Flame-retardant breakdown-resistant metallized film and capacitor

Abstract

The invention relates to a flame-retardant breakdown-resistant metallized film and a capacitor, the flame-retardant breakdown-resistant metallized film comprises an aluminum shell, a capacitor core and an epoxy resin layer for packaging the capacitor core, and the capacitor core is formed by winding and metal spraying the flame-retardant breakdown-resistant metallized film; and preparing a metal coating on the surface of the flame-retardant modified insulating film through a vacuum coating process. According to the flame-retardant breakdown-resistant thin-film capacitor, through a manufacturing process of modifying an existing insulating base film, adding a flame retardant into polymer particles, and then spraying a corona auxiliary liquid on the thin film to be matched with corona treatment, the defects that the hot shrinkage rate of the thin film is too large and the impact strength is low due to the addition of the flame retardant can be overcome; and finally, the flame retardance and the breakdown resistance of the thin film capacitor are remarkably improved.

Description

Technical Field

[0001] The present invention and the field of capacitors specifically relate to a flame retardant and anti-puncture type metallized film and a capacitor. Background Art

[0002] Film capacitors are also called plastic film capacitors, which use plastic film as dielectric.

[0003] The structure of existing film capacitors generally includes an aluminum shell, a capacitor core, and an epoxy resin layer for encapsulating the capacitor core. After the metallized film is wound into a core, gold is sprayed on both ends of the core to obtain the capacitor core. The metallized film is obtained by forming an aluminum layer on the surface of the insulating film through a vacuum aluminum plating process.

[0004] For film capacitors, their flame retardancy depends on the capacitor core and the epoxy resin layer. The flame retardancy of the epoxy resin layer is generally improved by adding a large amount of fillers, as long as other properties of the epoxy resin are not considered. For the capacitor core, its flame retardancy generally depends on the flame retardancy of the insulating base film. However, the existing insulating base films are usually polyethylene films, polypropylene films or polycarbonate films, which have very poor flame retardancy. If the flame retardancy is improved by adding flame retardants to the raw materials of the film, it will significantly affect the performance of the film, especially for films made by biaxial stretching, which will cause defects such as cracks, large thermal shrinkage and low impact strength.

[0005] Based on this, the present invention is proposed. Summary of the invention

[0006] The specific technical solutions of the present invention are as follows:

[0007] A capacitor comprises a capacitor core made of a flame retardant and anti-puncture metallized film by winding and gold spraying, an aluminum shell, and an epoxy resin layer for encapsulating the capacitor core. The capacitor core is made of a flame retardant and anti-puncture metallized film by winding and gold spraying. The preparation method of the flame retardant and anti-puncture metallized film comprises the following steps:

[0008] A metal coating is formed on the surface of the flame-retardant modified insulating film by a vacuum coating process, thus obtaining the flame-retardant and anti-puncture metallized film.

[0009] In an optional embodiment, the preparation process of the flame retardant modified insulating film comprises the following steps:

[0010] Step 1, mixing polymer particles with flame retardant and extruding them into thin film sheets through an extruder;

[0011] Step 2: biaxially stretch the extruded film sheet to obtain a stretched film; biaxial stretching includes longitudinal stretching and transverse stretching, so that the film is evenly stretched in two directions to improve its mechanical properties and transparency.

[0012] Step 3: Cool the stretched film through a cooling roller to obtain a solidified film; ensure its flatness and transparency.

[0013] Step 4, spraying a corona auxiliary liquid on the surface of the cured film, the corona auxiliary liquid forms a grid-shaped liquid film layer on the surface of the cured film, and then performing a corona treatment on the surface of the cured film on the side sprayed with the liquid film layer;

[0014] Step 5: After the corona treatment is completed, the film is washed with deionized water and dried to obtain the flame retardant modified insulating film.

[0015] In an optional embodiment, the corona auxiliary liquid is prepared by mixing sodium hexafluoroantimonate, glycerol and water in a mass ratio of 1:6300:999.

[0016] In an optional embodiment, the polymer particles are one or more of polyethylene particles, polypropylene particles, and polycarbonate particles.

[0017] In an optional embodiment, the mass ratio of the polymer particles to the flame retardant is 100:2.3.

[0018] In an optional embodiment, the flame retardant is tris(isopropylphenyl) phosphate or resorcinol bis(diphenyl phosphate).

[0019] In an optional embodiment, a thin film corona treatment machine is used for corona treatment, wherein the output power of the thin film corona treatment machine is 10-15 kW, and the corona treatment voltage is 12000-13000V.

[0020] In an optional embodiment, the raw material of the epoxy resin layer consists of epoxy resin glue and flame retardant filler.

[0021] In an optional embodiment, the mass ratio between the epoxy resin glue and the flame retardant filler is 100:(30-50).

[0022] In an optional embodiment, the flame retardant filler is aluminum hydroxide or magnesium hydroxide.

[0023] In the present invention, the flame-retardant and anti-puncture film capacitor can improve the defects of excessive thermal shrinkage and low impact strength of the film caused by the addition of flame retardants by modifying the manufacturing process of the existing insulating base film, adding flame retardants to polymer particles, and then spraying corona auxiliary liquid on the film in combination with corona treatment, thereby significantly improving the flame retardancy and anti-puncture performance of the film capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a curve diagram of the change of x and impact strength in Test Example 1;

[0025] Figure 2 This is a real photo of the capacitor core in Example 1. DETAILED DESCRIPTION

[0026] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] A capacitor comprises an aluminum shell, a capacitor core, and an epoxy resin layer for encapsulating the capacitor core, wherein the capacitor core is made of a flame retardant and anti-puncture metallized film through winding and gold spraying. Figure 2 As shown, the method for preparing the flame retardant and anti-puncture type metallized film comprises the following steps:

[0029] A metal coating is formed on the surface of the flame-retardant modified insulating film by a vacuum coating process, thus obtaining the flame-retardant and anti-puncture metallized film.

[0030] The preparation process of the flame retardant modified insulating film comprises the following steps:

[0031] Step 1, mixing polymer particles with flame retardant and extruding them into thin film sheets through an extruder;

[0032] Step 2, biaxially stretching the extruded film sheet to obtain a stretched film;

[0033] Step 3, cooling the stretched film through a cooling roller to obtain a solidified film;

[0034] Step 4, spraying a corona auxiliary liquid on the surface of the cured film, the corona auxiliary liquid forms a grid-shaped liquid film layer on the surface of the cured film, and then performing a corona treatment on the surface of the cured film on the side sprayed with the liquid film layer;

[0035] Step 5: After the corona treatment is completed, the film is washed with deionized water and dried to obtain the flame retardant modified insulating film.

[0036] The corona auxiliary liquid is prepared by mixing sodium hexafluoroantimonate, propylene glycol and water in a mass ratio of 1:6300:999.

[0037] The polymer particles are polyethylene particles, and the mass ratio of the polymer particles to the flame retardant is 100:2.3.

[0038] The flame retardant is triisopropylphenyl phosphate.

[0039] The corona treatment is carried out by using a film corona treater, the output power of which is 10kW and the corona treatment voltage is 12000V.

[0040] The raw materials of the epoxy resin layer are composed of epoxy resin glue and flame retardant filler. The mass ratio of the epoxy resin glue to the flame retardant filler is 100:30. The flame retardant filler is magnesium hydroxide.

[0041] Example 2

[0042] A capacitor comprises an aluminum shell, a capacitor core, and an epoxy resin layer for encapsulating the capacitor core, wherein the capacitor core is made of a flame-retardant and anti-puncture metallized film through winding and gold spraying, and the preparation method of the flame-retardant and anti-puncture metallized film comprises the following steps:

[0043] A metal coating is formed on the surface of the flame-retardant modified insulating film by a vacuum coating process, thus obtaining the flame-retardant and anti-puncture metallized film.

[0044] The preparation process of the flame retardant modified insulating film comprises the following steps:

[0045] Step 1, mixing polymer particles with flame retardant and extruding them into thin film sheets through an extruder;

[0046] Step 2, biaxially stretching the extruded film sheet to obtain a stretched film;

[0047] Step 3, cooling the stretched film through a cooling roller to obtain a solidified film;

[0048] Step 4, spraying a corona auxiliary liquid on the surface of the cured film, the corona auxiliary liquid forms a grid-shaped liquid film layer on the surface of the cured film, and then performing a corona treatment on the surface of the cured film on the side sprayed with the liquid film layer;

[0049] Step 5: After the corona treatment is completed, the film is washed with deionized water and dried to obtain the flame retardant modified insulating film.

[0050] The corona auxiliary liquid is prepared by mixing sodium hexafluoroantimonate, propylene glycol and water in a mass ratio of 1:6300:999.

[0051] The polymer particles are polypropylene particles. The mass ratio of the polymer particles to the flame retardant is 100:2.3.

[0052] The flame retardant is triisopropylphenyl phosphate.

[0053] The corona treatment is carried out by using a thin film corona treater, the output power of which is 12kW and the corona treatment voltage is 12000V.

[0054] The raw materials of the epoxy resin layer are composed of epoxy resin glue and flame retardant filler. The mass ratio of the epoxy resin glue to the flame retardant filler is 100:40. The flame retardant filler is aluminum hydroxide.

[0055] Example 3

[0056] A capacitor comprises an aluminum shell, a capacitor core, and an epoxy resin layer for encapsulating the capacitor core, wherein the capacitor core is made of a flame-retardant and anti-puncture metallized film through winding and gold spraying, and the preparation method of the flame-retardant and anti-puncture metallized film comprises the following steps:

[0057] A metal coating is formed on the surface of the flame-retardant modified insulating film by a vacuum coating process, thus obtaining the flame-retardant and anti-puncture metallized film.

[0058] The preparation process of the flame retardant modified insulating film comprises the following steps:

[0059] Step 1, mixing polymer particles with flame retardant and extruding them into thin film sheets through an extruder;

[0060] Step 2, biaxially stretching the extruded film sheet to obtain a stretched film;

[0061] Step 3, cooling the stretched film through a cooling roller to obtain a solidified film;

[0062] Step 4, spraying a corona auxiliary liquid on the surface of the cured film, the corona auxiliary liquid forms a grid-shaped liquid film layer on the surface of the cured film, and then performing a corona treatment on the surface of the cured film on the side sprayed with the liquid film layer;

[0063] Step 5: After the corona treatment is completed, the film is washed with deionized water and dried to obtain the flame retardant modified insulating film.

[0064] The corona auxiliary liquid is prepared by mixing sodium hexafluoroantimonate, propylene glycol and water in a mass ratio of 1:6300:999.

[0065] The polymer particles are carbonate particles. The mass ratio of the polymer particles to the flame retardant is 100:2.3.

[0066] The flame retardant is triisopropylphenyl phosphate.

[0067] The corona treatment is carried out by using a film corona treater, the output power of which is 15kW and the corona treatment voltage is 13000V.

[0068] The raw materials of the epoxy resin layer are composed of epoxy resin glue and flame retardant filler. The mass ratio of the epoxy resin glue to the flame retardant filler is 100:50. The flame retardant filler is aluminum hydroxide.

[0069] Comparative Example 1

[0070] The only difference between this example and Example 1 is that the flame retardant in this example is resorcinol bis(diphenyl phosphate), and the rest is the same as Example 1.

[0071] Comparative Example 2

[0072] The only difference between this example and Example 1 is that in step 1, the polymer particles are directly extruded into thin film sheets through an extruder; the rest is the same as Example 1.

[0073] Comparative Example 3

[0074] The difference between this example and Example 1 is that step 4 and step 5 are omitted, and the metal coating is directly formed on the surface of the cured film by vacuum coating process, and the rest is the same as Example 1.

[0075] Comparative Example 4

[0076] The only difference between this example and Example 1 is that in step 4, corona auxiliary liquid is not sprayed, and corona treatment is directly performed; the rest is the same as Example 1.

[0077] Comparative Example 5

[0078] The only difference between this example and Example 1 is that the corona auxiliary liquid is replaced by a sodium chloride solution with a mass fraction of 0.01%, and the rest is the same as Example 1.

[0079] The test results of Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1:

[0080] Table 1

[0081]

[0082]

[0083] The flame retardant test of capacitor core is to cut and polish it into 5mm thick samples and then test it. The voltage of all capacitors is 850V.

[0084] In the present invention, although adding flame retardant to polymer particles can significantly improve flame retardancy, it will seriously affect the thermal shrinkage and impact strength of the film; if the film is treated by corona process, it can only improve the thermal shrinkage of the film, but has little effect on the impact strength of the film; but using a special corona auxiliary liquid combined with corona process can also improve the impact strength of the film. Adding tri(isopropylphenyl) phosphate as a flame retardant in the film raw material and combining it with corona process, this has excellent process improvement effect for polyethylene film and polypropylene film, but cannot be used for polycarbonate film.

[0085] The lower the thermal shrinkage rate and the higher the impact strength of the metallized film, the less restricted it is in the vacuum coating process, and the yield rate is significantly improved, which helps to improve the coating quality of the metallized film, thereby effectively improving its anti-puncture performance.

[0086] Test Example 1

[0087] The more water content in the corona auxiliary liquid, the more blurred the grid of the liquid film layer of the corona auxiliary liquid on the surface of the cured film, resulting in huge differences in the thermal shrinkage rate of the film in different areas, with the maximum difference reaching more than 2.1%, which seriously affects the uniformity and quality of the film. After a large number of tests, it was found that when the water content is below 12.04%, the uniformity is best, and the maximum difference is below 0.4%.

[0088] The corona auxiliary liquid is prepared by mixing sodium hexafluoroantimonate, propylene glycol and water in a mass ratio of 1:x:999. The corresponding impact strength change curve is shown in FIG. Figure 1 .

[0089] Depend on Figure 1 It can be seen that x is preferably 6300.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame retardant and anti-puncture metallized film, characterized in that: The flame retardant and anti-puncture metallized film is obtained by forming a metal coating on the surface of the flame retardant modified insulating film through a vacuum coating process; the preparation process of the flame retardant modified insulating film comprises the following steps: Step 1, mixing polymer particles with flame retardant and extruding them into thin film sheets through an extruder; Step 2, biaxially stretching the extruded film sheet to obtain a stretched film; Step 3, cooling the stretched film through a cooling roller to obtain a solidified film; Step 4, spraying a corona auxiliary liquid on the surface of the cured film, the corona auxiliary liquid forms a grid-shaped liquid film layer on the surface of the cured film, and then performing a corona treatment on the surface of the cured film on the side sprayed with the liquid film layer; Step 5: After the corona treatment is completed, the film is washed with deionized water and dried to obtain the flame retardant modified insulating film.

2. The flame retardant and anti-puncture metallized film according to claim 1, characterized in that: The corona auxiliary liquid is prepared by mixing sodium hexafluoroantimonate, propylene glycol and water in a mass ratio of 1:6300:

999.

3. The flame retardant and anti-puncture metallized film according to claim 1, characterized in that: The polymer particles are one or more of polyethylene particles, polypropylene particles, and polycarbonate particles.

4. The flame retardant and anti-puncture metallized film according to claim 1, characterized in that: The mass ratio of the polymer particles to the flame retardant is 100:2.

3.

5. The flame retardant and anti-puncture metallized film according to claim 1, characterized in that: The flame retardant is tris(isopropylphenyl) phosphate or resorcinol bis(diphenyl phosphate).

6. The flame retardant and anti-puncture metallized film according to claim 1, characterized in that: A film corona treatment machine is used for corona treatment, the output power of which is 10-15kW, and the corona treatment voltage is 12000-13000V.

7. A capacitor, comprising an aluminum shell, a capacitor core, and an epoxy resin layer for encapsulating the capacitor core, characterized in that: The capacitor core is made of a flame-retardant and anti-puncture metallized film as claimed in any one of claims 1 to 6 through winding and gold spraying.

8. A capacitor according to claim 7, characterized in that: The raw materials of the epoxy resin layer are composed of epoxy resin glue and flame retardant filler.

9. A capacitor according to claim 8, characterized in that: The mass ratio between the epoxy resin glue and the flame retardant filler is 100:(30-50).

10. A capacitor according to claim 8, characterized in that: The flame retardant filler is aluminum hydroxide or magnesium hydroxide.

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