High-performance polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a high-performance polypropylene composite material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The high-performance polypropylene composite material is prepared from the following components in parts by volume: 80 to 99.99 parts of polypropylene and 0.1 to 5 parts of inorganic nano filler. The inorganic nano-filler is introduced into the polypropylene, and the inorganic nano-filler can improve the microstructure of the polypropylene and reduce the enhancement effect of a local electric field, so that the composite film can bear higher electric field intensity while reducing the loss; the inorganic nano filler has high thermal conductivity, so that heat generated under the action of an electric field can be quickly conducted out, breakdown caused by local overheating is prevented, and the service life of the material in a high-temperature environment is prolonged, so that the high-performance polypropylene composite material disclosed by the embodiment of the invention effectively improves the breakdown field strength and the characteristics of high temperature resistance and high pressure resistance; the problem of low breakdown field strength at high temperature is practically solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a high-performance polypropylene composite material and a preparation method and application thereof. Background Art

[0002] With the continuous growth of global energy demand and the increase in fossil fuel consumption, energy and environmental issues are becoming increasingly prominent, and there is an urgent need to find sustainable solutions. In this context, energy storage technology is not only a hot topic in scientific research, but also an indispensable part of modern industry. With the rapid development of the microelectronics and power industries, the demand for energy storage devices is becoming increasingly diversified, and requirements such as lightweight, miniaturization and high performance are becoming more and more prominent. As a key electronic energy storage device, film capacitors are widely used in many fields such as electric vehicles, renewable energy systems, communication equipment and medical devices. They have excellent energy density, self-healing and processing flexibility. In particular, polymer dielectric materials play an important role in high-energy-density pulse capacitors due to their high energy storage density and low energy loss. In order to meet the needs of national security and economic development, the development of new dielectric materials with higher energy storage density has become a top priority.

[0003] Given the variability of capacitor operating environments, there is an urgent need for alternative polypropylene composites that can maintain excellent dielectric and energy storage properties under high temperature and high pressure. Currently, a common method is to prepare polypropylene-based composites by doping them with high-dielectric ceramics such as barium titanate. Although this method can improve energy density and dielectric constant, it significantly reduces discharge efficiency due to prominent organic-inorganic interface issues. Another common approach is to enhance the dielectric properties of PP materials under high temperature and high pressure by adding antioxidants through physical blending. However, antioxidants are significantly unevenly distributed in the material and are difficult to completely consume free radicals generated by thermal decomposition, which may increase conductivity and reduce voltage resistance. Alternatively, chemical modification of the side groups of the PP polymer chain and grafting of specific functional monomers can be used to improve its dielectric properties and oxidation resistance, but the grafting efficiency is low and unsuitable for large-scale production. Furthermore, the dielectric strength of domestically produced PP film is 600-650 MV / m, which, while close to the material's performance limit, is still 50-100 MV / m lower than imported film, limiting the breakdown field strength of domestic film capacitors and, in turn, making it difficult to further increase their energy density.

[0004] As can be seen from the above, the temperature resistance of PP films in the existing technology is poor. As the temperature increases, its breakdown field strength decreases significantly, which seriously restricts its performance in high-temperature applications. Summary of the Invention

[0005] The present invention provides a high-performance polypropylene composite material, a preparation method and application thereof, aiming to solve the problem of low breakdown field strength at high temperature in the prior art.

[0006] The first aspect of the present invention provides a high-performance polypropylene composite material, comprising the following components in parts by volume: 80-99.99 parts of polypropylene and 0.1-5 parts of inorganic nanofiller.

[0007] In some embodiments of the first aspect, the polypropylene is homopolypropylene or block copolymer polypropylene.

[0008] In some embodiments of the first aspect, the inorganic nanofiller is any one of boron nitride, silicon dioxide, magnesium oxide, barium titanate, and molybdenum disulfide.

[0009] In some embodiments of the first aspect, the inorganic nanofiller has a particle size of 1-5 μm.

[0010] In some embodiments of the first aspect, the volume fraction of the polypropylene is 99.3-99.7 parts, and the volume fraction of the inorganic nanofiller is 0.1-0.15 parts.

[0011] In some embodiments of the first aspect, the high-performance polypropylene composite material further comprises the following components in parts by volume: 0.1-1 part of an auxiliary agent, wherein the auxiliary agent is one or more of a plasticizer, an antioxidant, and a light stabilizer.

[0012] The second aspect of the present invention provides a method for preparing the high-performance polypropylene composite material described in the first aspect, comprising the following steps: melt blending the components in proportion, then melt-extruding and granulating to obtain the polypropylene composite material.

[0013] In some embodiments of the second aspect, before melt blending the components in proportion, the method further comprises the following steps:

[0014] The inorganic nanofiller is placed in an organic solution, and the organic solvent containing the inorganic nanofiller is ultrasonically stripped, and the stripped product is dried;

[0015] The parameters of ultrasonic peeling are power of 1800-2000W and time of ultrasonic peeling of 6-8h.

[0016] A third aspect of the present invention provides a capacitor film using the high-performance polypropylene composite material described in the first aspect, comprising the following steps: melt-extruding the high-performance polypropylene composite material to obtain an initial film; and high-temperature annealing the initial film to obtain a capacitor film. In some embodiments of the third aspect, the power capacitor film has a thickness of 5-30 μm.

[0017] The fourth aspect of the present invention provides an application of the high-performance polypropylene composite material according to the first aspect or the capacitor film according to the third aspect in a power capacitor, wherein the power capacitor includes any one of a high-energy storage pulse capacitor, an automotive capacitor, a power system capacitor, and an aerospace capacitor.

[0018] It can be seen from the above technical solutions that the present invention has the following advantages:

[0019] This embodiment provides a high-performance polypropylene composite material. Since inorganic nanofillers are introduced into polypropylene, the inorganic nanofillers can improve the microstructure of polypropylene and reduce the defect density in the film. At the same time, interfaces are formed between polypropylene and the inorganic nanofillers. These interfaces can effectively scatter and suppress the local accumulation of charges, effectively reduce leakage current and inhibit the growth and expansion of electrical dendrites, reduce the enhancement effect of local electric fields, and enable the composite film to reduce losses while withstanding higher electric field strengths. The high thermal conductivity of the inorganic nanofillers helps to quickly conduct away the heat generated by the electric field, prevent local overheating from causing breakdown, and extend the service life of the material in high-temperature environments. Therefore, the high-performance polypropylene composite material of this embodiment effectively improves the breakdown field strength and the high temperature and high pressure resistance characteristics, and effectively solves the problem of low breakdown field strength at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A process diagram for preparing a capacitor film according to an embodiment of the present invention;

[0022] Figure 2 SEM images provided for embodiments of the present invention;

[0023] Figure 3 A breakdown strength diagram provided by an embodiment of the present invention;

[0024] Figure 4 A graph showing dielectric constant and dielectric loss in accordance with an embodiment of the present invention;

[0025] Figure 5 This is an energy density curve provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention provide a high-performance polypropylene composite material, a preparation method thereof, and an application thereof, which are used to solve the technical problem of low breakdown field strength at high temperature in the prior art.

[0027] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] In a first aspect, this embodiment provides a high-performance polypropylene composite material, comprising the following components in parts by volume: 80-99.99 parts of polypropylene and 0.1-5 parts of inorganic nanofiller.

[0029] In this embodiment, polypropylene is used as the matrix material and inorganic nanofillers are used as reinforcing components. Inorganic nanofillers are used as heterogeneous nucleating agents to regulate the grain size / crystal form of polypropylene, that is, to achieve a heterogeneous nucleation effect to increase the crystallinity, improve the microstructure of polypropylene, reduce the defect density in the film, and achieve improved heat resistance and mechanical strength. In addition, the inorganic nanofillers can form interfaces with the polypropylene, which can effectively scatter and inhibit the local accumulation of charges, reduce the enhancement effect of the local electric field, and thus increase the breakdown field strength. Furthermore, the high thermal conductivity of the inorganic nanofillers helps to quickly conduct the heat generated by the electric field to prevent local overheating from causing breakdown. In addition, after the introduction of inorganic nanofillers, on the one hand, the energy storage density of the high-performance polypropylene composite material is significantly improved compared to pure polypropylene, which is particularly suitable for energy storage devices with high energy density requirements. On the other hand, the thermal decomposition temperature of the composite material is significantly increased, which extends the service life of the material in a high temperature environment.

[0030] Compared with existing technologies, it has the following advantages: first, it has good high-voltage resistance. The introduction of inorganic nanofillers can increase the breakdown field strength; second, it has improved energy storage performance. The energy storage density of high-performance polypropylene composite materials can reach up to 8.31J / cm 3 , suitable for devices with high energy density requirements; thirdly, it has good thermal stability. The thermal decomposition temperature of high-performance polypropylene composite materials is 10-50°C higher than that of pure polypropylene. It has good high-temperature thermal stability and is suitable for use in high-temperature environments.

[0031] In a specific embodiment, a ratio of polypropylene and inorganic nanofiller is further provided, wherein the volume fraction of polypropylene is 99.3-99.7 parts, and the volume fraction of inorganic nanofiller is 0.1-0.15 parts. For example, the volume fraction of polypropylene is 99.7 parts, and the volume fraction of inorganic nanofiller is 0.15 parts; or the volume fraction of polypropylene is 99.6 parts, and the volume fraction of inorganic nanofiller is 0.15 parts; or the volume fraction of polypropylene is 99.5 parts, and the volume fraction of inorganic nanofiller is 0.15 parts; or the volume fraction of polypropylene is 99.4 parts, and the volume fraction of inorganic nanofiller is 0.15 parts; or the volume fraction of polypropylene is 99.3 parts, and the volume fraction of inorganic nanofiller is 0.15 parts. After adopting this ratio, the DC breakdown field strength of polypropylene can be increased to above 671 MV / m at room temperature, highlighting the high voltage and high temperature resistance advantages of the ratio adopted in this embodiment.

[0032] In a specific embodiment, a feasible method for preparing polypropylene is further provided. The polypropylene is a homopolymer polypropylene or a block copolymer polypropylene, preferably a polypropylene with a narrow molecular weight distribution and a moderate melt flow rate (MFR), so that it has better processability in subsequent blending and processing.

[0033] In a specific embodiment, a feasible method for using an inorganic nanofiller is further provided. The inorganic nanofiller is boron nitride, and the type of boron nitride selected is hexagonal boron nitride. Hexagonal boron nitride has a layered structure similar to graphite. Boron atoms and nitrogen atoms in the layers are connected by covalent bonds, and the layers interact with each other through van der Waals forces, so that hexagonal boron nitride has good lubricity, high-temperature stability, chemical stability, and insulation.

[0034] In one embodiment, the particle size of the inorganic nanofiller is 1-5 μm, that is, the particle size of the hexagonal boron nitride is 1-5 μm. By refining the size of the boron nitride powder, it is beneficial to increase the specific surface area and improve the interaction between boron nitride and polypropylene, thereby promoting better dispersion; at the same time, it can also reduce agglomeration, destroy agglomerates, reduce the formation of large particles, and improve the uniformity of distribution.

[0035] In a specific embodiment, an addible component of a high-performance polypropylene composite material is further provided. In addition to the above-mentioned polypropylene and boron nitride, the high-performance polypropylene composite material also includes 0.1-1 parts of an auxiliary agent, wherein the auxiliary agent is one or more of a plasticizer, an antioxidant, and a light stabilizer to improve the processing performance and service life of the composite material.

[0036] In one embodiment, the auxiliary agent is a plasticizer, and the plasticizer is a low-volatile phthalate plasticizer.

[0037] In one embodiment, the auxiliary agent is an antioxidant, which is a hindered phenol antioxidant, and the added amount is 0.1-1 vol%, which removes unstable free radicals to improve the composite material's resistance to oxidative degradation and high-temperature degradation, and protect the material's physical properties and service life.

[0038] In one embodiment, the light stabilizer is a benzophenone, benzotriazole, or salicylate compound, which is an additive used to inhibit or slow down the photodegradation and photooxidation reaction of the polypropylene composite material under the action of light, thereby extending the service life of the polypropylene composite material.

[0039] A second aspect of this embodiment provides a method for preparing a high-performance polypropylene composite material, comprising the following steps:

[0040] S1, material pretreatment, pretreating polypropylene, boron nitride and antioxidant to obtain pretreated polypropylene, boron nitride and antioxidant;

[0041] S2. Mixing uniformly: placing the pretreated polypropylene, boron nitride and antioxidant in a ball mill in proportion for physical mixing;

[0042] S3, melt-blending the physically mixed materials, extruding and granulating them to obtain a high-performance polypropylene composite material.

[0043] In this embodiment, the high-performance polypropylene composite material prepared has a breakdown strength increased by 10-50%, an energy storage density increased by 10-50%, and a thermal decomposition temperature increased by 10-50°C compared to traditional pure polypropylene materials. In addition, after adopting the melt blending method, the process for preparing the high-performance polypropylene composite material is simple, suitable for industrial large-scale production, and does not require complicated post-processing steps.

[0044] In a specific embodiment, an implementable method of step S1 is further provided, and step S1 specifically includes the following steps:

[0045] S10, placing the polypropylene pellets, antioxidant, and inorganic nanofiller in an oven set at 50°C for 12 hours for drying to remove residual moisture in the raw materials;

[0046] S11, ultrasonically exfoliate the inorganic nanofiller to refine the nano size, that is, place an appropriate amount of inorganic nanofiller in an organic solution and place it in a cell crusher. The ultrasonic exfoliation parameter is 2000W power. Ice bags need to be added to ensure that the water temperature is not too high. The ice bags are replaced after 1-2 hours, and ultrasonic exfoliation is performed for 6-8 hours. The exfoliated product is then obtained by centrifugation and placed in an oven for drying.

[0047] In specific implementation, by refining the size of inorganic nanofillers, it is beneficial to increase the specific surface area and improve its interaction with the PP matrix, thereby promoting better dispersion; at the same time, it can also reduce agglomeration, destroy agglomerates, reduce the formation of large particles, and improve the uniformity of distribution.

[0048] Among them, such as Figure 2 As shown, Figure 2 (a) is an SEM image of an unpeeled inorganic nanofiller (boron nitride BN). The SEM test characterizes the size of the inorganic nanofiller (boron nitride BN) in the unpeeled state. The BN powder without any treatment presents a two-dimensional lamellar distribution with a two-dimensional size of approximately 40 μm. The SEM image also shows its vertical lamination characteristics, which is not conducive to achieving uniform dispersion in PP. Figure 2 (b) is an SEM image of an inorganic nanofiller (boron nitride BN) with insufficient exfoliation. After 3-4 hours of ultrasonic exfoliation and refinement, SEM testing revealed that the size of the boron nitride BN powder was significantly refined, not only reducing the size in the two-dimensional plane to 5μm, but also reducing the stacking phenomenon in the vertical direction; Figure 2 (c) SEM image of fully exfoliated inorganic nanofiller (boron nitride BN). By extending the ultrasonic exfoliation and refinement operation of BN powder to 6-8h, it was found that its size can be further reduced to below 1μm; for comparison, Figure 2 (d) is the SEM image of PP / BN-0.35. Figure 2 (e) is the SEM image of PP / BN-0.45. Figure 2 (f) SEM image of PP / BN-0.55.

[0049] In a specific embodiment, an implementable method of step S2 is further provided, and step S2 specifically includes the following steps:

[0050] S20, placing the polypropylene powder in a ball mill tank, setting the speed of the double-roll mill to 100 r / min, mixing for 20 minutes and then taking it out. The purpose of this mixing of polypropylene pellets is to clean the ball mill;

[0051] S21, placing 80-99.99 parts of polypropylene, 0.1-1 parts of antioxidant, and 0.1-5 parts of inorganic nanofiller into a cleaned ball mill jar, and physically mixing them to form a physically mixed substance.

[0052] In specific implementation, the purpose is to make the filler more evenly dispersed in the polypropylene powder to ensure the uniformity of the film; if the material size is not refined, boron nitride exists in the form of large two-dimensional flakes. If it is directly added to the polypropylene powder, the prepared film will have obvious large particles of boron nitride filler, which cannot achieve effective uniform dispersion.

[0053] The total amount of addition is required to be no more than 2 / 3 of the volume of the ball mill to ensure sufficient blending. At this time, the speed of the double-roll mill is set to 60r / min and the blending is carried out for 6-8h.

[0054] In a specific embodiment, an implementable method of step S3 is further provided. Step S3 specifically comprises: melt-blending the physically mixed materials at a blending temperature of 125-250° C., extruding and granulating to obtain a polypropylene composition.

[0055] Please refer to Figure 1 A third aspect of this embodiment provides a capacitor film, specifically comprising the following steps:

[0056] A1. Put the high-performance polypropylene composite material into a melt extrusion cast film machine, stretch, heat-set, reel and cut to obtain the initial film.

[0057] A2. Performing high-temperature annealing on the initial film to obtain a capacitor film.

[0058] In this embodiment, the capacitor film produced has high mechanical breakdown strength, high overheat-induced breakdown performance, and good dielectric and breakdown resistance at high temperatures. In addition, due to the high-temperature annealing treatment of the initial film, internal stress can be reduced and problems such as organic / inorganic interface bonding can be improved, thereby improving the mechanical and electrical properties of the composite film. It can be widely used in high-energy storage pulse equipment, hybrid electric vehicles, electromagnetic catapult equipment, smart power grid equipment, aerospace equipment, military and defense equipment, and other fields.

[0059] In a specific embodiment, an implementable method of step A1 is further provided, and step A1 is specifically: putting the high-performance polypropylene composite material into a melt extrusion cast film machine to prepare a high-energy storage and high-temperature resistant modified polypropylene film, the temperature is 120-250°C, and the film winding speed is 5-20r / min.

[0060] In one embodiment, the capacitor film has a thickness of 5-30 μm. With this thickness, under the conditions of a heat shrinkage test temperature of 50-150° C. and a time of 10-100 minutes, the sum of the longitudinal heat shrinkage rate and the transverse heat shrinkage rate is less than or equal to 1-50%.

[0061] In a specific embodiment, an implementable method of step A2 is further provided. Step A2 specifically comprises: performing high-temperature annealing at 120° C. for 6 hours on the initial film to obtain a capacitor film.

[0062] After specific implementation, annealing treatment can optimize different holding temperatures and times, release internal stress, increase Young's modulus, enhance interface bonding, and improve the uniformity and structural stability of the composite film. The final prepared PP-based composite capacitor film exhibits low loss, high breakdown, high energy storage and high thermal stability, showing broad application prospects.

[0063] It should be noted that the above embodiments are methods for preparing capacitor films based on the presence of a readily available polypropylene composition. When a readily available polypropylene composition is unavailable, a person skilled in the art can directly prepare a capacitor film by the following steps:

[0064] B1. Polypropylene, antioxidant, and inorganic nanofiller are placed in an oven set at 50°C for 12 hours for drying to remove residual moisture in the raw materials; the inorganic nanofiller is subjected to ultrasonic exfoliation to refine the nanosize, that is, an appropriate amount of inorganic nanofiller is placed in an organic solution, placed in a cell crusher, and ultrasonically exfoliated for 6-8 hours. The exfoliated product is then obtained by centrifugation and placed in an oven for drying.

[0065] B2. Place the polypropylene powder in a ball mill jar, set the speed of the double-roll mill to 100 r / min, and take it out after mixing for 20 minutes. The purpose of mixing the polypropylene pellets is to clean the ball mill; 80-99.99 parts of polypropylene, 0.1-1 part of antioxidant, and 0.1-5 parts of inorganic nanofiller are placed in the cleaned ball mill jar and physically mixed to form a physically mixed substance.

[0066] B3, melt blending the physically mixed materials at a blending temperature of 125-250°C.

[0067] B4, prepare high energy storage and high temperature resistant modified polypropylene film at a temperature of 120-250°C and a film winding speed of 5-20r / min. Subsequently, the initial film is annealed at 120°C for 6 hours to obtain a capacitor film.

[0068] The fourth aspect of this embodiment provides an application of a high-performance polypropylene composite material. The high-performance polypropylene composite material can be used in the field of preparing capacitors. The capacitor equipment that introduces the high-performance polypropylene composite material has significantly improved dielectric properties, mechanical properties and energy storage density, and is suitable for applications in scenarios requiring high electric fields and high energy density.

[0069] In one application scenario, high-performance polypropylene composite materials and capacitor films made therefrom can be used as materials for preparing capacitors. Polypropylene composite materials can increase the high-voltage and high-temperature resistance of metallized capacitors. Capacitors are widely used as energy storage devices in various modern electronic devices, including but not limited to high-energy storage pulse capacitors, automotive capacitors, electromagnetic catapult capacitors, power grid capacitors, and aerospace capacitors.

[0070] Example 1

[0071] Embodiment 1 of the present invention provides a capacitor film, which includes 99.7 vol % of polypropylene, 0.15 vol % of antioxidant, and 0.15 vol % of hexagonal boron nitride.

[0072] The preparation of the capacitor film of this embodiment includes the following steps:

[0073] Step 1: Place polypropylene, antioxidant, and inorganic nanofiller in an oven set at 50° C. for 12 hours for drying; ultrasonically exfoliate the inorganic nanofiller for 7 hours, then centrifuge the exfoliated product and dry it in an oven.

[0074] Step 2: Place the polypropylene powder in a ball mill, set the speed of the double-roll mill to 100 r / min, and take it out after mixing for 20 minutes; and put 99.7 vol% of polypropylene, 0.15 vol% of antioxidant, and 0.15 vol% of hexagonal boron nitride into the cleaned ball mill, set the speed to 60 r / min, blend for 6-8 hours, and physically mix evenly to form a physically mixed substance.

[0075] Step 3: melt-blending the physically mixed materials at a blending temperature of 187.5°C.

[0076] Step 4: Prepare a high-energy storage and high-temperature resistant modified polypropylene film at a temperature of 187°C and a film winding speed of 12.5 r / min. Subsequently, the initial film is annealed at 120°C for 6 hours to obtain a capacitor film.

[0077] Example 2

[0078] Example 2 of the present invention provides a capacitor film, which has a structure and preparation method that are basically the same as those in Example 1, except that the composition ratio of the capacitor film is different, that is, instead of 99.7 vol% polypropylene, 0.15 vol% antioxidant, and 0.15 vol% hexagonal boron nitride, the composition ratio is 99.6 vol% polypropylene, 0.25 vol% antioxidant, and 0.15 vol% hexagonal boron nitride. That is, the ratio of polypropylene and antioxidant is different.

[0079] Example 3

[0080] Example 3 of the present invention provides a capacitor film, which has a structure and preparation method that are basically the same as those in Example 1, except that the composition ratio of the capacitor film is different, that is, instead of 99.7 vol% polypropylene, 0.15 vol% antioxidant, and 0.15 vol% hexagonal boron nitride, the composition ratio is 99.5 vol% polypropylene, 0.35 vol% antioxidant, and 0.15 vol% hexagonal boron nitride. That is, the ratio of polypropylene and antioxidant is different.

[0081] Example 4

[0082] Example 4 of the present invention provides a capacitor film, which has a structure and preparation method that are basically the same as those in Example 1, except that the composition ratio of the capacitor film is different, that is, instead of 99.7 vol% polypropylene, 0.15 vol% antioxidant, and 0.15 vol% hexagonal boron nitride, the composition ratio is 99.4 vol% polypropylene, 0.45 vol% antioxidant, and 0.15 vol% hexagonal boron nitride. That is, the ratio of polypropylene and antioxidant is different.

[0083] Example 5

[0084] Example 5 of the present invention provides a capacitor film, which has a structure and preparation method that are basically the same as those in Example 1, except that the composition ratio of the capacitor film is different, that is, instead of 99.7 vol% polypropylene, 0.15 vol% antioxidant, and 0.15 vol% hexagonal boron nitride, the composition ratio is 99.3 vol% polypropylene, 0.55 vol% antioxidant, and 0.15 vol% hexagonal boron nitride. That is, the ratio of polypropylene and antioxidant is different.

[0085] Comparative Example 1

[0086] Comparative Example 1 provides a pure polypropylene film, which has the same process conditions as Example 1, that is, comprising 99.7 vol % of polypropylene and 0.15 vol % of antioxidant.

[0087] It can be seen from Examples 1 to 5 that Examples 1 to 5 are all power capacitor films with hexagonal boron nitride. The difference between the five is the different ratios. Next, performance characterization tests are carried out on Examples 1 to 3 and Comparative Example 1, including breakdown strength test, energy storage performance test and thermal stability test. Among them, the breakdown strength test uses a standard electrical breakdown test instrument to perform a breakdown strength test on the composite material, the energy storage performance test measures the energy storage density of the composite material by a capacitor charge and discharge test, and the thermal stability test uses a thermogravimetric analyzer to characterize the thermal stability of the composite material. The test results are as follows: Figures 3 to 5 shown.

[0088] The capacitor film (PP / 0.15 vol% BN) prepared in Example 1 is as follows Figure 3 As shown in Figure 2, the breakdown field strength α can reach 587MV / m at room temperature; Figure 5 As shown in the figure, under the electric field of 600MV / m at room temperature, the energy storage density Ue=7.00J / cm3 and the release efficiency η=90.7%.

[0089] The capacitor film (PP / 0.25 vol% BN) prepared in Example 2 is as follows Figure 3 As shown in Figure 2, the breakdown field strength α can reach 624MV / m at room temperature; Figure 5 As shown in the figure, under the electric field of 600MV / m at room temperature, the energy storage density Ue=6.72J / cm3 and the release efficiency η=92.3%.

[0090] The capacitor film (PP / 0.35 vol% BN) prepared in Example 3 is as follows Figure 3 As shown in Figure 2, the breakdown field strength α can reach 671MV / m at room temperature; Figure 5 As shown in the figure, under the electric field of 650MV / m at room temperature, the energy storage density Ue=8.31J / cm3 and the release efficiency η=90.1%.

[0091] The capacitor film (PP / 0.45 vol% BN) prepared in Example 4 is as follows Figure 3 As shown in Figure 2, the breakdown field strength α can reach 580MV / m at room temperature; Figure 5 As shown in the figure, under the electric field of 600MV / m at room temperature, the energy storage density Ue=6.81J / cm3 and the release efficiency η=87.3%.

[0092] The capacitor film (PP / 0.55 vol% BN) prepared in Example 5 is as follows Figure 3 As shown in Figure 2, the breakdown field strength α can reach 539MV / m at room temperature; Figure 5 As shown in the figure, under the electric field of 550MV / m at room temperature, the energy storage density Ue=5.8J / cm3 and the release efficiency η=92.1%.

[0093] It can be seen that the breakdown strength test results show that the introduction of capacitor film with inorganic nanofillers effectively improves the breakdown voltage of polypropylene, and the breakdown strength of the composite material is 10-50% higher than that of pure PP material, and can withstand higher electric field strength; the capacitor charge and discharge test results show that the energy storage density of the capacitor film is 10-50% higher than that of pure polypropylene, and it still maintains excellent capacitance effect under higher electric field strength; the thermal stability of the capacitor film is characterized by thermogravimetric analyzer (TGA), and the results show that the introduction of capacitor film with inorganic nanofillers significantly increases the thermal decomposition temperature of the composite material, which is 10-50°C higher than that of pure polypropylene. It has good high-temperature thermal stability and is suitable for use in high-temperature environments.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0095] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

Claims

1. A high-performance polypropylene composite material, characterized in that: The invention comprises the following components in parts by volume: 80-99.99 parts of polypropylene and 0.1-5 parts of inorganic nano filler.

2. The high performance polypropylene composite material according to claim 1, characterized in that The polypropylene is homopolymer polypropylene or block copolymer polypropylene.

3. The high performance polypropylene composite material according to claim 1, characterized in that The inorganic nanofiller is any one of boron nitride, silicon dioxide, magnesium oxide, barium titanate, and molybdenum disulfide.

4. The high performance polypropylene composite material according to claim 1, characterized in that The particle size of the inorganic nanofiller is 1-10 μm.

5. The high performance polypropylene composite material according to claim 1, characterized in that: The volume fraction of the polypropylene is 99.3-99.7 parts, and the volume fraction of the inorganic nanofiller is 0.1-0.15 parts.

6. The high performance polypropylene composite material according to claim 1, characterized in that: The high-performance polypropylene composite material further comprises the following components in parts by volume: 0.1-1 parts of auxiliary agents, wherein the auxiliary agents are one or more of plasticizers, antioxidants, light stabilizers, voltage stabilizers, plasticizers, nucleating agents, and antistatic agents.

7. A method for preparing the high-performance polypropylene composite material according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: pouring powder materials in which all components are fully and evenly mixed into equipment, and then subjecting the powder materials to melt extrusion and casting into a film to obtain the polypropylene composite film.

8. A capacitor film, characterized in that: The high-performance polypropylene composite material according to any one of claims 1 to 6 is used, comprising the following steps: Melting and extruding the high-performance polypropylene composite material to obtain an initial film; The initial film is subjected to high temperature annealing treatment to obtain a capacitor film.

9. The power capacitor film according to claim 8, characterized in that: The thickness of the power capacitor film is 5-30 μm.

10. Use of the high-performance polypropylene composite material according to any one of claims 1 to 6 or the capacitor film according to any one of claims 8 to 9 in a power capacitor, characterized in that: The applications include any of high energy storage pulse capacitors, automotive capacitors, power system capacitors, and aerospace capacitors.

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