A metallized polypropylene film, its preparation and use

Abstract

The application belongs to the technical field of metallized polypropylene film, and particularly relates to a metallized polypropylene film, a preparation method and application thereof. The metallized polypropylene film comprises, from bottom to top, a polypropylene base film, an interface bonding layer, a metal layer and an aluminum oxide layer. The interface bonding layer is obtained by immersing the polypropylene base film into an interface bonding solution and performing amidation reaction. The metallized polypropylene film has good heat resistance, high dielectric strength at room temperature and 105 DEG C, and the capacitor prepared by using the metallized polypropylene film has good high-temperature and high-humidity resistance and temperature cycle resistance.

Description

Technical Field

[0001] This invention belongs to the field of metallized polypropylene film technology, specifically relating to a metallized polypropylene film, its preparation method, and its application. Background Technology

[0002] Metallized film capacitors are capacitors made by depositing one or more layers of metal film onto the surface of an organic plastic film as the dielectric, replacing traditional metal foil as electrodes, and then winding them. Among them, metallized polypropylene film capacitors have broad application prospects in new energy vehicles, renewable energy, and industrial frequency conversion due to their advantages such as low cost, high stability, and long lifespan.

[0003] With the rapid development of power electronics technology towards high frequency and high power density, the reliability requirements of metallized polypropylene films in harsh environments are also increasing in fields such as new energy vehicles, renewable energy and industrial frequency conversion.

[0004] The insufficient dielectric properties of traditional metallized polypropylene films at high temperatures and the performance degradation under high temperature and high humidity are key bottlenecks restricting their application in scenarios with higher reliability requirements.

[0005] There are few reports in the prior art regarding metallized polypropylene films that possess both high temperature resistance and high temperature and humidity resistance. Among them, Chinese Patent No. CN 117467942 B discloses a method for preparing and applying a double-sided metallized polypropylene film. The preparation method includes the following steps: (1) immersing a polypropylene film in a polyvinyl alcohol solution, removing it, and drying it to obtain a pretreated polypropylene film; (2) vacuum-depositing a first aluminum metal layer on one side of the pretreated polypropylene film, and then vacuum-depositing a first CuBi alloy metal layer on the surface of the first aluminum metal layer to obtain a single-sided metallized polypropylene film; (3) vacuum-depositing a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, and then vacuum-depositing a second CuBi alloy metal layer on the surface of the second aluminum metal layer to obtain a double-sided metallized polypropylene film. Chinese Patent No. CN 117558555A discloses a metallized polypropylene film for high temperature and humidity resistant capacitors, its preparation method, and its application. The metallized polypropylene film comprises a polypropylene film and a metal layer. The metal layer consists of a first copper layer, a first zinc layer, a second copper layer, and a second zinc layer. The first copper layer is located on the surface of the polypropylene film, the first zinc layer covers the surface of the first copper layer, the second copper layer covers the surface of the first zinc layer, and the second zinc layer covers the surface of the second copper layer. This invention utilizes a unique metal layer structure formed by alternating copper and zinc layers deposited on the surface of the polypropylene film. Compared to a copper and zinc composite layer, this structure imparts superior oxidation resistance to the metal layer and improves the capacitor's resistance to high temperatures and humidity.

[0006] However, the dual 85 test in the above technical solution only lasts for 500 hours, which cannot verify its long-term reliability.

[0007] In addition, the operating temperature range of electric vehicles is usually from -40°C to 105°C or even higher, and they need to withstand frequent charge and discharge cycles. Metallized polypropylene film capacitors will undergo repeated temperature cycles due to their own power consumption and changes in ambient temperature, resulting in capacitance decay. Therefore, the temperature cycling performance of metallized polypropylene film capacitors is also an important indicator for evaluating their reliability in harsh environments in fields such as new energy vehicles, renewable energy and industrial frequency conversion. There are few reports on this technology. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a metallized polypropylene film, its preparation method, and its application.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] The first aspect of the present invention provides a metallized polypropylene film, which comprises, from bottom to top, a polypropylene base film, an interface bonding layer, a metal layer, and an alumina layer;

[0011] The interfacial bonding layer is obtained by impregnating a polypropylene base film into an interfacial bonding solution and performing an amidation reaction.

[0012] The raw materials of the interface bonding solution include: aminated nano silica, modified silane, EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride), NHS (N-hydroxysuccinimide), and an aqueous ethanol solution A.

[0013] The modified silane is obtained by reacting a mixture of aminosilane A, mercaptosilane, tetraethyl orthosilicate, and an aqueous ethanol solution B.

[0014] Currently, existing technologies often use physical pretreatments such as corona discharge and plasma to increase the surface polarity of polypropylene base films, thereby increasing their adhesion to metal coatings. However, under prolonged high temperature and humidity conditions or changes in ambient temperature, the polarity of the polypropylene base film will gradually weaken, leading to a decrease in the adhesion between the two and a decline in capacitor performance.

[0015] To address this technical problem, this invention creatively introduces an interfacial bonding layer. A polypropylene base film pretreated with oxygen plasma is immersed in an interfacial bonding solution for amidation. The oxygen plasma pretreatment introduces active functional groups such as carboxyl and hydroxyl groups into the polypropylene base film. Under the influence of EDC and NHS, the aminated nano-silica and modified silane in the interfacial bonding solution are bonded to the surface of the polypropylene base film through an amidation reaction. On one hand, the presence of nano-silica improves the surface roughness of the polypropylene base film, facilitating the adhesion of the metal coating, and also enhances the high-temperature resistance, high-temperature and high-humidity resistance, and temperature cycling resistance of the metallized polypropylene film. On the other hand, the modified silane of this invention is obtained by reacting a mixture of aminosilane, mercaptosilane, tetraethyl orthosilicate, and an aqueous ethanol solution B. The mercapto groups in the modified silane have a strong interaction with the metal coating, further improving the bonding strength between the polypropylene base film and the metal coating. Furthermore, the modified silane and aminated nano-silica form a dense hybrid network, effectively blocking the intrusion of water molecules under high temperature and high humidity conditions.

[0016] In addition, the present invention pre-forms a thin aluminum oxide layer on the metal layer, which, although slightly reducing the dielectric strength of the metallized polypropylene film, can further improve the capacitor's resistance to high temperature and humidity and its resistance to temperature cycling to a certain extent.

[0017] Preferably, the thickness of the polypropylene base film is 2-4 μm.

[0018] Preferably, the polypropylene base membrane is pretreated with oxygen plasma, wherein the gas flow rate of the oxygen plasma pretreatment is 100-200 sccm, the ion source power is 3-6 kW, and the time is 30-60 s.

[0019] Preferably, the raw materials of the interface bonding liquid, by mass percentage, include: 2-6% aminated nano-silica, 1-3% modified silane, 0.3-0.6% EDC, 0.3-0.5% NHS, and ethanol aqueous solution A to make up the balance to 100%.

[0020] Preferably, the amidation reaction is carried out at a temperature of 30-60°C for 2-5 hours.

[0021] Preferably, the aminated nano-silica is prepared by modifying nano-silica with aminosilane B.

[0022] Preferably, the preparation method of the amino-modified nano-silica is as follows: aminosilane B and aqueous ethanol solution C are mixed and hydrolyzed under acidic conditions, nano-silica is added and mixed, heated and stirred, filtered, washed and dried after completion.

[0023] Preferably, the particle size of the nano-silica is 50-200 nm.

[0024] Preferably, the mass ratio of aminosilane B, aqueous ethanol solution C, and nano-silica is 1-3:100:40-50.

[0025] Preferably, the pH value of the acidic conditions is 2-6.

[0026] Preferably, the hydrolysis temperature is 15-25℃ and the time is 1-5h.

[0027] Preferably, the heating and stirring temperature is 50-60℃ and the time is 3-6h.

[0028] Preferably, the modified silane is prepared by mixing tetraethyl orthosilicate, aminosilane A, mercaptosilane and aqueous ethanol solution B, adjusting the pH to 3-6, reacting at room temperature for 1-3 hours under nitrogen protection, then heating to 50-70°C and continuing the reaction for 1-2 hours, and then distilling under reduced pressure after the reaction is completed.

[0029] Preferably, the mass ratio of tetraethyl orthosilicate, aminosilane A, mercaptosilane, and aqueous ethanol solution B is 1-2:20-30:20-30:50-60.

[0030] Preferably, aminosilane A and aminosilane B are each independently selected from at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

[0031] Preferably, the mercaptosilane is selected from at least one of γ-mercaptopropyltriethoxysilane and γ-mercaptopropyltrimethoxysilane.

[0032] Preferably, the mass concentrations of the ethanol aqueous solution A, ethanol aqueous solution B, and ethanol aqueous solution C are each independently 80-90%.

[0033] Preferably, the metal layer is an aluminum layer, a zinc-aluminum alloy layer, or a magnesium-aluminum alloy layer.

[0034] Preferably, the metal layer is prepared by vacuum evaporation.

[0035] Preferably, the alumina layer is prepared by an oxidation method.

[0036] Preferably, the thickness of the metal layer is 100-200 nm.

[0037] Preferably, the thickness of the alumina layer is 6-8 nm.

[0038] A second aspect of the present invention provides a method for preparing a metallized polypropylene film, comprising the following steps:

[0039] S1. The polypropylene base film pretreated by oxygen plasma is immersed in the interfacial bonding solution for amidation reaction, and then dried to obtain a polypropylene base film containing an interfacial bonding layer.

[0040] S2. A metal layer is vacuum-deposited on one side of the polypropylene base film containing the interfacial bonding layer, and then an aluminum oxide layer is formed in a vacuum oxidation furnace to obtain a metallized polypropylene film.

[0041] Preferably, the vacuum evaporation deposition to form a metal layer includes the following steps: placing a polypropylene base film containing an interfacial bonding layer in a vacuum evaporation coating machine, evacuating the vacuum evaporation coating machine, placing aluminum, zinc-aluminum alloy, or magnesium-aluminum alloy in an evaporation boat, heating the evaporation boat, starting the polypropylene base film winding system, the polypropylene base film containing the interfacial bonding layer begins to move, and the gaseous metal evaporated by the heat is deposited on one side surface of the polypropylene base film containing the interfacial bonding layer to form a metal layer.

[0042] Preferably, the vacuum evaporation coating machine is evacuated to a vacuum level of 1×10⁻⁶. -3 Pa.

[0043] Preferably, the gas in the vacuum oxidation furnace is oxygen, the temperature is 140-160℃, the oxygen flow rate is 5-20 sccm, and the time in the vacuum oxidation furnace is 20-30 min.

[0044] A third aspect of the present invention provides the application of metallized polypropylene film in the preparation of high-temperature and high-humidity resistant capacitors.

[0045] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0046] 1. This invention creatively introduces an interfacial bonding layer, in which a polypropylene base film pretreated with oxygen plasma is immersed in an interfacial bonding solution for an amidation reaction. On the one hand, the presence of nano-silica can improve the surface roughness of the polypropylene base film, which is beneficial to the adhesion of the metal coating, and can also improve the high temperature resistance, high temperature and humidity resistance, and temperature cycling resistance of the metallized polypropylene film. On the other hand, the modified silane of this invention is obtained by reacting a mixture of aminosilane, mercaptosilane, tetraethyl orthosilicate, and aqueous ethanol solution B. The mercapto groups therein have a strong interaction with the metal coating, which further improves the bonding strength between the polypropylene base film and the metal coating. In addition, the modified silane and amino-modified nano-silica form a dense hybrid network, which effectively blocks the intrusion of water molecules under high temperature and humidity.

[0047] 2. The present invention also pre-forms a thin aluminum oxide layer on the metal layer. Although this will slightly reduce the dielectric strength of the metallized polypropylene film, it can further improve the capacitor's resistance to high temperature and humidity and its resistance to temperature cycling to a certain extent.

[0048] 3. Test results show that the metallized polypropylene film provided by this invention has good heat resistance, with a dielectric strength of >630V / μm at room temperature and >580V / μm at 105℃.

[0049] 4. Test results verify that the capacitors prepared using the metallized polypropylene film provided by this invention have good high temperature and high humidity resistance and temperature cycling resistance. After 500 hours of double 85 testing, the capacitance decay rate is <0.4%, after 1000 hours, the capacitance decay rate is <0.9%, and after 100 cycles of alternating cycling at -55℃ (30 min) and +125℃ (30 min), the capacitance decay rate is <0.7%. Attached Figure Description

[0050] Figure 1 This is a photograph of the metallized polypropylene film of Example 2;

[0051] Figure 2 The metallized polypropylene film of Example 2 is shown in the SEM image.

[0052] Figure 3 The test results show the fluorine, chlorine, bromine, and iodine content in the metallized polypropylene film of Example 2.

[0053] Figure 4 and Figure 5 The results show the test results for the content of lead, cadmium, mercury, hexavalent chromium, bromobiphenyl, polybrominated diphenyl ethers, and phthalates in the metallized polypropylene film of Example 2. Detailed Implementation

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Unless otherwise specified in the examples and comparative examples, the conditions were performed under standard conditions or as recommended by the manufacturer. All reagents and instruments used were commercially available products unless otherwise specified.

[0056] Preparation example:

[0057] The preparation method of aminated nano silica is as follows: γ-aminopropyltriethoxysilane and an aqueous ethanol solution (mass concentration of 80%) are mixed, the pH is adjusted with acetic acid, and hydrolysis is carried out at pH 4 (hydrolysis temperature is 25℃ and time is 4h). Nano silica (particle size of 100nm) is added and mixed, and heated and stirred at 55℃ for 5h. After the process is completed, the mixture is filtered, washed, and dried to obtain the final product.

[0058] The mass ratio of γ-aminopropyltriethoxysilane, aqueous ethanol solution C, and nano-silica is 3:100:50.

[0059] The preparation method of modified silane A is as follows: Tetraethyl orthosilicate, γ-aminopropyltriethoxysilane, γ-mercaptopropyltriethoxysilane and ethanol aqueous solution (mass concentration of 80%) are mixed, the pH is adjusted to 4 with acetic acid, and the reaction is carried out at room temperature for 2 hours under nitrogen protection. Then the temperature is raised to 60℃ and the reaction is continued for 1.5 hours. After the reaction is completed, the modified silane A is obtained by vacuum distillation.

[0060] The mass ratio of tetraethyl orthosilicate, γ-aminopropyltriethoxysilane, γ-mercaptopropyltriethoxysilane and aqueous ethanol solution is 2:20:25:53.

[0061] The modified silane B is prepared by mixing tetraethyl orthosilicate, γ-mercaptopropyltriethoxysilane and an aqueous ethanol solution (mass concentration of 80%), adjusting the pH to 4 with acetic acid, reacting at room temperature for 2 hours under nitrogen protection, then heating to 60℃ and continuing the reaction for 1.5 hours, and then distilling under reduced pressure after the reaction is completed.

[0062] The mass ratio of tetraethyl orthosilicate, γ-mercaptopropyltriethoxysilane, and aqueous ethanol solution is 2:45:53.

[0063] The modified silane C is prepared by mixing tetraethyl orthosilicate, γ-aminopropyltriethoxysilane and an aqueous ethanol solution (mass concentration of 80%), adjusting the pH to 4 with acetic acid, reacting at room temperature for 2 hours under nitrogen protection, then heating to 60℃ and continuing the reaction for 1.5 hours, and finally distilling under reduced pressure after the reaction is completed.

[0064] The mass ratio of tetraethyl orthosilicate, γ-aminopropyltriethoxysilane, and aqueous ethanol solution is 2:45:53.

[0065] Example 1 This example provides a metallized polypropylene film, which includes, from bottom to top, a polypropylene base film, an interface bonding layer, an aluminum layer, and an alumina layer.

[0066] A method for preparing metallized polypropylene films includes the following steps:

[0067] S1. The polypropylene base film is pretreated with oxygen plasma (the gas flow rate of oxygen plasma pretreatment is 150 sccm, the ion source power is 5 kW, and the time is 60 s); the oxygen plasma pretreated polypropylene base film is immersed in the interfacial bonding solution and subjected to amidation reaction at 40℃ for 3 h, and then taken out and dried to obtain a polypropylene base film containing an interfacial bonding layer.

[0068] The raw materials of the interface bonding liquid, by mass percentage, include: 4% aminated nano-silica, 2% modified silane A, 0.5% EDC, 0.4% NHS, and an aqueous ethanol solution (mass concentration of 80%) to make up the balance to 100%.

[0069] S2. Place the polypropylene base film containing the interfacial bonding layer in a vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to a vacuum level of 1×10⁻⁶. -3 Pa, place metallic aluminum in an evaporation boat, heat the evaporation boat, start the polypropylene base film winding system, the polypropylene base film containing the interfacial bonding layer begins to move, the gaseous aluminum metal evaporated by the heated aluminum is deposited on one side of the polypropylene base film containing the interfacial bonding layer to form a metallic aluminum layer, and then in a vacuum oxidation furnace (gas is oxygen, temperature is 150℃, oxygen flow rate is 10 sccm, time is 25min) an aluminum oxide layer is formed, thus obtaining the metallized polypropylene film.

[0070] The thickness of the polypropylene base film is 3 μm.

[0071] The thickness of the aluminum layer is 10 nm.

[0072] The thickness of the alumina layer is 6 nm.

[0073] Example 2 This example provides a metallized polypropylene film, which includes, from bottom to top, a polypropylene base film, an interface bonding layer, an aluminum layer, and an alumina layer.

[0074] A method for preparing metallized polypropylene films includes the following steps:

[0075] S1. The polypropylene base film is pretreated with oxygen plasma (the gas flow rate of oxygen plasma pretreatment is 150 sccm, the ion source power is 5 kW, and the time is 60 s); the oxygen plasma pretreated polypropylene base film is immersed in the interfacial bonding solution and subjected to amidation reaction at 40℃ for 3 h, and then taken out and dried to obtain a polypropylene base film containing an interfacial bonding layer.

[0076] The raw materials of the interface bonding liquid, by mass percentage, include: 5% aminated nano silica, 3% modified silane A, 0.6% EDC, 0.5% NHS, and an aqueous ethanol solution (mass concentration of 80%) to make up the balance to 100%.

[0077] S2. Place the polypropylene base film containing the interfacial bonding layer in a vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to a vacuum level of 1×10⁻⁶. -3Pa, place metallic aluminum in an evaporation boat, heat the evaporation boat, start the polypropylene base film winding system, the polypropylene base film containing the interfacial bonding layer begins to move, the gaseous aluminum metal evaporated by the heated aluminum is deposited on one side of the polypropylene base film containing the interfacial bonding layer to form a metallic aluminum layer, and then in a vacuum oxidation furnace (gas is oxygen, temperature is 150℃, oxygen flow rate is 10 sccm, time is 25min) an aluminum oxide layer is formed, thus obtaining the metallized polypropylene film.

[0078] The thickness of the polypropylene base film is 3 μm.

[0079] The thickness of the aluminum layer is 100 nm.

[0080] The thickness of the alumina layer is 6 nm.

[0081] A physical image of the metallized polypropylene film prepared in this embodiment is shown below. Figure 1 As shown, the SEM image is as follows: Figure 2 As shown.

[0082] Comparative Example 1 This comparative example provides a metallized polypropylene film, which includes, from bottom to top, a polypropylene base film, an aluminum layer, and an aluminum oxide layer.

[0083] A method for preparing metallized polypropylene films includes the following steps:

[0084] S1. Polypropylene base membrane is pretreated with oxygen plasma (gas flow rate of oxygen plasma pretreatment is 150 sccm, ion source power is 5 kW, time is 60 s) to obtain oxygen plasma pretreated polypropylene base membrane.

[0085] S2. Place the oxygen plasma pretreated polypropylene substrate film in a vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to a vacuum level of 1×10⁻⁶. -3 Pa, place metallic aluminum in an evaporation boat, heat the evaporation boat, start the polypropylene base film winding system, and the oxygen plasma pretreated polypropylene base film begins to move. The gaseous aluminum metal evaporated by the heated aluminum is deposited on one side of the oxygen plasma pretreated polypropylene base film to form a metallic aluminum layer. Then, in a vacuum oxidation furnace (gas is oxygen, temperature is 150℃, oxygen flow rate is 10 sccm, time is 25 min), an aluminum oxide layer is formed, thus obtaining a metallized polypropylene film.

[0086] The thickness of the polypropylene base film is 3 μm.

[0087] The thickness of the aluminum layer is 10 nm.

[0088] The thickness of the alumina layer is 60 nm.

[0089] Comparative Example 2 provides a metallized polypropylene film, which differs from Example 2 only in that it does not have an aluminum oxide layer; otherwise, they are the same.

[0090] Comparative Example 3 provides a metallized polypropylene film, which differs from Example 2 only in that the modified silane A in the interfacial bonding liquid is replaced with modified silane B; all other aspects are the same.

[0091] Comparative Example 4 provides a metallized polypropylene film, which differs from Example 2 only in that the modified silane A in the interfacial bonding liquid is replaced with modified silane C; all other aspects are the same.

[0092] Comparative Example 5 provides a metallized polypropylene film, which differs from Example 2 only in that the modified silane A in the interfacial bonding solution is replaced with γ-aminopropyltriethoxysilane; all other aspects are the same.

[0093] Comparative Example 6 provides a metallized polypropylene film, which differs from Example 2 only in that the raw materials of the interfacial bonding liquid, by mass percentage, include: modified silane A 3%, EDC 0.6%, NHS 0.5%, and an aqueous ethanol solution (mass concentration of 80%) to make up the balance to 100%; all other components are the same.

[0094] Comparative Example 7 provides a metallized polypropylene film, which differs from Example 2 only in that the raw materials of the interfacial bonding liquid, by mass percentage, include: 5% aminated nano-silica, 0.6% EDC, 0.5% NHS, and an aqueous ethanol solution (mass concentration of 80%) to make up the balance to 100%; all other components are the same.

[0095] Performance Test 1: Dielectric strength test was performed on the metallized polypropylene films prepared in the above examples and comparative examples: The breakdown voltage of the metallized polypropylene films at room temperature (25℃) and 105℃ was tested sequentially using a withstand voltage tester at a voltage of 12kV, a voltage rise rate of 200V / s, and a voltage rise time of 60s. The dielectric strength (V / μm) = breakdown voltage / thickness was calculated, and the results are shown in Table 1.

[0096] Table 1

[0097]

[0098] As can be seen from Table 1, the metallized polypropylene film provided in Examples 1-2 of the present invention has good heat resistance, with a dielectric strength of >630V / μm at room temperature and >580V / μm at 105℃.

[0099] Compared with Example 2, Comparative Example 1 does not have an interfacial bonding layer, and the composition of the interfacial bonding liquid in the interfacial bonding layers of Comparative Examples 3-6 has changed, resulting in a decrease in the dielectric strength of the metallized polypropylene film at room temperature and 105°C. This indicates that the interfacial bonding layer provided by the present invention can effectively improve the interfacial bonding force between the metal layer and the polypropylene base film, reduce physical defects at the metal / base film interface, and suppress carrier migration and partial discharge.

[0100] Performance Test 2: The fluorine, chlorine, bromine, and iodine content in the metallized polypropylene film of Example 2 were tested, and the results are as follows: Figure 3 As shown.

[0101] Performance Test 3: The metallized polypropylene film of Example 2 was tested for lead, cadmium, mercury, hexavalent chromium, brominated biphenyls, polybrominated diphenyl ethers, and phthalates. The results are as follows: Figure 4 and Figure 5 As shown.

[0102] Application Example: The metallized polypropylene films prepared in the above embodiments and comparative examples are wound into capacitor core packages, hot-pressed, and flattened. A metal contact layer (tin-zinc alloy) is sprayed onto the electrode portions at both ends of the capacitor core package. The leads are soldered onto the metal contact layer. The capacitor core package is inserted into a plastic shell, and potting compound is poured into the plastic shell for encapsulation to prepare a capacitor. The following performance tests are performed on the obtained capacitor:

[0103] 1. High temperature and high humidity resistance: Referencing IEC 60068-2-78, test temperature: 85℃, relative humidity: 85%RH, test voltage: 305V, current: 3A, test frequency: 1KHz, durations: 500h and 1000h respectively, testing the capacity change rate (C). 1- C0 / C0), where C0 represents the initial capacity before the test and C0 represents the capacity after the test. The results are shown in Table 2.

[0104] 2. Temperature Cycling Resistance: Referencing IEC 60068-2-14, the test conditions are: alternating cycles of -55℃ (30 min) and +125℃ (30 min) for 100 cycles, with each transition time ≤ 5 min. The capacity change rate (C) is then measured. 1- C0 / C0), where C0 represents the initial capacity before the test and C0 represents the capacity after the test. The results are shown in Table 2.

[0105] Table 2

[0106]

[0107] As shown in Table 2, the capacitors prepared using the metallized polypropylene films provided in Examples 1-2 of this invention have good high temperature and high humidity resistance and temperature cycling resistance. After 500 hours of the "double 85" test, the capacitance decay rate is <0.4%, after 1000 hours, the capacitance decay rate is <0.9%, and after 100 cycles of alternating cycling at -55℃ (30 min) and +125℃ (30 min), the capacitance decay rate is <0.7%.

[0108] Compared with Example 2, Comparative Example 1 does not have an interfacial bonding layer, and the interfacial bonding liquid composition in the interfacial bonding layers of Comparative Examples 2-6 has changed, resulting in a decrease in the high temperature and humidity resistance and temperature cycling resistance of the prepared capacitors. This indicates that the interfacial bonding layer provided by the present invention can not only effectively improve the interfacial bonding force between the metal layer and the polypropylene base film, making the metal coating structure more compact, but also effectively improve the high temperature and humidity resistance and temperature cycling resistance of the capacitor.

[0109] The absence of an alumina layer in Comparative Example 2 resulted in a decrease in the high temperature and humidity resistance and temperature cycling resistance of the prepared capacitor, indicating that pre-forming an alumina layer can improve the high temperature and humidity resistance and temperature cycling resistance of the capacitor to a certain extent.

[0110] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A metallized polypropylene film, characterized in that, From bottom to top, it includes a polypropylene base film, an interface bonding layer, a metal layer, and an alumina layer; The interfacial bonding layer is obtained by impregnating a polypropylene base film into an interfacial bonding solution and performing an amidation reaction. The raw materials of the interface bonding liquid include: aminated nano-silica, modified silane, EDC, NHS and ethanol aqueous solution A; The modified silane is obtained by reacting a mixture of aminosilane A, mercaptosilane, tetraethyl orthosilicate, and an aqueous ethanol solution B.

2. The metallized polypropylene film according to claim 1, characterized in that, The polypropylene base membrane is pretreated with oxygen plasma. The gas flow rate of the oxygen plasma pretreatment is 100-200 sccm, the ion source power is 3-6 kW, and the time is 30-60 s.

3. The metallized polypropylene film according to claim 2, characterized in that, The raw materials of the interface bonding liquid, by mass percentage, include: 2-6% aminated nano-silica, 1-3% modified silane, 0.3-0.6% EDC, 0.3-0.5% NHS, and ethanol aqueous solution A to make up the balance to 100%.

4. The metallized polypropylene film according to any one of claims 1-3, characterized in that, The aminated nano-silica was prepared by modifying nano-silica with aminosilane B.

5. The metallized polypropylene film according to claim 4, characterized in that, The preparation method of the amino-modified nano-silica is as follows: aminosilane B and aqueous ethanol solution C are mixed and hydrolyzed under acidic conditions. Nano-silica is then added and mixed, heated and stirred. After the mixture is finished, it is filtered, washed, and dried to obtain the final product.

6. The metallized polypropylene film according to claim 5, characterized in that, The modified silane is prepared by mixing tetraethyl orthosilicate, aminosilane A, mercaptosilane and aqueous ethanol solution B, adjusting the pH to 3-6, reacting at room temperature for 1-3 hours under nitrogen protection, then heating to 50-70℃ and continuing the reaction for 1-2 hours, and then distilling under reduced pressure after the reaction is completed.

7. The metallized polypropylene film according to claim 6, characterized in that, The aminosilane A and aminosilane B are each independently selected from at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane; the mercaptosilane is selected from at least one of γ-mercaptopropyltriethoxysilane and γ-mercaptopropyltrimethoxysilane.

8. The metallized polypropylene film according to claim 1, characterized in that, The thickness of the metal layer is 100-200 nm; the thickness of the aluminum oxide layer is 6-8 nm.

9. The method for preparing the metallized polypropylene film according to any one of claims 1-8, characterized in that, Includes the following steps: S1. The polypropylene base film pretreated by oxygen plasma is immersed in the interfacial bonding solution for amidation reaction, and then dried to obtain a polypropylene base film containing an interfacial bonding layer. S2. A metal layer is vacuum-deposited on one side of the polypropylene base film containing the interfacial bonding layer, and then an aluminum oxide layer is formed in a vacuum oxidation furnace to obtain a metallized polypropylene film.

10. The application of the metallized polypropylene film according to any one of claims 1-8 in the preparation of high-temperature and high-humidity resistant capacitors.

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