Composite film and use thereof

Abstract

The present invention belongs to the field of polymer materials, and relates to a composite film comprising a substrate layer and a functional layer and the use thereof. The functional layer in the composite film comprises a metal region and an organic compound region. The organic compound in the organic compound region has a high stability and is free from the element fluorine; moreover, the overall resistance to heat and humidity is improved while the high stability is achieved, thereby achieving the beneficial effects of efficient production, an improved performance, and an environmentally friendly product.

Description

A composite thin film and its application Technical Field

[0001] This invention belongs to the field of polymer materials and relates to a composite film containing a substrate layer and a functional layer. Background Technology

[0002] Due to their high reliability and relatively low production cost, metallized film capacitors (MFCs) are widely used in various industries, including electronics, home appliances, communications, power, electrified railways, hybrid vehicles, wind power, and solar power. MFCs possess typical characteristics such as extremely low loss factor, high volumetric energy density, minimal capacitance variation with temperature, and strong self-healing capability. The self-healing process electrically isolates fault points and allows the capacitor to recover its integrity with minimal characteristic changes. With the rapid development of industries such as new energy vehicles and renewable energy power generation, the market for metallized film capacitors is experiencing rapid growth.

[0003] Metallized film capacitors use metallized films with both metallic and non-metallic regions. Currently, the non-metallic regions are achieved by vapor-depositing organic compounds to inhibit metal adhesion. Commonly used organic compounds are PFPE (perfluoropolyether). For example, Patent Document 1 discloses a method for manufacturing a metallized plastic film with clearly defined non-metallized regions (B). This method uses an apparatus including a first support for winding the film, a second support for winding the metallized film, at least one reaction roller between the two supports for supporting the film when it faces the metallization device, and at least one unit including at least one nozzle for delivering PFPE oil mist to the non-metallized regions of the film. Patent Document 2 discloses that the metal anti-deposition liquid is preferably a fluorinated oil or a silicone oil.

[0004] Although fluorinated oils have good anti-metal adhesion effects, they contain carbon-fluorine bonds (CF) that are extremely difficult to break, which prevents them from decomposing in nature. This makes them persistent and prone to long-distance spread in the natural environment, and they may exacerbate global warming. They also have effects on human health, including reproductive toxicity and even carcinogenicity.

[0005] Existing technical documents

[0006] Patent Document 1: US4749591A

[0007] Patent Document 2: JP2024024284A Summary of the Invention

[0008] To address the aforementioned problems, this invention proposes a composite film that possesses the functionality required for capacitor films while also exhibiting excellent performance. This composite film is fluorine-free, thus mitigating the environmental damage caused by the use of carbon-fluorine bond (CF) materials in existing technologies. It also demonstrates high stability while improving overall resistance to damp heat, achieving the beneficial effects of efficient production, enhanced performance, and environmentally friendly products.

[0009] The purpose of this invention is to provide a composite film comprising a substrate layer and a functional layer. The substrate layer has a thickness of 1-15 μm, and the functional layer comprises metal regions and organic compound regions on top of the substrate layer. Ion chromatography analysis of the composite film shows a fluorine content not exceeding 1000 μg / m³. 2 .

[0010] In the field of film capacitors, considering the requirement for miniaturization, a substrate thickness of 1.5-6 μm is preferred.

[0011] The test standard for the above-mentioned fluorine content test method can be EN14582-2016. Considering the environmental impact, the preferred fluorine content is no more than 10 μg / m³. 2 .

[0012] Since the organic compound region needs to have metallic shielding properties, preferably, when the organic compound used in the organic compound region is tested by field desorption mass spectrometry, the content of aliphatic hydrocarbon groups with an unsaturation degree of 0-2 is 70 wt% or more. In order to improve the product's resistance to damp heat, the content of aliphatic hydrocarbon groups with an unsaturation degree of 0-2 is further preferably 80-100 wt%.

[0013] When performing 1H NMR spectroscopy on organic compounds in the aforementioned organic compound region, 1 The H chemical shift is below 2.00 ppm. When the peak integral value in the range of 1.00-1.12 ppm is considered as 'a' and the peak integral value in the range of 0.50-0.96 ppm is considered as 'b', considering the metal shielding properties of organic compounds, the preferred a / b or b / a ratio is in the range of 0-0.4. Considering the overall appearance and moisture resistance of the product, the preferred a / b range is 0-0.08, or 0.1-0.4, or b / a range is 0-0.4.

[0014] When performing surface free energy analysis on the organic compound region, the polar component of the surface free energy ranges from 0 to 2.9 mN / m, and the ratio of surface free energy to polar component is greater than 13.

[0015] For production feasibility, it is preferred that the organic compound in the organic compound region has a kinematic viscosity of 10-80 mm at 40°C.2 / s. Considering processability, the preferred kinematic viscosity is 10-40 mm. 2 / s.

[0016] The organic compound in the functional layer of the composite film is not limited, but considering metal shielding and availability, one or more of the following are preferred: alkane oil, polypropylene, polyethylene, poly-α-olefin, n-hexane, isohexane, dodecane, octadecane, pentadecane, cyclopentadecane, hexadecylcyclohexane, or octadecylpiperidine. By selecting different molecular structures and molecular weights, the different properties of the organic compound and the product performance it exhibits are determined.

[0017] Considering the miniaturization requirements of film capacitors and the requirement for film flexibility, the substrate layer preferably contains one or more of polypropylene, polyethylene, polyester, polyphenylene sulfide, polycarbonate, or polystyrene film. Further considering factors such as film voltage resistance, dielectric properties, and cost, one or more of polypropylene, polyethylene, polyester, or polyphenylene sulfide are preferred as the main component of the substrate. Considering the self-healing properties of the substrate, polypropylene is further preferred as the main component.

[0018] Considering the conductivity requirements of the positive and negative electrodes in the film capacitor, the metal in the metal region is preferably one or more of gold, silver, copper, zinc, chromium, aluminum, or magnesium. This invention preferably uses a zinc-aluminum alloy as the metal layer material of the metallized film. Aluminum and zinc have better stability compared to other commonly used metals, with aluminum exhibiting relatively good resistance to damp heat. However, aluminum has poor corona resistance; in damp heat resistance tests, under applied voltage, even a small amount of air inside the capacitor can break down, causing a corona phenomenon that leads to metal scattering and a decrease in capacitor capacitance. Zinc, on the other hand, has better corona resistance. To balance damp heat resistance and corona resistance, this invention further preferably uses a zinc-aluminum alloy as the electrode material of the metallized film.

[0019] In the functional layer of the composite film, the distribution shape of the metal region is not particularly limited. Based on the overall performance requirements of the film capacitor and for ease of production, a strip shape is preferred.

[0020] The thickness of the functional layer in the composite thin film is not particularly limited and can range from 10 to 200 nanometers. Considering the balance between the conductivity of the metal region and the product cost, the thickness of both the metal region and the organic compound region of the functional layer is preferably 30-80 nanometers.

[0021] Considering the different types of products and application fields, the width requirements of the organic compound region are also different. Preferably, the organic compound region in the functional layer of the composite film has a width of 0.05-10.0 mm in the width direction.

[0022] The composite film product may have a protective layer added as needed, preferably a protective layer containing Si-O-Si functional groups on the surface of the composite film. The thickness of the protective layer can be adjusted according to the product design performance.

[0023] Furthermore, to improve the moisture and heat resistance of the composite film, the protective layer preferably contains one or more functional groups selected from propionic acid, epoxy, hydroxyl, phenyl, carboxyl, amino, vinyl, mercapto, alkyl groups having four or more carbon atoms, and acid anhydrides. To further protect the surface of the composite film from oxidation, the protective layer preferably contains one or more functional groups selected from hydroxyl, amino, vinyl, and mercapto. Moreover, when the composite film is immersed in isopropanol for more than 24 hours, the ratio of Si element content before and after immersion is in the range of 0.5-1.1.

[0024] The present invention also provides a capacitor element comprising the above-described composite film. The capacitor element is formed by winding positive and negative electrodes or stacking positive and negative electrodes.

[0025] The invention also provides a circuit comprising the aforementioned capacitor element. Capacitors made from the aforementioned capacitor element are used in circuit systems of railways, new energy vehicles, photovoltaic and wind power generation systems, as well as general household appliances and electrical appliances.

[0026] The composite film of the present invention contains a substrate layer and a functional layer. The organic compound in the organic compound region has high stability and does not contain fluorine. The organic compound region has high metal shielding properties, thereby achieving good insulation and conductivity separation, resulting in a composite film with good performance and improving the basic performance of the film capacitor. Detailed Implementation

[0027] The present invention will be described in more detail through the following embodiments, but the embodiments do not constitute a limitation of the present invention.

[0028] 1. Raw materials

[0029] (1) Substrate

[0030] Polypropylene (PP) film: manufactured by Toray Industries, Inc. Thickness 5μm

[0031] Polyethylene terephthalate (PET) film: manufactured by Toray Industries, Inc. 10μm thickness

[0032] Polyethylene naphthalate (PEN) film: manufactured by Toyobo Co., Ltd. Thickness 15μm

[0033] Polyphenylene sulfide (PPS) film: manufactured by Toray Industries, Inc. Thickness 1μm

[0034] (2) Organic compounds

[0035] A1: PFPE

[0036] A2: Methyl silicone oil

[0037] A3: Mineral oil, molecular weight Mn = 523, PDI = 1.2

[0038] A4: Liquid polyethylene oil 1, molecular weight Mn = 347, PDI = 1.12

[0039] A5: Liquid polyethylene oil 2, molecular weight Mn = 449, PDI = 1.13

[0040] A6: Fully synthetic alkane oil 3, molecular weight Mn = 567, PDI = 1.10, viscosity less than 6600 mmHg at -30℃. 2 / s, viscosity at 100℃: 9.3-12.5mm 2 / s

[0041] A7: Liquid polypropylene oil 4, molecular weight Mn = 566, PDI = 1.09

[0042] A8: Isotriane, molecular weight Mn = 419, PDI = 1.12

[0043] A9: Poly-α-olefin

[0044] A10: Polyisobutylene

[0045] (3) Protective layer

[0046] B1: Silanol-modified siloxane, molecular weight Mn = 2303, PDI = 1.18

[0047] B2: Low molecular weight epoxy-modified polysiloxane, molecular weight Mn = 641, PDI = 1.09

[0048] (4) Other

[0049] Target materials (gold, silver, zinc, aluminum, magnesium, aluminum / zinc alloy): Zhongnuo New Materials (Beijing) Co., Ltd.

[0050] 2. The methods for determining the relevant performance in the embodiments and comparative examples of the present invention are as follows. For all tests, unless otherwise specified, the test temperature is 23°C.

[0051] (1) Proton NMR spectrum:

[0052] Sample: Immerse 0.3-0.5 g of the composite film in deuterated chloroform for 4-6 hours. Remove the insoluble composite film and analyze the deuterated chloroform solution.

[0053] Test method: Proton nuclear magnetic resonance (NMR) spectrum

[0054] Instrument: Nuclear magnetic resonance spectrometer (JEOL-400)

[0055] Test conditions: Deuterated chloroform (CDCl3) solvent, 1024 scans. Data processing: Peaks within the corresponding chemical shift ranges were integrated separately, and then calculations were performed.

[0056] (2) Fluorine content

[0057] Sample: Take 30 grams of composite film sample, test 3 times and take the average value. Test method: Pretreatment is performed by oxygen bomb combustion method, followed by water absorption capture according to EN ISO 3696 standard, and then fluoride ion content is tested by ion chromatography.

[0058] Analytical items: Halogens (F, Cl, Br, I)

[0059] Instrument: Ion Chromatograph

[0060] Test conditions: Refer to standard EN14582-2016

[0061] (3) Unsaturation

[0062] Sample: Immerse 0.1-0.3 g of the composite film in hexane for 4-6 hours. Remove the insoluble composite film, add methanol to the hexane solution for liquid-liquid extraction, and analyze the hexane layer.

[0063] Test method: Field desorption mass spectrometry (FD-MS)

[0064] Instrument: JMS-T200GCV (Japan Electronics)

[0065] Test conditions: Import method: Direct import

[0066] Ionization method: FD+

[0067] Cathode voltage: -10kV

[0068] Ion source temperature: RT (room temperature and pressure)

[0069] Emitter current: 0→48mA (rate 51.2mA / min)

[0070] Resolution: >6000

[0071] Measurement mass range: m / z 30–1600

[0072] Analysis software: Polymerix Ver. 3.01 (manufactured by Shierra Analytics)

[0073] Matching tolerance: ±0.1Da

[0074] Threshold: 0.1%RA

[0075] Anti-isotope: CH2

[0076] (4) Kinetic viscosity

[0077] Sample: Liquid from the organic compound region of the composite film was extracted using a micro-sampler and analyzed. The average value was taken from three tests.

[0078] Testing equipment: Rotating microviscometer

[0079] Test conditions: 40℃ temperature; the obtained dynamic viscosity value was converted to obtain the kinematic viscosity.

[0080] (5) Metal content in organic compound regions

[0081] Sample: Composite film, with testing performed on selected organic compound regions.

[0082] Test method: SEM-EDX scan

[0083] Instrument: Hitachi S-3400N

[0084] Data processing: Three areas were scanned to test the metal content. The average value was selected. The lower the metal content in the organic compound area, the better the insulation and appearance of that area.

[0085] (6) Surface free energy analysis

[0086] Sample: Organic compound area evaluation method for composite films: The sample was laid flat on the test platform, and the contact angle of four liquids (water, ethylene glycol, formamide, and diiodomethane) was tested. Then, the angles were calculated using equations (1) and (2).

[0087] Calculation formula: γ = γ d +γ p +γ h Equation (1)

[0088] In equation (1): γ is the surface free energy of the sample, γ d As the dispersive component, γ p As a polar component, γ h Hydrogen bond components

[0089] In equation (2): γ L For liquid surface energy, γ L d γ is the dispersive component of the liquid. L p It is a liquid polar component, γL p It is a liquid hydrogen-bonded component, γ S d γ is the dispersive component of the sample. S p γ is the polar component of the sample. S h Hydrogen-bonded components of the sample

[0090] (7) Black and white density

[0091] Sample: Metallic region of composite thin film

[0092] Instrument: Black and white densitometer

[0093] Test method: Place the metal region of the composite film at the test probe and measure the initial black-and-white density D1. Then, place the composite film at 105℃*100RH% for 3 hours and test the black-and-white density of the metal region again. Measure the black-and-white density D2.

[0094] Calculation formula: Black and white density change rate = (D1-D2) / D1*100%

[0095] (8) Ratio of silicon content before and after isopropanol immersion

[0096] Sample: Composite film with protective layer

[0097] Test method: Atomic absorption spectrometer

[0098] Instrument: Thermo Fisher iCE 3500AAS

[0099] Method: The silicon content of the composite film before immersion was c1, and the silicon content after immersion in isopropanol for 24 hours was measured to be c2.

[0100] Calculation formula: Silicon content ratio before and after isopropanol immersion = c1 / c2

[0101] (9) Capacitance change rate of capacitors after treatment at 85℃*85RH%.

[0102] Sample: A composite film was fabricated into a capacitor element, and a damp heat resistance test was conducted. Test method: The capacitance change rate of the capacitor was measured after operating at 85℃*85RH%*220VAC voltage for 500 hours.

[0103] The rate of change of capacitor capacitance ΔC / C=(C-C1) / C

[0104] Where C is the initial capacitor capacitance, and C1 is the capacitor capacitance after treatment at 85℃*85RH%*220VAC.

[0105] ΔC / C < ±10% is considered acceptable, and ΔC / C < ±5% is considered excellent.

[0106] 3. The specific implementation method is as follows:

[0107] First, confirm the cleanliness of the substrate surface. If contaminated, clean and dry with ethanol before use. Once the substrate is confirmed to be clean and free of contamination, the functional layer can be prepared on it. Organic compounds are introduced into the organic compound regions through methods such as spraying or coating; then, metal is deposited to form metal regions. The organic compounds in the organic compound regions have the property of inhibiting metal adhesion, therefore no metal adheres to the organic compound regions, thus forming an alternating metal and organic compound region on the functional layer, obtaining a composite film.

[0108] If it is a double-sided metallized film, the above film can be processed again through the above steps to form a composite film with functional layers on both sides on the other side of the substrate, or it can be processed using a double-sided processing equipment to obtain a double-sided metallized film.

[0109] Examples 1, 2, and Comparative Example 1

[0110] Composite thin film preparation method: 1. Perform plasma treatment on one side of the substrate. 2. Locally spray organic compound onto the plasma-treated surface to form an organic compound region with a strip-shaped outline. 3. Evaporate metal onto this surface.

[0111] The composite film preparation methods in all embodiments and comparative examples are the same, and the materials used, the thickness settings of each layer, the performance test results, etc. are listed in Table 1.

[0112] Table 1 shows that, comparing Examples 1 and 2 with Comparative Example 1 (Prior Art), the present invention uses an organic compound that does not contain fluorine, which can obtain a product with a good appearance and also improve the resistance to damp heat. In contrast, the fluorine content of the composite film of Comparative Example 1 is much higher than the fluorine content specified in the present invention, and its resistance to damp heat is worse than that of Examples 1 and 2.

[0113] Table 1.

[0114] Examples 3-9

[0115] The composite film preparation method is the same as in Example 1. The materials used, the thickness settings of each layer, and the performance test results are listed in Table 2.

[0116] As shown in Tables 1 and 2, when the content of the organic compound with unsaturation degree 0-2 is above 70 wt% in Examples 2-4 and Example 9, the overall performance of the composite film is improved compared with the prior art (Comparative Example 1). Furthermore, Examples 2-4 show that increasing the content of the organic compound with unsaturation degree 0-2 improves the composite film's resistance to damp heat and other properties.

[0117] In Examples 2, 3, 4, 5, and 6, organic compounds 1 The NMR ratios a / b or b / a in the H range of 0-0.1 are superior to existing technologies (Comparative Example 1) and it does not contain fluorine. Furthermore, a comparison between Example 2 and Examples 5-6 shows that the organic compound... 1 H NMR shows better performance in terms of damp heat resistance and other properties compared to a / b at a ratio of 0-0.08.

[0118] As shown in Examples 1-8, the kinematic viscosity of the organic compounds is between 10-80 mm. 2 The composite film required by this invention can be obtained within a range of / s.

[0119] As can be seen from Examples 1-9, products with a surface free energy polar component below 2.9 mN / m have better product performance and appearance, and products with a surface free energy to polar component ratio above 13 have better product performance.

[0120] Table 2.

[0121] Examples 10-12

[0122] The composite film preparation method is the same as in Example 1. The materials used, the thickness settings of each layer, and the performance test results are listed in Table 3.

[0123] The results of damp heat resistance vary depending on the type of substrate, which is related to the functional groups of the substrate. For comparison examples 2 and 10-12, PP substrate is superior to PPS, PEN, and PET, with PP being the preferred substrate.

[0124] Table 3.

[0125] Examples 13-15

[0126] Composite thin film preparation method: 1. Perform plasma treatment on one side of the substrate. 2. Locally spray organic compound onto the plasma-treated surface to form an organic compound region with a strip-shaped outline. 3. Evaporate metal onto this surface.

[0127] Examples 13-14 added a protective layer vapor deposition process.

[0128] Example 15 is based on Example 2, with the addition of the component preparation process and the capacity change rate test at 85℃*85RH%*220VAC.

[0129] During the device fabrication process, the device is formed by stacking and winding two composite thin films, which serve as positive and negative electrodes respectively.

[0130] The composite thin film was prepared using the same method. The materials used, the thickness of each layer, and the performance test results are listed in Table 4.

[0131] As shown in Table 4, adding a protective layer in Examples 13 and 14 can improve the moisture and heat resistance of the composite film. The component performance evaluation results of Example 15 are excellent and can be used in capacitor applications.

[0132] Table 4.

Claims

1. A composite thin film, characterized in that: It contains a substrate layer and a functional layer. The substrate layer has a thickness of 1-15 μm. Above the substrate layer is a functional layer containing metal regions and organic compound regions. Ion chromatography analysis of the composite film shows that the fluorine content does not exceed 1000 μg / m³. 2 .

2. The composite film according to claim 1, characterized in that: When the organic compounds used in the organic compound region are tested by field desorption mass spectrometry, the content of aliphatic hydrocarbon groups with an unsaturation degree of 0-2 is more than 70%.

3. The composite film according to claim 1 or 2, characterized in that: When performing 1H NMR spectroscopy on the organic compounds used in the aforementioned organic compound region, 1 The chemical shift of H is below 2.00 ppm.

4. The composite film according to any one of claims 1-3, characterized in that: When performing 1H NMR spectroscopy on the organic compounds used in the aforementioned organic compound region, 1 When the peak integral value of H chemical shift in the range of 1.0 to 1.12 ppm is counted as a and the peak integral value in the range of 0.50 to 0.96 ppm is counted as b, the ratio of a / b or b / a is in the range of 0 to 0.

4.

5. The composite film according to any one of claims 1-4, characterized in that: When performing 1H NMR spectroscopy on the organic compounds used in the aforementioned organic compound region, 1 When the peak integral value of H chemical shift in the range of 1.0 to 1.12 ppm is counted as a and the peak integral value in the range of 0.50 to 0.96 ppm is counted as b, a / b = 0 to 0.08, a / b = 0.1 to 0.4, and b / a = 0 to 0.

4.

6. The composite film according to any one of claims 1-5, characterized in that: When performing surface free energy analysis on the organic compound region, the polar component ranges from 0 to 2.9 mN / m.

7. The composite film according to any one of claims 1-6, characterized in that: When performing surface free energy analysis on the organic compound region, the ratio of surface free energy to polar component is greater than 13.

8. The composite film according to any one of claims 1-7, characterized in that: The organic compounds used in the organic compound region have a kinematic viscosity of 10-80 mmHg at 40°C. 2 / s.

9. The composite film according to any one of claims 1-8, characterized in that: The organic compound region contains one or more of the following: alkane oil, polypropylene, polyethylene, poly-α-olefin, polyisobutylene, n-hexane, isohexane, dodecane, octadecane, pentadecane, cyclopentadecane, hexadecylcyclohexane, or octadecylpiperidine.

10. The composite film according to any one of claims 1-9, characterized in that: The substrate layer contains one or more of polypropylene, polyethylene, polyester, polyphenylene sulfide, polycarbonate, or polystyrene film.

11. The composite film according to any one of claims 1-10, characterized in that: The metal in the metal region is one or more of gold, silver, copper, zinc, chromium, aluminum, or magnesium.

12. The composite film according to any one of claims 1-11, characterized in that: The organic compound region in the functional layer has a width of 0.05-10.0 mm in the width direction.

13. The composite film according to any one of claims 1-12, characterized in that: The surface of the composite film is also provided with a protective layer containing Si-O-Si functional groups.

14. The composite film according to claim 13, characterized in that: The protective layer also contains one or more functional groups selected from propionic hydroxyl, epoxy, hydroxyl, phenyl, carboxyl, amino, vinyl, mercapto, alkyl with four or more carbon atoms, and acid anhydride.

15. The composite film according to claim 13, characterized in that: When the composite film is immersed in isopropanol for more than 24 hours, the ratio of Si content before and after immersion is in the range of 0.5-1.

1.

16. A capacitor element comprising the composite film according to any one of claims 1-15.

17. A circuit comprising the capacitor element of claim 16.

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