A water-based nano heating film containing graphene and carbon nanotubes and preparation method thereof

Abstract

The present invention belongs to the field of new electric heating, and specifically relates to a water-based nano heating film containing graphene and carbon nanotubes and a preparation method thereof. It comprises a first insulating flame-retardant flexible film, a water-based nano three-dimensional conductive layer containing graphene and carbon nanotubes, a copper-silver composite electrode, a temperature-resistant glue and a second insulating flame-retardant flexible film, wherein the heating film has a multilayer film structure, and the thickness of the first insulating flame-retardant flexible film is greater than that of the second insulating flame-retardant flexible film. This water-based nano heating film containing graphene and carbon nanotubes has an electro-thermal radiation conversion efficiency of up to 70% to 75%, uniform temperature, basically zero power attenuation, and a heating temperature adjustable from 35°C to 180°C. It is heat-resistant and flame-resistant, and solves the problems of low electro-thermal radiation conversion efficiency, uneven heating, power attenuation, and poor heat resistance and flame resistance of the current heating film, and prevents the occurrence of safety accidents.

Description

Technical Field

[0001] The present invention belongs to the field of novel electric heating, and specifically relates to an aqueous nano heating film containing graphene and carbon nanotubes and a preparation method thereof. Background Art

[0002] Since the invention of carbon nanomaterials, their excellent mechanical, electrical, and thermal properties have been widely studied and applied, among which carbon nanotubes and graphene are the hot spots of research. Carbon nanotubes are a one-dimensional quantum material with a special structure (radial size is nanometers, axial size is micrometers, and both ends of the tube are basically sealed). They are composed of several to dozens of layers of coaxial circular tubes of carbon atoms arranged in hexagons. Graphene is a kind of carbon atom in the form of sp 2 The honeycomb-shaped planar film formed by hybridization has a unique two-dimensional hexagonal honeycomb single-layer square lattice structure that gives it excellent physical and chemical properties. The large-scale controllable preparation of graphene has also become a prerequisite for further industrial application.

[0003] Currently, the heating films on the market are mainly carbon crystal and carbon fiber heating films, which generally have problems such as low electric-thermal radiation conversion efficiency, uneven heating, short power attenuation life, and extremely poor temperature, heat and flame resistance. There is no after-sales maintenance and safety accidents occur frequently. Summary of the invention

[0004] The purpose of the present invention is to provide an aqueous nano-heating film containing graphene and carbon nanotubes and a preparation method thereof, which solves the problems in the background technology. The aqueous nano-heating film containing graphene and carbon nanotubes has an electro-thermal radiation conversion efficiency of up to 70%~75%, which is 10%~15% higher than the 60%~65% of carbon crystal and carbon fiber electro-thermal films on the market. The temperature is uniform, the power is basically zero attenuation, the heating temperature can be adjusted from 35°C to 180°C, and it is heat-resistant and flame-resistant. It solves the problems of low electro-thermal radiation conversion efficiency, uneven heating, power attenuation, and poor heat resistance, and prevents the occurrence of safety accidents.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: a water-based nano heating film containing graphene and carbon nanotubes, characterized in that it includes a first insulating flame-retardant flexible film, a water-based nano three-dimensional conductive layer containing graphene and carbon nanotubes, a copper-silver composite electrode, a temperature-resistant glue and a second insulating flame-retardant flexible film, the heating film has a multi-layer film structure, and the thickness of the first insulating flame-retardant flexible film is greater than that of the second insulating flame-retardant flexible film. Furthermore, the insulating flame-retardant flexible film is one or more of a polyester film, a polyimide film, and a polycarbonate film, and its thickness is 0.1mm~0.3mm.

[0006] Furthermore, the aqueous nano three-dimensional conductive layer containing graphene and carbon nanotubes includes graphene, carbon nanotubes, nano conductive carbon black, aqueous resin binder, and surfactant, wherein: the graphene content is 1%~8%, the carbon nanotube content is 3%~10%, the nano conductive carbon black content is 20%~40%, the aqueous resin binder content is 28%~39%, and the surfactant content is 5%~30%.

[0007] Furthermore, the copper-silver composite electrode is a silver electrode covered with a copper electrode, wherein the width of the silver electrode is 1 cm to 1.5 cm, the width of the copper electrode is 0.8 cm to 1.3 cm, and the width of the silver electrode is greater than that of the copper electrode.

[0008] Furthermore, the temperature-resistant adhesive is EVA hot-melt adhesive.

[0009] The present invention provides a method for preparing a water-based nano heating film containing graphene and carbon nanotubes, comprising the following preparation steps:

[0010] (1) According to the design of the water-based nano heating film, the conductive silver paste is first printed on the electrode position of the insulating flame-retardant flexible film and then dried in a drying oven;

[0011] (2) The aqueous nano-conductive ink containing graphene and carbon nanotubes is applied to an insulating flame-retardant flexible film printed with silver electrodes by gravure printing, screen printing, or automatic coating, and then dried in a drying oven to form an aqueous nano-three-dimensional conductive layer.

[0012] (3) According to the design of the water-based nano heating film, the copper electrode is covered on the silver electrode and hot-pressed together with the insulating flame-retardant flexible film covered with a temperature-resistant adhesive to form the water-based nano heating film.

[0013] Furthermore, in the step (1), the baking oven temperature of the conductive silver paste for printing the silver electrode is 180°C to 220°C.

[0014] Furthermore, in the step (2), the thickness of the aqueous nano three-dimensional conductive layer is 10 μm to 30 μm, and the drying oven temperature is 120 to 270 °C.

[0015] Furthermore, the design of the water-based nano heating film in the step (3) can be achieved by adjusting the power density P required for the water-based nano heating film to generate heat, the area S of the unit heating area, the operating voltage U and other parameters, and calculating the surface resistance R of the unit heating area (R = (U2 / P) / S), thereby obtaining a water-based nano heating film with a surface temperature of 35°C to 180°C and a power density of 150W / m2 to 2500W / m2, and the hot pressing composite temperature is 80~300°C.

[0016] The technical effect of the present invention is: This aqueous nano heating film containing graphene and carbon nanotubes has an electric-thermal radiation conversion efficiency of up to 70%~75%, which is 10%~15% higher than the 60%~65% of carbon crystal and carbon fiber electric heating films on the market. It has uniform temperature, basically zero power attenuation, and the heating temperature can be adjusted from 35°C to 180°C. It is heat-resistant and flame-resistant, which solves the problems of low electric-thermal radiation conversion efficiency, uneven heating, power attenuation, and poor temperature, heat and flame resistance of current heating films, and prevents the occurrence of safety accidents. DETAILED DESCRIPTION

[0017] A water-based nano heating film containing graphene and carbon nanotubes, comprising a first insulating flame-retardant flexible film 1, an aqueous nano three-dimensional conductive layer 2 containing graphene and carbon nanotubes, a copper-silver composite electrode 3, a temperature-resistant glue 4 and a second insulating flame-retardant flexible film 5. The heating film has a multi-layer film structure, and the thickness of the first insulating flame-retardant flexible film 1 is greater than that of the second insulating flame-retardant flexible film 5.

[0018] Preferably, the insulating flame-retardant flexible film is one or more of a polyester film, a polyimide film, and a polycarbonate film, with a thickness of 0.1 mm to 0.3 mm, a relative dielectric constant of 2.9 to 3.4, and a flame retardancy rating of UL94V-0.

[0019] Preferably, the aqueous nano three-dimensional conductive layer containing graphene and carbon nanotubes includes graphene, carbon nanotubes, nano conductive carbon black, an aqueous resin binder, and a surfactant, wherein: the graphene content is 1% to 8%, the carbon nanotube content is 3% to 10%, the nano conductive carbon black content is 20% to 40%, the aqueous resin binder content is 28% to 39%, and the surfactant content is 5% to 30%.

[0020] Preferably, the graphene is prepared by liquid phase exfoliation, the graphene sheet thickness is less than 10 nm, the number of layers is less than 10, and the volume resistivity is less than 10 -2 Ω•cm, the carbon nanotubes are multi-walled carbon nanotubes with a volume resistivity of less than 10 -2 Ω•cm.

[0021] Preferably, the copper-silver composite electrode is a silver electrode covered with a copper electrode, wherein the width of the silver electrode is 1 cm to 1.5 cm, the width of the copper electrode is 0.8 cm to 1.3 cm, and the width of the silver electrode is greater than that of the copper electrode.

[0022] Preferably, the temperature-resistant adhesive is EVA hot-melt adhesive.

[0023] The present invention also provides a method for preparing an aqueous nano heating film containing graphene and carbon nanotubes, comprising the following preparation steps:

[0024] (1) According to the design of the water-based nano heating film, the conductive silver paste is first printed on the electrode position of the insulating flame-retardant flexible film and then dried in a drying oven;

[0025] (2) The aqueous nano-conductive ink containing graphene and carbon nanotubes is applied to an insulating flame-retardant flexible film printed with silver electrodes by gravure printing, screen printing, or automatic coating, and then dried in a drying oven to form an aqueous nano-three-dimensional conductive layer.

[0026] (3) According to the design of the water-based nano heating film, the copper electrode is covered on the silver electrode and hot-pressed together with the insulating flame-retardant flexible film covered with a temperature-resistant adhesive to form the water-based nano heating film.

[0027] Preferably, in step (1), the baking oven temperature for printing the silver electrode with the conductive silver paste is 180° C. to 220° C.

[0028] Preferably, in the step (2), the thickness of the aqueous nano three-dimensional conductive layer is 10 μm to 30 μm, and the drying oven temperature is 120 to 270°C.

[0029] Preferably, the design of the water-based nano heating film in step (3) can be calculated by adjusting the power density P, the area S of the unit heating area, the working voltage U and other parameters required for the water-based nano heating film to generate heat, and the surface resistance R (R = (U 2 / P) / S), and thus the surface temperature can be between 35℃~180℃ and the power density can be between 150W / m 2 ~2500W / m 2 The water-based nano heating film, the hot pressing composite temperature is 80~300℃.

[0030] The present invention will be described in detail below through examples. In the following examples, the test methods of various performance parameters are tested according to the methods in JG / T 286-2010 "Low-temperature radiant electric heating film" and GB / T 4654-2008 "General technical conditions for non-metallic substrate infrared radiation heaters". Example

[0031] This example is used to illustrate the preparation of an aqueous nano heating film containing graphene and carbon nanotubes using the method of the present invention.

[0032] (1) The surface temperature of the water-based nano heating film is designed to be 45°C, its power density is 220W / m2, its operating voltage is 220V, and the unit heating area is 0.1 m2. The square resistance of the water-based nano three-dimensional conductive layer is: R=2200Ω.

[0033] (2) According to the design, the conductive silver paste is printed on the flame-retardant PET film and dried in a 200°C oven. Then, the water-based nano-conductive ink containing graphene and carbon nanotubes is gravure-printed on the flame-retardant PET printed with silver electrodes and dried in a 120°C oven to form a water-based nano-three-dimensional conductive layer. The water-based nano-three-dimensional conductive layer has a thickness of 15 microns, wherein the graphene content is 3%, the carbon nanotube content is 5%, the nano-conductive carbon black content is 29.5%, the water-based resin binder content is 38%, and the surfactant content is 24.5%. Example

[0034] (1) The surface temperature of the water-based nano heating film is designed to be 80°C, its power density is 1000W / m2, the working voltage is 220V, and the unit heating area is 0.5 m2. The sheet resistance of the water-based nano three-dimensional conductive layer is: R=96.8Ω.

[0035] (2) According to the design, the conductive silver paste is printed on the flame-retardant PI film and dried in a 200°C oven. Then, the water-based nano-conductive ink containing graphene and carbon nanotubes is screen-printed on the flame-retardant PI film printed with silver electrodes and dried in a 120°C oven to form a water-based nano-three-dimensional conductive layer. The water-based nano-three-dimensional conductive layer has a thickness of 15 microns, wherein the graphene content is 5%, the carbon nanotube content is 7%, the nano-conductive carbon black content is 32%, the water-based resin binder content is 36%, and the surfactant content is 20%.

[0036] (3) The copper electrode is placed on top of the silver electrode and hot-pressed together with a PI film covered with EVA hot melt adhesive at a temperature of 200°C to form a water-based nano heating film. Example

[0037] (1) The surface temperature of the water-based nano heating film is designed to be 130°C, its power density is 1600W / m2, the working voltage is 220V, and the unit heating area is 0.5 m2. The square resistance of the water-based nano three-dimensional conductive layer is: R=60.5Ω.

[0038] (2) According to the design, the conductive silver paste is printed on the flame-retardant PI film and dried in a 200°C oven. Then, the water-based nano-conductive ink containing graphene and carbon nanotubes is screen-printed on the flame-retardant PI film printed with silver electrodes and dried in a 120°C oven to form a water-based nano-three-dimensional conductive layer. The water-based nano-three-dimensional conductive layer has a thickness of 15 microns, wherein the graphene content is 8%, the carbon nanotube content is 10%, the nano-conductive carbon black content is 33%, the water-based resin binder content is 33%, and the surfactant content is 16%.

[0039] (3) The copper electrode is placed on top of the silver electrode and hot-pressed together with a PI film covered with EVA hot melt adhesive at a temperature of 200°C to form a water-based nano heating film.

[0040] The performance test results are shown in Table 1. The test methods of the following items are tested in accordance with the test methods of GB / T 7287-2008 "Infrared Radiation Heater Test Methods".

[0041] Table 1

[0042] Performance Indicators Working temperature / ℃ Temperature non-uniformity / ℃ Heating time / min Working life / h Electric-thermal radiation conversion efficiency / % Power change rate (300V, 1200h) / % Heat and flame resistance Example 1 40 2 1 >100000 68 -0.86 The insulation of heating elements and internal wiring should have sufficient heat resistance and flame resistance Example 2 80 3 1 >100000 75 +1.1 The insulation of heating elements and internal wiring should have sufficient heat resistance and flame resistance Example 3 130 5 1 >100000 78 +0.78 The insulation of heating elements and internal wiring should have sufficient heat resistance and flame resistance

[0043] From the test results of the above examples 1-3, it can be seen that the water-based nano heating film prepared by the method of the present invention has a small temperature difference, fast heating, long service life, small power change, and basically no attenuation. The test data in Table 1 show that the performance of the water-based nano heating film is excellent.

[0044] The water-based nano heating film prepared by the method of the present invention has uniform heating, small temperature difference, long service life, stable electrical performance, and basically no power attenuation. After the water-based nano heating film is connected to the power supply, it quickly heats up to reach the designed surface temperature, and at the same time triggers itself to generate far infrared rays, and sends heat into the space in the form of far infrared thermal energy radiation, so that the human body and objects feel warm, and naturally and evenly increase the indoor temperature. It is widely used in the fields of heating of buildings such as homes and public buildings, agricultural cultivation, pipeline insulation, ground snow melting devices, far infrared health care and physiotherapy, etc., providing theoretical and practical basis.

Claims

1. A water-based nano heating film containing graphene and carbon nanotubes, characterized in that: It includes a first insulating flame-retardant flexible film, an aqueous nano three-dimensional conductive layer containing graphene and carbon nanotubes, a copper-silver composite electrode, a temperature-resistant glue and a second insulating flame-retardant flexible film, wherein the heating film has a multi-layer film structure, and the thickness of the first insulating flame-retardant flexible film is greater than that of the second insulating flame-retardant flexible film; The thickness of the insulating flame-retardant flexible film is 0.1 mm to 0.3 mm; The aqueous nano three-dimensional conductive layer containing graphene and carbon nanotubes comprises graphene, carbon nanotubes, nano conductive carbon black, aqueous resin binder, and surfactant, wherein: the graphene content is 1% to 8%, the carbon nanotube content is 3% to 10%, the nano conductive carbon black content is 20% to 40%, the aqueous resin binder content is 28% to 39%, and the surfactant content is 5% to 30%; The graphene is prepared by liquid phase exfoliation, the graphene sheet thickness is less than 10nm, the number of layers is less than 10, and the volume resistivity is less than 10 -2 Ω•cm, the carbon nanotubes are multi-walled carbon nanotubes with a volume resistivity of less than 10 -2 Ω•cm; The copper-silver composite electrode is a silver electrode covered with a copper electrode, wherein the width of the silver electrode is 1 cm to 1.5 cm, the width of the copper electrode is 0.8 cm to 1.3 cm, and the width of the silver electrode is greater than that of the copper electrode.

2. The aqueous nano heating film containing graphene and carbon nanotubes according to claim 1, characterized in that: The insulating flame-retardant flexible film is one or more of a polyester film, a polyimide film, and a polycarbonate film, and the temperature-resistant adhesive is an EVA hot-melt adhesive.

3. The method for preparing an aqueous nano heating film containing graphene and carbon nanotubes according to any one of claims 1 to 2, characterized in that: The preparation steps include: (1) According to the design of the water-based nano heating film, the conductive silver paste is first printed on the electrode position of the insulating flame-retardant flexible film and then dried in a drying oven; (2) applying a water-based nano-conductive ink containing graphene and carbon nanotubes onto an insulating flame-retardant flexible film printed with a silver electrode by gravure printing, screen printing, or automatic coating, and drying in a drying oven to form a water-based nano-three-dimensional conductive layer; (3) According to the design of the water-based nano heating film, the copper electrode is covered on the silver electrode and hot-pressed together with the insulating flame-retardant flexible film covered with a temperature-resistant adhesive to form the water-based nano heating film.

4. The method for preparing a water-based nano heating film containing graphene and carbon nanotubes according to claim 3, characterized in that: In the step (1), the baking oven temperature of the conductive silver paste for printing the silver electrode is 180°C to 220°C.

5. The method for preparing a water-based nano heating film containing graphene and carbon nanotubes according to claim 3, characterized in that: In the step (2), the thickness of the aqueous nano three-dimensional conductive layer is 10 μm to 30 μm, and the drying oven temperature is 120 to 270°C.

6. The method for preparing a water-based nano heating film containing graphene and carbon nanotubes according to claim 3, characterized in that: In the step (3), the design of the water-based nano heating film is to adjust the power density P, the area S of the unit heating area, and the working voltage U required for the water-based nano heating film to generate heat, and calculate the surface resistance R (R = (U 2 / P) / S), and thus the surface temperature can be between 35℃~180℃ and the power density can be between 150W / m 2 ~2500W / m 2 The water-based nano heating film has a hot pressing composite temperature of 80~300℃.