halogenated magnesium alcohol complex particles to the halogenated titanium liquid at -50-20°C, reacting for 10 minutes to 5 hours, and the molar ratio of magnesium to titanium is 1:5-1:100; (2) warming to 0-90°C, adding an internal electron donor compound, and the molar ratio of magnesium to the internal electron donor compound is 2:1-20:1; (3) warming to 100-130°C, reacting for 1-6 hours; (4) adding the same amount of halogenated titanium liquid as in step 1 after filtering, reacting at 110-130°C for 1-4 hours, and then filtering, washing and drying to obtain the supported main catalyst.

[0022] The catalyst for the polypropylene used for the lithium battery diaphragm in the present application, the aluminoxane is a compound with the structure shown in general formula (II):

[0023]

[0024] wherein Y is C1-C 12 hydrocarbon group, Y2 is two Y groups, a is an integer of 4-30, Al is aluminum, and O is oxygen; the aluminoxane is, for example but not limited to, at least one of methyl aluminoxane, ethyl aluminoxane, n-propyl aluminoxane, isopropyl aluminoxane, butyl aluminoxane, preferably the aluminoxane is methyl aluminoxane.

[0025] The present application is not particularly limited to the operation method for modifying the aluminoxane with halogenated alkane or halogenated cycloalkane, the operation method for modification is, for example but not limited to, vacuum-nitrogen replacement three times for the dry polymer bottle, adding a certain amount of toluene solution of aluminoxane into the bottle, and obtaining the dry powder of aluminoxane through vacuum distillation; then mixing the obtained dry powder of aluminoxane with halogenated alkane or halogenated cycloalkane to form a solution or suspension with a certain concentration, and then used for propylene polymerization.

[0026] Optionally, the catalyst for the polypropylene used for the lithium battery diaphragm in the present application, the aluminoxane modified by halogenated alkane or halogenated cycloalkane is a solution or suspension formed by mixing the dry powder of aluminoxane with halogenated alkane or halogenated cycloalkane; preferably, the molar ratio of the dry powder of aluminoxane (calculated by aluminum) to halogenated alkane or halogenated cycloalkane is 1:1-20, preferably 1:4-10.

[0027] Optionally, the catalyst for the polypropylene used for the lithium battery diaphragm in the present application, the molar ratio of the aluminoxane modified by halogenated alkane or halogenated cycloalkane to the alkyl aluminum compound is 1:1-50, preferably 1:1-30, more preferably 1:1-10.

[0028] Optionally, the catalyst for the polypropylene used for the lithium battery diaphragm in the present application, the halogenated alkane in the aluminoxane modified by halogenated alkane or halogenated cycloalkane is a compound containing at least one halogen atom and 1-20 carbon atoms; preferably at least one of monochloromethane, dichloromethane, trichloromethane, tetrachloromethane, monochloroethane, 1,2-dichloroethane, monochloropropane, monochlorobutane, monochloro-sec-butane, monochloro-tert-butane, chlorobenzene, monobromomethane, monobromopropane, monobromobutane, and monoiodomethane;

[0029] The halogenated cycloalkane is monochlorocyclohexane or monochlorocyclopentane.

[0030] Optionally, the catalyst for the polypropylene used for the lithium battery diaphragm in the present application, the general formula of the alkyl aluminum compound is AlZ n X (3-n) ; wherein Z is C1-C20 alkyl, C6-C20 aryl or C7-C20 aralkyl; X is halogen (fluorine, chlorine, bromine, iodine), preferably chlorine; n is an integer from 0 to 3, and Al is aluminum. The alkyl aluminum compound is, for example, but not limited to, at least one of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-hexyl aluminum, diethyl aluminum chloride and diisobutyl aluminum chloride, preferably triethyl aluminum or triisobutyl aluminum.

[0031] Optionally, the catalyst for the preparation of polypropylene for lithium battery separator of the present application further comprises an organic external electron donor, and the organic external electron donor is an alkoxysilane compound selected from at least one of cyclohexyl methyl dimethoxysilane, dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, dimethoxy dimethyl silane, diethoxy dimethyl silane or dimethoxy diphenyl silane, preferably cyclohexyl methyl dimethoxysilane.

[0032] In the catalyst for the preparation of polypropylene for lithium battery separator of the present application, the molar ratio of the main catalyst calculated based on titanium, the cocatalyst calculated based on aluminum and the organic external electron donor calculated based on silicon is 1:5-1000:1-500; when applied to the polymerization of propylene, preferably, the molar ratio of the main catalyst, the cocatalyst and the organic external electron donor is 1:10-50:1-5.

[0033] Another object of the present application is to provide a method for preparing a propylene polymer, which uses the above-mentioned catalyst for the preparation of polypropylene for lithium battery separator to catalyze the high-temperature polymerization or copolymerization of propylene, and can exhibit high catalytic activity and stereoregularity, and in-situ generate polypropylene with a certain content of β-crystal for the preparation of dry-process biaxially-stretched lithium battery separator.

[0034] To achieve the above-mentioned objects, the present application provides a method for preparing a propylene polymer, which uses the above-mentioned catalyst for the preparation of polypropylene for lithium battery separator to catalyze the high-temperature polymerization or copolymerization of propylene; preferably, the catalyst for the preparation of polypropylene for lithium battery separator is used to catalyze the homopolymerization or copolymerization of propylene in liquid phase (liquid monomer or monomer in inert solvent) or gas phase medium at 85-120℃ for 0.5-2h.

[0035] In the specific preparation process, the above-mentioned main catalyst, cocatalyst and organic external electron donor can be directly added to the polymerization reactor, or can be added to the polymerization reactor after pre-complexation and / or pre-polymerization known in the art. Whether to perform pre-complexation or pre-polymerization can be selected according to actual needs.

[0036] Optionally, the application provides the above-mentioned propylene polymer preparation method, wherein the propylene polymer preparation method comprises a catalyst pre-complexation step; preferably, the catalyst pre-complexation temperature is -10-40 DEG C, more preferably 5-30 DEG C, and the catalyst pre-complexation time is 1-10 min.

[0037] Optionally, the application provides the above-mentioned propylene polymer preparation method, wherein the propylene polymer preparation method comprises a pre-polymerization step; preferably, the pre-polymerization temperature is -10-60 DEG C, more preferably 20-50 DEG C, and the pre-polymerization time is 5-20 min.

[0038] The application further provides a propylene polymer prepared by the above-mentioned propylene polymer preparation method, wherein the propylene polymer has an isotacticity of ≥96.5%, a beta crystal content of ≥3.5% in the propylene polymer, and an ash content of ≤40 ppm.

[0039] The application further provides an application of the propylene polymer prepared by the above-mentioned propylene polymer preparation method in preparing a lithium battery separator; preferably, the application in preparing a lithium battery separator by a dry two-way stretching method.

[0040] The application has the following beneficial effects:

[0041] 1. In the prior art, in the dry two-way stretching process of the polypropylene lithium battery separator, the introduction of the beta crystal nucleating agent into the polypropylene not only increases the production cost, but also introduces ash, which affects the performance of the lithium battery separator. The catalyst system of the polypropylene for the lithium battery separator provided by the application can in-situ catalyze the preparation of the primary beta crystal polypropylene with a certain content, which can be directly used as the raw material for the dry two-way stretching process of the lithium battery separator, thereby avoiding the introduction of the beta crystal nucleating agent and ensuring the catalytic activity and stereoregularity.

[0042] 2. The catalyst of the polypropylene for the lithium battery separator provided by the application comprises a diphosphine compound containing a thiophene structure. The lone pair electrons of the phosphorus atom and the sulfur atom in the diphosphine compound can stabilize the central metal titanium, so that the catalyst has high activity in the propylene polymerization. The phosphorus atom and the sulfur atom in the diphosphine compound containing the thiophene structure provide two different chemical environments, and the space structure provided by the thiophene skeleton is relied on, thereby solving the problem of low isotacticity of the prepared polymer.

[0043] 3, The present application adopts halogenated alkane or halogenated cycloalkane to modify aluminoxane, and then mixes with aluminum alkyl compound to assist catalyst, and combines with other catalytic components, so that the polymerization activity of the catalyst system under the condition of high temperature polymerization or copolymerization of propylene (85-120℃) is ensured, and the problem of low isotacticity of the prepared polymer is solved. The reason for the low isotacticity of the polymer prepared by the existing catalyst system under high temperature polymerization may be that under the condition of high temperature polymerization, the titanium active center of the catalyst is excessively reduced, thereby reducing the polymerization activity of the catalyst, and the generated oligomer increases. In the present application, after introducing halogenated alkane or halogenated cycloalkane modified aluminoxane, the polarity of halogenated hydrocarbon can further oxidize the titanium active center of the catalyst, thereby improving the polymerization activity of the catalyst and the isotacticity of the polymer. DETAILED DESCRIPTION

[0044] The following detailed description of the embodiments of the present application is given: The present embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation methods and processes are given, but the protection scope of the present application is not limited to the following embodiments. The experimental methods not specified in the following embodiments are usually carried out under conventional conditions.

[0045] Test method

[0046] Polymer isotacticity: determined by heptane extraction method (heptane boiling extraction for 6 hours), that is, the ratio of the weight (g) of the remaining polymer after 1 gram of dried polymer sample is extracted with boiling heptane in a soxhlet extractor for 6 hours to 1 is the isotacticity.

[0047] Polymer beta crystal content: according to the D1 type mold in GB / T 17037.3-2003 standard, a 60mmx60mmx1mm injection sample is prepared, XRD test is carried out, and XRD spectrum is analyzed, and the beta crystal content is calculated by turner-jones formula.

[0048] Determination of polymer ash content: according to GB / T 9345.1-2008 standard, the ash content of the polymer is tested.

[0049] Synthesis of internal electron donor

[0050] The present application does not particularly limit the preparation method of the internal electron donor. For convenience of description, taking 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene as an example, the preparation method of the internal electron donor can adopt the following steps:

[0051] 2,5-dimethylthiophene 1.0 g and NaOAc 1.9 g were added into 50 mL of CH2Cl2at room temperature in dark for 5 min, then cooled to 0°C, while gradually adding Br20.96 mL, after the end of the drop, warmed to room temperature, reaction 2 h after adding 10% Na2S2O3solution, liquid-liquid, the aqueous phase was extracted with CH2Cl2, combined organic phase was washed with water, the organic phase was dried with anhydrous MgSO4, then column chromatography was used to separate the colorless solid 3,4-dibromo-2,5-dimethylthiophene 1.87 g, yield 75%.

[0052] 3,4-dibromo-2,5-dimethylthiophene 6 g was added into 70 mL of THF under nitrogen atmosphere, cooled to -78°C, slowly droped into 18.8 mL of n-butyllithium in n-hexane solution, kept the temperature at -78°C, stirred for 1 h, then added diphenylchlorophosphine 8.41 mL, warmed to room temperature, reaction 5 h after quenching the reaction with water, the organic phase was extracted with CH2Cl2, dried and evaporated the organic solvent, then column chromatography was used to separate the white solid 7.42 g, yield 69%.

[0053] 3,4-dibromo-2,5-dimethylthiophene: molecular formula, C 30 H 26 P2S; molecular weight, 480.12; elemental analysis, C, 74.98; H, 5.45; P, 12.89; S, 6.67. 31 PNMR (CDC13, 120 MHz) δ: -21.45.

[0054] The internal electron donors used in the following examples can be synthesized according to this method, and the corresponding raw materials for preparing the internal electron donors in each example can be obtained by market purchase.

[0055] Example 1

[0056] Preparation of magnesium halide alcohol complex carrier: white oil, methyl silicone oil as dispersion medium, adding magnesium chloride, ethanol, warming and melting for 7 h, then quickly stirring the above-mentioned molten alcohol complex and transferring it to hexane medium at -35°C, to prepare microspherical magnesium chloride alcohol complex particles. The average particle size of the magnesium chloride alcohol complex carrier is 30-60 μm, the specific surface area is 150-230 m2 / g, the molar ratio of alcohol to magnesium chloride content is 2.85:1, and the molecular formula is MgCl2-2.85CH3CH2OH. 2

[0057] ​Preparation of the main catalyst: 5.0 g of the above microspherical magnesium chloride alcoholate carrier was added to 140 mL of titanium tetrachloride liquid at -20°C under anhydrous and anaerobic conditions, and after 1 hour of reaction, the temperature was gradually increased to 60°C; 1.2 g of 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene was added, and the temperature was gradually increased to 120°C, and after 2 hours of reaction, the mixture was filtered; 140 mL of titanium tetrachloride was added again, and the mixture was reacted at 120°C for 2 hours and filtered. The mixture was washed with 50 mL of hexane at 50°C for 4 times, and washed with 50 mL of hexane at room temperature for 2 times, and after vacuum drying, the main catalyst was obtained.

[0058] Preparation of modified aluminoxane: A dried 1 L polymerization bottle was vacuumed and replaced with nitrogen for three times, 500 mL of MAO produced by Shanghai Yabao (0.5 mol / L MAO toluene solution) was added to the polymerization bottle under nitrogen protection, and the solvent toluene was distilled under reduced pressure until the methylaluminoxane in the polymerization bottle was in the form of white dry powder, indicating that the free trimethylaluminum was removed, the reaction was stopped, and the compound was marked as MMAO. In the glove box, 5 g of MMAO dry powder was mixed with 34.8 mL of chloroform to form a solution, and the molar ratio of aluminum in the MMAO to chloroform was 1:5, which was ready for use.

[0059] Pre-complexation of the catalyst system: under nitrogen protection, 30 mg of the main catalyst, 10 mL of a triethylaluminum hexane solution (1 mol / L), 1 mL of the above MMAO chloroform solution, and 0.2 mL of cyclohexylmethyldimethoxysilane were added to a 100 mL polymerization bottle treated by vacuum drying, and pre-complexed at 0°C for 5 min.

[0060] Propylene pre-polymerization: in a 5 L propylene high-temperature polymerization kettle treated by vacuum drying and replaced with nitrogen-propylene for three times, 1 kg of propylene, the pre-complexed catalyst system, and 0.5 kg of propylene were added to flush the catalyst addition pipeline, 0.2 g of hydrogen was added, and stirring was maintained, and pre-polymerization was carried out at 25°C for 10 min.

[0061] Propylene high-temperature polymerization: the temperature of the polymerization kettle was quickly increased to 93°C, and after 1 hour of polymerization, the remaining propylene was discharged to obtain a high-temperature polymer.

[0062] The polymerization results are shown in Table 1.

[0063] Example 2

[0064] Preparation of the magnesium halide alcoholate carrier, the main catalyst, the modified aluminoxane, and propylene high-temperature polymerization were the same as in Example 1, except that the pre-complexation temperature of the catalyst system was increased to 10°C, and the pre-polymerization temperature was increased to 40°C.

[0065] The polymerization results are shown in Table 1.

[0066] Example 3

[0067] Example 1, except that the precomplexation temperature was 20°C and the prepolymerization was carried out at 50°C for 15 min.

[0068] The polymerization results are shown in Table 1.

[0069] Example 4

[0070] Example 1, except that the catalyst system was not precomplexed and not prepolymerized.

[0071] Example 1.

[0072] The polymerization results are shown in Table 1.

[0073] Example 5

[0074] Example 1.

[0075] Example 1.

[0076] Example 1.

[0077] Example 1.

[0078] The polymerization results are shown in Table 1.

[0079] Example 6

[0080] Example 1.

[0081] Preparation of modified aluminoxane: In a glove box, 2 g of MMAO dry powder was mixed with 49.5 mL of chloroform to form a solution, in which the molar ratio of aluminum in MMAO to chloroform was 1:18, and was ready for use.

[0082] Pre-complexation of catalyst system: Under nitrogen protection, 30 mg of the main catalyst, 10 mL of triethylaluminum hexane solution (1 mol / L), 0.5 mL of the above MMAO chloroform solution, and 0.2 mL of cyclohexylmethyl dimethoxysilane were added into a 100 mL vacuum-dried polymerization bottle, and pre-complexed at 10°C for 5 min.

[0083] High-temperature polymerization of propylene: In a 5L high-temperature propylene polymerization kettle which was vacuum-dried and replaced with nitrogen-propylene three times, 1 kg of propylene, the pre-complexed catalyst system, and 0.5 kg of propylene were added to flush the catalyst addition line, 0.2 g of hydrogen was added, stirring was maintained, and the temperature was quickly raised to 93°C. After 1 hour of polymerization, the remaining propylene was discharged to obtain the high-temperature polymer.

[0084] The polymerization results are shown in Table 1.

[0085] Example 7

[0086] Preparation of halogenated magnesium alcohol complex carrier, main catalyst, and modified aluminoxane was the same as in Example 1, except that the catalyst system was not pre-complexed.

[0087] Propylene pre-polymerization: In a 5L high-temperature propylene polymerization kettle which was vacuum-dried and replaced with nitrogen-propylene three times, 30 mg of the main catalyst, 10 mL of triethylaluminum hexane solution (1 mol / L), 0.5 mL of MMAO chloroform solution (in which the molar ratio of aluminum in MMAO to chloroform was 1:5), 0.1 mL of cyclohexylmethyl dimethoxysilane, 1.5 kg of propylene, and 0.2 g of hydrogen were added, stirring was maintained, and the temperature was quickly raised to 45°C for pre-polymerization for 20 min.

[0088] High-temperature polymerization of propylene was the same as in Example 1.

[0089] The polymerization results are shown in Table 1.

[0090] Example 8

[0091] Preparation of halogenated magnesium alcohol complex carrier, main catalyst, and modified aluminoxane was the same as in Example 1, except that the catalyst system was not pre-complexed.

[0092] Pre-polymerization of propylene: Into a 5L reactor for high temperature polymerization of propylene, which was vacuum dried and replaced with nitrogen-propylene for three times, 30mg of the main catalyst, 10ml of triisobutylaluminium in hexane (1mol / L), 1ml of MMAO in chloroform (the molar ratio of aluminium in MMAO to chloroform is 1:5), 0.2ml of cyclohexylmethyldimethoxysilane, 1.5kg of propylene and 0.2g of hydrogen were added. The temperature was quickly raised to 45°C and the pre-polymerization was carried out for 15min.

[0093] High temperature polymerization of propylene was carried out according to the procedure of Example 1.

[0094] The results of polymerization are shown in Table 1.

[0095] Example 9

[0096] The preparation of the halogenated magnesium alcohol complex carrier and the main catalyst, the preparation of modified aluminoxane and the pre-complexation of the catalyst system were carried out according to the procedure of Example 1. The only difference was that the pre-complexation temperature was 25°C.

[0097] Pre-polymerization of propylene: Into a 5L reactor for high temperature polymerization of propylene, which was vacuum dried and replaced with nitrogen-propylene for three times, 30mg of the main catalyst, 10ml of triisobutylaluminium in hexane (1mol / L), 1ml of MMAO in chloroform (the molar ratio of aluminium in MMAO to chloroform is 1:5), 0.2ml of cyclohexylmethyldimethoxysilane, 1.5kg of propylene and 0.2g of hydrogen were added. The temperature was quickly raised to 45°C and the pre-polymerization was carried out for 15min.

[0098] High temperature copolymerization of ethylene-propylene: The temperature of the reactor was quickly raised to 93°C and the mixture of ethylene-propylene (the volume fraction of ethylene was 3%) was introduced into the reactor. After 1 hour of polymerization, the unreacted mixture of ethylene-propylene was discharged and the high temperature copolymer of ethylene-propylene was obtained.

[0099] The results of polymerization are shown in Table 1.

[0100] Example 10

[0101] The preparation of the halogenated magnesium alcohol complex carrier and the main catalyst, the preparation of modified aluminoxane and the pre-complexation of the catalyst system were carried out according to the procedure of Example 1. The only difference was that the pre-complexation temperature was 25°C.

[0102] The preparation of 3,4-bis(dimethylphosphino)-2-isopropylthiophene was similar to the preparation of 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene in Example 1. 3,4-bis(dimethylphosphino)-2-isopropylthiophene: molecular formula, C 11 H 20 P2S; molecular weight, 246.29; elemental analysis, C, 53.64; H, 8.19; P, 25.15; S, 13.02.

[0103] Under anhydrous and anaerobic conditions, 5.0 g of the above microspherical magnesium chloride alcoholate particles were added to 140 mL of liquid titanium tetrachloride at -20°C, and after 1 hour of reaction, the temperature was gradually increased to 60°C; 0.6 g of 3,4-bis(dimethylphosphino)-2-isopropylthiophene was added, and the temperature was gradually increased to 120°C, and after 2 hours of reaction, the mixture was filtered; 140 mL of titanium tetrachloride was added again, and the mixture was reacted at 120°C for 2 hours and filtered. The particles were washed with 50 mL of hexane at 40-60°C for 4 times, and washed with 50 mL of hexane at room temperature for 2 times, and then dried under vacuum to obtain the main catalyst.

[0104] Catalyst pre-complexation: under nitrogen protection, 30 mg of the main catalyst, 10 mL of a hexane solution of triethylaluminum (1 mol / L), 1 mL of a chloroform solution of MMAO, and 0.2 mL of cyclohexylmethyldimethoxysilane were added into a 100 mL vacuum-dried polymerization bottle, and pre-complexed at 25°C for 5 min.

[0105] Propylene pre-polymerization was similar to that in Example 5, except that in this example, the temperature of the propylene pre-polymerization was 40°C, and the pre-polymerization time was 10 min.

[0106] High-temperature propylene polymerization was similar to that in Example 5.

[0107] The polymerization results are shown in Table 1.

[0108] Example 11

[0109] The preparation of the magnesium halide alcoholate carrier and the modified aluminoxane was similar to that in Example 1, except that in the preparation of the main catalyst, different internal electron donors were used, and the main catalyst prepared in this example was used in the high-temperature propylene polymerization step. The preparation steps of the main catalyst in this example were as follows:

[0110] The preparation method of 3,4-bis(dicyclohexylphosphino)-2,5-dimethylthiophene was similar to that of 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene in Example 1. 3,4-bis(dicyclohexylphosphino)-2,5-dimethylthiophene: molecular formula, C 30 H 38 P2S; molecular weight, 492.64; elemental analysis, C, 73.14; H, 7.78; P, 12.57; S, 6.51.

[0111] Under anhydrous and anaerobic conditions, 5.0 g of the above-mentioned microspherical magnesium chloride alcoholate particles were added to 140 mL of liquid titanium tetrachloride at -20°C, and after 1 hour of reaction, the temperature was gradually increased to 60°C; 1.2 g of 3,4-bis(dicyclohexylphosphino)-2,5-dimethylthiophene was added, and the temperature was gradually increased to 120°C, and after 2 hours of reaction, the mixture was filtered; 140 mL of titanium tetrachloride was further added, and the mixture was reacted at 120°C for 2 hours and filtered. The particles were washed with 50 mL of hexane at 40-60°C for 4 times, and washed with 50 mL of hexane at room temperature for 2 times, and after vacuum drying, the main catalyst was obtained.

[0112] The catalyst system was pre-complexed, pre-polymerized, and propylene was high-temperature polymerized according to Embodiment 5.

[0113] The polymerization results are shown in Table 1.

[0114] Embodiment 12

[0115] The preparation of the magnesium halide alcoholate carrier and the main catalyst was the same as in Embodiment 1, except that the ratio of the MMAO dry powder to chloroform was different in the preparation process of the modified aluminoxane, and the modified aluminoxane prepared in this embodiment was used in the propylene high-temperature polymerization step. The preparation steps of the modified aluminoxane in this embodiment are as follows:

[0116] In the glove box, 2.5 g of MMAO dry powder was mixed with 34.8 mL of chloroform to form a solution, and the molar ratio of aluminum in the MMAO to chloroform was 1:10.

[0117] Catalyst pre-complexation: under nitrogen protection, 30 mg of the main catalyst, 10 mL of a triethylaluminum hexane solution (1 mol / L), 1 mL of the above-mentioned MMAO chloroform solution, and 0.2 mL of cyclohexylmethyldimethoxysilane were added to a 100 mL polymerization bottle treated by vacuum drying, and pre-complexed at 25°C for 5 min.

[0118] Propylene pre-polymerization and propylene high-temperature polymerization were carried out according to Embodiment 5.

[0119] The polymerization results are shown in Table 1.

[0120] Embodiment 13

[0121] The preparation of the magnesium halide alcoholate carrier and the main catalyst was the same as in Embodiment 1, except that the halogenated alkane used in the preparation process of the modified aluminoxane was different, and the modified aluminoxane prepared in this embodiment was used in the propylene high-temperature polymerization step. The preparation steps of the modified aluminoxane in this embodiment are as follows:

[0122] In the glove box, 5 g of MMAO dry powder was mixed with 27.6 mL of dichloromethane to form a solution, and the molar ratio of aluminum in the MMAO to dichloromethane was 1:5.

[0123] Catalyst pre-complexation: under nitrogen protection, in a 100 mL polymerization flask dried by vacuum, add 30 mg of the procatalyst, 10 mL of triethylaluminum in hexane (1 mol / L), 1 mL of the MMAO solution in dichloromethane as described above, and 0.2 mL of cyclohexylmethyldimethoxysilane, and pre-complex at 25 °C for 5 min.

[0124] Propylene prepolymerization and propylene high temperature polymerization as in Example 5.

[0125] The polymerization results are shown in Table 1.

[0126] Example 14

[0127] The preparation of the magnesium halide alcoholate carrier and the procatalyst is the same as in Example 1, except that the halogenated alkane used in the preparation of the modified aluminoxane is different, and the propylene high temperature polymerization step uses the modified aluminoxane prepared in this example. The specific preparation steps of the modified aluminoxane in this example are as follows:

[0128] In the glove box, 5 g of MMAO dry powder is mixed with 31.2 mL of monochloroethane to form a solution, wherein the molar ratio of aluminum in the MMAO to monochloroethane is 1:5, and is ready for use.

[0129] Catalyst pre-complexation: under nitrogen protection, in a 100 mL polymerization flask dried by vacuum, add 30 mg of the procatalyst, 10 mL of triethylaluminum in hexane (1 mol / L), 1 mL of the MMAO solution in dichloromethane as described above, and 0.2 mL of cyclohexylmethyldimethoxysilane, and pre-complex at 25 °C for 5 min.

[0130] Propylene prepolymerization and propylene high temperature polymerization as in Example 5.

[0131] The polymerization results are shown in Table 1.

[0132] Example 15

[0133] The preparation of the magnesium halide alcoholate carrier and the procatalyst is the same as in Example 1, except that the halogenated alkane used in the preparation of the modified aluminoxane is different, and the propylene high temperature polymerization step uses the modified aluminoxane prepared in this example. The specific preparation steps of the modified aluminoxane in this example are as follows:

[0134] In the glove box, 5 g of MMAO dry powder is mixed with 51 mL of monochlorocyclohexane to form a solution, wherein the molar ratio of aluminum in the MMAO to monochlorocyclohexane is 1:4.3, and is ready for use.

[0135] Pre-complexation of catalyst: under nitrogen protection, in a 100 mL polymerization flask dried by vacuum, 30 mg of the procatalyst, 10 mL of triethylaluminum solution in hexane (1 mol / L), 1 mL of the MMAO monochlorocyclohexane solution described above and 0.2 mL of cyclohexylmethyldimethoxysilane were added and pre-complexed at 25 °C for 5 min.

[0136] Pre-polymerization of propylene and high-temperature polymerization of propylene were carried out according to Example 5.

[0137] The polymerization results are shown in Table 1.

[0138] Example 16

[0139] Preparation of the magnesium halide alcoholate carrier and the procatalyst was the same as in Example 1, except that the halogenated alkane used in the preparation of the modified aluminoxane was different, and the modified aluminoxane prepared in this example was used in the high-temperature polymerization step. The preparation steps of the modified aluminoxane in this example are as follows:

[0140] In a glove box, 5 g of MMAO dry powder was mixed with 39.2 mL of monobromopropane to form a solution, wherein the molar ratio of aluminum in the MMAO to monobromopropane was 1:5, and was ready for use.

[0141] Pre-complexation of catalyst: under nitrogen protection, in a 100 mL polymerization flask dried by vacuum, 30 mg of the procatalyst, 10 mL of triethylaluminum solution in hexane (1 mol / L), 1 mL of the MMAO monobromopropane solution described above and 0.2 mL of cyclohexylmethyldimethoxysilane were added and pre-complexed at 25 °C for 5 min.

[0142] Pre-polymerization of propylene and high-temperature polymerization of propylene were carried out according to Example 5.

[0143] The polymerization results are shown in Table 1.

[0144] Example 17

[0145] Preparation of the magnesium halide alcoholate carrier and the procatalyst, preparation of the modified aluminoxane, pre-complexation of the catalyst system, and pre-polymerization were the same as in Example 13, except that the polymerization temperature was replaced by 85 °C instead of 93 °C.

[0146] The polymerization results are shown in Table 1.

[0147] Example 18

[0148] Preparation of the magnesium halide alcoholate carrier and the procatalyst, preparation of the modified aluminoxane, and amount of the cocatalyst were the same as in Example 1, except that the pre-complexation of the catalyst system, pre-polymerization, and propylene polymerization were the same as in Example 5, except that the high-temperature polymerization temperature was replaced by 120 °C instead of 93 °C.

[0149] The polymerization results are shown in Table 1.

[0150] Comparative Example 1

[0151] The preparation of the magnesium halide alcoholate support and the preparation of the procatalyst are similar to Example 1, except that in the present comparative example, diisobutyl phthalate is used instead of 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene in the preparation of the procatalyst. The preparation of the procatalyst in the present comparative example is as follows:

[0152] Under anhydrous and anaerobic conditions, 5.0 g of the above-mentioned microspherical magnesium chloride alcoholate particles are added to 140 mL of liquid titanium tetrachloride at -20°C, and after 1 hour of reaction, the temperature is gradually increased to 60°C; 0.7 mL of diisobutyl phthalate is added, and the temperature is gradually increased to 120°C, and after 2 hours of reaction, the mixture is filtered; 140 mL of titanium tetrachloride is added again, and after 2 hours of reaction at 120°C, the mixture is filtered. The mixture is washed with 50 mL of hexane at 40-60°C for 4 times, and washed with 50 mL of hexane at room temperature for 2 times, and after vacuum drying, the procatalyst is obtained.

[0153] High-temperature polymerization of propylene: in a 5L high-temperature polymerization reactor for propylene which has been treated by vacuum drying and replaced with nitrogen-propylene for 3 times, 1 kg of propylene, 30 mg of the above-mentioned procatalyst, 10 mL of a hexane solution of triethylaluminum (1 mol / L), and 0.2 mL of cyclohexylmethyldimethoxysilane are added, the temperature of the polymerization reactor is rapidly increased to 93°C, and the polymerization reaction is carried out for 1 hour. After the unreacted propylene is discharged, the polymer prepared at 93°C is obtained.

[0154] The polymerization results are shown in Table 1.

[0155] Comparative Example 2

[0156] The preparation of the magnesium halide alcoholate support and the preparation of the procatalyst are similar to Example 1, except that in the present comparative example, diisobutyl phthalate is used instead of 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene in the preparation of the procatalyst. The preparation of the procatalyst in the present comparative example is as follows:

[0157] The co-catalyst is a hexane solution of triethylaluminum and a toluene solution of MMAO.

[0158] Pre-complexation of the catalyst system: under nitrogen protection, 30 mg of the procatalyst of Comparative Example 1, 10 mL of a hexane solution of triethylaluminum (1 mol / L), 10 mL of a toluene solution of MAO (0.5 mol / L), and 0.2 mL of cyclohexylmethyldimethoxysilane are added to a 100 mL polymerization bottle which has been treated by vacuum drying, and pre-complexed at 0°C for 5 min.

[0159] Pre-polymerization of propylene: in a 5L high-temperature polymerization reactor for propylene which has been treated by vacuum drying and replaced with nitrogen-propylene for 3 times, 1 kg of propylene, the pre-complexed catalyst system, and 0.2 g of hydrogen are added, and the catalyst addition pipeline is flushed with 0.5 kg of propylene, and the stirring is maintained, and the pre-polymerization is carried out at 25°C for 10 min.

[0160] High temperature polymerization of propylene: the temperature of the polymerizer was quickly raised to 93°C, and the polymerization was carried out for 1 hour. The unreacted propylene was discharged to obtain the high temperature polymer.

[0161] The polymerization results are shown in Table 1.

[0162] Comparative Example 3

[0163] The preparation of the magnesium halide alcoholate carrier and the preparation of the procatalyst were the same as in Comparative Example 1; the preparation of the modified aluminoxane was the same as in Example 1.

[0164] Pre-complexation of the catalyst system: under nitrogen protection, 30 mg of the procatalyst of Comparative Example 1, 10 mL of a hexane solution of triethylaluminum (1 mol / L), 1 mL of a chloroform solution of MMAO (wherein the molar ratio of aluminum in the MMAO to chloroform is 1:5), and 0.2 mL of cyclohexylmethyldimethoxysilane were added into a 100 mL vacuum-dried polymerization bottle, and pre-complexation was carried out for 5 min at 25°C.

[0165] Pre-polymerization of propylene: in a 5 L high temperature polymerization reactor of propylene which was vacuum-dried and replaced with nitrogen-propylene three times, 1 kg of propylene, the pre-complexed catalyst system, and 0.2 g of hydrogen were added, and the catalyst addition pipeline was flushed with 0.5 kg of propylene, and stirring was maintained, and pre-polymerization was carried out for 15 min at 45°C.

[0166] High temperature polymerization of propylene was the same as in Example 1.

[0167] The polymerization results are shown in Table 1.

[0168] Comparative Example 4

[0169] The preparation of the procatalyst was the same as in Example 1.

[0170] Preparation of the cocatalyst: a dry 50 mL polymerization bottle was vacuumed and replaced with nitrogen three times, and under nitrogen protection, 20 mL of MAO produced by Shanghai Yabao (0.5 mol / L of a toluene solution of MAO) was added into the polymerization bottle, and 10 mL of a diethyl ether solution of BF3 (0.5 mol / L of a diethyl ether solution of BF3) was added dropwise, and the molar ratio of BF3 to MAO was 1:2, and after a certain period of time, a complex solution of BF3 and MAO was obtained, which was denoted as BMAO and was ready for use.

[0171] Pre-complexation of the catalyst system: under nitrogen protection, 30 mg of the procatalyst was added into a 100 mL glass bottle at room temperature, 1.25 mL of triethylaluminum (1 mol / L of a hexane solution), 2.5 mL of a mixed solution of BMAO, and 0.1 mL of cyclohexylmethyldimethoxysilane were added, and the catalyst system was pre-complexed in the glass bottle at room temperature for 5 min;

[0172] Pre-polymerization of propylene: in a 10 L high-temperature polymerizer which was vacuum dried and sufficiently replaced with nitrogen and propylene, 1 kg of propylene was added, and then the above-mentioned pre-complexed catalyst system was added under nitrogen protection, and 0.5 kg of propylene was continuously added, and stirring was kept, and pre-polymerization was carried out at 10℃ for 10 min;

[0173] High-temperature polymerization of propylene: same as Example 1.

[0174] Polymerization results are shown in Table 1.

[0175] Polymerization results of Examples and Comparative Examples are shown in Table 1.

[0176]

[0177]

[0178] From the results of the examples and comparative examples, it can be seen that the present application uses a double phosphine compound containing a thiophene structure as a main catalyst, and a mixture of halogenated alkane modified aluminoxane and aluminum alkyl as a composite cocatalyst, and under the conditions of high-temperature propylene homopolymerization and ethylene-propylene copolymerization, propylene polymers with a certain β crystal content are obtained, and the β crystal content of the polymer reaches 17.8% at the highest; at the same time, the catalyst system ensures a relatively high catalytic activity, and the high-temperature homopolymerization activity of propylene reaches 63.5 kgPP / gCat·h, and the high-temperature copolymerization activity of ethylene-propylene reaches 65.5 kgPP / gCat·h, and the prepared high-temperature polymer has a relatively high isotacticity index.

[0179] The above examples are typical examples listed for detailed description of the technical solutions of the present application, and the protection scope of the present application is subject to the protection scope of the claims and the invention content, and is not limited by the described examples. Simple replacement or change of the present application is still within the protection scope of the present application.

Claims

1. A catalyst for polypropylene for lithium battery separators, characterized by, Comprise: a titanium-containing procatalyst and a cocatalyst; the procatalyst comprises a magnesium halide alcoholate carrier, a titanium halide and an internal electron donor, characterized in that the internal electron donor is a bisphosphine compound with a molecular skeleton of a thiophene structure of a general formula (I): the general formula (I); wherein R1, R2, R3 and R4 are the same or different, and each is independently selected from a hydrogen atom, a C1-C20 straight chain or branched alkyl group, a C3-C20 cycloalkyl group, a C6-C20 aryl group, a C7-C20 aralkyl group and a C7-C20 alkoxyaryl group; P is phosphorus; and S is sulfur; the cocatalyst is a mixture of an alkylaluminum compound and an aluminoxane modified by a haloalkane or a halocycloalkane.

2. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized by that, The internal electron donor is selected from the group consisting of 3,4-bis(dimethylphosphino)-thiophene, 3,4-bis(diethylphosphino)-thiophene, 3,4-bis(di-n-propylphosphino)-thiophene, 3,4-bis(diisopropylphosphino)-thiophene, 3,4-bis(dimethylphosphino)-2-(4-ethylphenyl)thiophene, 3,4-bis(di-n-butylphosphino)-thiophene, 3,4-bis(diisobutylphosphino)-thiophene, 3,4-bis(di-n-pentylphosphino)-thiophene, 3,4-bis(dicyclopentylphosphino)-thiophene, 3,4-bis(di-n-hexylphosphino)-thiophene, 3,4-bis(dicyclohexylphosphino)-thiophene, 3,4-bis(diphenylphosphino)-thiophene, 3,4-bis(di-p-tolylphosphino)-thiophene, 3,4-bis(di-m-tolylphosphino)-thiophene, 3,4-bis(di-p-methoxyphenylphosphino)-thiophene, 3,4-bis(di-m-methoxyphenylphosphino)-thiophene, 3,4-bis(di-o-methoxyphenylphosphino)-thiophene, 3,4-bis(dimethylphosphino)-2-methylthiophene, 3,4-bis(diethylphosphino)-2-methylthiophene, 3,4-bis(di-n-propylphosphino)-2-methylthiophene, 3,4-bis(diisopropylphosphino)-2-methylthiophene, 3,4-bis(di-n-butylphosphino)-2-methylthiophene, 3,4-bis(diisobutylphosphino)-2-methylthiophene, 3,4-bis(di-n-pentylphosphino)-2-methylthiophene, 3,4-bis(dicyclopentylphosphino)-2-methylthiophene, 3,4-bis(di-n-hexylphosphino)-2-methylthiophene, 3,4-bis(dicyclohexylphosphino)-2-methylthiophene, 3,4-bis(diphenylphosphino)-2-methylthiophene, 3,4-bis(di-p-tolylphosphino)-2-methylthiophene, 3,4-bis(di-m-tolylphosphino)-2-methylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-methylthiophene, 3,4-bis(di-m-methoxyphenylphosphino)-2-methylthiophene, 3,4-bis(di-o-methoxyphenylphosphino)-2-methylthiophene, 3,4-bis(dimethylphosphino)-2-ethylthiophene, 3,4-bis(diethylphosphino)-2-ethylthiophene, 3,4-bis(di-n-propylphosphino)-2-ethylthiophene, 3,4-bis(diisobutylphosphino)-2-ethylthiophene, 3,4-bis(dicyclopentylphosphino)-2-ethylthiophene, 3,4-bis(dicyclohexylphosphino)-2-ethylthiophene, 3,4-bis(diphenylphosphino)-2-ethylthiophene, 3,4-bis(di-p-tolylphosphino)-2-ethylthiophene, 3,4-bis(di-p-methoxyphenylphosphino)-2-ethylthiophene, 3,4-bis(dimethylphosphino)-2-isopropylthiophene, 3,4-bis(diethylphosphino)-2-isopropylthiophene, 3,4-bis(di-n-propylphosphino)-2-isopropylthiophene, 3,4-bis(diisobutylphosphino)-2-isopropylthiophene, 3,4-bis(dicyclopentylphosphino)-2-isopropylthiophene, 3,4-bis(dicyclohexylphosphino)-2-isopropylthiophene, 3,4-bis(diphenylphosphino)-2-isopropylthiophene,4-di(2,6-dimethylphenylphosphino)-2-ethylthiophene, 4-di(2,6-dimethylphenylphosphino)-2- isopropylthiophene, 4-di(2,6-dimethylphenylphosphino)-2-cyclopentylthiophene, 4-di(2,6- dimethylphenylphosphino)-2-phenylthiophene, 4-di(2,6-dimethylphenylphosphino)-2-(4- methoxyphenyl)thiophene, 4-di(2,6-dimethylphenylphosphino)-2,5-dimethylthiophene, 4- di(2,6-dimethylphenylphosphino)-2,5-diethylthiophene, 4-di(2,6-dimethylphenylphosphino)- 2,5-dicyclohexylthiophene, 4-di(2,6-dimethylphenylphosphino)-2,5-diphenylthiophene, 4- di(2,6-dimethylphenylphosphino)-2,5-di(4-methoxyphenyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylphenyl)thiophene, 4-di(2,6-dimethylphenyl- phosphino)-2,5-di(2,6-dimethoxyphenyl)thiophene, 4-di(2,6-dimethylphenylphosphino)- 2,5-di(2,6-dichlorophenyl)thiophene, 4-di(2,6-dimethylphenylphosphino)-2,5-di(2,6- dimethylpyridyl)thiophene, 4-di(2,6-dimethylphenylphosphino)-2,5-di(2,6-dimethyl- imidazolyl)thiophene, 4-di(2,6-dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolyl)thi- ophene, 4-di(2,6-dimethylphenylphosphino)-2,5-di(2,6-dimethyltriazolyl)thiophene, 4- di(2,6-dimethylphenylphosphino)-2,5-di(2,6-dimethyltetrazolyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpyrrolidinyl)thiophene, 4-di(2,6- dimethylphenylphosphino)-2,5-di(2,6-dimethylpiperidinyl)thiophene, 4-di(2,6-4-diisobutylphosphino-2,5-diethylthiophene, 3,4-di(dicylopentylphosphino)-2,5-diethylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-diethylthiophene, 3,4-di(diphenylphosphino)-2,5-diethylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-diethylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diethylthiophene, 3,4-di(dimethylphosphino)-2,5-diisopropylthiophene, 3,4-di(diethylphosphino)-2,5-diisopropylthiophene, 3,4-di(di-n-propylphosphino)-2,5-diisopropylthiophene, 3,4-di(diisobutylphosphino)-2,5-diisopropylthiophene, 3,4-di(dicylopentylphosphino)-2,5-diisopropylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-diisopropylthiophene, 3,4-di(diphenylphosphino)-2,5-diisopropylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-diisopropylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diisopropylthiophene, 3,4-di(dimethylphosphino)-2,5-di-n-butylthiophene, 3,4-di(diethylphosphino)-2,5-di-n-butylthiophene, 3,4-di(di-n-propylphosphino)-2,5-di-n-butylthiophene, 3,4-di(diisobutylphosphino)-2,5-di-n-butylthiophene, 3,4-di(dicylopentylphosphino)-2,5-di-n-butylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-di-n-butylthiophene, 3,4-di(diphenylphosphino)-2,5-di-n-butylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-di-n-butylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-di-n-butylthiophene, 3,4-di(dimethylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(diethylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(di-n-propylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(diisobutylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(dicylopentylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(diphenylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-dicyclohexylthiophene, 3,4-di(dimethylphosphino)-2,5-diphenylthiophene, 3,4-di(diethylphosphino)-2,5-diphenylthiophene, 3,4-di(di-n-propylphosphino)-2,5-diphenylthiophene, 3,4-di(diisobutylphosphino)-2,5-diphenylthiophene, 3,4-di(dicylopentylphosphino)-2,5-diphenylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-diphenylthiophene, 3,4-di(diphenylphosphino)-2,5-diphenylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-diphenylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diphenylthiophene,4-di(p-tolylphosphino)-2,5-diphenylthiophene, 3,4-di(di-p-methoxyphenylphosphino)-2,5-diphenylthiophene, 3,4-di(dimethylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(diethylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(di-n-propylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(diisobutylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(dicyclopentylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(dicyclohexylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(diphenylphosphino)-2,5-di-p-tolylthiophene, 3,4-di(di-p-tolylphosphino)-2,5-di-p-tolylthiophene, and 3,4-di(di-p-methoxyphenylphosphino)-2,5-di-p-tolylthiophene.

3. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized in that, The procatalyst comprises the following components by weight percentage: Internal electron donor 5-20% Titanium 1-10% Magnesium 10-25% Halogen 45-60%.

4. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized in that, The aluminoxane modified by the haloalkane or the halocycloalkane is a solution or a suspension formed by mixing an aluminoxane dry powder with the haloalkane or the halocycloalkane.

5. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized in that, The ratio of the aluminoxane modified by the haloalkane or the halocycloalkane to the alkylaluminum compound is 1:1-50 in terms of the molar ratio of aluminum to aluminum.

6. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized in that, The aluminoxane is a compound with a structure shown in the following general formula (II): Formula (II); wherein Y is a C1-C12 hydrocarbon group, Y2 is two Y groups, Al is aluminum, O is oxygen, and a is an integer of 4-30.

7. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized in that, The haloalkane is a compound containing at least one halogen atom and 1-20 carbon atoms; and the halocycloalkane is monochlorocyclohexane or monochlorocyclopentane.

8. The catalyst for polypropylene for lithium battery separators according to claim 1, characterized in that, The general formula of the aluminum alkyl compound is AlZnX n X （3-n） ; wherein Al is aluminum; Z is a C1-C20 alkyl group, a C6-C20 aryl group, or a C7-C20 aralkyl group; X is a halogen; and n is an integer from 0 to 3, and is not 0.

9. The catalyst for polypropylene for lithium battery separators according to any one of claims 1 to 8, characterized in that, The catalyst further comprises an external organic electron donor, and the external organic electron donor is an alkoxy silane compound selected from at least one of cyclohexyl methyl dimethoxysilane, dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, dimethoxy dimethyl silane, diethoxy dimethyl silane and dimethoxy diphenyl silane.

10. The catalyst for polypropylene for lithium battery separators according to claim 9, characterized in that, The molar ratio of the procatalyst (calculated based on titanium), the cocatalyst (calculated based on aluminum) and the external organic electron donor (calculated based on silicon) is 1:5-1000:1-500.

11. The catalyst for polypropylene for lithium battery separators according to claim 2, characterized in that, The internal electron donor is selected from at least one of 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene, 3,4-bis(dimethylphosphino)-2-isopropylthiophene, 3,4-bis(diphenylphosphino)-2,5-diethylthiophene, 3,4-bis(dicyclohexylphosphino)-2,5-dimethylthiophene, 3,4-bis(dimethylphosphino)-2-(4-methoxyphenyl)thiophene and 3,4-bis(dimethylphosphino)-2-(4-ethylphenyl)thiophene.

12. The catalyst for polypropylene for lithium battery separators according to claim 4, characterized in that, The molar ratio of the aluminoxane dry powder (calculated based on aluminum) to the haloalkane or the halocycloalkane is 1:1-20.

13. The catalyst for polypropylene for lithium battery separators according to claim 12, characterized in that, The molar ratio of the aluminoxane dry powder (calculated based on aluminum) to the haloalkane or the halocycloalkane is 1:4-10.

14. The catalyst for polypropylene for lithium battery separators according to claim 5, characterized in that, The ratio of the aluminoxane modified by the haloalkane or the halocycloalkane to the alkylaluminum compound is 1:1-30 in terms of the molar ratio of aluminum to aluminum.

15. The catalyst for polypropylene for lithium battery separators according to claim 14, characterized in that, The ratio of the aluminoxane modified by the haloalkane or the halocycloalkane to the alkylaluminum compound is 1:1-10 in terms of the molar ratio of aluminum to aluminum.

16. The catalyst for polypropylene for lithium battery separators according to claim 6, characterized in that, The aluminoxane is at least one of methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane and butylaluminoxane.

17. The catalyst for polypropylene for lithium battery separators according to claim 16, characterized in that, The aluminoxane is methylaluminoxane.

18. The catalyst for polypropylene for lithium battery separators according to claim 7, characterized in that, The halogenated alkane is at least one of monochloromethane, dichloromethane, trichloromethane, tetrachloromethane, monochloroethane, 1,2-dichloroethane, monochloropropane, monochlorobutane, monochloro-sec-butane, monochloro-tert-butane, chlorobenzene, monobromomethane, monobromopropane, monobromobutane and monoiodomethane.

19. The catalyst for polypropylene for lithium battery separators according to claim 8, characterized in that, X is chlorine.

20. The catalyst for polypropylene for lithium battery separators according to claim 8, characterized in that, The alkylaluminum compound is at least one of trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diethylaluminum chloride and diisobutylaluminum chloride.

21. The catalyst for polypropylene for lithium battery separators according to claim 20, characterized in that, The alkylaluminum compound is triethylaluminum or triisobutylaluminum.

22. The catalyst for polypropylene for lithium battery separators according to claim 9, characterized in that, The organic external electron donor is cyclohexylmethyldimethoxysilane.

23. The catalyst for polypropylene used in lithium battery separators according to claim 10, characterized in that, The molar ratio of the procatalyst, the cocatalyst and the organic external electron donor is 1:10-50:1-5.

24. A process for the preparation of a propylene polymer, characterized by, The catalyst for the lithium battery separator polypropylene catalyzes high-temperature polymerization or copolymerization of propylene according to any one of claims 1-23.

25. The method of claim 24, wherein, The method for preparing the propylene polymer comprises a step of catalyst pre-complexation. The method for preparing the propylene polymer comprises a step of prepolymerization.

26. The method of claim 24, wherein, The catalyst for the lithium battery separator polypropylene catalyzes high-temperature polymerization or copolymerization of propylene in a liquid or gaseous medium at 85-120℃.

27. The preparation method according to claim 25, characterized in that, The temperature of the catalyst pre-complexation is -10-40℃, and the time of the catalyst pre-complexation is 1-10min.

28. The preparation method according to claim 25, characterized in that, The temperature of the catalyst pre-complexation is 5-30℃.

29. The preparation method according to claim 25, characterized in that, The temperature of the prepolymerization is -10-60℃, and the time of the prepolymerization is 5-20min.

30. The method of claim 29, wherein, The temperature of the prepolymerization is 20-50℃.

31. The propylene polymer obtainable by the process according to any one of claims 24 to 30, characterized in that, The isotacticity of the propylene polymer is ≥96.5%, the β-crystal content in the propylene polymer is ≥3.5%, and the ash content of the propylene polymer is ≤40ppm.

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