Preparation method of carbon nanotube/glass fiber cloth flexible film heater
Technical Field
The invention belongs to the technical field of flexible film heater preparation, and particularly relates to a solution method preparation and coating process of a carbon nanotube material.
Background
The flexible film heater is a film-shaped device which can be bent to a certain degree, can be folded and can generate heat after being electrified. The film heater is a typical planar heater, and has extremely high heat exchange power due to large heat exchange area. The heat dissipation device has the advantages of high heating efficiency, good heat dissipation, high surface power density, difficult ablation and the like. In recent years, flexible film heaters are widely applied to the fields of buildings, industry, agriculture, military, household products and the like to solve the problems of heating, deicing, freezing prevention or heating, and particularly in the field of industrial production, the demand for the flexible film heaters is more prominent. For example, in a workshop or a field construction area, a plurality of valves or molds need to be heated or preheated to meet the requirements of deicing, freezing prevention and the like, but because the valve or the mold is irregular in shape, the heating is very inconvenient by using a resistance wire. Most inorganic thin film heaters are rigid and therefore unsuitable for heating in such applications. For the carbon nanotube/glass fiber cloth composite film heater, the conductive carbon nanotube is coated on the insulating and highly flexible glass fiber substrate by a simple bar coating method, various complex film heating devices can be manufactured, the heater can be bent, folded and wrapped freely according to the shape of a die, the heating speed is high, the power consumption is low, and the heating requirements of parts such as a valve die and the like can be met smoothly. In addition, the carbon nanotube/glass fiber cloth composite film heater belongs to electroheating, and no open fire is generated in heating, so that the carbon nanotube/glass fiber cloth composite film heater is very safe and reliable to use in places needing heating, such as coal mines, chemical plants, oil depots and the like. In the field of daily life, the carbon nanotube/glass fiber cloth composite film heater can be completely suitable for heating equipment with high requirements on flexibility, such as a portable heating mat, a thermal therapy blanket and the like, and has the advantages of small volume, folding and carrying, and low driving voltage, so that the film heater has extremely high application value.
Disclosure of Invention
The invention aims to provide a preparation method of a carbon nanotube/glass fiber cloth flexible film heater, and the prepared composite film heater has a stable structure, a high heating rate and high flexibility, and has great application potential in industrial production, household and daily use and the like.
The technical scheme of the invention is as follows: the main steps are that firstly, the glass fiber cloth substrate is washed clean by water, and the required size is cut. And coating the prepared single-walled carbon nanotube dispersion liquid on a glass fiber cloth substrate layer by adopting a Meyer rod coating method, and coating the next layer after each layer is completely dried. The number of coating layers is controlled according to the sheet resistance of the film. Then, the carbon nano tube/glass fiber cloth film is placed on a heating plate, heated to 200 ℃ for annealing, and repeated twice, so that the carbon nano tube nodes are welded, and the surface resistance of the film is reduced. The annealed film has excellent conductivity and high mechanical strength. And then, sticking a layer of copper foil electrode with the width of about 1cm on any two opposite sides, connecting the two copper electrodes of the film with a voltage-regulating power supply through a lead, and controlling the heating temperature of the surface of the film by controlling the voltage of the voltage-regulating power supply. For the film with the surface resistance of 20 omega/sq, the temperature can be raised to 170 ℃ only within 25s under the voltage of 30V.
The main innovation points of the invention are as follows: the carbon nano tube with high conductivity and high elasticity is compounded with the glass fiber cloth with high flexibility and high mechanical strength by a Meyer rod coating method, so that the novel ultra-flexible film heater is constructed.
The method for preparing the carbon nano tube dispersion liquid in the method of the invention comprises the following steps: the single-walled carbon nanotube with the purity of more than 95 wt%, the outer diameter of 1-2 nm and the length of 5-30 mu m is used as a raw material, sodium dodecyl benzene sulfonate is used as a dispersing agent, and distilled water is used as a solvent. Weighing the single-walled carbon nanotube and sodium dodecyl benzene sulfonate in a ratio of 10: 1, adding distilled water in a corresponding ratio to enable the concentration of the carbon nanotube to be 1-2mg/ml, carrying out ultrasonic treatment for 50min by using an ultrasonic dispersion machine, centrifuging for 20min at a speed of 8000r/min by using a centrifugal machine, and extracting supernatant to obtain carbon nanotube dispersion liquid.
Reagents and materials used in the invention: single-walled carbon nanotubes, glass fiber cloth, sodium dodecyl benzene sulfonate, 3M copper tape, distilled water and the like.
In the invention, a Scanning Electron Microscope (SEM) is adopted to represent the appearance of the prepared carbon nano tube/glass fiber cloth film. And adopting a Gicherie 2700 four-probe resistance measuring instrument to represent the surface resistance of the prepared carbon nano tube/glass fiber cloth film. A T-type thermocouple was used to characterize the temperature at which the film was heated.
Drawings
FIG. 1 is a flow chart of a process for manufacturing a carbon nanotube/glass fiber cloth film heater.
FIG. 2 is a schematic diagram of a carbon nanotube/glass fiber cloth film heater.
FIG. 3 is a SEM low-magnification view of a carbon nanotube/glass fiber cloth film.
FIG. 4 is a high magnification SEM image of a carbon nanotube/glass fiber cloth film.
FIG. 5 is a temperature rise curve of 20 Ω/sq carbon nanotube/glass fiber cloth film under different voltages.
Detailed Description
The present invention will be described in detail with reference to specific examples.
Example 1:
taking 20mg of single-walled carbon nanotube and 200mg of sodium dodecyl benzene sulfonate into a beaker, adding 20mL of distilled water, performing ultrasonic treatment for 50min by using an ultrasonic dispersion machine, centrifuging for 20min at 8000r/min by using a centrifugal machine, and extracting supernatant to obtain the carbon nanotube dispersion liquid with the concentration of 1 mg/mL. A10 cm by 10cm clean glass fiber cloth was then stuck on a hot plate, set at a temperature of 105 ℃. The carbon nanotube dispersion was then layered on a glass fiber cloth substrate using a mayer rod. Before coating each layer, the upper layer is completely dried, and after 5 layers of coating, the surface resistance of the carbon nano tube/glass fiber cloth composite film is about 100 omega/sq. Subsequently, the heating plate on which the composite film was placed was heated to 200 ℃, and after 5 minutes of heat preservation, the plate was annealed to room temperature, and repeated 2 times. The sheet resistance of the film is reduced to 65 omega/sq. A layer of copper foil electrode with the width of about 1cm is pasted on any two opposite sides of the composite film, the two copper electrodes of the film are connected with a voltage-stabilized power supply through a lead, and the heating temperature of the surface of the film is controlled by controlling the voltage of the voltage-regulated power supply. The maximum steady state temperature was 152 ℃ when the voltage was 60V.
Example 2:
taking 40mg of single-walled carbon nanotube and 400mg of sodium dodecyl benzene sulfonate in a beaker, adding 20mL of distilled water, performing ultrasonic treatment for 50min by using an ultrasonic dispersion machine, centrifuging for 20min at 8000r/min by using a centrifugal machine, and extracting supernatant to obtain carbon nanotube suspension with the concentration of 2 mg/mL. A10 cm by 10cm clean glass fiber cloth was then stuck on a hot plate, set at a temperature of 105 ℃. And then, the carbon nanotube suspension is coated on the glass fiber cloth substrate layer by using a Meyer rod. And (3) completely drying the previous layer before coating each layer, and after 7 layers of coating, controlling the surface resistance of the carbon nano tube/glass fiber cloth composite film to be about 20 omega/sq. Subsequently, the heating plate on which the composite film was placed was heated to 200 ℃, and after 5 minutes of heat preservation, the plate was annealed to room temperature, and repeated 2 times. The sheet resistance of the film is reduced to about 8 omega/sq. A layer of copper foil electrode with the width of about 1cm is pasted on any two opposite sides of the composite film, the two copper electrodes of the film are connected with a regulated power supply through a lead, and the heating temperature of the surface of the film is controlled by controlling the voltage of the regulated power supply. The maximum steady state temperature was 214 ℃ when the voltage was 30V.