Special composite additive for lithium battery diaphragm polypropylene with high oxidation induction period

Abstract

The invention relates to the technical field of special composite additives for polypropylene, and discloses a special composite additive for lithium battery diaphragm polypropylene with a high oxidation induction period, which is prepared from the following raw materials in parts by weight: 0.05-0.2 part of beta nucleating agent, 1-3 parts of composite antioxidant, 1-5 parts of stabilizer, 1-3 parts of triethyl aluminum, 1-5 parts of titanium tetrachloride, 4-6 parts of acid remover and 1-3 parts of cyclohexylmethyldimethoxysilane. According to the special composite additive for the lithium battery diaphragm polypropylene with the high oxidation induction period, the beta-crystal nucleation performance of the polypropylene is improved by adding the beta-nucleating agent which is beneficial for forming a beta-crystal form in the crystallization process of the polypropylene into the composite additive, and the thermal deformation temperature of the polypropylene is improved by adding the composite antioxidant and the stabilizer and cooperating with the beta-nucleating agent; by adding titanium tetrachloride, triethyl aluminum and hexylmethyldimethoxysilane, the oxidation induction time of polypropylene is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of special composite additives for polypropylene, in particular to a special composite additive for polypropylene for lithium battery separators with a high oxidation induction period. Background Art

[0002] Lithium batteries are widely used in portable devices (mobile phones, notebooks), electric vehicles, electric bicycles, and aerospace fields due to their high energy density, no memory effect, long cycle life, and environmental friendliness. With the rapid development of lithium batteries, lithium battery separators, as one of the key materials of lithium battery structure, have become a research hotspot in the field of lithium batteries. Polyolefin microporous membranes have the advantages of high porosity, excellent mechanical properties, good chemical stability, and low cost, especially with appropriate thermal shutdown performance. Therefore, polyolefin is the most commonly used lithium-ion battery separator, mainly polyethylene (PE) and polypropylene (PP), as well as composite separators developed on the basis of the above two materials.

[0003] The polypropylene lithium battery separators currently on the market have a low heat deformation temperature (the heat deformation temperature of PE is about 80-85°C, and the heat deformation temperature of PP is about 100°C), and the β-crystal nucleation performance and oxidation induction period are poor. The β-crystal nucleation performance and oxidation induction period of polypropylene lithium battery separators are important performance indicators. The β-crystal nucleation performance directly affects the mechanical strength, thermal stability, electrolyte wettability of the separator and the overall performance of the battery. The oxidation induction period refers to the time required for the separator to undergo obvious oxidation reactions (such as mass loss, performance degradation, etc.) from the beginning of heating in a high temperature and oxygen environment. The longer this time interval is, the better the antioxidant properties of the separator. Therefore, how to increase the heat deformation temperature, β-crystal nucleation performance and oxidation induction period of polypropylene materials is an urgent problem to be solved.

[0004] Therefore, we proposed a special composite additive for polypropylene with a high oxidation induction period for lithium battery separators in order to solve the above-mentioned problems. Summary of the invention

[0005] The purpose of the invention is to solve the problems of low heat deformation temperature, poor β-crystal nucleation performance and poor oxidation induction period of polypropylene lithium battery separators currently on the market.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a special composite auxiliary agent for polypropylene of lithium battery separator with high oxidation induction period, which is composed of the following raw materials in parts by weight: 0.05-0.2 parts of β-nucleating agent, 1-3 parts of composite antioxidant, 1-5 parts of stabilizer, 1-3 parts of triethyl aluminum, 1-5 parts of titanium tetrachloride, 4-6 parts of acid scavenger, and 1-3 parts of cyclohexylmethyldimethoxysilane.

[0007] The composite antioxidant is a mixture of antioxidant 1010 and antioxidant 168.

[0008] Furthermore, the special composite auxiliary agent is composed of the following raw materials in parts by weight: 0.2 parts of β-nucleating agent, 2 parts of composite antioxidant, 3 parts of stabilizer, 3 parts of triethylaluminum, 2 parts of titanium tetrachloride, 4 parts of acid scavenger, and 2 parts of cyclohexylmethyldimethoxysilane.

[0009] Furthermore, the β-nucleating agent is one of cyclohexylphthalate, quinacridone quinone, triphendithiazine, cyclohexylphthalate, zinc pimelate, and zinc adipate.

[0010] Furthermore, the acid scavenger is one of calcium stearate, polyvinyl alcohol and hydrated aluminum oxide.

[0011] Furthermore, the hydrated alumina is prepared by ordinary hydrothermal reaction of an aluminum source and a precipitant, wherein the aluminum source is one of aluminum nitrate, basic aluminum acetate, and aluminum lactate, and the precipitant is one of N,N-dimethylformamide, formamide, and N-diethylformamide.

[0012] Furthermore, the composite auxiliary agent is applied to polypropylene resin to prepare a modified polypropylene composite material, and the weight ratio of the polypropylene resin to the composite auxiliary agent is 100 / 10-15.

[0013] The present invention also provides a method for preparing a modified polypropylene composite material, comprising the following steps: (1) Preparation of the antioxidant grafted modified cross-linked polyethylene: polypropylene resin and cyclohexylmethyldimethoxysilane are mixed uniformly in order according to the weight ratio, and extruded in a single screw extruder to obtain a cross-linked high-density polypropylene, the extrusion process temperature is 187-230°C, and the screw speed is 60r / min; then the composite antioxidant, stabilizer and acid scavenger and the prepared cross-linked high-density polypropylene are placed in a high-speed mixer and fully mixed, stirred uniformly to obtain a mixture A, the mixture A is placed on a double-roller and fully heated until the raw materials are fully melted and blended, and cooled to obtain an antioxidant grafted modified cross-linked polypropylene. (2) Preparation of hydrated aluminum oxide: the aluminum source is impregnated with a precipitant and butyric acid, and reacted at 170-200°C for 12 hours. (3) The antioxidant grafted modified cross-linked polypropylene, β-nucleating agent, triethylaluminum and titanium tetrachloride are placed in a high-speed mixer and mixed thoroughly and stirred evenly; (4) In a twin-screw extruder with a screw speed of 2000 r / min, the blending, extrusion and pelletization are carried out at a processing temperature of 220 to 250° C. to prepare modified polypropylene composite material particles.

[0014] The beneficial effects of the present invention are as follows: the present invention provides a composite auxiliary agent, to which a β-nucleating agent which is beneficial to the formation of β-crystal form of polypropylene during the crystallization process is added, thereby improving the β-crystal nucleation performance of polypropylene, and by adding a composite antioxidant and a stabilizer in combination with the β-nucleating agent, the heat deformation temperature of polypropylene is improved, and by adding titanium tetrachloride, triethylaluminum, and hexylmethyldimethoxysilane, the oxidation induction time of polypropylene is improved. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail in conjunction with the following examples.

[0016] The invention provides a special composite auxiliary agent for polypropylene of lithium battery diaphragm with high oxidation induction period. The special composite auxiliary agent is composed of the following raw materials in parts by weight: 0.05-0.2 parts of beta nucleating agent, 1-3 parts of composite antioxidant, 1-5 parts of stabilizer, 1-3 parts of triethyl aluminum, 1-5 parts of titanium tetrachloride, 4-6 parts of acid scavenger, and 1-3 parts of cyclohexylmethyldimethoxysilane. The composite antioxidant is a mixture of antioxidant 1010 and antioxidant 168. Antioxidant 168 is used as an auxiliary antioxidant. When it is compounded with a main antioxidant such as antioxidant 1010, it can exert a synergistic effect to further enhance thermal stability. It is stable to hydrolysis and can significantly improve the light stability of the product. When antioxidant 1010 and antioxidant 168 are mixed and used, the two can complement each other and act on polypropylene material together to significantly improve its antioxidant performance. This synergistic effect helps to reduce the oxidative degradation of lithium battery diaphragm during production and use and maintain its good performance.

[0017] The special composite auxiliary agent is composed of the following raw materials in parts by weight: 0.2 parts of a beta nucleating agent, 2 parts of a composite antioxidant, 3 parts of a stabilizer, 3 parts of triethylaluminum, 2 parts of titanium tetrachloride, 4 parts of an acid scavenger, and 2 parts of cyclohexylmethyldimethoxysilane.

[0018] The beta nucleating agent is one of cyclohexyl phthalate, quinacridone quinone, triphenothiazine, cyclohexyl phthalate, zinc pimelate and zinc adipate.

[0019] The acid scavenger is one of calcium stearate, polyvinyl alcohol and hydrated aluminum oxide.

[0020] The hydrated alumina is prepared by ordinary hydrothermal reaction of an aluminum source and a precipitant, wherein the aluminum source is one of aluminum nitrate, basic aluminum acetate, and aluminum lactate, and the precipitant is one of N,N-dimethylformamide, formamide, and N-diethylformamide.

[0021] The composite auxiliary agent is applied to polypropylene resin to prepare a modified polypropylene composite material, and the weight ratio of the polypropylene resin to the composite auxiliary agent is 100 / 10-15.

[0022] The present invention also provides a method for preparing a modified polypropylene composite material, comprising the following steps: (1) Preparation of the antioxidant grafted modified cross-linked polyethylene: polypropylene resin and cyclohexylmethyldimethoxysilane are mixed uniformly in order according to the weight ratio, and extruded in a single screw extruder to obtain a cross-linked high-density polypropylene, the extrusion process temperature is 187-230°C, and the screw speed is 60r / min; then the composite antioxidant, stabilizer and acid scavenger and the prepared cross-linked high-density polypropylene are placed in a high-speed mixer and fully mixed, stirred uniformly to obtain a mixture A, the mixture A is placed on a double-roller and fully heated until the raw materials are fully melted and blended, and cooled to obtain an antioxidant grafted modified cross-linked polypropylene. (2) Preparation of hydrated aluminum oxide: the aluminum source is impregnated with a precipitant and butyric acid, and reacted at 170-200°C for 12 hours. (3) The antioxidant grafted modified cross-linked polypropylene, β-nucleating agent, triethylaluminum and titanium tetrachloride are placed in a high-speed mixer and mixed thoroughly and stirred evenly; (4) In a twin-screw extruder with a screw speed of 2000 r / min, the blending, extrusion and pelletization are carried out at a processing temperature of 220 to 250° C. to prepare modified polypropylene composite material particles.

[0023] Embodiments of the present invention:

[0024] Embodiment 1

[0025] A special composite auxiliary agent for polypropylene of lithium battery diaphragm with high oxidation induction period is composed of the following raw materials in parts by weight: 0.2 parts of cyclohexyl phthalic acid amide, 2 parts of a mixture of antioxidant 1010 and antioxidant 168, 3 parts of stabilizer, 3 parts of triethyl aluminum, 2 parts of titanium tetrachloride, 4 parts of hydrated aluminum oxide, and 2 parts of cyclohexylmethyldimethoxysilane.

[0026] Embodiment 2

[0027] A special composite auxiliary agent for polypropylene of lithium battery diaphragm with high oxidation induction period is composed of the following raw materials in parts by weight: 0.15 parts of cyclohexyl phthalic acid amide, 3 parts of a mixture of antioxidant 1010 and antioxidant 168, 4 parts of a stabilizer, 2 parts of triethyl aluminum, 4 parts of titanium tetrachloride, 4 parts of hydrated aluminum oxide, and 3 parts of cyclohexylmethyldimethoxysilane.

[0028] Embodiment 3

[0029] A special composite auxiliary agent for polypropylene of lithium battery diaphragm with high oxidation induction period is composed of the following raw materials in parts by weight: 0.1 parts of cyclohexyl phthalic acid amide, 1.5 parts of a mixture of antioxidant 1010 and antioxidant 168, 2 parts of stabilizer, 1 part of triethyl aluminum, 3 parts of titanium tetrachloride, 4 parts of hydrated aluminum oxide, and 2.5 parts of cyclohexylmethyldimethoxysilane.

[0030] Five different modified polypropylene composite materials were prepared by mixing the special composite additives for polypropylene of lithium battery separator with high oxidation induction period described in Examples 1-3 with polypropylene resin in a weight ratio of 10-15 / 100.

[0031] The β-nucleating agent is removed from the formula described in Example 1, and a polypropylene composite material is prepared using the obtained composite additive as Comparative Example 1;

[0032] A polypropylene composite material prepared by removing the mixture of antioxidant 1010 and antioxidant 168 and the stabilizer from the formula described in Example 2 is used as Comparative Example 2;

[0033] The polypropylene composite material prepared by removing titanium tetrachloride, triethylaluminum, and hexylmethyldimethoxysilane from the formula described in Example 3 is used as Comparative Example 3;

[0034] Comprehensive performance tests were performed on Examples 1-3 and Comparative Examples 1-3, and the test results are shown in Table 1.

[0035] Table 1

[0036]

[0037] It can be seen from Examples 1-3 and Comparative Examples 1-3 that the addition of a β-nucleating agent, a composite antioxidant, a stabilizer, titanium tetrachloride, triethylaluminum, and hexylmethyldimethoxysilane can significantly improve the β-crystal nucleation performance of polypropylene, the heat deformation temperature of polypropylene, and the oxidation induction time of polypropylene. It can be seen from Examples 1-3 and Comparative Example 1 that as the proportion of the β-nucleating agent gradually decreases, the crystallinity of the β-crystal also gradually decreases. The β-nucleating agent can effectively improve the β-crystal nucleation performance of polypropylene. It can be seen from Examples 1-3 and Comparative Example 2 that the heat deformation temperature of polypropylene is effectively improved by adding a composite antioxidant and a stabilizer in combination with a β-nucleating agent. It can be seen from Examples 1-3 and Comparative Example 3 that the oxidation induction time of polypropylene is effectively improved by adding titanium tetrachloride, triethylaluminum, and hexylmethyldimethoxysilane.

Claims

1. A special composite additive for polypropylene of lithium battery separator with high oxidation induction period, characterized by: The method is composed of the following raw materials in parts by weight: 0.05-0.2 parts of a beta nucleating agent, 1-3 parts of a composite antioxidant, 1-5 parts of a stabilizer, 1-3 parts of triethylaluminum, 1-5 parts of titanium tetrachloride, 4-6 parts of an acid scavenger, and 1-3 parts of cyclohexylmethyldimethoxysilane; The composite antioxidant is a mixture of antioxidant 1010 and antioxidant 168.

2. The special composite auxiliary agent for polypropylene of lithium battery separator with high oxidation induction period according to claim 1, characterized in that: The invention is composed of the following raw materials in parts by weight: 0.2 parts of beta nucleating agent, 2 parts of composite antioxidant, 3 parts of stabilizer, 3 parts of triethylaluminum, 2 parts of titanium tetrachloride, 4 parts of acid scavenger and 2 parts of cyclohexylmethyldimethoxysilane.

3. The special composite auxiliary agent for polypropylene of lithium battery separator with high oxidation induction period according to claim 1, characterized in that: The beta nucleating agent is one of cyclohexyl phthalate, quinacridone quinone, triphenothiazine, cyclohexyl phthalate, zinc pimelate and zinc adipate.

4. The special composite auxiliary agent for polypropylene of lithium battery separator with high oxidation induction period according to claim 1, characterized in that: The acid scavenger is one of calcium stearate, polyvinyl alcohol and hydrated aluminum oxide.

5. The special composite auxiliary agent for polypropylene of lithium battery separator with high oxidation induction period according to claim 4, characterized in that: The hydrated alumina is prepared by ordinary hydrothermal reaction of an aluminum source and a precipitant, wherein the aluminum source is one of aluminum nitrate, basic aluminum acetate, and aluminum lactate, and the precipitant is one of N,N-dimethylformamide, formamide, and N-diethylformamide.

6. The use of a special composite auxiliary agent for polypropylene with a high oxidation induction period for lithium battery separators according to any one of claims 1 to 5, characterized in that: The composite auxiliary agent is applied to polypropylene resin to prepare a modified polypropylene composite material, and the weight ratio of the polypropylene resin to the composite auxiliary agent is 100 / 10-15.

7. The use of a special composite auxiliary agent for polypropylene of lithium battery separator with high oxidation induction period according to claim 6, characterized in that: The preparation method of the modified polypropylene composite material comprises the following steps: (1) Preparation of the antioxidant grafted modified cross-linked polyethylene: polypropylene resin and cyclohexylmethyldimethoxysilane are mixed uniformly in order according to the weight ratio, and extruded in a single screw extruder to obtain cross-linked high-density polypropylene, the extrusion process temperature is 187-230°C, and the screw speed is 60r / min; then the composite antioxidant, stabilizer and acid scavenger and the prepared cross-linked high-density polypropylene are placed in a high-speed mixer and fully mixed, stirred uniformly to obtain mixture A, and mixture A is placed on a double-roller machine and fully heated until the raw materials are fully melted and blended, and cooled to obtain antioxidant grafted modified cross-linked polypropylene. (2) Preparation of hydrated aluminum oxide: aluminum source is impregnated with a precipitant and butyric acid, and reacted at 170-200°C for 12 hours. (3) The antioxidant grafted modified cross-linked polypropylene, β-nucleating agent, triethylaluminum and titanium tetrachloride are placed in a high-speed mixer and mixed thoroughly and stirred evenly; (4) In a twin-screw extruder with a screw speed of 2000 r / min, the blending, extrusion and pelletization are carried out at a processing temperature of 220 to 250° C. to prepare modified polypropylene composite material particles.

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