Conductive resonance heating PVB (polyvinyl butyral) sandwich film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of PVB films, in particular to a conductive resonance heating PVB interlayer film and a preparation method and application thereof.The conductive resonance heating PVB interlayer film comprises a PVB middle layer and PVB protection layers located on the two sides of the PVB middle layer, a conductive heating layer is loaded on the PVB middle layer in a hot melting mode and is a conductive circuit based on a carbon-based conductive carrier, and the conductive heating layer is a conductive circuit based on the carbon-based conductive carrier. The carbon-based conductive carrier is a compound of a conductive polymer or a macromolecule and conductive powder, and the PVB middle layer and the PVB protective layer are both prepared from modified PVB resin. According to the conductive resonance heating PVB sandwich film and the preparation method and application thereof, a precise conductive circuit is constructed through the carbon-based conductive carrier, and the modified PVB resin base material is matched, so that the light transmittance, the heating efficiency, the weather resistance and the anti-interference performance are synergistically improved, and the multi-scene defrosting and demisting requirements are met.

Description

Technical Field

[0001] This invention relates to the field of PVB film technology, and in particular to a conductive resonant heating PVB sandwich film, its preparation method, and its application. Background Technology

[0002] PVB (polyvinyl butyral) interlayer film is the core bonding material for composite glass. Due to its excellent light transmittance, mechanical stability, and weather resistance, it is widely used in the automotive, construction, and rail transportation industries. With the increasing demand for glass defrosting and defogging in low-temperature environments, PVB interlayer films with conductive heating functions have become a research hotspot.

[0003] Currently, the mainstream automotive windshield heating system uses resistance wire embedded heating. This requires the resistance wire to be pre-embedded within the glass, which not only compromises the overall light transmittance (≤75%), reducing the driver's visibility, but also, due to the structural limitations of the linear heating element, concentrates heating energy around the resistance wire, resulting in a temperature difference of over 15°C across the glass. This can easily lead to localized overheating and stress cracking. Furthermore, defrosting efficiency is low, requiring over 15 minutes to fully defrost at -30°C, failing to meet emergency travel needs. While traditional conductive PVB films do not require embedded resistance wires, they often achieve heating by adding conductive components such as carbon black and metal powder. These conductive materials are prone to agglomeration, resulting in uneven dispersion and a heating efficiency of ≤50%. Moreover, the addition of a large number of conductive particles further reduces the film's light transmittance (typically ≤70%), making it difficult to simultaneously meet the dual requirements of high light transmittance and efficient heating.

[0004] Existing conductive heating PVB films lack precise eddy current control design. The eddy currents generated after being energized can easily penetrate the glass and act on electronic devices inside vehicles or indoors. In scenarios such as building curtain wall glass and rail transit vehicle windows, the commonly used overall heating PVB films cover the glass surface with a whole conductive film, which cannot adjust the heating area according to the local distribution characteristics of snow accumulation and fog.

[0005] While pure graphene-modified PVB films have high light transmittance, graphene is prone to embrittlement at low temperatures. Carbon black-filled PVB films have good weather resistance, but low light transmittance and high volume resistivity, resulting in insufficient heating power. Metal powder-modified PVB films suffer from the problem of declining conductivity due to metal particle oxidation, and their service life is far less than the designed life of more than 10 years for composite glass.

[0006] In summary, existing conductive heating PVB sandwich films cannot solve the problem of achieving multiple performance synergies such as high light transmittance, efficient heating, low energy consumption, anti-interference, and long lifespan. There is an urgent need to develop a conductive resonant heating PVB sandwich film with innovative structure and process. Summary of the Invention

[0007] The purpose of this invention is to provide a conductive resonant heating PVB sandwich film, its preparation method and application. By constructing a precise conductive circuit through a carbon-based conductive carrier and combining it with a modified PVB resin substrate, the light transmittance, heating efficiency, weather resistance and anti-interference are synergistically improved, meeting the defrosting and defogging needs of multiple scenarios.

[0008] To achieve the above objectives, the present invention provides a conductive resonant heating PVB sandwich film, comprising a PVB interlayer and PVB protective layers located on both sides of the PVB interlayer. A conductive heating layer is hot-melted loaded on the PVB interlayer. The conductive heating layer is a conductive circuit based on a carbon-based conductive carrier. The carbon-based conductive carrier is a composite of a conductive polymer or a polymer and a conductive powder. Both the PVB interlayer and the PVB protective layer are prepared from modified PVB resin.

[0009] Preferably, the conductive polymer includes one of polythiophene-graphene blend, polyaniline-graphene blend, and polypyrrole-graphene blend, wherein the mass of graphene accounts for 0.5 to 1 wt% of the total mass of the conductive polymer.

[0010] Preferably, the polymer in the composite of polymer and conductive powder includes one of polyethylene sheet, polypropylene sheet, and polyester sheet, and the conductive powder includes one of graphite powder, graphene, and silver nanowires.

[0011] Preferably, the modified PVB resin comprises, by weight percentage, 10-15 wt% polymethyl methacrylate, 0.5-1 wt% UV stabilizer, 0.2-0.5 wt% antioxidant, and the balance being PVB resin.

[0012] The above-mentioned method for preparing a conductive resonant heating PVB sandwich film includes the following steps: S1. Preparation of PVB intermediate layer and PVB protective layer: Polymethyl methacrylate, UV stabilizer, antioxidant and PVB resin are added to a high-speed mixer and mixed evenly to obtain modified PVB resin. The modified PVB resin is then pressed into tablets to form PVB intermediate layer and PVB protective layer. S2. Fabrication of conductive circuits: The carbon-based conductive carrier is fabricated into a grid-shaped or ring-shaped conductive circuit; S3, Composite PVB Interlayer Film: The conductive circuit prepared in S2 is placed on the surface of the PVB intermediate layer in S1, and placed in a hot press to fuse the conductive circuit onto the PVB intermediate layer. The PVB intermediate layer with the fused conductive circuit is placed between two PVB protective layers prepared in S1, and placed in a multi-layer co-extrusion machine for co-extrusion composite. After extrusion, it is cooled and shaped to obtain the PVB interlayer film.

[0013] Preferably, the mixing in S1 is carried out by stirring and mixing for 20 to 30 minutes at a speed of 800 to 1200 r / min and a temperature of 120 to 130°C.

[0014] Preferably, when the carbon-based conductive carrier in S2 is a conductive polymer, the conductive circuit is prepared by: weighing the conductive polymer, adding it to the hopper of a casting machine, casting it into a film to obtain a conductive polymer film with a thickness of 0.1~0.2mm; then using a laser etching machine to etch the conductive polymer film to form a ring-shaped or grid-shaped conductive circuit.

[0015] Preferably, when the carbon-based conductive carrier in S2 is a composite of polymer and conductive powder, the conductive circuit is prepared by: adding the polymer and conductive powder into a twin-screw extruder, extruding and molding to obtain a polymer-conductive powder composite film, and then processing a grid-shaped or ring-shaped conductive circuit on the surface of the composite film by chemical etching or laser etching process.

[0016] Preferably, the temperature of the hot melt load in S3 is 150~170℃, the pressure is 3~5MPa, and the time is 10~15min; the temperature of the multi-layer co-extrusion machine is 180~200℃, and the screw speed is 250~300r / min.

[0017] The above-mentioned conductive resonant heating PVB interlayer film is applied to automotive windshields, building curtain wall glass, or rail transit vehicle windows after a metal film layer is laminated on one side of the PVB interlayer film and a magnetic shielding layer is laminated on the other side of the PVB interlayer film.

[0018] Therefore, the present invention, employing the above-mentioned conductive resonant heating PVB sandwich film, its preparation method, and its application, has the following beneficial effects: (1) The addition of polymethyl methacrylate to the modified PVB resin of this invention and the micro-design of the conductive circuit make the light transmittance of the interlayer film ≥85%, which is better than that of traditional resistance wire glass; the high conductivity of the carbon-based conductive carrier ensures complete defrosting within 10 minutes at -30℃, and the heating efficiency is greatly improved.

[0019] (2) By combining a metal film layer and a magnetic shielding layer on both sides of the PVB interlayer film, the eddy current is precisely controlled at 1~2mm on the outer surface of the glass, reducing the interference value to electronic equipment; the addition of UV inhibitors and antioxidants improves the weather resistance of the interlayer film, so that the interlayer film does not crack after 50 cycles at -40℃~80℃, reducing the attenuation of conductivity and extending the service life.

[0020] (3) The process parameters of casting, extrusion, etching and co-extrusion in the preparation process of this invention are clear, which facilitates industrial production; two types of carbon-based conductive carriers can be flexibly selected, and the partitioned heating design is suitable for defrosting and defogging needs in different scenarios such as automobiles, buildings and rail transit, with a wide range of applications.

[0021] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0023] A conductive resonant heating PVB sandwich film includes a PVB interlayer and PVB protective layers located on both sides of the PVB interlayer. A conductive heating layer is hot-melted loaded on the PVB interlayer. The conductive heating layer is a conductive circuit based on a carbon-based conductive carrier. The carbon-based conductive carrier is a composite of a conductive polymer or a polymer and a conductive powder. Both the PVB interlayer and the PVB protective layer are made of modified PVB resin.

[0024] In this invention, the thickness of the PVB interlayer is 0.3~0.5mm, and it is made of modified PVB resin through pressing. It is used to support the conductive heating layer and ensure structural stability. There are two PVB protective layers, located on both sides of the PVB interlayer, each with a thickness of 0.2~0.3mm, which serve as physical protection and light transmission enhancement.

[0025] Preferably, the conductive polymer includes one of polythiophene-graphene blend, polyaniline-graphene blend, and polypyrrole-graphene blend, wherein the mass of graphene accounts for 0.5 to 1 wt% of the total mass of the conductive polymer.

[0026] Preferably, the polymer in the composite of polymer and conductive powder includes one of polyethylene sheet, polypropylene sheet, and polyester sheet, and the conductive powder includes one of graphite powder, graphene, and silver nanowires.

[0027] More preferably, the graphite powder has a particle size of 5~20μm and accounts for 5~8wt% of the total mass of the composite; the graphene monolayer ratio is ≥90% and accounts for 0.5~1wt% of the total mass of the composite; the silver nanowires have a diameter of 50~100nm and a length of 10~20μm and account for 1~2wt% of the total mass of the composite.

[0028] Preferably, the modified PVB resin comprises, by weight percentage, 10-15 wt% polymethyl methacrylate (PMMA), 0.5-1 wt% UV stabilizer, 0.2-0.5 wt% antioxidant, and the balance being PVB resin.

[0029] Preferably, the UV protectant is UV-531 and the antioxidant is antioxidant 1010.

[0030] The above-mentioned method for preparing a conductive resonant heating PVB sandwich film includes the following steps: S1. Preparation of PVB intermediate layer and PVB protective layer: Polymethyl methacrylate, UV stabilizer, antioxidant and PVB resin are added to a high-speed mixer and mixed evenly to obtain modified PVB resin. The modified PVB resin is then pressed into tablets to form PVB intermediate layer and PVB protective layer respectively. The tableting process is existing technology and is not further limited.

[0031] S2. Fabrication of conductive circuits: Carbon-based conductive carriers are fabricated into grid-shaped or ring-shaped conductive circuits.

[0032] S3, Composite PVB Interlayer Film: The conductive circuit prepared in S2 is placed on the surface of the PVB intermediate layer in S1, and placed in a hot press to fuse the conductive circuit onto the PVB intermediate layer. The PVB intermediate layer with the fused conductive circuit is placed between two PVB protective layers prepared in S1, and placed in a multi-layer co-extrusion machine for co-extrusion composite. After extrusion, it is cooled and shaped to obtain the PVB interlayer film.

[0033] Preferably, the mixing in S1 is carried out by stirring and mixing for 20 to 30 minutes at a speed of 800 to 1200 r / min and a temperature of 120 to 130°C.

[0034] Preferably, when the carbon-based conductive carrier in S2 is a conductive polymer, the conductive circuit is prepared by: weighing the conductive polymer, adding it to the hopper of a casting machine, casting it into a film to obtain a conductive polymer film with a thickness of 0.1~0.2mm; then using a laser etching machine to etch the conductive polymer film to form a ring-shaped or grid-shaped conductive circuit.

[0035] More preferably, the temperature of the casting machine hopper is 120~140℃, the casting speed is 0.5~1m / min, the line width of the conductive circuit is 0.1~0.3mm, and the spacing between adjacent conductive circuits is 0.5~2cm.

[0036] Preferably, when the carbon-based conductive carrier in S2 is a composite of polymer and conductive powder, the conductive circuit is prepared by: adding the polymer and conductive powder into a twin-screw extruder, extruding and forming a polymer-conductive powder composite film, and then processing a grid-shaped or ring-shaped conductive circuit on the surface of the composite film by chemical etching or laser etching.

[0037] More preferably, the temperature of the twin-screw extruder is 160~180℃, the screw speed is 300~400r / min, the radius of the conductive circuit is 1~3cm, and the spacing between adjacent conductive circuits is 0.5~2cm.

[0038] Preferably, the temperature of the hot melt load in S3 is 150~170℃, the pressure is 3~5MPa, and the time is 10~15min; the temperature of the multi-layer co-extrusion machine is 180~200℃, and the screw speed is 250~300r / min.

[0039] The above-mentioned conductive resonant heating PVB interlayer film is applied to automotive windshields, building curtain wall glass, or rail transit vehicle windows after a metal film layer is laminated on one side of the PVB interlayer film and a magnetic shielding layer is laminated on the other side of the PVB interlayer film.

[0040] Preferably, the thickness of the metal film is 50~100nm, and the metal film includes one of copper alloy film, silver alloy film, and nickel alloy film.

[0041] Preferably, the thickness of the magnetic shielding layer is 20~50μm, and the material of the magnetic shielding layer includes permalloy.

[0042] In this invention, the metal film layer and the conductive heating layer form a resonant heating system, which precisely defines the eddy current action area; the magnetic shielding layer blocks the penetration of eddy currents, avoids interference with electronic equipment, and adapts to the usage requirements of different scenarios.

[0043] Example 1 A conductive resonant heating PVB sandwich film includes a PVB interlayer and PVB protective layers located on both sides of the PVB interlayer. A conductive heating layer is thermally fused onto the PVB interlayer. The conductive heating layer is a conductive circuit based on a polythiophene-graphene blend (graphene accounts for 0.5 wt% of the total mass of the blend). Both the PVB interlayer and the PVB protective layers are prepared from modified PVB resin. The modified PVB resin comprises, by mass percentage, 10 wt% polymethyl methacrylate, 0.5 wt% UV-531, 0.2 wt% antioxidant 1010, and the balance being PVB resin.

[0044] The above-mentioned method for preparing a conductive resonant heating PVB sandwich film, wherein the raw materials are used in the above proportions, includes the following steps: S1. Preparation of PVB intermediate layer and PVB protective layer: Polymethyl methacrylate, UV stabilizer, antioxidant and PVB resin are added to a high-speed mixer and stirred for 20 minutes at a speed of 800 r / min and a temperature of 120℃ to obtain modified PVB resin. The modified PVB resin is then pressed into tablets to form PVB intermediate layer and PVB protective layer.

[0045] S2. Fabrication of the conductive circuit: Weigh the polythiophene-graphene blend and add it to the hopper of a casting machine. Cast the mixture at 130℃ and a casting speed of 0.8m / min to obtain a conductive polymer film with a thickness of 0.2mm. Subsequently, etch the conductive polymer film using a laser etching machine to form a ring-shaped conductive circuit. The linewidth of the conductive circuit is 0.1mm, and the spacing between adjacent conductive circuits is 0.5cm.

[0046] S3, Composite PVB Interlayer Film: The conductive circuit prepared in S2 is placed on the surface of the PVB intermediate layer in S1, and placed in a hot press. Under the conditions of 150℃ and 3MPa, the conductive circuit is hot-melted and loaded for 10 minutes to fuse the conductive circuit onto the PVB intermediate layer. The PVB intermediate layer with the fused conductive circuit is placed between two PVB protective layers prepared in S1, and placed in a multi-layer co-extruder. Co-extrusion is carried out at a temperature of 180℃ and a screw speed of 250r / min. After extrusion, it is cooled and shaped to obtain the PVB interlayer film.

[0047] Example 2 The difference from Example 1 lies in that the conductive heating layer is a conductive circuit based on a polyaniline-graphene blend (graphene accounts for 0.8 wt% of the total mass of the blend). Step S2 involves weighing the polyaniline-graphene blend, adding it to the hopper of a casting machine, and casting it into a 0.1 mm thick conductive polymer film at a temperature of 120°C and a casting speed of 0.5 m / min. Subsequently, the conductive polymer film is etched using a laser etching machine to form a mesh-like conductive circuit. The linewidth of the conductive circuit is 0.1 mm, and the spacing between adjacent conductive circuits is 0.5 cm. Everything else is the same as in Example 1.

[0048] Example 3 The difference from Example 1 lies in that the conductive heating layer is a conductive circuit based on a polypyrrole-graphene blend (graphene accounts for 1 wt% of the total mass of the blend). Step S2 involves weighing the polypyrrole-graphene blend, adding it to the hopper of a casting machine, and casting it into a film at a temperature of 140°C and a casting speed of 1 m / min to obtain a conductive polymer film with a thickness of 0.2 mm. Subsequently, the conductive polymer film is etched using a laser etching machine to form a ring-shaped conductive circuit. The linewidth of the conductive circuit is 0.3 mm, and the spacing between adjacent conductive circuits is 2 cm. Everything else is the same as in Example 1.

[0049] Example 4 A conductive resonant heating PVB sandwich film includes a PVB interlayer and PVB protective layers located on both sides of the PVB interlayer. A conductive heating layer is hot-melt-loaded on the PVB interlayer. The conductive heating layer is a conductive circuit based on a polyethylene sheet and graphite powder composite (graphite powder accounts for 7 wt% of the total mass of the composite). Both the PVB interlayer and the PVB protective layers are prepared from modified PVB resin. The modified PVB resin includes, by mass percentage, 15 wt% polymethyl methacrylate, 1 wt% UV-531, 0.5 wt% antioxidant 1010, and the balance being PVB resin.

[0050] The above-mentioned method for preparing a conductive resonant heating PVB sandwich film, wherein the raw materials are used in the above proportions, includes the following steps: S1. Preparation of PVB intermediate layer and PVB protective layer: Polymethyl methacrylate, UV stabilizer, antioxidant and PVB resin are added to a high-speed mixer and stirred for 30 minutes at a speed of 1200 r / min and a temperature of 130℃ to obtain modified PVB resin. The modified PVB resin is then pressed into tablets to form PVB intermediate layer and PVB protective layer.

[0051] S2. Fabrication of Conductive Circuits: Polyethylene sheets and graphite powder are added to a twin-screw extruder and extruded at 160℃ and 300 r / min to obtain a polyethylene sheet-graphite powder composite film. Then, a grid-shaped conductive circuit is fabricated on the surface of the composite film using chemical etching or laser etching. The radius of the conductive circuit is 1 cm, and the spacing between adjacent conductive circuits is 0.5 cm.

[0052] S3, Composite PVB Interlayer Film: The conductive circuit prepared in S2 is placed on the surface of the PVB intermediate layer in S1, and placed in a hot press. Under the conditions of temperature 170℃ and pressure 5MPa, the conductive circuit is hot-melted and loaded for 15 minutes to fuse the conductive circuit onto the PVB intermediate layer. The PVB intermediate layer with the fused conductive circuit is placed between two PVB protective layers prepared in S1, and placed in a multi-layer co-extruder. Co-extrusion is carried out under the conditions of temperature 200℃ and screw speed 300r / min. After extrusion, it is cooled and shaped to obtain the PVB interlayer film.

[0053] Example 5 The difference from Example 4 lies in that the conductive heating layer is a conductive circuit based on a polypropylene sheet and a graphene composite (graphene accounts for 0.8 wt% of the total mass of the composite). Step S2 involves adding polyethylene sheet and graphite powder into a twin-screw extruder and extruding them at a temperature of 170°C and a screw speed of 350 r / min to obtain a polyethylene sheet-graphite powder composite film. Then, a grid-shaped conductive circuit is processed on the surface of the composite film using chemical etching or laser etching. The radius of the conductive circuit is 2 cm, and the spacing between adjacent conductive circuits is 1.0 cm. Everything else is the same as in Example 4.

[0054] Example 6 The difference from Example 4 lies in that the conductive heating layer is a conductive circuit based on a composite of polyester sheet and silver nanowires (the silver nanowires account for 2 wt% of the total mass of the composite). Step S2 is as follows: the polyester sheet and silver nanowires are added to a twin-screw extruder and extruded at a temperature of 180°C and a screw speed of 400 r / min to obtain a polymer-conductive powder composite film. Then, a ring-shaped conductive circuit is processed on the surface of the composite film by chemical etching or laser etching. The radius of the conductive circuit is 3 cm, and the spacing between adjacent conductive circuits is 2 cm. Everything else is the same as in Example 4.

[0055] Application Example 1 The above-described embodiment 1 describes the application of a conductive resonant heating PVB interlayer film. A copper alloy film with a thickness of 50 nm is laminated on one side of the PVB interlayer film, and a permalloy magnetic shielding layer with a thickness of 20 μm is laminated on the other side of the PVB interlayer film. The film is then hot-pressed together with an automotive windshield.

[0056] Application Example 2 The above-described embodiment 2 describes the application of a conductive resonant heating PVB interlayer film. A silver alloy film with a thickness of 80 nm is laminated on one side of the PVB interlayer film, and a permalloy magnetic shielding layer with a thickness of 30 μm is laminated on the other side of the PVB interlayer film before hot-pressing it with building curtain wall glass.

[0057] Application Example 3 The above-described embodiment 3 describes the application of a conductive resonant heating PVB interlayer film. A nickel alloy film with a thickness of 100 nm is laminated on one side of the PVB interlayer film, and a permalloy magnetic shielding layer with a thickness of 50 μm is laminated on the other side of the PVB interlayer film. The film is then hot-pressed and laminated with rail transit vehicle window glass.

[0058] Comparative Example 1 Pure PVB resin (without any modifying additives) is added to a single-screw extruder and extruded into a film at a temperature of 180℃ and a screw speed of 200r / min. After cooling and setting, a regular PVB film is obtained.

[0059] Comparative Example 2 Pure PVB resin and 15 wt% carbon black (particle size 30 μm) were added to a low-speed mixer and stirred for 15 min at a speed of 500 r / min and a temperature of 110℃ to obtain a carbon black-PVB mixture.

[0060] The prepared carbon black-PVB mixture was added to a single-screw extruder and extruded into a film at a temperature of 170℃ and a screw speed of 180r / min. After cooling and shaping, a conductive PVB film filled with ordinary carbon black was obtained.

[0061] Comparative Example 3 1 wt% graphene was added to an ethanol solution and ultrasonically dispersed for 30 min (300 W) to obtain a graphene dispersion. The dispersion was mixed with pure PVB resin and stirred for 20 min at 120℃ and 800 r / min. The mixture was then dried at 90℃ for 45 min to remove the ethanol, resulting in a graphene-PVB mixture.

[0062] The graphene-PVB mixture was added to the hopper of the casting machine and cast into a film at a temperature of 130℃ and a casting speed of 0.8m / min. After cooling and shaping, a pure graphene PVB film (without etched circuits and conductive throughout) was obtained.

[0063] Application Comparative Example 1 The ordinary film prepared in Comparative Example 1 was used as a PVB interlayer film to be laminated with glass. Resistance wires with a diameter of 0.1 mm and a spacing of 1 cm were pre-embedded inside the glass. No metal film layer or magnetic shielding layer was laminated. It was directly applied to the windshield of an automobile.

[0064] Application Comparative Example 2 A conductive PVB film filled with ordinary carbon black, prepared in Comparative Example 2, was used as a PVB interlayer film. Without composite metal film and magnetic shielding layer, the conductive PVB film was sandwiched between two layers of ultra-clear glass for building curtain walls and then applied to the building curtain wall glass after hot pressing.

[0065] Application Comparative Example 3 The pure graphene PVB film prepared in Comparative Example 3 was used as the PVB interlayer film. Without the composite metal film layer and magnetic shielding layer, the pure graphene PVB film was hot-pressed and composited with rail transit tempered glass and then applied to the window glass of rail transit vehicles.

[0066] Performance testing The glass containing the PVB interlayer film in corresponding use cases 1-3 and application comparison examples 1-3 were used as sample glass for performance testing, with blank glass as a reference. The test method is as follows: (1) Transmittance: The transmittance of the above sample glass was tested using a UV-Vis spectrophotometer (model: UV-2600, wavelength range 400~760nm, accuracy ±7). The blank glass was used as a reference. Three evenly distributed test points were selected on the surface of each sample glass (avoiding the edge by 5cm). The transmittance was tested separately, and the average value was taken as the final result. The unit is %. The results are shown in Table 1.

[0067] Table 1. Light transmittance of glass with different PVB laminated films

[0068] As shown in Table 1, the glass containing conductive resonant heating PVB interlayer film in Application Examples 1-3 of this invention maintains a light transmittance of over 84%, exhibiting high light transmittance characteristics overall, and the data stability is good. Compared with traditional resistance wire glass (Application Comparative Example 1), it is 16.7%~19.4% higher, overcoming the problem of vision obstruction caused by the embedding of resistance wire in glass, and meeting the core requirements of high light transmittance for automotive windshields, building curtain wall glass, etc. Compared with carbon black filled conductive PVB film glass (Application Comparative Example 2), it is 25.4%~28.4% higher, solving the light scattering problem caused by the agglomeration of conductive powder (such as carbon black) in traditional conductive PVB film. Compared with pure graphene PVB film glass (Application Comparative Example 3), it is 5%~7.5% higher. This invention significantly reduces the light obstruction of the conductive layer through the synergistic effect of modified PVB resin and conductive circuit, achieving a performance balance between high conductivity and high light transmittance.

[0069] (2) Low temperature defrosting efficiency: The high and low temperature environment chamber (model: GDW-100, temperature control range -60 range 00 model, temperature control accuracy ± temperature control accuracy) and electronic stopwatch (accuracy 0.01s) were used to test the low temperature defrosting efficiency of the above sample glass. The sample glass was placed in the high and low temperature environment chamber, cooled to -30 and kept warm for 1 hour; deionized water was evenly sprayed on the sample surface with a sprayer to form a uniform frost layer of 2mm thickness, and left to stand for 30 minutes; the rated voltage was connected (12V for automotive / rail transit scenarios, 220V for building scenarios), and the stopwatch was started to record the time when the frost layer completely melted (no visible frost traces), in min; the sample that was not completely defrosted was recorded as ">20min (not completely defrosted)", and the results are shown in Table 2.

[0070] Table 2 Low-temperature defrosting efficiency of glass with different PVB laminated films

[0071] As shown in Table 2, the defrosting efficiency of Application Examples 1-3 of the present invention in a low temperature environment of -30℃ is significantly better than that of Application Comparative Examples 1-3. The overall defrosting time of Application Examples 1-3 is ≤9.5min, and the data fluctuation is small (deviation ≤0.2min), demonstrating outstanding heating stability and rapid defrosting capability. Compared to traditional resistance wire glass (Application Comparative Example 1), the defrosting time is shortened by 44.4%~47.4%, solving the inherent defects of linear heating elements of resistance wire. Traditional resistance wire heating is concentrated around the wire, resulting in a large temperature difference (up to 15°C or more) across the glass. In contrast, this invention utilizes the planar heating characteristics of carbon-based conductive circuits, combined with a resonant heating system of metal film layers, to achieve uniform heat coverage on the glass surface, significantly reducing defrosting time. Compared to carbon black-filled conductive PVB film glass (Application Comparative Example 2), the defrosting time is shortened by 25.8%~29.7%. The carbon-based conductive carriers used in this invention (such as polythiophene-graphene blends and silver nanowire composites) have low volume resistivity, far superior to carbon black-filled films, resulting in higher conductivity and faster heat generation. Compared to pure graphene PVB film glass (Application Comparative Example 3), the defrosting time is shortened by 20.8%~25%. The precise zoning of the conductive circuit in this invention allows for targeted heating of the frost distribution area. The resonant effect of the metal film layer and the conductive heating layer further enhances the heat conduction efficiency, avoiding the problem of easy heat loss in pure graphene films. The conductive resonant heating PVB interlayer film of this invention can quickly and uniformly defrost in extremely cold environments, fully meeting the needs for efficient heating in scenarios such as emergency car travel and rapid defrosting of building glass.

[0072] (3) Eddy current interference value: Using an electromagnetic interference tester (model: ESCI-3, test frequency 30MHz~1GHz, range 0~120dBμV / m), to simulate the actual application scenario, the PVB interlayer film prepared in Examples 1-6 and Comparative Examples 1-3 and the above sample glass were fixed at a distance of 30cm from the simulated electronic equipment (automotive ECU / building thermostat, working frequency 1MHz~50MHz); the power supply of the PVB interlayer film and sample glass was turned on and kept in a heated state, and the electromagnetic interference value of 3 points around the electronic equipment (10cm, 20cm and 30cm away from the equipment) was tested. The maximum value was taken as the final result, and the unit was dBμV / m; non-conductive was marked as "no conductive function, no eddy current interference", and the results are shown in Table 3.

[0073] Table 3 Eddy current interference values ​​of different PVB interlayer films and glasses with different PVB interlayer films.

[0074] As shown in Table 3, the eddy current interference control capability of the embodiments and application examples of the present invention is significantly better than that of the prior art. The eddy current interference values ​​of Examples 1-6 are lower than those of Comparative Examples 1-3. In Application Examples 1-3 after the composite magnetic shielding layer, the eddy current interference value is further reduced, fully meeting the electromagnetic compatibility requirements of electronic devices. By limiting the size of the conductive circuit parameters, Examples 1-5 ensure that the eddy currents generated by the resonance between the conductive heating layer and the metal film layer act precisely at a distance of 1-2 mm from the outer surface of the glass, preventing the eddy currents from diffusing into the inner electronic devices. Therefore, the interference value without the composite magnetic shielding layer is lower than that of the pure graphene film (Comparative Example 3). In Application Examples 1-3, a 20-50 μm thick permalloy is composited on the non-heated side of the glass, which can further absorb the residual eddy currents penetrating the glass. The interference value is further reduced compared to the embodiments without the composite magnetic shielding layer, and is much lower than that of Application Examples 1-3, completely solving the interference problem of existing conductive heating technology on navigation, sensors and other electronic devices.

[0075] (4) Weather resistance and conductivity degradation rate: The weather resistance and conductivity degradation rate were tested using a high and low temperature cycling test chamber (model: THB-100, temperature range -40°C, humidity range 20%~98%) and a four-probe resistivity meter (model: ST2258C, accuracy ±). The PVB interlayer films prepared in Examples 1-6 and Comparative Examples 1-3 and the above sample glass were placed in the test chamber, and the cycling program was set as follows: -40°C for 2 hours, then heated to 80°C (heating rate 5%). The temperature was maintained at a constant temperature for 2 hours, then decreased to -40°C at a rate of 5:1, completing one cycle. A total of 50 cycles were performed. After the cycles, the PVB interlayer film and the sample glass surface were observed for cracking or delamination, and the appearance was recorded. The volume resistivity before and after the cycles was tested using a four-probe tester, and the conductivity decay rate was calculated (decay rate = (resistivity before cycle - resistivity after cycle) / resistivity before cycle × resistance before cycle). Non-conductive samples were marked as "no conductivity, decay rate not calculated". The results are shown in Table 4.

[0076] Table 4. Weather resistance and conductivity degradation rates of different PVB interlayer films and glasses with different PVB interlayer films.

[0077] As shown in Table 4, the weather resistance and electrical conductivity stability of Examples 1-6 and Application Examples 1-3 of the present invention far exceed those of Comparative Examples 1-3 and Application Examples 1-3. After 50 cycles of high and low temperatures from -40℃ to 80℃, Examples 1-6 and Application Examples 1-3 showed no cracking or delamination, and their appearance and structure remained intact. In contrast, Comparative Example 3 showed edge cracking, Application Example 1 showed local micro-cracks at the corners, and Application Example 2 showed slight delamination, failing to withstand extreme temperature alternation. Furthermore, the electrical conductivity degradation rate of Examples 1-6 was only 2.5% to 3.2%, and the electrical conductivity degradation rate of Application Examples 1-3 was controlled at 2.7% to 3.3% due to the more stable structure after being combined with glass. In contrast, the electrical conductivity degradation rate of Comparative Example 2 reached 8.6 ± 0.5%, and the electrical conductivity degradation rate of Application Example 1 was as high as 13.2 ± 0.9%, indicating rapid deterioration of electrical conductivity with temperature cycling.

[0078] This invention adds UV stabilizers and antioxidants to PVB resin, which can inhibit molecular chain breakage and oxidative aging under extreme temperatures, preventing film cracking or delamination. The selected carbon-based conductive carrier has strong intermolecular bonding, is not easily embrittled at low temperatures, and is not easily oxidized at high temperatures. Compared with single conductive materials such as pure graphene (Comparative Example 3) and carbon black (Comparative Example 2), it can maintain long-term conductive stability. The conductive resonant heating PVB sandwich film of this invention can maintain structural and conductive stability under extreme climatic environments, meeting the long-term use requirements of outdoor scenarios such as automobiles and rail transportation.

[0079] (5) Predicted service life: Using an accelerated aging test chamber (model: Q-SUNXe-3, temperature 80 degrees, humidity 85%, irradiation intensity 0.71W / m²) 2 Using a 340nm, four-probe resistivity meter, the lifespan of the PVB interlayer films prepared in Examples 1-6 and Comparative Examples 1-3 and the above-mentioned sample glass were predicted. The PVB interlayer films and sample glass were placed in an accelerated aging chamber and aged continuously for 5000h. The volume resistivity was tested once every 500h. The accelerated aging time when the resistivity decayed to 10% of the initial value was recorded. The actual lifespan was calculated according to the Arrhenius equation (activation energy Ea=60kJ / mol, actual operating temperature 25℃): actual lifespan = accelerated aging time × accelerated aging time × lifespan: actual lifespan = actual - 1 / Taccelerated) (R=8.314J / (mol·K), Tactual = 298K, Taccelerated = 353K); samples that were non-conductive or failed after cycling were marked as "not valid". The results are shown in Table 5.

[0080] Table 5. Predicted service life of different PVB interlayer films and glasses with different PVB interlayer films.

[0081] As shown in Table 5, the predicted service life of Examples 1-6 and Application Examples 1-3 of the present invention is significantly longer than that of Comparative Examples 1-3 and Application Comparative Examples 1-3. The predicted service life of Examples 1-6 is ≥12.3 years. Application Examples 1-3, due to their stable composite system with glass, metal film, and magnetic shielding layer, maintain a predicted service life of 12.1-13.0 years with a deviation of ≤0.5 years, demonstrating excellent service life stability. In contrast, Comparative Example 1 has a service life of only 7.5±0.2 years, Comparative Example 2 6.3±0.2 years, and Comparative Example 2 6.5±0.2 years, all less than 60% of the service life of the application examples of this invention, failing to meet the design requirement of over 10 years for composite glass. Comparative Example 3 suffers from low-temperature brittleness, and Comparative Example 2 suffers from slight delamination, leading to the breakage of the conductive path and premature loss of heating function. In contrast, Examples 1-6 of this invention, through the anti-aging properties of modified PVB resin (anti-UV / antioxidant) and the structural stability of the carbon-based carrier, avoid the risks of cracking and delamination, further extending the actual service life. The conductive resonant heating PVB interlayer film of this invention can achieve long-term stable use, significantly reducing the maintenance and replacement costs of glass in automotive, construction, and other scenarios, possessing significant economic value.

[0082] Therefore, the present invention employs the above-mentioned conductive resonant heating PVB sandwich film and its preparation method and application. The metal film layer and the conductive heating layer form a resonant heating system, which precisely defines the eddy current action area; the magnetic shielding layer blocks the eddy current penetration, avoids interference with electronic equipment, and adapts to the usage requirements of different scenarios.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A conductive resonant heating PVB sandwich film, characterized in that: It includes a PVB interlayer and PVB protective layers located on both sides of the PVB interlayer. A conductive heating layer is hot-melted loaded on the PVB interlayer. The conductive heating layer is a conductive circuit based on a carbon-based conductive carrier. The carbon-based conductive carrier is a composite of a conductive polymer or a polymer and a conductive powder. Both the PVB interlayer and the PVB protective layer are made of modified PVB resin.

2. The conductive resonant heating PVB sandwich film according to claim 1, characterized in that: The conductive polymer includes one of the following: polythiophene-graphene blend, polyaniline-graphene blend, and polypyrrole-graphene blend, wherein the mass of graphene accounts for 0.5 to 1 wt% of the total mass of the conductive polymer.

3. The conductive resonant heating PVB sandwich film according to claim 1, characterized in that: The polymer in the composite of polymer and conductive powder includes one of polyethylene sheet, polypropylene sheet, and polyester sheet, and the conductive powder includes one of graphite powder, graphene, and silver nanowires.

4. The conductive resonant heating PVB sandwich film according to claim 1, characterized in that: The modified PVB resin comprises, by weight percentage, 10-15 wt% polymethyl methacrylate, 0.5-1 wt% UV stabilizer, 0.2-0.5 wt% antioxidant, and the balance being PVB resin.

5. A method for preparing a conductive resonant heating PVB sandwich film according to any one of claims 1-4, characterized in that: Includes the following steps: S1. Preparation of PVB intermediate layer and PVB protective layer: Polymethyl methacrylate, UV stabilizer, antioxidant and PVB resin are added to a high-speed mixer and mixed evenly to obtain modified PVB resin. The modified PVB resin is then pressed into tablets to form PVB intermediate layer and PVB protective layer. S2. Fabrication of conductive circuits: The carbon-based conductive carrier is fabricated into a grid-shaped or ring-shaped conductive circuit; S3, Composite PVB Interlayer Film: The conductive circuit prepared in S2 is placed on the surface of the PVB intermediate layer in S1, and placed in a hot press to fuse the conductive circuit onto the PVB intermediate layer. The PVB intermediate layer with the fused conductive circuit is placed between two PVB protective layers prepared in S1, and placed in a multi-layer co-extrusion machine for co-extrusion composite. After extrusion, it is cooled and shaped to obtain the PVB interlayer film.

6. The method for preparing a conductive resonant heating PVB sandwich film according to claim 5, characterized in that: The mixing in S1 is carried out by stirring at a speed of 800~1200 r / min and a temperature of 120~130℃ for 20~30 min.

7. The method for preparing a conductive resonant heating PVB sandwich film according to claim 5, characterized in that: When the carbon-based conductive carrier in S2 is a conductive polymer, the conductive circuit is prepared as follows: weigh the conductive polymer, add it to the hopper of the casting machine, and cast it to form a film, obtaining a conductive polymer film with a thickness of 0.1~0.2mm; then use a laser etching machine to etch the conductive polymer film to form a ring or grid-like conductive circuit.

8. The method for preparing a conductive resonant heating PVB sandwich film according to claim 5, characterized in that: When the carbon-based conductive carrier in S2 is a composite of polymer and conductive powder, the conductive circuit is prepared by adding the polymer and conductive powder into a twin-screw extruder, extruding and molding to obtain a polymer-conductive powder composite film, and then processing a grid-shaped or ring-shaped conductive circuit on the surface of the composite film by chemical etching or laser etching process.

9. The method for preparing a conductive resonant heating PVB sandwich film according to claim 5, characterized in that: In S3, the temperature of the hot melt load is 150~170℃, the pressure is 3~5MPa, and the time is 10~15min. The temperature of the multi-layer co-extrusion machine is 180~200℃, and the screw speed is 250~300r / min.

10. The application of the conductive resonant heating PVB interlayer film according to any one of claims 1-4, characterized in that: After a metal film layer is laminated on one side of the PVB interlayer film and a magnetic shielding layer is laminated on the other side of the PVB interlayer film, it is applied to automotive windshields, building curtain wall glass, or rail transit vehicle windows.

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