A method for preparing a composite insulating film for PTC using a polyimide film as a carrier

Abstract

The application discloses a preparation method of a composite insulating film for PTC with a polyimide film as a carrier, and relates to the field of heat-conducting insulating films.The technical scheme is as follows: S1, preparing a first coupling agent; S2, performing surface treatment on a polyimide film layer; S3, preparing a first heat-conducting adhesive layer with a heat conductivity of 2.0 W / m*K-9.0 W / m*K; S4, preparing a second heat-conducting adhesive layer with a heat conductivity of 0.5 W / m*K-7.0 W / m*K; S5, forming a heat-conducting polyimide-based composite insulating film; and S6, pasting a release layer.The application has the advantages of high heat conductivity and low thermal resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat-conducting insulation film, more particularly, it relates to a preparation method of a composite insulation film for PTC with a polyimide film as a carrier. BACKGROUND

[0002] The positive temperature coefficient thermistor (PTC) ceramic is a ferroelectric ceramic with semiconductor properties, which presents a stepwise increase in resistance due to phase transition above the Curie temperature. Due to such resistance-temperature characteristics, the material increases in resistance and decreases in power after temperature rise, and decreases in resistance and increases in power after temperature drop, which can produce a similar effect as a thermostat. Existing electric heating assemblies based on PTC ceramic usually adopt PTC ceramic sheets covered with planar electrodes and metal electrode sheets, which are pressed or welded together and insulated by wrapping polyimide (PI) insulation film. Although the polyimide film has good heat resistance and electrical insulation, it has low thermal conductivity (<0.8 W / m·K), which results in poor heat dissipation, thereby hindering the heat dissipation of PTC ceramic and causing low thermal efficiency and reduced long-term reliability.

[0003] In addition, the currently marketed heat-conducting sheet also has a double-layer heat-conducting sheet including a PI film and a heat-conducting adhesive layer arranged on one side of the PI film. In order to achieve high heat-conducting effect, such heat-conducting sheet is usually filled with a large particle size and a large number of heat-conducting powders, which makes the heat-conducting sheet have poor adhesion and cannot be closely attached between the PTC and the heated object, resulting in large heat loss and poor heat-conducting performance.

[0004] Therefore, it is necessary to propose a new scheme to solve this problem. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application aims to provide a preparation method of a composite insulation film for PTC with a polyimide film as a carrier, which has the advantages of high heat conductivity and low thermal resistance.

[0006] The above technical purpose of the present application is achieved by the following technical scheme: a preparation method of a composite insulation film for PTC with a polyimide film as a carrier, comprising the following steps:

[0007] S1, preparing a first coupling agent: preparing a first coupling agent containing a group capable of undergoing coupling hydrolysis reaction at one end and a hydrogen silicon group at the other end;

[0008] S2, surface treatment of the polyimide film layer: the two surfaces of the polyimide film layer are respectively subjected to corona or plasma treatment, the first coupling agent is diluted, and then is coated on the two surfaces of the polyimide film after corona or plasma treatment by spraying or dipping, and the surface-treated polyimide film layer is obtained after high-temperature baking.

[0009] S3, preparing a first thermal conductive adhesive layer with a thermal conductivity of 2.0 W / m·K-9.0 W / m·K;

[0010] S4, preparing a second thermal conductive adhesive layer with a thermal conductivity of 0.5 W / m·K-7.0 W / m·K;

[0011] S5, forming of the thermal conductive polyimide-based composite insulation film: the first thermal conductive adhesive layer and the second thermal conductive adhesive layer are respectively calendered on both sides of the surface-treated polyimide film layer by using a calender forming process, and a thermal conductive polyimide-based composite insulation film semi-finished product is obtained after heating and curing;

[0012] S6, pasting release layers: the first release layer and the second release layer are respectively pasted on both sides of the thermal conductive polyimide-based composite insulation film semi-finished product, and a thermal conductive polyimide-based composite insulation film finished product is obtained.

[0013] The first thermal conductive adhesive layer and the second thermal conductive adhesive layer both comprise vinyl silicone oil.

[0014] In one embodiment, the method for preparing the first coupling agent in step S1 comprises the following steps: under a nitrogen environment, a reaction container equipped with a stirrer and a reflux condenser is added with 100 g of double-end hydrogen-containing silicone oil with a viscosity of 100 cps, 200 g of isopropyl alcohol, and 0.1 g of platinum gold catalyst with a platinum gold content of 20,000 ppm; after uniform stirring at a temperature of 50°C, 28.9 g of isopropyl alcohol solution containing 10% trimethoxyvinylsilane is added dropwise; and then the reaction is carried out at a temperature of 80°C for 2 hours to obtain the first coupling agent.

[0015] In one embodiment, the first thermal conductive adhesive layer and the second thermal conductive adhesive layer both further comprise hydrogen-containing silicone oil, an inhibitor, a second coupling agent, aluminum nitride, zinc oxide, color powder, and multiple types of aluminum oxide with different particle sizes, wherein the aluminum oxide is spherical-like aluminum oxide or block-shaped aluminum oxide.

[0016] In one embodiment, the method for preparing the first thermal conductive adhesive layer comprises the following steps:

[0017] S31, in a first planetary mixer, vinyl silicone oil, hydrogen-containing silicone oil, an inhibitor, a second coupling agent, and color powder are sequentially added and stirred uniformly, and then platinum gold catalyst is added;

[0018] S32, after step S31 is completed, rapid stirring is carried out under vacuum, and after uniform stirring, aluminum oxide with different particle sizes, aluminum nitride, and zinc oxide are sequentially added;

[0019] S33, after step S32, stirring is carried out under a vacuum degree of ≤0.1 MPa for 1.5 hours to obtain the first thermal conductive adhesive layer.

[0020] In one embodiment, the preparation method of the second thermal conductive glue layer comprises the following steps:

[0021] S41, in the second planetary mixer, add vinyl silicone oil, hydrogen-containing silicone oil, inhibitor and second coupling agent in turn, after stirring evenly, add platinum gold catalyst;

[0022] S42, after completing step S41, then under the condition of vacuum pumping, stir quickly, after stirring evenly, add aluminum oxide, aluminum nitride and zinc oxide with different particle sizes in turn;

[0023] S43, after step S42, stir for 1.5 hours under the condition of vacuum degree≤0.1MPa, obtain the second thermal conductive glue layer.

[0024] In one embodiment, the inhibitor is cyclohexyl alkyne alcohol, and the second coupling agent is trimethoxy octadecyl silane.

[0025] In one embodiment, the thickness of the polyimide film layer is 0.01mm-1.10mm.

[0026] In one embodiment, the first coupling agent in step S2 is diluted by isopropyl alcohol by 30-40 times.

[0027] In one embodiment, the group that can occur coupling hydrolysis reaction in step S1 is trimethoxy or triethoxy.

[0028] In one embodiment, the inhibitor is cyclohexyl alkyne alcohol.

[0029] In summary, the present application has the following advantages: the present application uses a first coupling agent with a silicon-hydrogen group that can react with vinyl silicone oil to perform surface treatment on the polyimide film layer, so that the first thermal conductive adhesive layer, the second thermal conductive adhesive layer and the polyimide film layer are connected by chemical connection, thereby improving the tightness and stability of the connection, and by setting the thermal conductivity of the first thermal conductive adhesive layer to 2.0 W / m·K-9.0 W / m·K and the thermal conductivity of the second thermal conductive adhesive layer to 0.5 W / m·K-7.0 W / m·K, the particle size of the thermal conductive powder in the first thermal conductive adhesive layer is larger, and the thermal conductive paths are more easily formed between the large particle size thermal conductive powders, so that the first thermal conductive adhesive layer has good thermal conductivity, the connection between the first thermal conductive adhesive layer and the PTC is usually connected in a sleeved manner, and the large particle size thermal conductive powder has little effect on the connection stability between the first thermal conductive adhesive layer and the polyimide film layer, so that the heat of the PTC can be discharged to the target heat receiver in a large amount, the target heat receiver is usually connected to the second thermal conductive adhesive layer by pasting, and the second thermal conductive adhesive layer uses small particle size thermal conductive powder, so that the roughness of the small particle size thermal conductive powder is relatively small, so that the contact area between the second thermal conductive adhesive layer and the target heat receiver is larger and the adhesion is tighter, which is beneficial to eliminating the interfacial thermal resistance between the second thermal conductive adhesive layer and the target heat receiver, so that the present application has the advantages of high thermal conductivity and low thermal resistance. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] Embodiment 1

[0032] The embodiments of the present application provide a preparation method of a PTC composite insulating film taking a polyimide film as a carrier, which comprises the following steps:

[0033] S1, preparing a first coupling agent: preparing a first coupling agent containing a group capable of undergoing coupling hydrolysis reaction at one end and a hydrogen silicon group at the other end;

[0034] S2, surface treatment of the polyimide film layer: performing corona or plasma treatment on both sides of the polyimide film layer respectively, diluting the first coupling agent, and then coating it on both sides of the polyimide film layer treated by corona or plasma by spraying or dipping, and obtaining the surface-treated polyimide film layer after high-temperature baking;

[0035] S3, preparing a first thermal conductive adhesive layer with a thermal conductivity of 5.5 W / m·K;

[0036] S4, preparing a second thermal conductive adhesive layer with a thermal conductivity of 3.5 W / m·K;

[0037] S5, forming of the thermal conductive polyimide-based composite insulation film: using a calendering forming process, the first thermal conductive adhesive layer and the second thermal conductive adhesive layer are respectively calendered on both sides of the surface-treated polyimide film layer, and after heating and curing, a thermal conductive polyimide-based composite insulation film semi-finished product is obtained;

[0038] S6, the first release layer and the second release layer are respectively attached to both sides of the thermal conductive polyimide-based composite insulation film semi-finished product, and a thermal conductive polyimide-based composite insulation film finished product is obtained.

[0039] The first thermal conductive adhesive layer and the second thermal conductive adhesive layer both comprise vinyl silicone oil.

[0040] In this embodiment, the method for preparing the first coupling agent in step S1 is as follows: under a nitrogen environment, a reaction container equipped with a stirrer and a reflux condenser is added with 100 g of double-end hydrogen-containing silicone oil with a viscosity of 100 cps, 200 g of isopropyl alcohol, and 0.1 g of platinum gold catalyst with a platinum gold content of 20,000 ppm. After uniform stirring at a temperature of 50°C, 28.9 g of isopropyl alcohol solution containing 10% trimethoxyvinylsilane is added dropwise, and then the reaction is carried out at a temperature of 80°C for 2 hours to obtain the first coupling agent.

[0041] In this embodiment, the first thermal conductive adhesive layer and the second thermal conductive adhesive layer both further comprise hydrogen-containing silicone oil, an inhibitor, a second coupling agent, aluminum nitride, zinc oxide, color powder, and multiple types of aluminum oxide with different particle sizes. The aluminum oxide is spherical-like aluminum oxide or block-shaped aluminum oxide.

[0042] In this embodiment, the method for preparing the first thermal conductive adhesive layer with a thermal conductivity of 5.5 W / m·K comprises the following steps:

[0043] S31, in the first planetary mixer, 80 g of vinyl silicone oil with a viscosity of 500 cps, 21 g of hydrogen-containing silicone oil with a viscosity of 500 cps, 4 g of an inhibitor, 0.3 g of a second coupling agent, and 2 g of blue color powder are sequentially added, and after uniform stirring, 1 g of platinum gold catalyst with a platinum gold content of 20,000 ppm is added;

[0044] S32, after step S31, then under the condition of vacuum, fast stirring, stirring uniform after adding different particle size of alumina, D50 particle size of 10 microns of aluminum nitride 87g and D50 particle size of 1 microns of zinc oxide 160g; The different particle size of alumina is specifically: D50 particle size of 2 microns of alumina 275g, D50 particle size of 15 microns of alumina 550g, D50 particle size of 100 microns of alumina 900g. It should be noted that the different particle size of alumina, aluminum nitride and zinc oxide are called heat conducting powder.

[0045] S33, after step S32, under the condition of vacuum degree≤0.1MPa, stirring for 1.5 hours, the first heat conducting glue layer is obtained.

[0046] In this embodiment, the preparation method of the second heat conducting glue layer with thermal conductivity of 3.5W / m·K includes the following steps:

[0047] S41, in the second planetary mixer, 90g of vinyl silicone oil with viscosity of 500cps, 31g of hydrogen containing silicone oil with viscosity of 500cps, 4g of inhibitor, 0.3g of second coupling agent and 2g of blue color powder are added in turn, and after stirring uniformly, 1g of platinum gold catalyst with platinum gold content of 20000ppm is added;

[0048] S42, after step S41, then under the condition of vacuum, fast stirring, stirring uniform after adding different particle size of alumina, D50 particle size of 10 microns of aluminum nitride 87g and D50 particle size of 1 microns of zinc oxide 160g; The different particle size of alumina is specifically: D50 particle size of 2 microns of alumina 275g, D50 particle size of 15 microns of alumina 550g, D50 particle size of 50 microns of alumina 900g.

[0049] S43, after step S42, under the condition of vacuum degree≤0.1MPa, stirring for 1.5 hours, the first heat conducting glue layer is obtained.

[0050] In this embodiment, the inhibitor is cyclohexyl alkyne alcohol, and the second coupling agent is trimethoxy octadecyl silane.

[0051] In this embodiment, the thickness of the polyimide film layer is 0.01mm-1.10mm, and preferably 0.38mm in this embodiment.

[0052] In this embodiment, the first coupling agent in step S2 is specifically diluted by isopropyl alcohol by 30 times.

[0053] In this embodiment, the group capable of coupling hydrolysis reaction in step S1 is trimethoxy or triethoxy.

[0054] In this embodiment, the inhibitor is cyclohexyl alkyne alcohol.

[0055] In this embodiment, the first thermal conductive adhesive layer has a thickness of 0.26 mm and a Shore 0085 hardness, and the second thermal conductive adhesive layer has a thickness of 0.08 mm and a Shore 0085 hardness.

[0056] Embodiment 2:

[0057] A preparation method of a composite insulating film for PTC using a polyimide film as a carrier, which is substantially the same as that of Embodiment 1, except that:

[0058] In this embodiment, a first thermal conductive adhesive layer having a thermal conductivity of 7.5 W / m·K is prepared, and a second thermal conductive adhesive layer having a thermal conductivity of 3.0 W / m·K is prepared.

[0059] In this embodiment, the preparation method of the first thermal conductive adhesive layer having a thermal conductivity of 7.5 W / m·K comprises the following steps:

[0060] S31, 170g of vinyl silicone oil with a viscosity of 500cps, 16g of hydrogen-containing silicone oil with a viscosity of 500cps, 4g of inhibitor, 0.3g of second coupling agent and 2g of black color powder or 2g of blue color powder are sequentially added in the first planetary mixer, and after uniform stirring, 1g of platinum gold catalyst with a platinum gold content of 20000ppm is added;

[0061] S32, after completing step S31, rapid stirring is then carried out under vacuum condition, and after uniform stirring, different particle size alumina, 87g of aluminum nitride with a D50 particle size of 20 microns and 160g of zinc oxide with a D50 particle size of 0.5 microns are sequentially added; the different particle size alumina is specifically: 275g of alumina with a D50 particle size of 2 microns, 550g of alumina with a D50 particle size of 15 microns and 350g of alumina with a D50 particle size of 45 microns.

[0062] S33, after step S32, stirring is carried out under the condition that the vacuum degree is less than or equal to 0.1 MPa for 1.5 hours, and the first thermal conductive adhesive layer is obtained.

[0063] In this embodiment, the preparation method of the second thermal conductive adhesive layer having a thermal conductivity of 3.0 W / m·K comprises the following steps:

[0064] S41, 90g of vinyl silicone oil with a viscosity of 500cps, 31g of hydrogen-containing silicone oil with a viscosity of 500cps, 4g of inhibitor, 0.3g of second coupling agent and 2g of blue color powder are sequentially added in the second planetary mixer, and after uniform stirring, 1g of platinum gold catalyst with a platinum gold content of 20000ppm is added;

[0065] S42, after step S41, then under the condition of vacuum, fast stirring, stirring uniform after adding different particle size of alumina, D50 particle size of 10 microns of aluminum nitride 87g and D50 particle size of 1 microns of zinc oxide 160g; the different particle size of alumina is specifically: D50 particle size of 2 microns of alumina 275g, D50 particle size of 15 microns of alumina 550g, D50 particle size of 20 microns of alumina 900g.

[0066] S43, after step S42, under the condition of vacuum degree≤0.1MPa, stirring 1.5 hours, the first thermal conductive adhesive layer is obtained;

[0067] In this embodiment, the first coupling agent in step S2 is specifically diluted by isopropyl alcohol by 40 times.

[0068] The thickness of the first thermal conductive adhesive layer obtained in this embodiment is 0.26mm, and the hardness is Shore 0060, the thickness of the second thermal conductive adhesive layer is 0.08mm, and the hardness is Shore 0060.

[0069] Example 3:

[0070] A preparation method of a composite insulating film for PTC using a polyimide film as a carrier, this embodiment is basically the same as example 1, the only difference is:

[0071] In this embodiment, the first thermal conductive adhesive layer with thermal conductivity of 7.5W / m·K is prepared; the second thermal conductive adhesive layer with thermal conductivity of 2.5W / m·K is prepared;

[0072] In this embodiment, the preparation method of the first thermal conductive adhesive layer with thermal conductivity of 7.5W / m·K adopts the same method as the preparation method of the first thermal conductive adhesive layer with thermal conductivity of 7.5W / m·K in example 2, which will not be described in detail in this embodiment.

[0073] In this embodiment, the preparation method of the second thermal conductive adhesive layer with thermal conductivity of 2.5W / m·K includes the following steps:

[0074] S41, secondly, 90g of vinyl silicone oil with viscosity of 500cps, 25g of hydrogen-containing silicone oil with viscosity of 500cps, 4g of inhibitor, 0.3g of second coupling agent and 2g of blue color powder are added in the planetary mixer, and then 1g of platinum gold catalyst with platinum gold content of 20000ppm is added after stirring uniformly;

[0075] S42, after step S41, then under the condition of vacuum, fast stirring, stirring uniform after adding different particle size of alumina, D50 particle size of 10 microns of aluminum nitride 87g and D50 particle size of 0.5 microns of zinc oxide 100g; the different particle size of alumina is: D50 particle size of 2 microns of alumina 275g, D50 particle size of 15 microns of alumina 550g, D50 particle size of 45 microns of alumina 650g.

[0076] S43, after step S42, under the condition of vacuum degree≤0.1MPa, stirring for 1.5 hours, the first thermal conductive adhesive layer is obtained.

[0077] In this embodiment, the first coupling agent in step S2 is specifically diluted 40 times by isopropyl alcohol.

[0078] The thickness of the first thermal conductive adhesive layer obtained in this embodiment is 0.26mm, the hardness is Shore 0060, the thickness of the second thermal conductive adhesive layer is 0.33mm, the hardness is Shore 0075.

[0079] Comparative example 1: compared with example 2, this embodiment only coats the first thermal conductive adhesive layer with thermal conductivity of 7.5W / m·K on one side of the polyimide film.

[0080] Comparative example 2: compared with example 2, it is basically the same as example 2, the only difference is that the thermal conductivity of the first thermal conductive adhesive layer and the second thermal conductive adhesive layer is 7.5W / m·K.

[0081] Take example 1 to example 3 and comparative example 1 and comparative example 2 to carry out thermal resistance experiment analysis in actual use, the specific experimental method is: the first thermal conductive adhesive layer of the application is connected with PTC, the second thermal conductive adhesive layer is connected with target heat receiver, the heat of fixed temperature is emitted by PTC, and then the heat received by target heat receiver is detected, so that the experimental results can be calculated, and the results are as follows:

[0082]

[0083] It can be seen from the above embodiment 1, embodiment 2 and embodiment 3 that in embodiment 2, when the thermal conductivity of the first thermal conductive adhesive layer is 7.5 W / m·K and the thermal conductivity of the second thermal conductive adhesive layer is 3.0 W / m·K, the thermal resistance of the polyimide-based composite insulation film is the smallest and the thermal conductivity is the best; it can be seen from the comparison between embodiment 2 and comparative example 1 that when the first thermal conductive adhesive layer is coated on only one side of the polyimide film, the thermal resistance of the polyimide-based composite insulation film is the largest and the thermal conductivity is the worst; in comparative example 2, although a first thermal conductive adhesive layer with a higher thermal conductivity is used, no second thermal conductive adhesive layer is provided, resulting in a large interfacial thermal resistance between the polyimide-based composite insulation film and the target heated body, and the heat entering the polyimide-based composite insulation film will be blocked and retained, so that it cannot be transferred to the target heated body in large quantities and efficiently; it can be seen from the comparison between embodiment 2 and comparative example 2 that in comparative example 2, a first thermal conductive adhesive layer and a second thermal conductive adhesive layer with a higher thermal conductivity are used, which effectively reduces the thermal resistance of the polyimide-based composite insulation film, but the thermal resistance is still larger than that of embodiment 2. The reason for this situation may be that the first thermal conductive adhesive layer and the second thermal conductive adhesive layer both use a larger thermal conductivity, so that the particle size of the thermal conductive powder of the first thermal conductive adhesive layer and the second thermal conductive adhesive layer is larger, and the roughness is larger, so that the first thermal conductive adhesive layer and the PTC and the second thermal conductive adhesive layer and the target heated body are not tightly fitted, which easily causes the loss of heat, thereby resulting in relatively weak thermal conductivity.

[0084] It should be noted that the above embodiments are only preferred embodiments of the present application, as long as the thermal conductivity of the first thermal conductive adhesive layer is 2.0 W / m·K-9.0 W / m·K and the thermal conductivity of the second thermal conductive adhesive layer is 0.5 W / m·K-7.0 W / m·K, they are within the protection scope of the present application.

[0085] In summary, the application uses a first coupling agent with a silicon hydrogen group that can react with a vinyl silicone oil to perform surface treatment on a polyimide film layer, so that the first thermally conductive adhesive layer, the second thermally conductive adhesive layer, and the polyimide film layer are connected by chemical connection, thereby improving the tightness and stability of the connection, and by setting the thermal conductivity of the first thermally conductive adhesive layer to 2.0 W / m·K-9.0 W / m·K and the thermal conductivity of the second thermally conductive adhesive layer to 0.5 W / m·K-7.0 W / m·K, the particle size of the thermally conductive powder in the first thermally conductive adhesive layer is larger, and the thermally conductive paths between the large particle size thermally conductive powders are more easily formed, so that the first thermally conductive adhesive layer has good thermal conductivity, the connection between the first thermally conductive adhesive layer and the PTC is usually connected in a sleeved manner, and the large particle size thermally conductive powder has little effect on the connection stability between the first thermally conductive adhesive layer and the polyimide film layer, so that the heat of the PTC can be largely directed towards the target heat receiver, the target heat receiver is usually connected to the second thermally conductive adhesive layer by pasting, and the second thermally conductive adhesive layer uses a small particle size thermally conductive powder, and the roughness of the small particle size thermally conductive powder is relatively small, so that the contact area between the second thermally conductive adhesive layer and the target heat receiver is larger and the adhesion is tighter, which is conducive to eliminating the interfacial thermal resistance between the second thermally conductive adhesive layer and the target heat receiver, thereby making the application have the advantages of high thermal conductivity and low thermal resistance.

[0086] The above is only a preferred embodiment of the application, and the protection scope of the application is not limited to the above-mentioned embodiments. It should be noted that in the above-mentioned embodiments of the application, only the case of surface treatment of the polyimide film layer by the first coupling agent containing a hydrogen silicon group to make the surface of the polyimide film layer have a hydrogen silicon group is described, and in other embodiments, the hydrogen silicon group in the first coupling agent can be replaced by a vinyl group, so that after surface treatment of the polyimide film layer, the surface of the polyimide film layer contains a vinyl group, and then the first thermally conductive adhesive layer and the second thermally conductive adhesive layer containing an excess of hydrogen silicon groups are compounded with the vinyl group on the surface of the polyimide film layer to have good adhesion. That is, in this embodiment, the first coupling agent, the first thermally conductive adhesive layer, and the second thermally conductive adhesive layer can be used interchangeably, and any technical solution falling within the scope of the application is within the protection scope of the application. It should be noted that for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the application are also considered to be within the protection scope of the application.

Claims

1. A method for producing a composite insulating film for PTC using a polyimide film as a carrier, characterized by: It comprises the following steps: ​ S1, preparing a first coupling agent: preparing a first coupling agent containing a coupling hydrolysis group at one end and a hydrogen silicon group at the other end; S2, surface treatment of the polyimide film layer: respectively performing corona or plasma treatment on both sides of the polyimide film layer, diluting the first coupling agent, and then coating it on both sides of the polyimide film after corona or plasma treatment by spraying or dipping, and obtaining the surface-treated polyimide film layer after high-temperature baking; S3, preparing a first thermal conductivity adhesive layer with a thermal conductivity of 2.0 W / m·K-9.0 W / m·K; S4, preparing a second thermal conductivity adhesive layer with a thermal conductivity of 0.5 W / m·K-7.0 W / m·K; S5, forming of the thermal conductive polyimide-based composite insulation film: using calendering forming process to calender the first and second thermal conductivity adhesive layers on both sides of the surface-treated polyimide film layer respectively, and obtaining the thermal conductive polyimide-based composite insulation film semi-finished product after heating and curing; S6, covering release layer: covering the first and second release layers on both sides of the thermal conductive polyimide-based composite insulation film semi-finished product respectively, and obtaining the thermal conductive polyimide-based composite insulation film finished product, The first and second thermal conductivity adhesive layers both comprise vinyl silicone oil, The particle size of the thermal conductive powder in the first thermal conductivity adhesive layer is larger than that in the second thermal conductivity adhesive layer, The method for preparing the first coupling agent in step S1 is: under nitrogen environment, adding 100g of double-end hydrogen-containing silicone oil with a viscosity of 100cps, 200g of isopropyl alcohol, and 0.1g of platinum gold catalyst with a platinum gold content of 20000ppm into a reaction container equipped with a stirrer and a reflux condenser, stirring uniformly at a temperature of 50℃, then adding 28.9g of isopropyl alcohol solution containing 10% of trimethoxyvinylsilane, and then reacting for 2 hours at a temperature of 80℃ to obtain the first coupling agent; The first and second thermal conductivity adhesive layers both further comprise hydrogen-containing silicone oil, inhibitor, second coupling agent, aluminum nitride, zinc oxide, color powder, and multiple types of aluminum oxide with different particle sizes, and the aluminum oxide is spherical-like or block-shaped.

2. The method for producing a polyimide film-supported composite insulation film for PTC according to claim 1, characterized by: The preparation method of the first thermal conductivity adhesive layer comprises the following steps: S31, adding vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, second coupling agent, and color powder into a first planetary mixer in sequence, stirring uniformly, and then adding platinum gold catalyst; S32, after completing step S31, then rapidly stirring under vacuum condition, and then adding aluminum oxide with different particle sizes, aluminum nitride, and zinc oxide in sequence after stirring uniformly; S33, after step S32, stirring for 1.5 hours under the condition of vacuum degree ≤0.1MPa to obtain the first thermal conductivity adhesive layer.

3. The method for producing a polyimide film-supported composite insulation film for PTC according to claim 1, characterized by: The preparation method of the second thermal conductivity adhesive layer comprises the following steps: S41, adding vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and second coupling agent into a second planetary mixer in sequence, stirring uniformly, and then adding platinum gold catalyst; S42, after completing step S41, then rapidly stirring under vacuum condition, and then adding aluminum oxide with different particle sizes, aluminum nitride, and zinc oxide in sequence after stirring uniformly; S43、after step S42, stirring for 1.5 hours under the condition of vacuum degree ≤0.1 MPa, to obtain the second thermal conductive adhesive layer.

4. The method of claim 1, wherein the polyimide film is prepared by the steps of: (1) dissolving a polyimide precursor in a solvent to prepare a polyimide solution; (2) coating the polyimide solution on a substrate to form a polyimide film; and (3) drying the polyimide film. The inhibitor is cyclohexyl alkyne alcohol, and the second coupling agent is trimethoxy octadecyl silane.

5. The method of claim 1, wherein the polyimide film is prepared by the steps of: (1) dissolving a polyimide precursor in a solvent to prepare a polyimide solution; (2) coating the polyimide solution on a substrate to form a polyimide film; and (3) drying the polyimide film. The thickness of the polyimide film layer is 0.01 mm-1.10 mm.

6. The method of claim 1, wherein the polyimide film is prepared by the steps of: (1) dissolving a polyimide precursor in a solvent to prepare a polyimide solution; (2) coating the polyimide solution on a substrate to form a polyimide film; and (3) drying the polyimide film. The first coupling agent in step S2 is specifically used in isopropanol diluted by 30-40 times.

7. The method of claim 1, wherein the polyimide film is prepared by the steps of: (1) dissolving a polyimide precursor in a solvent to prepare a polyimide solution; (2) coating the polyimide solution on a substrate to form a polyimide film; and (3) drying the polyimide film. The group capable of coupling hydrolysis reaction in step S1 is trimethoxy or triethoxy.

8. The method of claim 1, wherein the polyimide film is prepared by the steps of: (1) dissolving a polyimide precursor in a solvent to prepare a polyimide solution; (2) coating the polyimide solution on a substrate to form a polyimide film; and (3) drying the polyimide film. The inhibitor is cyclohexyl alkyne alcohol.

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