Composite heating film and its preparation method and application

Abstract

The present invention discloses a composite heating film and a preparation method and application thereof, comprising the following steps: S10: providing a slurry, making the slurry adhere to the surface of a base film, preparing a preheating film, wherein the slurry contains graphite, and the material of the base film contains polyimide; S20: heat treating the preheating film at 220°C to 230°C for 1h to 3h, at 1000°C to 1500°C for 1h to 3h, and at 2500°C to 3100°C for 1h to 3h. The slurry containing graphite is subjected to a porous treatment and is sintered at high temperature on the base film to form a porous structure oil-conducting layer, which can not only effectively penetrate smoke and not block smoke, but also further store and absorb oil and facilitate the heating of the heating film, and is combined with a carbonized and graphitized polyimide film. The composite heating film obtained after the two are combined is not only resistant to high temperature and oxidation, but also has good flexibility and can be installed in special-shaped smoking utensils and a variety of modular equipment with oil storage and oil-conducting structures.

Description

Technical Field

[0001] The present invention relates to the field of tobacco, and in particular to a composite heating film and a preparation method and application thereof. Background Art

[0002] Electronic cigarettes (E-Cigarette), also known as electronic nicotine delivery systems, are electronic devices that deliver nicotine to the respiratory system through electronic heating. The device uses a heating wire to electrically heat the nicotine-containing electronic cigarette liquid to generate smoke, which is inhaled into the mouth and absorbed through the lungs, thereby simulating the entire process of smoking real cigarettes. The components of electronic cigarettes mainly include batteries, atomizers, and cigarette cartridges. By heating the electronic cigarette liquid in the cigarette cartridge, a smoke aerosol is generated to achieve the smoking behavior of simulated cigarettes. Electronic cigarette smoke, also known as electronic cigarette aerosol, is an aerosol mainly containing a mixture of flavors and fragrances such as 1,2-propylene glycol, glycerin or nicotine.

[0003] Traditional electronic cigarettes use heating wires or heating sheets to generate heat. The surface of the wires or sheets is difficult to roughen, so small holes are etched on the metal surface to increase the oil absorption surface so that the oil can be absorbed in a timely manner. After the oil is absorbed, it can bring better atomization effect and obtain a better taste. However, the above process is complicated, and it will reduce the strength of the heating wire and the service life is short. Summary of the invention

[0004] Based on this, in order to ensure the atomization effect and optimize the process of preparing the heating film, it is necessary to provide a composite heating film and its preparation method and application.

[0005] The present invention provides a method for preparing a composite heating film, comprising the following steps:

[0006] S10: providing a slurry and a base film, and making the slurry adhere to the surface of the base film to prepare a preheating film, wherein the slurry comprises graphite, and the base film comprises polyimide;

[0007] S20: heat-treating the preheating film at 220° C. to 230° C. for 1 h to 3 h, heat-treating at 1000° C. to 1500° C. for 1 h to 3 h, and heat-treating at 2500° C. to 3100° C. for 1 h to 3 h to prepare a laminated oil-conducting layer and a heating network.

[0008] In one embodiment, in step S10, the slurry forms a plurality of discontinuous holes on the surface of the base film.

[0009] In one of the embodiments, in step S10, using a screen printing method, the slurry passes through the screen printing plate with circular patterns of different diameters in sequence from small to large, and is attached to the surface of the base film to form a plurality of discontinuous holes.

[0010] In one embodiment, after step S10 and before step S20, the base film is further subjected to a punching process to form a porous structure.

[0011] In one embodiment, the diameter of each hole in the porous structure is 50 microns to 150 microns.

[0012] In one embodiment, the slurry comprises the following components in parts by weight: 30 to 45 parts of graphite, 20 to 35 parts of resin, and 30 to 60 parts of additives.

[0013] In one embodiment, the size of the graphite is 800 mesh to 1250 mesh.

[0014] In one embodiment, the preparation method satisfies one or more of the following conditions:

[0015] (1) In step S20, heat treatment is performed in a nitrogen atmosphere at a temperature of 1000° C. to 1500° C. for 1 h to 3 h;

[0016] (2) In step S20, heat treatment is performed in an argon atmosphere at a temperature of 2500°C to 3100°C for 1 hour to 3 hours.

[0017] In one embodiment, after step S20, a step of preparing an electrode sheet on the heating net is also included.

[0018] Furthermore, the present invention also provides a composite heating film, which is prepared according to the above-mentioned preparation method of the composite heating film.

[0019] The present invention further provides the use of the above-mentioned composite heating film in the preparation of electronic cigarettes.

[0020] By making the above-mentioned slurry containing graphite porous, that is, forming a porous oil-conducting layer after high-temperature sintering on the base membrane, it can not only effectively pass smoke without blocking smoke, but also further store and absorb oil and facilitate the heating of the heating film. In combination with the carbonized and graphitized polyimide film, the composite heating film obtained by the combination of the two is not only resistant to high temperature and oxidation, but also has good flexibility and can be installed in special-shaped smoking utensils and a variety of modular equipment with oil storage and oil guide structures as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1A side cross-sectional view of a composite heating film provided in one embodiment;

[0022] Figure 2 A top view of a composite heating film provided in one embodiment;

[0023] Figure 3 A side cross-sectional view of a composite heating film provided in yet another embodiment;

[0024] Figure 4 A bottom view of a composite heating film provided in another embodiment;

[0025] Wherein, 10: composite heating film, 101: oil conductive layer, 102: heating net, 103: electrode sheet, d is the diameter of the hole formed by the slurry attached to the surface of the base film. DETAILED DESCRIPTION

[0026] The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present invention, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0028] Unless otherwise indicated, all percentages, fractions and ratios are calculated based on the total mass of the composition of the present invention. Unless otherwise indicated, all masses of listed ingredients are given as active substances, so they do not include solvents or by-products that may be contained in commercially available materials. The term "mass percentage content" herein may be represented by the symbol "%".

[0029] As used herein, "includes," "comprising," "including," "containing," "having," or other variations are intended to encompass non-closed inclusions, and no distinction is made between these terms. The term "comprising" means that other steps and ingredients that do not affect the end result may be added. The term "comprising" also includes the terms "consisting of" and "consisting essentially of." The compositions and methods / processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. As used herein, no distinction is made between the terms "efficacy," "performance," "effect," and "efficacy."

[0030] The words "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0031] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0033] The present invention provides a method for preparing a composite heating film, comprising the following steps S10 to S20:

[0034] Step S10: providing a slurry and a base film, and making the slurry adhere to the surface of the base film to prepare a preheating film, wherein the slurry comprises graphite, and the base film comprises polyimide;

[0035] Step S20: heat-treat the pre-heating film at 220°C to 230°C for 1h to 3h, heat-treat at 1000°C to 1500°C for 1h to 3h, and heat-treat at 2500°C to 3100°C for 1h to 3h to prepare a laminated oil-conducting layer and a heating network.

[0036] It can be understood that the oil-conducting layer is formed by heat-treating the slurry in the preheating film, and the heating network is formed by heat-treating the base film in the preheating film.

[0037] In a specific example, in step S10, the slurry adheres to the surface of the base film and forms a plurality of discontinuous holes.

[0038] Furthermore, the slurry is attached to the surface of the base film to form a plurality of holes with a diameter of 20 micrometers to 100 micrometers.

[0039] In a specific example, using the screen printing method, the slurry passes through the screen printing plates with circular patterns of different diameters in order from small to large, and is attached to the surface of the base film to form a plurality of discontinuous holes.

[0040] It can be understood that the same screen printing screen has a circular pattern with the same diameter and is discontinuous, the centers of the circular patterns on different screen printing screens can overlap, and the diameter of the circular pattern is 20 microns to 100 microns. Further, a plurality of screen printing screens with circular patterns of different diameters are provided, and the slurry is sequentially passed through the screen printing screens with circular patterns of different diameters according to the diameter of the circular patterns on the screen printing screens from small to large, and the centers of the circular patterns on different screen printing screens are overlapped when the slurry is applied multiple times, and the slurry is surrounded by a plurality of discontinuous holes on the surface of the base film, and the diameter of the hole is the smallest on the side close to the base film surface, and the diameter is the largest on the side away from the base film surface.

[0041] Furthermore, the thickness of the slurry is determined by the number of printings, that is, the more screen printing plates are selected, the more printing times are performed, and the thicker the slurry printed on the surface of the base film is. Specifically, the thickness of the slurry attached to the base film is 5 microns to 100 microns, and preferably, the thickness of the slurry attached to the base film is 10 microns to 30 microns.

[0042] In a specific example, the slurry includes the following components by weight: 30 to 45 parts of graphite, 20 to 35 parts of resin, and 30 to 60 parts of additives.

[0043] Furthermore, the composition of the above resin may include, but is not limited to, polyester and acrylic.

[0044] In a specific example, the above-mentioned auxiliary agent includes a binder and a solvent, specifically, the mass ratio of the binder to the solvent is (5-8): (30-50). It can be understood that the binder can be but is not limited to one or more of polyvinyl butyral (PVB), polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA), and the solvent can be but is not limited to one or more of N-methylpyrrolidone (NMP) and dimethylformamide (DMF).

[0045] Specifically, the slurry includes the following components in parts by weight: 30 to 45 parts of graphite, 20 to 35 parts of resin, 5 to 8 parts of binder, and 30 to 50 parts of solvent.

[0046] It can be understood that the above-mentioned graphite is preferably artificial synthetic graphite, which has strong heat generation explosiveness and extremely high thermal conductivity. After subsequent treatment at 220℃~230℃ for 1h~3h, a thin layer of porous carbon can be initially formed on the surface, which can effectively pass through the flue gas without blocking the flue gas. In addition, it can further store oil absorption and facilitate the heating of the heating film.

[0047] In a specific example, the size of the graphite is 800 mesh to 1250 mesh. It can be understood that graphite powder is preferably used here, and its size specifically refers to the particle size of the graphite powder being 800 mesh to 1250 mesh. Specifically, the size of the above-mentioned graphite can be but is not limited to 800 mesh, 850 mesh, 900 mesh, 950 mesh, 1000 mesh, 1050 mesh, 1100 mesh, 1150 mesh, 1200 mesh or 1250 mesh.

[0048] Furthermore, the processing temperature may be, but is not limited to, 220°C, 222°C, 224°C, 226°C, 228°C or 230°C.

[0049] By making the above-mentioned slurry containing graphite porous, that is, forming a porous oil-conducting layer after high-temperature sintering on the base membrane, and combining with a plurality of discontinuous holes surrounded by the slurry on the surface of the base membrane, it can not only effectively pass through the smoke without blocking the smoke, but also further reserve and absorb oil and facilitate the heating of the heating film. In combination with the carbonized and graphitized polyimide film, the composite heating film obtained by the combination of the two is not only resistant to high temperature and oxidation, but also has good flexibility and can be installed in special-shaped smoking utensils and a variety of modular equipment with oil storage and oil guide structures as needed.

[0050] In a specific example, after step S10 and before step S20, the base film is further punched to form a porous structure.

[0051] In a specific example, the diameter of each pore in the porous structure is 50 microns to 150 microns. The above-mentioned porous structure is punched on the surface of the base membrane (i.e., the horizontal surface) along the thickness direction (i.e., the vertical surface). The holes in the formed porous structure penetrate the surface of the base membrane (i.e., the horizontal surface), that is, the base membrane material on the surface of the base membrane (i.e., the horizontal surface) after the punching treatment is removed, and the holes in the porous structure do not overlap and are connected by the base membrane material.

[0052] Further, the thickness of the base film is 12 microns to 150 microns. Specifically, the thickness of the base film can be but is not limited to 12 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, 110 microns, 120 microns, 130 microns, 140 microns or 150 microns.

[0053] It can be understood that the shape of the pre-heating film can be limited according to shape requirements before heat treatment. For example, the pre-heating film forms a roll structure after being rolled, and the graphite tube core is placed in the center of the roll structure and heat treated together, wherein the slurry and the graphite tube core are respectively placed on both sides of the base film.

[0054] In a specific example, in step S20, before the heat treatment at 1000°C to 1500°C for 1h to 3h and after the heat treatment at 220°C to 230°C for 1h to 3h, it also includes heat treatment at 300°C to 350°C for 3h to 4h and then cooling to room temperature.

[0055] It can be understood that the above processing temperature can be but is not limited to 300°C, 310°C, 320°C, 330°C, 340°C or 350°C.

[0056] In a specific example, in step S20, heat treatment is performed in a nitrogen atmosphere at a temperature of 1000°C to 1500°C for 1 hour to 3 hours.

[0057] Further, the processing temperature may be, but is not limited to, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, 1400°C or 1500°C.

[0058] In a specific example, in step S20, heat treatment is performed in an argon atmosphere at a temperature of 2500° C. to 3100° C. for 1 h to 3 h.

[0059] Furthermore, the processing temperature may be, but is not limited to, 2500°C, 2600°C, 2700°C, 2800°C, 2900°C, 3000°C or 3100°C.

[0060] It can be understood that the purpose of the above-mentioned heat treatment at a temperature of 300℃~350℃, in a nitrogen atmosphere and an argon atmosphere is, firstly, to further form a thin layer of porous carbon on the surface with excellent oil conductivity, which can effectively pass through the smoke without blocking the smoke, and further reserve the absorbed oil and facilitate the heating of the heating film; secondly, to carbonize and graphitize the base film, and form a porous heating network in combination with the porous treatment, which can pass the smoke oil and smoke, and has low suction resistance.

[0061] In a specific example, after step S20, a step of preparing an electrode sheet on the heating net is also included.

[0062] Furthermore, the step of preparing the electrode sheet includes cleaning the preheating film after the heat treatment, and then preparing the electrode by physical vapor deposition method on the side of the preheating film away from the slurry under vacuum state.

[0063] It can be understood that the electrode material can be, but is not limited to, one or more of pure copper, brass, silver, graphite, iron, iron alloy and tungsten alloy.

[0064] Specifically, the physical vapor deposition method may be, but is not limited to, one or more of vacuum evaporation, sputtering and ion plating.

[0065] It can be understood that the preparation method of the composite heating film comprises the following steps:

[0066] Providing a slurry, the slurry comprising the following components by weight: 30 to 45 parts of graphite, 20 to 35 parts of resin, 5 to 8 parts of a binder, and 30 to 50 parts of a solvent;

[0067] Mix the components of the slurry, brush the slurry onto a screen printing plate with a circular pattern with a diameter of 20 micrometers to 100 micrometers, and form a corresponding pattern on the polyimide base film by screen printing;

[0068] After punching the polyimide film on the preheating film, put the preheating film into a carbonization furnace, heat the carbonization furnace uniformly at a rate of 10℃ / min~12℃ / min to 220℃~230℃, the treatment time is 1h~3h, heat the carbonization furnace uniformly at a rate of 10℃ / min~12℃ / min to 300~350℃, the treatment time is 3h~4h, and cool to room temperature. Then, in a nitrogen atmosphere, heat the membrane uniformly at a rate of 3℃ / min~5℃ / min to 1000℃~1500℃ in the carbonization furnace, the treatment time is 1h~3h. Then, in an argon atmosphere, use an ultra-high temperature furnace to raise the temperature to 2500℃~3100℃ at a heating rate of 3℃ / min~5℃ / min, the treatment time is 1h~3h, and cool to room temperature;

[0069] The preheating film after heat treatment is used to prepare an electrode on the side away from the slurry by physical vapor deposition method: the preheating film after heat treatment is ultrasonically cleaned in alcohol, and then placed in a physical vapor deposition device, the cavity is evacuated, and the electrode sheet is prepared by coating.

[0070] By making the above-mentioned slurry containing graphite porous, that is, forming an oil-conducting layer with a porous structure after high-temperature sintering on the base membrane, and combining with a plurality of discontinuous holes surrounded by the slurry on the surface of the base membrane, it can not only effectively penetrate the smoke without blocking the smoke, but also further reserve and absorb oil and facilitate the heating of the heating film. In combination with the carbonized and graphitized polyimide film, the composite heating film obtained by combining the two is not only resistant to high temperature and oxidation, but also has good flexibility and can be installed in special-shaped smoking utensils and a variety of modular equipment with oil storage and oil guide structures as needed.

[0071] Furthermore, if Figure 1 The present invention also provides a composite heating film 10, which is prepared according to the above-mentioned composite heating film preparation method, and includes a stacked porous heating mesh 102 and a porous oil-conducting layer 101, wherein d is the diameter of the holes formed by the slurry attached to the surface of the base film, that is, the diameter of the circular pattern on the screen printing screen used when the slurry is screen printed, that is, Figure 1 The slurry is sequentially printed onto the porous oil-conducting layer 101 formed by the base film according to the order of the diameters of the circular patterns of different screen printing plates from small to large. Figure 2 This is a top view of the composite heating film 10.

[0072] In a specific example, if Figure 3 The composite heating film 10 provided by the present invention further includes an electrode sheet 103, which is located on a side of the porous heating net 102 away from the porous oil-conducting layer 101. Figure 4 For this bottom view of the composite heating film 10, it can be understood that the top view of the composite heating film 10 is different from the top view of the composite heating film 10. Figure 2 same.

[0073] The present invention further provides the use of the above-mentioned composite heating film 10 in the preparation of electronic cigarettes.

[0074] The following specific examples are provided to further illustrate the composite heating film and the preparation method thereof in detail. Unless otherwise specified, the raw materials involved in the following specific implementation methods can all be commercially available.

[0075] Example 1

[0076] This embodiment provides a composite heating film, the preparation steps of which include:

[0077] Providing a slurry, the slurry comprises the following components by weight: 30 parts of artificial synthetic graphite, 30 parts of polyester and acrylic acid, 5 parts of a binder (PMMA, PVB, PVA) and 40 parts of a solvent (nitromethylpyrrolidone);

[0078] Mix the components of the above slurry, select four silk-screen screens with circular patterns of the same diameter, and the centers of the circular patterns on different silk-screen screens can overlap, the diameters of the circular patterns on the four silk-screen screens are 50 microns, 70 microns, 90 microns and 100 microns respectively, and print the slurry with a thickness of 5 microns on each silk-screen screen in the order of the diameter of the circular pattern from small to large, and print the slurry into a slurry with a thickness of 20 microns, and form a corresponding pattern on a polyimide base film with a thickness of 20 microns by silk-screen printing;

[0079] The polyimide film on the preheating film is punched to form a porous structure with a diameter of 50 microns. The preheating film is rolled to form a roll structure. The graphite tube core is placed in the center of the roll structure. The preheating film is placed in a carbonization furnace. The carbonization furnace is heated to 230°C at a rate of 10°C / min to 12°C / min for 3 hours. The carbonization furnace is heated to 350°C at a rate of 10°C / min to 12°C / min for 4 hours, and then cooled to room temperature. Then, the membrane is placed in a nitrogen atmosphere and the carbonization furnace is heated to 1500°C at a rate of 3°C / min to 5°C / min for 3 hours. Then, in an argon atmosphere, an ultra-high temperature furnace is used to raise the temperature to 3100°C at a heating rate of 3°C / min to 5°C / min. The treatment time is 3 hours, and then cooled to room temperature.

[0080] The heat-treated preheating film is deposited on the side away from the slurry by PVD to prepare an electrode: the heat-treated preheating film is ultrasonically cleaned in alcohol, and then placed in a PVD device, the cavity is vacuumed, and a coating is performed to prepare an electrode sheet.

[0081] Example 2

[0082] This embodiment provides a composite heating film, the preparation steps of which include:

[0083] Providing a slurry, the slurry comprises the following components by weight: 40 parts of artificial synthetic graphite, 30 parts of polyester and acrylic acid, 5 parts of a binder and 40 parts of a solvent;

[0084] Mix the components of the above slurry, select four silk-screen screens with circular patterns of the same diameter, and the centers of the circular patterns on different silk-screen screens can overlap, the diameters of the circular patterns on the four silk-screen screens are 50 microns, 70 microns, 90 microns and 100 microns respectively, and print the slurry with a thickness of 5 microns on each silk-screen screen in the order of the diameter of the circular pattern from small to large, and print the slurry into a slurry with a thickness of 20 microns, and form a corresponding pattern on a polyimide base film with a thickness of 20 microns by silk-screen printing;

[0085] The polyimide film on the preheating film is punched to form a porous structure with a diameter of 50 microns. The preheating film is rolled to form a roll structure. The graphite tube core is placed in the center of the roll structure. The preheating film is placed in a carbonization furnace. The carbonization furnace is heated to 230°C at a rate of 10°C / min to 12°C / min for 3 hours. The carbonization furnace is heated to 350°C at a rate of 10°C / min to 12°C / min for 4 hours, and then cooled to room temperature. Then, the membrane is placed in a nitrogen atmosphere and the carbonization furnace is heated to 1500°C at a rate of 3°C / min to 5°C / min for 3 hours. Then, in an argon atmosphere, an ultra-high temperature furnace is used to raise the temperature to 3100°C at a heating rate of 3°C / min to 5°C / min. The treatment time is 3 hours, and then cooled to room temperature.

[0086] The heat-treated preheating film is deposited on the side away from the slurry by PVD to prepare an electrode: the heat-treated preheating film is ultrasonically cleaned in alcohol, and then placed in a PVD device, the cavity is vacuumed, and a coating is performed to prepare an electrode sheet.

[0087] Example 3

[0088] This embodiment provides a composite heating film, the preparation steps of which include:

[0089] Providing a slurry, the slurry comprising the following components by weight: 45 parts of artificial synthetic graphite, 30 parts of polyester and acrylic acid, 5 parts of a binder and 40 parts of a solvent;

[0090] Mix the components of the above slurry, select four silk-screen screens with circular patterns of the same diameter, and the centers of the circular patterns on different silk-screen screens can overlap, the diameters of the circular patterns on the four silk-screen screens are 50 microns, 70 microns, 90 microns and 100 microns respectively, and print the slurry with a thickness of 5 microns on each silk-screen screen in the order of the diameter of the circular pattern from small to large, and print the slurry into a slurry with a thickness of 20 microns, and form a corresponding pattern on a polyimide base film with a thickness of 20 microns by silk-screen printing;

[0091] The polyimide film on the preheating film is punched to form a porous structure with a diameter of 50 microns. The preheating film is rolled to form a roll structure. The graphite tube core is placed in the center of the roll structure. The preheating film is placed in a carbonization furnace. The carbonization furnace is heated to 230°C at a rate of 10°C / min to 12°C / min for 3 hours. The carbonization furnace is heated to 350°C at a rate of 10°C / min to 12°C / min for 4 hours, and then cooled to room temperature. Then, the membrane is placed in a nitrogen atmosphere and the carbonization furnace is heated to 1500°C at a rate of 3°C / min to 5°C / min for 3 hours. Then, in an argon atmosphere, an ultra-high temperature furnace is used to raise the temperature to 3100°C at a heating rate of 3°C / min to 5°C / min. The treatment time is 3 hours, and then cooled to room temperature.

[0092] The heat-treated preheating film is deposited on the side away from the slurry by PVD to prepare an electrode: the heat-treated preheating film is ultrasonically cleaned in alcohol, and then placed in a PVD device, the cavity is vacuumed, and a coating is performed to prepare an electrode sheet.

[0093] Comparative Example 1

[0094] 35 parts of diatomaceous earth, 10 parts of SiO 2 , Li 2 O, ZnO, BaO, K 2 O and Na 2 O combination of glass powder, 20 parts of acrylic acid, 5 parts of binder (PMMA) and 30 parts of solvent (nitromethylpyrrolidone), silk-screened into a slurry with a thickness of 20 microns, the mesh size is 830 mesh silk-screen printing, and finally the test obtains a diatomaceous earth porous material with a thickness of 20 microns, which is cured at 150°C for 2h and sintered at 900°C for 3h to obtain a diatomaceous earth-based porous oil-absorbing layer, which is compounded with an unperforated artificial graphite sheet of the same thickness as the silk-screened slurry to form a heating element to obtain the composite heating film of this comparative example.

[0095] The oil absorption and atomization effect of the composite heating films provided in the above embodiments and the heating films provided in the comparative examples were tested, and the test results are shown in the following table.

[0096] Oil absorption of oil absorbing layer g Fever temperature ℃ Atomizing 2g of e-liquid time Comparative Example 1 2.21 200 5 Example 1 2.33 200 3 Example 2 2.44 200 4 Example 3 2.31 200 3

[0097] It can be seen that the composite heating film provided by the present invention not only has a higher oil absorption capacity but also has a good atomization effect at the same heating temperature.

[0098] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above-described embodiments only express several implementation methods of the present invention, which are convenient for understanding the technical solutions of the present invention in detail, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the contents of the attached claims, and the description and drawings can be used to explain the contents of the claims.

Claims

1. A method for preparing an electronic cigarette composite heating film, It is characterized in that The following steps are involved: S10: providing a slurry and a base film, and making the slurry adhere to the surface of the base film to prepare a preheating film, wherein the slurry comprises the following components by weight: 30 to 45 parts of graphite, 20 to 35 parts of resin, and 30 to 60 parts of an auxiliary agent, wherein the auxiliary agent comprises a binder and a solvent, and the material of the base film comprises polyimide; S20: heat-treating the preheating film at 220° C. to 230° C. for 1 h to 3 h, heat-treating at 1000° C. to 1500° C. for 1 h to 3 h, and heat-treating at 2500° C. to 3100° C. for 1 h to 3 h to prepare a laminated oil-conducting layer and a heating network.

2. The method for preparing the composite heating film according to claim 1, It is characterized in that In step S10, the slurry forms a plurality of discontinuous holes on the surface of the base film.

3. The method for preparing the composite heating film according to claim 2, It is characterized in that The slurry is attached to the surface of the base film to form a plurality of holes with a diameter of 20 micrometers to 100 micrometers.

4. The method for preparing the composite heating film according to claim 1, It is characterized in that After step S10 and before step S20, the base film is punched to form a porous structure.

5. The method for preparing the composite heating film according to claim 4, It is characterized in that The diameter of each hole in the porous structure is 50 microns to 150 microns.

6. The method for preparing the composite heating film according to claim 1, It is characterized in that The size of the graphite is 800-1250 meshes.

7. The method for preparing the composite heating film according to claim 1, It is characterized in that The preparation method meets one or more of the following conditions: (1) In step S20, heat treatment is performed in a nitrogen atmosphere at a temperature of 1000° C. to 1500° C. for 1 h to 3 h; (2) In step S20, heat treatment is performed in an argon atmosphere at a temperature of 2500°C to 3100°C for 1 hour to 3 hours.

8. The method for preparing the composite heating film according to any one of claims 1 to 7, It is characterized in that After step S20, the method further includes the step of preparing an electrode sheet on the heating net.

9. A composite heating film, It is characterized in that It is prepared according to the preparation method of the composite heating film according to any one of claims 1 to 8.

10. Use of the composite heating film as claimed in claim 9 in the preparation of electronic cigarettes.

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