阅读说明：本技术 一种聚丙烯锂电池膜料的生产方法 (Production method of polypropylene lithium battery membrane material ) 是由 李峰荣 付传玉 杨宏 李振明 谷英军 于 2019-09-05 设计创作，主要内容包括：本发明属于丙烯聚合生产技术领域,具体涉及一种聚丙烯锂电池膜料的生产方法。该方法采用液相反应釜与气相反应器串联的组合方式生产锂电池隔膜专用料聚丙烯树脂,在保证铝钛比nAL/nTi＝75:1的前提下,将催化剂的铝硅比设置为nAL/nSi＝4.5:1；将助剂的配比设置为1010抗氧剂:硬脂酸钙:245辅抗氧剂＝2:1:0.5。采用本方法能够改善膜料产品性能,获得理想的等规度与氧化诱导期时间。(The invention belongs to the technical field of propylene polymerization production, and particularly relates to a production method of a polypropylene lithium battery membrane material. The method adopts a combination mode of connecting a liquid phase reaction kettle and a gas phase reactor in series to produce the polypropylene resin special for the lithium battery diaphragm, and sets the ratio of aluminum to silicon of a catalyst to be nAL/nSi to be 4.5:1 on the premise of ensuring the ratio of aluminum to titanium to be nAL/nTi to be 75: 1; the proportion of the auxiliary agent is 1010 antioxidant, calcium stearate and 245 auxiliary antioxidant which are 2:1: 0.5. The method can improve the performance of the membrane material product and obtain ideal isotacticity and oxidation induction period time.)

1. A production method of a polypropylene lithium battery membrane material comprises the steps of producing polypropylene resin which is a special material for lithium battery membranes in a combined mode that a liquid phase reaction kettle and a gas phase reactor are connected in series, enabling a catalyst system to enter a first-stage liquid phase reaction kettle after prepolymerization and then enter a second-stage liquid phase reaction kettle which is connected in series, enabling the second-stage liquid phase reaction kettle to sequentially enter a third-stage gas phase reaction kettle and a fourth-stage gas phase reaction kettle which are connected in series, finally discharging polypropylene powder, and then enabling the polypropylene powder to enter a granulation process to add an auxiliary agent to produce the polypropylene resin which is a special; it is characterized in that the preparation method is characterized in that,

on the premise of ensuring that the ratio nAL/nTi is 75:1, setting the ratio of Al to Si of the catalyst to be 4.5: 1; the proportion of the auxiliary agent is 1010 antioxidant, calcium stearate and 245 auxiliary antioxidant which are 2:1: 0.5.

Technical Field

The invention belongs to the technical field of propylene polymerization production, and particularly relates to a production method of a polypropylene lithium battery membrane material.

Background

At present, the process for producing the polypropylene resin special for the lithium battery diaphragm by propylene polymerization by a reactor liquid-gas bulk method mainly adopts a combined mode of connecting a liquid-phase reaction kettle and a gas-phase reactor in series, and a catalyst system enters a primary liquid-phase reaction kettle after prepolymerization; and then the mixture enters a second-stage liquid phase reaction kettle connected in series, and finally the polypropylene powder is discharged after the mixture sequentially enters a third-stage gas phase reaction kettle and a fourth-stage gas phase reaction kettle connected in series from the second-stage liquid phase reaction kettle, and then the mixture enters a granulation process to be added with an auxiliary agent to produce the polypropylene resin special for the lithium battery diaphragm. Wherein the polymerization temperature of the primary liquid phase reaction kettle is 50-80 ℃, and the polymerization pressure is 2.5-3.2 MPa; the polymerization temperature of the secondary liquid phase reaction kettle is 50-70 ℃, and the polymerization pressure is 2.5-3.0 MPa; the polymerization temperature of the three-stage gas phase reaction kettle is 60-79 ℃, and the polymerization pressure is 1.6-2.0 MPa; the polymerization temperature of the four-stage gas phase reaction kettle is 60-85 ℃, and the polymerization pressure is 1.1-1.6 MPa; the catalyst is added from a first-stage liquid phase reaction kettle, and the auxiliary agent is added in the process of granulating the polypropylene powder. The polymerization process is carried out in a four-stage reaction kettle, wherein liquid phase polymerization is carried out in the first stage and the second stage, gas phase polymerization is carried out in the third stage and the fourth stage, and the process can be used for researching and developing the lithium battery film material polypropylene resin.

The performance of the lithium battery diaphragm directly influences the discharge capacity and the cycle service life of the battery, so the market has very strict requirements on the material of the diaphragm. The major drawbacks of films made of polypropylene resins produced by the above-mentioned methods include: the film has low mechanical property, low isotacticity, short oxidation induction period and the like.

Therefore, it is necessary to analyze and research the optimal mixture ratio of the catalyst and the auxiliary agent, respectively, so as to improve the isotacticity, the oxidation induction period and the like of the lithium battery separator special material product.

Disclosure of Invention

Technical problem to be solved

The invention provides a production method of a polypropylene lithium battery membrane material, which solves the technical problem of how to improve the performance of the membrane material product by obtaining the optimal ratio of a catalyst to an auxiliary agent.

(II) technical scheme

In order to solve the technical problems, the invention provides a production method of a polypropylene lithium battery membrane material, which comprises the steps of producing the polypropylene resin special for a lithium battery membrane by adopting a combination mode of connecting a liquid phase reaction kettle and a gas phase reactor in series, wherein a catalyst system enters a first-stage liquid phase reaction kettle after prepolymerization and then enters a second-stage liquid phase reaction kettle connected in series, and finally discharges polypropylene powder after entering a third-stage gas phase reaction kettle and a fourth-stage gas phase reaction kettle connected in series from the second-stage liquid phase reaction kettle in sequence, and then enters a granulation process to be added with an auxiliary agent to produce the polypropylene resin special for the lithium battery membrane; wherein, on the premise of ensuring that the ratio nAL/nTi is 75:1, the ratio of Al to Si of the catalyst is set to be 4.5: 1; the proportion of the auxiliary agent is 1010 antioxidant, calcium stearate and 245 auxiliary antioxidant which are 2:1: 0.5.

(III) advantageous effects

The production method of the polypropylene lithium battery membrane material provided by the invention adopts a combination mode of connecting a liquid phase reaction kettle and a gas phase reactor in series to produce the polypropylene resin special for the lithium battery membrane, and sets the ratio of aluminum to silicon of a catalyst to be nAL/nSi to be 4.5:1 on the premise of ensuring the ratio of aluminum to titanium to nAL/nTi to be 75: 1; the proportion of the auxiliary agent is 1010 antioxidant, calcium stearate and 245 auxiliary antioxidant which are 2:1: 0.5. The method can improve the performance of the membrane material product and obtain ideal isotacticity and oxidation induction period time.

Detailed Description

In order to make the objects, contents and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be given in conjunction with examples.

The embodiment provides a production method of a polypropylene lithium battery membrane material, which comprises the steps of producing polypropylene resin which is a special material for lithium battery membranes in a combined mode of series connection of a liquid phase reaction kettle and a gas phase reactor, wherein a catalyst system enters a first-stage liquid phase reaction kettle after prepolymerization and then enters a second-stage liquid phase reaction kettle which is connected in series, the second-stage liquid phase reaction kettle sequentially enters a third-stage gas phase reaction kettle and a fourth-stage gas phase reaction kettle which are connected in series, polypropylene powder is finally discharged, and then the polypropylene resin enters a granulation process and is added with an auxiliary agent to produce the polypropylene resin which is a special material.

The polypropylene product has high stereoregularity, and the isotacticity of the polypropylene product reaches more than 98 percent. The isotacticity means a fraction which cannot be extracted by boiling heptane, i.e., a highly stereoregular crystalline structure fraction, as a percentage of the whole polymer, and therefore the closer the isotacticity is to 100%, the higher the stereoregularity. The rigidity of polypropylene is determined by the stereoregularity of the crystalline structure, and the higher the stereoregularity, the better the rigidity. In this example, the catalyst aluminum-silicon ratio was set to be nAL (aluminum)/nSi (silicon) 4.5:1 with the proviso that the aluminum-titanium ratio nAL (aluminum)/nTi (titanium) was 75:1, and the respective reactor isotacticities obtained by sampling were: 93.90% of a first-stage liquid phase reaction kettle, 93.90% of a second-stage liquid phase reaction kettle, 96.2% of a third-stage gas phase reaction kettle and 96.80% of a fourth-stage gas phase reaction kettle. The isotacticity of the final product is detected by a nuclear magnetic method of 97.30 percent; 98.60% is detected by the n-heptane method. The isotacticity of the product obtained by adopting the catalyst proportion of the embodiment reaches the index of the product which is more than or equal to 98.0 percent, and the isotacticity is more ideal.

The oxidation induction period (OIT) is a time period for measuring the time for which the sample starts to undergo autocatalytic oxidation under oxygen conditions at high temperatures (200 ℃), and is an index for evaluating the ability of the material to withstand thermal degradation during molding, storage, welding and use. The heat resistance of the diaphragm determines the stability of the diaphragm, and the diaphragm can still keep the integrity of the diaphragm after large-area positive and negative electrodes are short-circuited in the charging and discharging processes. The oxidation induction period is realized by adding an auxiliary agent in the powder granulation process. The auxiliary agent comprises 1010 antioxidant, calcium stearate for lubricating and 245 auxiliary antioxidant. In this embodiment, the compounding ratio of the auxiliary agent is 1010 antioxidants, calcium stearate and 245 auxiliary antioxidants, 2:1:0.5, and the oxidation induction time (min) obtained by sampling is 36.8; 42.3 of the total weight of the mixture; 42.2; 42.7 of the total weight of the mixture; (1 time/6 h). By using the auxiliary agent with the proportion, the oxidation induction period is longer.

All quality indexes of the product produced by the method of the embodiment meet the standard requirements of lithium battery diaphragm materials, and the processing performance and physical performance of the product reach advanced levels in the row.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.