Polyphenylene sulfide film for capacitors and preparation method thereof

Abstract

The present invention provides a polyphenylene sulfide film for capacitors and a preparation method thereof, belonging to the technical field of capacitor film preparation. The method comprises the following steps: S01, mixing polyphenylene sulfide raw materials, melt-mixing, and weighing out molten mixtures 1 and 2 in a ratio of 2:1; S02, adding mixture 1 to a film blowing machine, blow-molding the mixture into a cylindrical film, and symmetrically cutting the cylindrical film into an upper film and a lower film; S03, uniformly mixing mixture 2 with insulating fiber shreds, and forming the product into a core film by tape casting; S04, placing the upper film and the lower film on either side of the core film, respectively, feeding the three-layer film into a laminating machine for hot-melt lamination, and after multiple extrusion and extension, extending the film into a film of a specified thickness. The insulating fiber shreds in the composite film enhance the strength and toughness of the capacitor film, and the polyphenylene sulfide films on both sides cover the insulating fibers, thereby protecting the capacitor film from subsequent metal plating.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitor film preparation, and in particular to a polyphenylene sulfide film for capacitors and a preparation method thereof. Background Art

[0002] Polyphenylene sulfide (PPS) film, a high-performance thermoplastic engineering plastic film, boasts excellent heat and corrosion resistance, insulation, flame retardancy, good mechanical properties, and dimensional stability. It holds broad market potential in China. Due to its exceptional properties, PPS film has been widely used in film capacitors.

[0003] However, in the increasingly mature capacitor technology, the thickness of the film is made thinner and thinner. While optimizing the thickness of the film, the strength and toughness of the film will also be reduced. During the capacitor processing, the scrap rate of the film increases, which increases the capacitor processing cost. Summary of the Invention

[0004] In view of the above problems in the prior art, the present invention provides a polyphenylene sulfide film for capacitors and a preparation method thereof.

[0005] In a first aspect, the present application provides a method for preparing a polyphenylene sulfide film for capacitors, using the following technical solution:

[0006] A method for preparing a polyphenylene sulfide film for a capacitor comprises the following steps:

[0007] S01: 60-75 parts of polyphenylene sulfide resin, 15-30 parts of inorganic filler, 3-5 parts of thermal conductive agent, 3-5 parts of curing agent, and 1-2 parts of toughening agent are mixed and melt-blended and extruded through an extruder. Molten mixture 1 and mixture 2 are weighed out in a ratio of 2:1.

[0008] S02, adding the mixture into a film blowing machine, blowing it into a cylindrical film, and symmetrically cutting the cylindrical film into an upper film and a lower film;

[0009] S03, adding 1.5 times the weight of insulating fiber shreds to the mixture 2, mixing them evenly using an oscillator, and forming a core film by casting and stretching using a casting machine;

[0010] S04, the upper film and the lower film are respectively attached to the upper and lower surfaces of the core film, and sent into a compounding machine, and are pressed into a composite film. After multiple extrusion and stretching, the composite film is stretched into a film of a specified thickness.

[0011] Furthermore, in step S03, the insulating fibers are broken into glass fibers.

[0012] Furthermore, in step S03, a blowing device is provided on the casting machine on the side of the core film on the casting roller away from the casting roller, and the blowing device is used to continuously blow air to the core film on the casting roller toward one end of the casting roller, and the temperature of the air blown out by the blowing device is 95~125℃.

[0013] Furthermore, a combing roller is rotatably provided at the outlet end of the casting machine. The combing roller is used to squeeze the core film, and a plurality of comb teeth are spirally provided on the outer wall of the combing roller.

[0014] Furthermore, the outlet end of the casting machine is located downstream of the carding roller and is rotatably provided with a smoothing roller, which contacts the same side of the core film as the carding roller and is used to flatten the surface of the core film.

[0015] Furthermore, in step S04, the explosion-proof agent is evenly coated on both sides of the core film before being fed into the laminating machine;

[0016] The explosion-proof agent is prepared by dissolving an antistatic agent and a UV light-curing resin in a solvent to obtain a coating liquid;

[0017] After the composite film is stretched to a specified thickness, it is irradiated with ultraviolet light to form an antistatic and explosion-proof layer on both sides of the core film in the composite film.

[0018] Furthermore, in step S04, adhesive is evenly applied to the upper and lower surfaces of the laminating machine that are in contact with the core film.

[0019] Furthermore, the insulating fiber shreds are made of glass fibers, and the diameter of the glass fibers is 5-17 μm.

[0020] Furthermore, in step S04, the edges of the upper film, lower film and core film in front of the compounding machine are cut so that the upper film, lower film and core film are aligned and overlapped when entering the compounding machine.

[0021] In a second aspect, the present application provides a polyphenylene sulfide film for capacitors, which adopts the following technical solution:

[0022] A polyphenylene sulfide film for capacitors is produced by adopting a preparation method according to the first aspect of the present application.

[0023] In summary, this application has at least one of the following beneficial effects:

[0024] 1. By laminating two layers of polyphenylene sulfide film on both sides of a composite film composed of a mixture of polyphenylene sulfide and insulating fiber shreds, and then pressing the three layers of film together into a single film, the insulating fiber shreds in the composite film are used to enhance the strength and toughness of the capacitor film. The polyphenylene sulfide films on both sides can effectively cover the insulating fibers, effectively preventing the insulating fibers from being exposed outside the capacitor film, thereby protecting the subsequent metal plating on the surface of the capacitor film.

[0025] 2.By blowing hot air in one direction on the core film wound by the casting roller on the casting machine, the core film on the casting roller is kept softened. At the same time, the insulating fibers in the core film are blown in one direction, so that the fibers can be tilted in the width direction of the core film, thereby reducing the possibility of the core film being lifted from the core film during the winding process.

[0026] 3. The surface of the core film is squeezed successively by the carding roller and the leveling roller, so that the fibers emerging from the surface of the core film can be squeezed into the core film, while keeping the surface of the core film flat, which is convenient for the subsequent composite process of the upper film and the lower film. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic flow chart of a method for preparing a polyphenylene sulfide film for a capacitor according to Example 1 of the present application;

[0028] Figure 2 This is a schematic structural diagram of the blowing device according to Example 1 of the present application;

[0029] Figure 3 This is a schematic structural diagram of the combing roller of Example 1 of the present application.

[0030] Among them, 1. Blowing device; 11. Blowing pipe; 12. Heater; 13. Blower; 2. Combing roller. DETAILED DESCRIPTION

[0031] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0032] Example 1

[0033] The embodiment of the present invention discloses a method for preparing a polyphenylene sulfide film for capacitors, referring to Figure 1 , including the following steps:

[0034] S01, 70 parts of polyphenylene sulfide resin, 28 parts of inorganic filler, 5 parts of thermal conductor, 5 parts of curing agent, and 2 parts of toughening agent are mixed, melt-blended and extruded through an extruder, and molten mixture 1 and mixture 2 are weighed out in a ratio of 2:1.

[0035] The inorganic filler may be calcium carbonate, talc, aluminum hydroxide, or the like. In the embodiment of the present application, borosilicate may be used as the inorganic filler. The thermal conductor may be one or more of methylbenzotriazole, triethanolamine, sodium tripolyphosphate, boron nitride, polyether, and diatomaceous earth. The curing agent may be one or more of polyamide, methyltetrahydrophthalic anhydride, and alicyclic amine. The toughening agent may be one or more of polyurethane, styrene, and polybutylene terephthalate.

[0036] S02, adding the mixture into a film blowing machine, forming the mixture into a cylindrical film through blow molding, and then symmetrically cutting the cylindrical film into an upper film and a lower film.

[0037] The upper film and the lower film are guided by conveyor rollers and transported forward separately.

[0038] S03, adding chopped insulating fibers to the second mixture, mixing them evenly, and forming the mixture into a core film by casting and stretching the mixture through a casting machine.

[0039] Among them, during the mixing process of the insulating fiber crumbs and the mixture 2, the two are weighed and mixed in a weight ratio of 1.5:1 to form the mixture 3, and the mixture 3 is placed in the shaker for shaking. During the shaking process, the mixture 3 is continuously stirred at a low speed so that the fiber crumbs can be fully immersed in the mixture 2, and the bubbles in the mixture 3 during the mixing process can be effectively shaken out to keep the mixture 3 compact.

[0040] Specifically, the insulating fiber can be glass fiber, wherein the diameter of the glass fiber is preferably 5-17 μm. Glass fiber has good insulation performance and strong heat resistance, and can effectively cope with the high voltage composite and high temperature working environment of capacitor film.

[0041] Furthermore, in order to make the fibers in the core film be biased to be parallel to the width direction of the core film, in an embodiment of the present application, a blowing device 1 is provided on the side of the core film on the casting roller away from the casting roller on the casting machine. The blowing device 1 is used to continuously blow air to the core film on the casting roller toward one end of the casting roller, and the temperature of the air blown out by the blowing device 1 is 95~125℃. The blowing device 1 may include a blowing pipe 11 arranged parallel to the casting roller, and a plurality of nozzles are spaced apart along the length direction of the blowing pipe 11 on the side of the blowing pipe 11 close to the casting roller, and the outlet axes of the plurality of nozzles are all inclined toward the same end of the casting roller. A heater 12 and a blower 13 are connected to one end of the blowing pipe 11 in sequence, and the blower 13 supplies air to the blowing pipe 11, and the heater 12 accurately controls the temperature and heats the air supplied to the blowing pipe 11.

[0042] By blowing hot air obliquely on the core film on the casting roller, the surface of the core film can be softened by heat melting, and the fiber fragments floating on the surface of the core film can be combed in the right direction. This can effectively prevent the fiber fragments on the surface of the core film parallel to the length direction of the core film from detaching from the core film and warping up during the process of winding the core film into a capacitor, so as to cause scratches and punctures on the metal plating in the capacitor, thereby improving the stability of the capacitor.

[0043] Furthermore, a combing roller 2 is rotatably mounted at the outlet end of the casting machine. The outer wall of the combing roller 2 is spirally provided with a plurality of comb teeth. The combing roller 2 is used to squeeze the core film. Specifically, during the rotation of the combing roller 2, the linear velocity of the edge of the combing roller 2 should not be equal to the conveying speed of the core film. As the core film passes over the combing roller 2, the comb teeth on the surface of the combing roller 2 can squeeze the surface of the core film in a direction that is the same as the blowing direction of the blowing device 1.

[0044] The combing roller 2 can further comb the fiber fragments on the surface of the core film. At the same time, when the combing roller 2 squeezes the core film, it can also cause the mixture in the core film to roll and squeeze the insulating fiber fragments, which can effectively squeeze the fiber fragments on the surface of the core film into the core film, thereby increasing the mixing effect of the fiber fragments in the core film.

[0045] After the core film is squeezed by the carding roller 2, uneven areas may appear on its surface. This can cause bubbles to form on the surface when it is subsequently bonded to the upper or lower film, affecting the final film formation. In an embodiment of the present application, a smoothing roller is provided at the outlet of the casting machine, located downstream of the carding roller 2. The smoothing roller and the carding roller 2 contact the same side of the core film and are used to flatten the surface of the core film. After the core film surface is flattened by the smoothing roller, the core film can be tightly and evenly bonded to the upper or lower film, improving the final film formation.

[0046] S04, the upper film and the lower film are respectively attached to the upper and lower surfaces of the core film, and sent into a compounding machine, and are pressed into a composite film. After multiple extrusion and stretching, the composite film is stretched into a film of a specified thickness.

[0047] Before entering the laminating machine, an explosion-proofing agent can be evenly applied to both sides of the core film before it enters the laminating machine. In the present embodiment, the explosion-proofing agent can be prepared by dissolving an antistatic agent and a UV-curable resin in a solvent to form a coating liquid. This coating liquid is evenly applied to both sides of the core film before being laminated with the upper and lower films. After lamination, the composite film is stretched to a specified thickness and then irradiated with ultraviolet light to form an antistatic and explosion-proof layer on both sides of the core film.

[0048] By forming an antistatic and explosion-proof layer on both sides of the core film, the strength and insulation capacity of the formed capacitor film can be effectively enhanced, thereby improving the stability and safety of the capacitor.

[0049] In order to ensure that the upper film and the lower film can be firmly adhered to the core film during the composite process, in an embodiment of the present application, adhesive is evenly coated on the upper film and the lower film in front of the composite machine on the side that is used to contact the core film. This can improve the structural strength between the upper film, the lower film and the core film in the composite film, so that the three-layer film can be evenly extended during the extension process of the composite film.

[0050] Furthermore, in an embodiment of the present application, a cutting device is provided at the entrance of the compounding machine, and the cutting device includes a cutting knife. The cutting device is mainly used to cut the upper film, lower film and core film in front of the compounding machine that have not been sprayed with explosion-proof agent and adhesive, so that the three layers of film in the compounding machine have the same width, the three layers of film are neatly aligned and pressed, and the film texture is uniform.

[0051] The working process of the present invention is as follows: two layers of polyphenylene sulfide film are sandwiched on both sides of a film made by mixing polyphenylene sulfide film solvent and insulating fiber shreds, and the three layers are then compositely pressed into a film. During the film formation process, the insulating fiber shreds can make the prepared capacitor film have higher performance. At the same time, since a layer of polyphenylene sulfide film is also composited on both sides of the core film, the fiber shreds can be effectively prevented from scratching or puncturing the metal coating on the capacitor film, thereby improving the safety performance of the capacitor.

[0052] Example 2

[0053] Based on the unified inventive concept, the present embodiment further discloses a polyphenylene sulfide film for capacitors. The polyphenylene sulfide film is manufactured using the method for preparing a polyphenylene sulfide film for capacitors provided in the first embodiment of the present invention.

[0054] It will be understood by those skilled in the art that although preferred embodiments of the present invention have been described, further changes and modifications may be made to these embodiments once those skilled in the art are aware of the underlying inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the claims and equivalents of the present invention.

Claims

1. A method for preparing a polyphenylene sulfide film for capacitors, characterized in that: include: S01: 60-75 parts of polyphenylene sulfide resin, 15-30 parts of inorganic filler, 3-5 parts of thermal conductive agent, 3-5 parts of curing agent, and 1-2 parts of toughening agent are mixed and melt-blended and extruded through an extruder. Molten mixture 1 and mixture 2 are weighed out in a ratio of 2:

1. S02, adding the mixture into a film blowing machine, blowing it into a cylindrical film, and symmetrically cutting the cylindrical film into an upper film and a lower film; S03, adding 1.5 times the weight of the second mixture of insulating fiber shreds to the second mixture, mixing them evenly using an oscillator, and forming the core film by casting and stretching using a casting machine; S04, laminating the upper film and the lower film to the upper and lower surfaces of the core film respectively, sending them into a laminating machine, and pressing them into a composite film. After multiple extrusion and stretching, the composite film is stretched into a film of a specified thickness.

2. The method for preparing a polyphenylene sulfide film for capacitors according to claim 1, characterized in that: In step S03, a blowing device is provided on the casting machine on the side of the core film on the casting roller away from the casting roller, and the blowing device is used to continuously blow air to the core film on the casting roller toward one end of the casting roller, and the temperature of the air blown out by the blowing device is 95-125°C.

3. The method for preparing a polyphenylene sulfide film for capacitors according to claim 2, wherein: A combing roller is rotatably provided at the outlet end of the casting machine. The combing roller is used to squeeze the core film. A plurality of comb teeth are spirally provided on the outer wall of the combing roller.

4. The method for preparing a polyphenylene sulfide film for capacitors according to claim 3, wherein: The outlet end of the casting machine is located downstream of the carding roller and is rotatably provided with a smoothing roller. The smoothing roller and the carding roller are in contact with the same side of the core film and are used to flatten the surface of the core film.

5. The method for preparing a polyphenylene sulfide film for capacitors according to claim 1, wherein: In the step S04, the explosion-proof agent is evenly coated on both sides of the core film before being fed into the laminating machine; The explosion-proof agent is dissolved in a solvent using an antistatic agent and a UV light-curing resin to obtain a coating liquid; After the composite film is stretched to a specified thickness, it is irradiated with ultraviolet light to form antistatic and explosion-proof layers on both sides of the core film in the composite film.

6. The method for preparing a polyphenylene sulfide film for capacitors according to claim 1, characterized in that: In step S04, adhesive is evenly applied to the surfaces of the upper and lower films in front of the laminating machine that are in contact with the core film.

7. The method for preparing a polyphenylene sulfide film for capacitors according to claim 1, characterized in that: The insulating fiber chops are made of glass fibers, and the diameter of the glass fibers is 5-17 μm.

8. The method for preparing a polyphenylene sulfide film for capacitors according to any one of claims 1 to 7, characterized in that: In step S04, the edges of the upper film, lower film and core film in front of the compounding machine are cut so that the upper film, lower film and core film are aligned and overlapped when entering the compounding machine.

9. A polyphenylene sulfide film for capacitors, characterized in that: The film is produced by the method for preparing a polyphenylene sulfide film for capacitors according to any one of claims 1 to 7.

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