Preparation method and application of double-sided metallized polypropylene film

Abstract

The present invention belongs to the technical field of capacitor films, and relates to a preparation method and application of a double-sided metallized polypropylene film. The preparation method comprises the following steps: (1) soaking a polypropylene film in a polyvinyl alcohol solution, taking out and drying to obtain a pretreated polypropylene film; (2) vacuum evaporating a first aluminum metal layer on one side of the pretreated polypropylene film, and then vacuum evaporating 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 evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, and then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer to obtain a double-sided metallized polypropylene film. The double-sided metallized polypropylene film of the present invention has excellent high temperature and high humidity resistance after being made into a capacitor.

Description

Technical Field

[0001] The invention belongs to the technical field of capacitor films and relates to a preparation method and application of a double-sided metallized polypropylene film. Background Art

[0002] Metallized film capacitors are capacitors made by winding and other methods, with organic plastic film as the dielectric. One or more layers of metal film are evaporated on the surface of the plastic film to replace the traditional metal foil as the electrode. The thickness of the metallized film layer is much smaller than the thickness of the metal foil, so the volume after winding is much smaller than that of the metal foil capacitor. Although common organic plastic film materials include polyester, polypropylene, polycarbonate, polyethylene terephthalate, etc., metallized film capacitors made of polypropylene are low in cost and have excellent electrical properties, high stability and long life. Metallized polypropylene film capacitors are gradually replacing aluminum electrolytic capacitors in more and more applications, and are developing rapidly in new energy markets represented by wind power generation, solar power generation, and electric vehicles.

[0003] At present, the metallized film capacitor industry generally uses Al, Zn, Cu or their alloys as the main metal layer. However, since the working surface of the polypropylene film is only subjected to corona discharge treatment, the adhesion between the polypropylene film and the metal coating is weak. During the capacitor winding process and the use of the capacitor, the metal coating is easily separated from the polypropylene film, causing the metal coating to be easily punctured, affecting the service life of the capacitor. In addition, the bonding strength between the polypropylene film and the metal coating will also decrease with the use of the capacitor.

[0004] In addition, metallized films with aluminum as the metal coating have the disadvantage of poor moisture resistance. For example, when working in a high temperature (85°C) and high humidity (85% RH) environment (the so-called double 85 resistance), when the air between the film layers is invaded by external moisture, the breakdown potential of the air will decrease, accelerating the ionization of the air and generating a large amount of ozone. The metal coating of the metallized film is composed of Al. When encountering oxygen after ozone decomposition, the metal Al will be immediately oxidized to generate non-conductive metal oxide, thereby reducing the area of ​​the aluminum metal coating of the metallized film, resulting in a rapid decrease in the capacity of the capacitor.

[0005] Therefore, improving the bonding strength between the polypropylene film and the evaporated metal coating and improving the stability of the metallized film are of great significance to maintaining the stability of the performance of the capacitor under high temperature and high humidity working conditions, and can effectively increase the service life of the capacitor. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method and application of a double-sided metallized polypropylene film in view of the deficiencies of the prior art.

[0007] The first object of the present invention is achieved by the following technical solutions:

[0008] A method for preparing a double-sided metallized polypropylene film comprises the following steps:

[0009] (1) soaking a polypropylene film in a polyvinyl alcohol solution, taking it out and drying it to obtain a pretreated polypropylene film;

[0010] (2) vacuum evaporating a first aluminum metal layer on one side of the pretreated polypropylene film to obtain a single-sided aluminum metallized polypropylene film;

[0011] (3) Vacuum evaporating a second aluminum metal layer on the other side of the single-sided aluminum metallized polypropylene film to obtain a double-sided aluminum metallized polypropylene film. The other side of the single-sided aluminum metallized polypropylene film refers to the side of the single-sided aluminum metallized polypropylene film on which the aluminum metal layer is not evaporated.

[0012] Preferably, in the above step (1), the polyvinyl alcohol solution is formed by dissolving polyvinyl alcohol in water, and the concentration of the polyvinyl alcohol solution is 0.1-5% (w / v). More preferably, the concentration of the polyvinyl alcohol solution is 0.3-3% (w / v).

[0013] The polypropylene film is immersed in a polyvinyl alcohol solution, wherein the amount of the polyvinyl alcohol solution is such that the entire polypropylene film is located in the polyvinyl alcohol solution.

[0014] The polypropylene film is immersed in the polyvinyl alcohol solution, and the immersion time is preferably 20 to 100 minutes.

[0015] The first aluminum metal layer and the second aluminum metal layer are formed by vacuum evaporation coating technology. Vacuum evaporation coating is to heat the coating material in a vacuum environment to make it evaporate in a very short time. The evaporated coating material molecules are deposited on the plastic surface to form a coating layer.

[0016] Preferably, the vacuum evaporation comprises the following steps: evacuating the vacuum evaporation coating machine, placing an aluminum block in a crucible, heating the crucible, causing the aluminum block to evaporate due to the heat, starting the polypropylene film winding system, causing the polypropylene film to start moving, and gaseous aluminum evaporated from the aluminum block due to the heat is deposited on one side of the polypropylene film to form an aluminum metal layer.

[0017] Preferably, the vacuum evaporation coating machine is evacuated to 0.01×10 -3 ~5×10 -3 Pa, evaporation under high vacuum helps to improve the quality of the coating.

[0018] Preferably, the purity of the aluminum block is ≥99.9%.

[0019] Preferably, the heating temperature of the crucible is 1400-1600° C. At the above temperature, aluminum is evaporated into gas by heat.

[0020] Preferably, the adhesion amount of the first aluminum metal layer on the polypropylene film is 50 to 200 mg / m 2 The adhesion of the second aluminum metal layer on the polypropylene film is 50-200 mg / m 2 .

[0021] More preferably, the adhesion amounts of the first aluminum metal layer and the second aluminum metal layer on the polypropylene film are the same.

[0022] Preferably, the double-sided aluminum metallized polypropylene film obtained in step (3) is placed in an environment with a dust-free grade of 10,000 or below, a temperature of 20 to 40° C., and a humidity of 10 to 40% for 20 to 50 hours.

[0023] The second object of the present invention is achieved by the following technical solutions:

[0024] A method for preparing a double-sided metallized polypropylene film comprises the following steps:

[0025] (1) soaking a polypropylene film in a polyvinyl alcohol solution, taking it out and drying it to obtain a pretreated polypropylene film;

[0026] (2) vacuum evaporating a first aluminum metal layer on one side of the pretreated polypropylene film, and then vacuum evaporating a first CuBi alloy metal layer on the surface of the first aluminum metal layer to obtain a single-sided metallized polypropylene film;

[0027] (3) vacuum evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, and then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer to obtain a double-sided metallized polypropylene film.

[0028] Preferably, in the above step (1), the polyvinyl alcohol solution is formed by dissolving polyvinyl alcohol in water, and the concentration of the polyvinyl alcohol solution is 0.1-5% (w / v). More preferably, the concentration of the polyvinyl alcohol solution is 0.3-3% (w / v).

[0029] The polypropylene film is immersed in a polyvinyl alcohol solution, wherein the amount of the polyvinyl alcohol solution is such that the entire polypropylene film is located in the polyvinyl alcohol solution.

[0030] The polypropylene film is immersed in the polyvinyl alcohol solution, and the immersion time is preferably 20 to 100 minutes.

[0031] Preferably, the vacuum evaporation to form an aluminum metal layer includes the following steps: evacuating the vacuum evaporation coating machine, placing an aluminum block in a crucible, heating the crucible, causing the aluminum block to evaporate due to the heat, starting the polypropylene film winding system, causing the polypropylene film to start moving, and gaseous aluminum evaporated from the aluminum block is deposited on one side of the polypropylene film to form an aluminum metal layer.

[0032] Preferably, the purity of the aluminum block is ≥99.9%.

[0033] Preferably, the heating temperature of the aluminum block is 1400-1600° C. At the above temperature, the aluminum is evaporated into a gaseous state by heat.

[0034] Preferably, the adhesion amount of the first aluminum metal layer on the polypropylene film is 50 to 200 mg / m 2 The adhesion of the second aluminum metal layer on the polypropylene film is 50-200 mg / m 2 .

[0035] Preferably, forming a CuBi alloy metal layer by vacuum evaporation includes the following steps: evacuating a vacuum evaporation coating machine, placing a CuBi alloy in a crucible, heating the crucible, causing the CuBi alloy to evaporate due to the heat, starting a polypropylene film winding system, causing the polypropylene film to start moving, and causing gaseous Cu and Bi evaporated from the CuBi alloy to deposit on the surface of the aluminum metal layer of the polypropylene film to form a CuBi alloy metal layer.

[0036] Preferably, the content of Bi in the CuBi alloy is 10-30 wt%.

[0037] Preferably, the heating temperature of the CuBi alloy is 1300-1600°C.

[0038] Preferably, in the first CuBi alloy metal layer, the Cu deposition amount is 0.5-5 mg / m 2 ; In the second CuBi alloy metal layer, the Cu adhesion amount is 0.5 to 5 mg / m 2 .

[0039] More preferably, the adhesion amount of Cu in the first CuBi alloy metal layer and the second CuBi alloy metal layer is the same.

[0040] Preferably, the vacuum evaporation coating machine is evacuated to a vacuum of 0.01×10 -3 ~5×10 -3 Pa, evaporation under high vacuum helps to improve the quality of the coating.

[0041] Preferably, the double-sided metallized polypropylene film obtained in step (3) is placed in an environment with a dust-free grade of 10,000 or below, a temperature of 20 to 40° C., and a humidity of 10 to 40% for 20 to 50 hours.

[0042] Preferably, the thickness of the polypropylene film used in the present invention is ≤4 μm.

[0043] The following is a detailed description of the method for preparing the polypropylene film, which is only used as an example and is not intended to limit the method for preparing the polypropylene film of the present invention.

[0044] The preparation method of polypropylene film comprises the following steps:

[0045] 1) Putting a polypropylene raw material into an extruder to melt extrude to obtain a melt, the die head temperature of the extruder is 230-250° C., the isotactic index of the polypropylene raw material is ≥98.0%, the melt index MFR is 3.2-4.0 g / 10 min (230° C., 2.16 kg), and the ash content is ≤20 ppm;

[0046] 2) chilling roller and air shower cooling and shaping: the melt prepared in step 1) is cooled and shaped by chilling roller and air shower cooling to obtain a casting sheet, the temperature of the chilling roller is 95-110° C., and the thickness of the obtained casting sheet is 200.0-400.0 μm;

[0047] 3) Longitudinal stretching step: the cast sheet obtained in step 2) is sequentially subjected to longitudinal preheating, longitudinal stretching and longitudinal shaping, the longitudinal preheating temperature is 100-135° C., the longitudinal stretching temperature is 140-145° C. and the longitudinal shaping temperature is 142-148° C., and the longitudinal stretching ratio is 5-8 times;

[0048] 4) Transverse stretching step: the film obtained in step 3) is sequentially subjected to transverse preheating, transverse stretching and transverse shaping, wherein the transverse preheating temperature is 160-175° C., the transverse stretching temperature is 155-160° C., and the transverse shaping temperature is 165-175° C., and the transverse stretching ratio is 7-10 times;

[0049] 5) Thickness measurement, trimming and corona treatment: To measure the thickness of the film, two electrodes are used to perform corona treatment on both sides of the film at the same time. During corona treatment, the output power of the electrodes is 6-20kW, the output voltage is 6-12kV, the pulse frequency is 15-50KHz, and the bombardment intensity of the electrodes is 7-10W·min / m 2 ;

[0050] 6) Winding: Winding tension is 10-30%, and winding pressure is 20-50%;

[0051] 7) First aging treatment: The rolled film is treated at a dust-free level of 10,000 or below at 20-40°C for 30-100 hours;

[0052] 8) Slitting: Slitting the film after the first aging treatment into small rolls of film of a certain width according to the needs;

[0053] 9) Second aging treatment: The slit small roll film is treated at a dust-free level of 10,000 or below, at 20-40° C. for 15-40 hours to obtain a finished polypropylene film.

[0054] The third object of the present invention is achieved by the following technical solutions:

[0055] Application of a double-sided metallized polypropylene film prepared by the above preparation method in capacitors.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The present invention pre-treats the polypropylene film by immersing the polypropylene film in a polyvinyl alcohol solution; the pre-treatment is beneficial to improving the bonding strength between the aluminum metal layer and the polypropylene film, and the bottom layer of the polypropylene film is firmly bonded to the metal coating, and the bottom layer of the plastic film and the metal coating will not peel off during normal use of the film;

[0058] (2) The present invention further evaporates a CuBi alloy metal layer on the surface of the aluminum metal coating. The evaporation of the CuBi alloy on the surface of the aluminum metal layer is beneficial to protecting the aluminum, preventing the aluminum from contacting oxygen and water vapor, and improving the capacitance stability of the capacitor under high temperature and high humidity;

[0059] (3) The effect of evaporating Cu or Bi alone on the stability of the capacitor under high temperature conditions is very limited. However, the present invention uses CuBi alloy as the evaporation material to form a CuBi alloy layer on the aluminum metal layer. The presence of this alloy layer has a very significant effect on improving the high temperature capacity stability of the capacitor. DETAILED DESCRIPTION

[0060] The technical scheme of the present invention is further described below by specific embodiments. It should be understood that the specific embodiments described herein are only used to help understand the present invention and are not intended to be used for specific limitations of the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0061] The raw materials in the following examples and comparative examples include:

[0062] Polyvinyl alcohol: Kuraray PVA105;

[0063] The aluminum block was purchased from Beijing Xingrongyuan Technology Co., Ltd., and the purity of the aluminum block was 99.99%;

[0064] CuBi alloy was purchased from Beijing Goldway Metal;

[0065] Polypropylene film, which is prepared by the following method:

[0066] 1) Putting polypropylene raw material into an extruder to melt and extrude to obtain a melt, the die head temperature of the extruder is 240° C. Polypropylene raw material: BOREALIS, model HC300BF;

[0067] 2) chilling roller and air shower cooling and shaping: the melt prepared in step 1) is cooled and shaped by chilling roller and air shower to obtain a casting sheet, and the temperature of the chilling roller is 100° C.;

[0068] 3) Longitudinal stretching step: the cast sheet obtained in step 2) is sequentially subjected to longitudinal preheating, longitudinal stretching and longitudinal shaping, wherein the longitudinal preheating has 8 rollers, the temperature of the 1st to 2nd rollers is set to 106°C, the temperature of the 3rd to 4th rollers is set to 122°C, the temperature of the 5th to 6th rollers is set to 128°C, and the temperature of the 7th to 8th rollers is set to 133°C; the longitudinal stretching has 6 rollers, the temperature of the 1st to 2nd rollers is set to 141°C, the temperature of the 3rd to 4th rollers is set to 144°C, and the temperature of the 5th to 6th rollers is set to 142°C; the longitudinal shaping has 4 rollers, the temperature of the 1st to 2nd rollers is set to 145°C, and the temperature of the 3rd to 4th rollers is set to 147°C; the longitudinal stretching ratio is 6 times;

[0069] 4) Transverse stretching step: the film obtained in step 3) is sequentially subjected to transverse preheating, transverse stretching and transverse shaping, wherein the transverse preheating has 8 sections, the temperature of sections 1 to 3 is set to 165°C, the temperature of sections 4 to 6 is set to 170°C; the temperature of sections 7 to 8 is set to 172°C; the transverse stretching has 6 sections, the temperature of sections 1 to 2 is set to 156°C, the temperature of sections 3 to 4 is set to 158°C, and the temperature of sections 5 to 6 is set to 160°C; the transverse shaping has 5 sections, the temperature of sections 1 to 3 is set to 170°C, and the temperature of sections 4 to 5 is set to 174°C; the transverse stretching ratio is 9 times;

[0070] 5) Thickness measurement, trimming and corona treatment: The thickness of the film was measured to be 3.5 μm. Two electrodes were used to perform corona treatment on both sides of the film at the same time. During corona treatment, the output power of the electrodes was 10 kW, the output voltage was 8 kV, the pulse frequency was 20 KHz, and the bombardment intensity of the electrodes was 9 W·min / m 2 ;

[0071] 6) Winding: Winding tension is 20%, winding pressure is 40%;

[0072] 7) First aging treatment: The rolled film is aged in an environment with a dust-free grade of 10,000 and a temperature of 35°C for 72 hours;

[0073] 8) Slitting: Slitting the film after the first aging treatment into small rolls of film of a certain width according to the needs;

[0074] 9) Second aging treatment: The slit small roll film is aged for 22 hours in an environment with a dust-free level of 10,000 and a temperature of 32° C. to obtain a finished polypropylene film.

[0075] Example 1

[0076] The double-sided metallized polypropylene film of this embodiment is prepared by the following steps:

[0077] (1) soaking a polypropylene film in a 1% (w / v) polyvinyl alcohol aqueous solution for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0078] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 1×10 -3 Pa; placing an aluminum block in a crucible, heating the crucible to a temperature of 1450°C, the aluminum block evaporates due to the heat, starting the polypropylene film winding system, the polypropylene film begins to move, and the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form a first aluminum metal layer, thereby obtaining a single-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 80 mg / m 2 ;

[0079] (3) Place the single-sided aluminum metallized polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 1×10 -3 Pa; placing an aluminum block in a crucible, heating the crucible to a temperature of 1450°C, the aluminum block is heated to evaporate, the polypropylene film winding system is started, the polypropylene film begins to move, and the gaseous aluminum evaporated by the aluminum block is deposited on the other side of the single-sided aluminum metallized polypropylene film (the other side of the single-sided aluminum metallized polypropylene film refers to the side of the single-sided aluminum metallized polypropylene film on which the aluminum metal layer is not evaporated) to form a second aluminum metal layer, thereby obtaining a double-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and obtaining an aluminum adhesion amount in the second aluminum metal layer of 80 mg / m 2 ;

[0080] (4) placing the double-sided aluminum metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain the finished product.

[0081] Example 2

[0082] The double-sided metallized polypropylene film of this embodiment is prepared by the following steps:

[0083] (1) soaking a polypropylene film in a 2% (w / v) polyvinyl alcohol aqueous solution for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0084] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 0.8×10 -3Pa; placing an aluminum block in a crucible, heating the crucible to a temperature of 1500°C, the aluminum block evaporates due to the heat, starting the polypropylene film winding system, the polypropylene film begins to move, and the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form a first aluminum metal layer, thereby obtaining a single-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 70 mg / m 2 ;

[0085] (3) Place the single-sided aluminum metallized polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 0.8×10 -3 Pa; placing an aluminum block in a crucible, heating the crucible to a temperature of 1500°C, the aluminum block is heated to evaporate, the polypropylene film winding system is started, the polypropylene film begins to move, and the gaseous aluminum evaporated by the aluminum block is deposited on the other side of the single-sided aluminum metallized polypropylene film to form a second aluminum metal layer, thereby obtaining a double-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and the aluminum adhesion in the second aluminum metal layer is 70 mg / m 2 ;

[0086] (4) placing the double-sided aluminum metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 30° C., and a humidity of 35% for 48 hours; and packaging to obtain the finished product.

[0087] Comparative Example 1

[0088] The difference between Comparative Example 1 and Example 1 is that the polypropylene film of Comparative Example 1 is not pretreated, and the other steps are the same as those of Example 1. The specific steps of the double-sided metallized polypropylene film of Comparative Example 1 are:

[0089] (1) placing a polypropylene film in a vacuum evaporation coating machine, and performing the vacuum evaporation steps in the same manner as in Example 1 to obtain a single-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and obtaining an aluminum adhesion of 65 mg / m 2 ;

[0090] (2) Placing a single-sided aluminum metallized polypropylene film in a vacuum evaporation coating machine, and performing the vacuum evaporation coating steps in the same manner as in Example 1 to obtain a double-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and obtaining an aluminum adhesion amount in the second aluminum metal layer of 65 mg / m 2 ;

[0091] (3) placing the double-sided aluminum metallized polypropylene film obtained in step (2) in an environment with a dust-free grade of 10,000, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain the finished product.

[0092] Comparative Example 2

[0093] The difference between Comparative Example 2 and Example 1 is that the polypropylene film of Comparative Example 2 is immersed in water, and the other steps are the same as those of Example 1. The specific steps of the double-sided metallized polypropylene film of Comparative Example 2 are:

[0094] (1) soaking a polypropylene film in water for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0095] (2) The pretreated polypropylene film was placed in a vacuum evaporation coating machine, and the vacuum evaporation steps were the same as in Example 1 to obtain a single-sided aluminum metallized polypropylene film; a polypropylene film sample was taken to test the coating adhesion, and the aluminum adhesion was 68 mg / m 2 ;

[0096] (3) Placing the single-sided aluminum metallized polypropylene film in a vacuum evaporation coating machine, and performing the vacuum evaporation coating steps in the same manner as in Example 1 to obtain a double-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and obtaining an aluminum adhesion amount in the second aluminum metal layer of 68 mg / m 2 ;

[0097] (4) placing the double-sided aluminum metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain the finished product.

[0098] Comparative Example 3

[0099] The difference between Comparative Example 3 and Example 1 is that the polypropylene film of Comparative Example 3 is immersed in a 10% (w / v) polyvinyl alcohol solution, and the other steps are the same as those of Example 1. The specific steps of the double-sided metallized polypropylene film of Comparative Example 3 are:

[0100] (1) soaking a polypropylene film in a 10% (w / v) polyvinyl alcohol aqueous solution for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0101] (2) The pretreated polypropylene film was placed in a vacuum evaporation coating machine, and the vacuum evaporation steps were the same as in Example 1 to obtain a single-sided aluminum metallized polypropylene film; a polypropylene film sample was taken to test the coating adhesion, and the aluminum adhesion was 74 mg / m 2 ;

[0102] (3) Placing the single-sided aluminum metallized polypropylene film in a vacuum evaporation coating machine, and performing the vacuum evaporation process in the same manner as in Example 1 to obtain a double-sided aluminum metallized polypropylene film; taking a polypropylene film sample to test the coating adhesion, and obtaining an aluminum adhesion amount in the second aluminum metal layer of 74 mg / m 2 ;

[0103] (4) placing the double-sided aluminum metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain the finished product.

[0104] The bonding performance between the aluminum metal layer and the polypropylene film in the double-sided aluminum metallized polypropylene film of Examples 1-2 and Comparative Examples 1-3 was measured by a hundred-grid test: 100 2 mm 2 The square grid, the scratch extends to the polypropylene surface, and 3M 250 tape is pasted. The tape is quickly torn off after being tightly attached, and the operation is performed twice on the same position. According to the percentage of the peeling area of ​​the coating to the total area, the classification includes: 0 (no peeling of the grid), 1 (peeling part ≤ 5%), 2 (peeling part exceeds 5%, not higher than 15%), 3 (peeling part exceeds 15%, not higher than 35%), 4 (peeling part exceeds 35%, not higher than 65%), 5 (peeling part exceeds 65%). The results are shown in Table 1.

[0105] Table 1 Binding strength of Examples 1-2 and Comparative Examples 1-3

[0106]

[0107]

[0108] As can be seen from Table 1, Comparative Examples 1-2 use the same vacuum evaporation coating conditions as Example 1, but because the polypropylene film is not pretreated or the pretreatment method is inappropriate, the aluminum adhesion amount of Comparative Examples 1-2 decreases, indicating that pretreatment will affect the deposition of aluminum on the film; at the same time, from the bonding performance data of Comparative Examples 1-2, it can be seen that even if aluminum is successfully evaporated on the film, the bonding strength between aluminum and the film is poor, and peeling occurs more easily.

[0109] Example 3

[0110] The double-sided metallized polypropylene film of this embodiment is prepared by the following steps:

[0111] (1) soaking a polypropylene film in a 1% (w / v) polyvinyl alcohol aqueous solution for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0112] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 1×10 -3Pa, put the aluminum block in the crucible, heat the crucible to 1450℃, the aluminum block evaporates by heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form the first aluminum metal layer, and obtain a single-sided aluminum metalized polypropylene film; take a polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 80mg / m 2 ; Continue to place the single-sided aluminum metallized polypropylene film in the vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to 1×10 -3 Pa, a CuBi alloy (Bi content of 15wt%) is placed in a crucible, and the crucible is heated to a temperature of 1450°C, the CuBi alloy is heated to evaporate, the polypropylene film winding system is started, the polypropylene film begins to move, and the gaseous Cu and Bi evaporated by the CuBi alloy are deposited on the surface of the aluminum metal layer of the polypropylene film to form a first CuBi alloy metal layer. The polypropylene film sample is taken to detect the coating adhesion, and the Cu adhesion in the first CuBi alloy metal layer is 1.6mg / m 2 , the amount of Bi attached is 0.28mg / m 2 ;

[0113] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer, the vacuum evaporation step of the second CuBi alloy metal layer is the same as the vacuum evaporation step of the first CuBi alloy metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0114] (4) placing the double-sided metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain the finished product.

[0115] Example 4

[0116] The double-sided metallized polypropylene film of this embodiment is prepared by the following steps:

[0117] (1) soaking a polypropylene film in a 2% (w / v) polyvinyl alcohol aqueous solution for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0118] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 0.8×10 -3Pa, put the aluminum block in the crucible, heat the crucible to 1500℃, evaporate the aluminum block by heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form the first aluminum metal layer, and obtain a single-sided aluminum metalized polypropylene film; take the polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 70mg / m 2 ; Continue to place the single-sided aluminum metallized polypropylene film in the vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to 1×10 -3 Pa, put CuBi alloy (Bi content is 10wt%) in a crucible, heat the crucible to 1500℃, the CuBi alloy evaporates under the heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous Cu and Bi evaporated by the CuBi alloy are deposited on the surface of the aluminum metal layer of the polypropylene film to form the first CuBi alloy metal layer, take the polypropylene film sample to test the coating adhesion, and the Cu adhesion in the first CuBi alloy metal layer is 1.75mg / m 2 ;

[0119] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer, the vacuum evaporation step of the second CuBi alloy metal layer is the same as the vacuum evaporation step of the first CuBi alloy metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0120] (4) placing the double-sided metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 30° C., and a humidity of 35% for 48 hours; and packaging to obtain the finished product.

[0121] Example 5

[0122] The double-sided metallized polypropylene film of this embodiment is prepared by the following steps:

[0123] (1) soaking a polypropylene film in a 0.5% (w / v) polyvinyl alcohol aqueous solution for 60 minutes; and drying the film to obtain a pretreated polypropylene film;

[0124] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 1.0 × 10 -3Pa, put the aluminum block in the crucible, heat the crucible to 1480℃, the aluminum block evaporates by heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form the first aluminum metal layer, and obtain a single-sided aluminum metalized polypropylene film; take a polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 90mg / m 2 ; Continue to place the single-sided aluminum metallized polypropylene film in the vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to 1.0×10 -3 Pa, a CuBi alloy (Bi content of 30wt%) is placed in a crucible, and the crucible is heated to a temperature of 1450°C, the CuBi alloy is heated to evaporate, the polypropylene film winding system is started, the polypropylene film begins to move, and the gaseous Cu and Bi evaporated by the CuBi alloy are deposited on the surface of the aluminum metal layer of the polypropylene film to form a first CuBi alloy metal layer. The polypropylene film sample is taken to detect the coating adhesion, and the Cu adhesion in the first CuBi alloy metal layer is 1.25mg / m 2 ;

[0125] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer, the vacuum evaporation step of the second CuBi alloy metal layer is the same as the vacuum evaporation step of the first CuBi alloy metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0126] (4) placing the double-sided metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 28° C., and a humidity of 40% for 48 hours; and packaging to obtain the finished product.

[0127] Example 6

[0128] The difference between Example 6 and Example 3 is that the Bi content in the CuBi alloy used in Example 6 is 5wt%, and the rest is the same as Example 3. The double-sided metallized polypropylene film of Example 6 is specifically prepared by the following steps:

[0129] (1) The steps are the same as step (1) of Example 3;

[0130] (2) The pretreated polypropylene film was placed in a vacuum evaporation coating machine. The vacuum evaporation steps of aluminum metal and CuBi alloy were the same as those in Example 3, wherein the Bi content in the CuBi alloy was 5 wt %, and the aluminum adhesion amount was 80 mg / m 2 The Cu adhesion in the first CuBi alloy metal layer is 1.8 mg / m2 ;

[0131] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer, the vacuum evaporation step of the second CuBi alloy metal layer is the same as the vacuum evaporation step of the first CuBi alloy metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0132] (4) placing the double-sided metallized polypropylene film obtained in step (3) in an environment with a dust-free level of 10,000 or less, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain a finished product.

[0133] Example 7

[0134] The difference between Example 7 and Example 3 is that the Bi content in the CuBi alloy used in Example 7 is 45wt%, and the rest is the same as Example 3. The double-sided metallized polypropylene film of Example 7 is specifically prepared by the following steps:

[0135] (1) The steps are the same as step (1) of Example 3;

[0136] (2) The pretreated polypropylene film was placed in a vacuum evaporation coating machine. The vacuum evaporation steps of aluminum metal and CuBi alloy were the same as those in Example 3, wherein the Bi content in the CuBi alloy was 45 wt %, and the aluminum adhesion amount was 80 mg / m 2 The Cu content in the first CuBi alloy metal layer is 1.05 mg / m 2 ;

[0137] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer, the vacuum evaporation step of the second CuBi alloy metal layer is the same as the vacuum evaporation step of the first CuBi alloy metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0138] (4) placing the double-sided metallized polypropylene film obtained in step (3) in an environment with a dust-free grade of 10,000, a temperature of 35° C., and a humidity of 30% for 40 hours; and packaging to obtain the finished product.

[0139] Comparative Example 4

[0140] The double-sided metallized polypropylene film of Comparative Example 4 was prepared by the following steps:

[0141] (1) Same as step (1) of Example 3;

[0142] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 1×10 -3 Pa, put the aluminum block in the crucible, heat the crucible to 1450℃, the aluminum block evaporates by heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form the first aluminum metal layer, and obtain a single-sided aluminum metalized polypropylene film; take a polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 80mg / m 2 ; Continue to place the single-sided aluminum metallized polypropylene film in the vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to 1×10 -3 Pa, put Cu in a crucible, heat the crucible to 1500℃, Cu evaporates by heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous Cu evaporated by heat is deposited on the surface of the aluminum metal layer of the polypropylene film to form the first Cu metal layer, take the polypropylene film sample to test the coating adhesion, and the Cu adhesion in the first Cu metal layer is 1.9mg / m 2 ;

[0143] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, wherein the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum-evaporating a second Cu metal layer on the surface of the second aluminum metal layer, wherein the vacuum evaporation step of the second Cu metal layer is the same as the vacuum evaporation step of the first Cu metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0144] (4) Same as step (4) of Example 3.

[0145] Comparative Example 5

[0146] The double-sided metallized polypropylene film of Comparative Example 5 was prepared by the following steps:

[0147] (1) Same as step (1) of Example 3;

[0148] (2) Place the pretreated polypropylene film in a vacuum evaporation coating machine and evacuate the vacuum evaporation coating machine to a vacuum of 1×10 -3Pa, put the aluminum block in the crucible, heat the crucible to 1450℃, the aluminum block evaporates by heat, start the polypropylene film winding system, the polypropylene film starts to move, the gaseous aluminum evaporated by the aluminum block is deposited on one side of the polypropylene film to form the first aluminum metal layer, and obtain a single-sided aluminum metalized polypropylene film; take a polypropylene film sample to test the coating adhesion, and the aluminum adhesion is 80mg / m 2 ; Continue to place the single-sided aluminum metallized polypropylene film in the vacuum evaporation coating machine, and evacuate the vacuum evaporation coating machine to 1×10 -3 Pa, Bi is placed in a crucible, and the crucible is heated to 550°C, Bi evaporates under the heat, the polypropylene film winding system is started, and the polypropylene film begins to move. The gaseous Bi evaporated by the heat is deposited on the surface of the aluminum metal layer of the polypropylene film to form the first Bi metal layer. The polypropylene film sample is taken to test the coating adhesion, and the Bi adhesion in the first Bi metal layer is 1.9 mg / m 2 ;

[0149] (3) placing the single-sided metallized polypropylene film obtained in step (2) in a vacuum evaporation coating machine, vacuum-evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, wherein the vacuum evaporation step of the second aluminum metal is the same as the vacuum evaporation step of the first aluminum metal in step (2); then vacuum-evaporating a second Bi metal layer on the surface of the second aluminum metal layer, wherein the vacuum evaporation step of the second Bi metal layer is the same as the vacuum evaporation step of the first Bi metal layer in step (2), to obtain a double-sided metallized polypropylene film;

[0150] (4) Same as step (4) of Example 3.

[0151] The double-sided metallized polypropylene film prepared in the above-mentioned Examples 1-7 and Comparative Examples 1-5 is wound into a capacitor core package, hot-pressed, and flattened into shape. A metal contact layer (tin-zinc alloy) is sprayed on the electrode parts at both ends of the capacitor core package, and the pins are welded on the metal contact layer. The capacitor core package is inserted into a plastic shell, and a potting material is potted in the plastic shell for packaging to prepare a capacitor.

[0152] High temperature and high humidity load test of capacitors:

[0153] Test equipment: Constant temperature and humidity test machine (QP08), LCR bridge (LQC09)

[0154] Test temperature: 85°C, relative humidity 85%RH, test voltage: ACR.V=275VAC, current: 3A, test frequency: CS is 1KHz.

[0155] For each capacitor prepared in the embodiment and the comparative example, 10 samples were taken and operated under the experimental conditions of 85°C and 85%RH for 500 hours to test the capacity change rate (△C / C0 ), take the average value, and the results are shown in Table 2.

[0156] Table 2 High temperature and high humidity resistance of capacitors prepared in Examples and Comparative Examples

[0157]

[0158]

[0159] As can be seen from Table 2, in Comparative Example 1-2, CuBi alloy was not evaporated on the aluminum metal layer, and the polypropylene film was not properly pretreated. The bonding performance between the aluminum metal layer and the polypropylene was poor. After 500 hours of operation at high temperature and high humidity, the aluminum metal layer was detached and the capacity dropped sharply. In the pretreatment process of Comparative Example 3, a high concentration of polyvinyl alcohol solution was used. Although it did not have a great effect on the bonding force, the initial capacity of Comparative Example 3 was reduced compared with Example 1, and after operation under high temperature and high humidity conditions, the capacity reduction was greater than that of Example 1. The polypropylene film of Example 1-2 was treated with a polyvinyl alcohol solution, but CuBi alloy was not evaporated on the aluminum metal layer. The capacitor produced had a serious capacity attenuation after running for 500 hours in a high humidity environment of 85°C, but it was better than the performance of Comparative Example 1-3. The capacitor produced in Example 3-5 has excellent high temperature and high humidity resistance.

[0160] In Comparative Examples 4 and 5, a Cu metal layer and a Bi metal layer are respectively evaporated on the aluminum metal layer. Evaporation of Cu or Bi alone has very limited effect on improving the capacity stability of the capacitor operating at high temperatures.

[0161] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and not limiting of the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0162] In the preparation method of the present invention, the order of each step is not limited to the order listed. For those skilled in the art, without creative work, the order of each step is also within the protection scope of the present invention. In addition, two or more steps or actions can be performed simultaneously.

[0163] Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A method for preparing a double-sided metallized polypropylene film, characterized in that: The following steps are involved: (1) soaking a polypropylene film in a polyvinyl alcohol solution, taking it out and drying it to obtain a pretreated polypropylene film; (2) vacuum evaporating a first aluminum metal layer on one side of the pretreated polypropylene film, and then vacuum evaporating 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 evaporating a second aluminum metal layer on the other side of the single-sided metallized polypropylene film, and then vacuum evaporating a second CuBi alloy metal layer on the surface of the second aluminum metal layer to obtain a double-sided metallized polypropylene film; The polyvinyl alcohol solution is formed by dissolving polyvinyl alcohol in water, and the concentration of the polyvinyl alcohol solution is 0.1~5%w / v; The vacuum evaporation method for forming a CuBi alloy metal layer includes the following steps: evacuating a vacuum evaporation coating machine, placing a CuBi alloy in a crucible, heating the crucible, evaporating the CuBi alloy by heating, starting a polypropylene film winding system, causing the polypropylene film to move, and depositing gaseous Cu and Bi evaporated by the CuBi alloy on the surface of the aluminum metal layer of the polypropylene film to form a CuBi alloy metal layer; The content of Bi in the CuBi alloy is 10-30wt%.

2. The method for preparing a double-sided metallized polypropylene film according to claim 1, characterized in that: The soaking time of step (1) is 20 to 100 minutes.

3. The method for preparing a double-sided metallized polypropylene film according to claim 1, characterized in that: The process of forming an aluminum metal layer by vacuum deposition includes the following steps: evacuating a vacuum evaporation coating machine, placing an aluminum block in a crucible, heating the crucible, causing the aluminum block to evaporate due to the heat, starting a polypropylene film winding system, causing the polypropylene film to start moving, and causing gaseous aluminum evaporated from the aluminum block to deposit on one side of the polypropylene film to form an aluminum metal layer.

4. The method for preparing a double-sided metallized polypropylene film according to claim 3, characterized in that: The purity of the aluminum block is ≥99.9%; The vacuum evaporation coating machine was evacuated to 0.01×10 -3 ~5×10 -3 Pa; The heating temperature of the crucible is 1400~1600℃.

5. The method for preparing a double-sided metallized polypropylene film according to claim 1, characterized in that: The adhesion of the first aluminum metal layer on the polypropylene film is 50~200mg / m 2 The adhesion of the second aluminum metal layer on the polypropylene film is 50~200mg / m 2 .

6. The method for preparing a double-sided metallized polypropylene film according to claim 1, characterized in that: The heating temperature of the CuBi alloy is 1300-1600°C.

7. The method for preparing a double-sided metallized polypropylene film according to claim 1, characterized in that: In the first CuBi alloy metal layer, the Cu deposition amount is 0.5-5 mg / m 2 ; In the second CuBi alloy metal layer, the Cu adhesion amount is 0.5~5mg / m 2 .

8. The method for preparing a double-sided metallized polypropylene film according to claim 7, characterized in that: The first CuBi alloy metal layer and the second CuBi alloy metal layer have the same deposition amount of Cu.

9. The method for preparing a double-sided metallized polypropylene film according to claim 1, characterized in that: The double-sided metallized polypropylene film obtained in step (3) is placed in an environment with a dust-free level of 10,000 or less, a temperature of 20-40° C., and a humidity of 10-40% for 20-50 hours.

10. Use of the double-sided metallized polypropylene film prepared by the preparation method according to claim 1 in capacitors.

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