CN101868067B - Plane heat source - Google Patents

Abstract

The invention relates to a surface heat source, comprising: a heating element, the heating element includes a matrix and a plurality of carbon nanotubes distributed in the matrix; and at least two electrodes are arranged at intervals and electrically connected to the heating element, wherein the heating element A plurality of carbon nanotubes in the carbon nanotube structure form at least one self-supporting carbon nanotube structure, and the carbon nanotubes in the carbon nanotube structure are arranged randomly, arranged in the same preferred orientation or arranged in preferred orientations in different directions. The surface heat source can be used to manufacture self-heating heating clothes, heating gloves or heating shoes, electric heaters, infrared therapeutic apparatus, electric heaters, etc., and has a wide range of applications.

Description

surface heat source

technical field

The invention relates to a surface heat source, in particular to a surface heat source based on carbon nanotubes.

Background technique

Heat sources play an important role in people's production, life and scientific research. A surface heat source is a type of heat source. The surface heat source is a two-dimensional structure, and the object to be heated is placed above the two-dimensional structure to heat the object. Therefore, the surface heat source can heat all parts of the object to be heated at the same time, with a large heating surface, uniform heating and high efficiency. Surface heat sources have been successfully used in industrial fields, scientific research fields, or living fields, such as electric heaters, electric blankets, infrared therapeutic devices, and electric heaters.

The existing surface heat source generally includes a heating element and at least two electrodes, the at least two electrodes are arranged on the surface of the heating element and electrically connected with the heating element. When a voltage or current is applied to the heating element through the electrodes, due to the high resistance of the heating element, the electric energy passed into the heating element is converted into heat energy and released from the heating element. Now commercially available surface heat sources usually use electric heating wires made of metal wires or carbon fibers as heating elements for electrothermal conversion.

However, both metal wire and carbon fiber have the disadvantages of low strength, low electrothermal conversion efficiency, and high mass. The wire is prone to breakage, especially when it is bent multiple times or bent at an angle, and it is prone to fatigue, so its application is limited. In addition, the heat generated by the electric heating wire made of metal wire or carbon fiber radiates outward at ordinary wavelengths, and its electrothermal conversion efficiency is not high, which is not conducive to saving energy. It is necessary to add cotton thread coated with far-infrared paint to improve the electrothermal conversion efficiency. , is not conducive to energy saving and environmental protection. The mass of carbon fiber and metal wire is relatively large, which is unfavorable for reducing the weight of the heat source. At the same time, the size of carbon fibers is not small enough to be used in miniature heat sources.

Since the early 1990s, nanomaterials represented by carbon nanotubes (see Helical microtubules of graphiticcarbon, Nature, Sumio Iijima, vol 354, p56 (1991)) have attracted great attention for their unique structures and properties. focus on. In recent years, with the continuous deepening of research on carbon nanotubes and nanomaterials, their broad application prospects continue to emerge. A Chinese patent application No. CN101090586A published by Fan Shoushan et al. on December 19, 2007 discloses a nano-flexible electrothermal material. The electrothermal material includes a flexible matrix and a plurality of carbon nanotubes dispersed in the flexible matrix. The plurality of carbon nanotubes exist in a powder state, and the bonding force between them is very weak, so that a self-supporting structure with a specific shape cannot be formed. When the powdered carbon nanotubes are mixed with the polymer solution, the powdered carbon nanotubes are easily agglomerated, resulting in uneven dispersion of the carbon nanotubes in the matrix. In order to avoid the agglomeration of carbon nanotubes in the polymer solution, on the one hand, the mixture of the carbon nanotubes and the polymer solution needs to be treated by ultrasonic vibration during the dispersion process; on the other hand, the carbon nanotubes in the electrothermal material The mass percentage of the pipe should not be too high, only 0.1 to 4%.

Moreover, after the carbon nanotubes are dispersed, even if the carbon nanotubes can be in contact with each other, the binding force is weak, and a self-supporting carbon nanotube structure cannot be formed. Due to the small content of carbon nanotubes, the thermal response speed of the thermoelectric material is not fast enough, and the electrothermal conversion efficiency is not high enough, so the heating temperature of the electrothermal material is not high enough, which limits its application range. In addition, in order to disperse carbon nanotubes in the liquid phase, when preparing electrothermal materials, the flexible matrix can only choose polymer materials, and the heat-resistant temperature of polymer materials is low. The material approach limits the choice of matrix material.

Contents of the invention

In view of this, it is indeed necessary to provide a surface heat source with high electrothermal conversion efficiency and wide heating temperature range.

A surface heat source, comprising: a heating element, the heating element includes a substrate and at least one self-supporting carbon nanotube structure, the carbon nanotube structure includes at least one layer of carbon nanotube rolling film, each layer Adjacent carbon nanotubes in the carbon nanotube rolling film partially overlap each other, and are attracted to each other by van der Waals force, and are tightly combined; and at least two electrodes are arranged at intervals and electrically connected to the heating element, and the at least one integral The self-supporting carbon nanotube structure is embedded in the matrix and composited with the matrix, and basically maintains the shape before the composite. The carbon nanotubes in the carbon nanotube structure are arranged in disorder, and the carbon nanotubes in the carbon nanotube structure are arranged along the same Directional preferred orientation arrangement or carbon nanotubes in the carbon nanotube structure are arranged in different directions preferred orientations.

A surface heat source, comprising: a heating element and at least two electrodes spaced apart and electrically connected to the heating element, the heating element comprising at least one integral self-supporting carbon nanotube structure, and a matrix material compounded on the carbon nanotube In the structure, the carbon nanotube structure includes at least one layer of carbon nanotube rolling film, and the adjacent carbon nanotubes in each layer of carbon nanotube rolling film partially overlap each other, and are attracted to each other by van der Waals force, tightly combined , the carbon nanotube structure in the heating element basically maintains the shape before compounding, the carbon nanotubes in the carbon nanotube structure are arranged in disorder, the carbon nanotubes in the carbon nanotube structure are arranged in the same direction, or the carbon nanotubes are arranged in the same direction The carbon nanotubes in the nanotube structure are preferentially oriented in different directions, the carbon nanotube structure has a plurality of micropores, and the matrix material is evenly compounded in the micropores of the carbon nanotube structure.

Compared with the prior art, since the surface heat source adopts a self-supporting carbon nanotube structure, and the carbon nanotubes are evenly distributed in the carbon nanotube structure, the self-supporting carbon nanotube structure is directly compounded with the matrix, There is no need to solve the dispersion problem of carbon nanotubes, and the content of carbon nanotubes is not limited, so that the carbon nanotubes in the heating element formed after compounding can still be combined with each other to maintain the shape of a carbon nanotube structure, so that the heat source has better heating performance. In addition, the type of the matrix material is not limited to polymer, and the temperature range is wide, which makes the application range of the heat source more extensive. The carbon nanotubes in the carbon nanotube structure are evenly distributed, so they have uniform thickness and resistance, uniform heating, and high electrothermal conversion efficiency of carbon nanotubes, so the surface heat source has rapid temperature rise, small thermal hysteresis, fast heat exchange speed, and radiation Features of high efficiency.

Description of drawings

Fig. 1 is a schematic structural diagram of a surface heat source according to a first embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view along line II-II of Fig. 1 .

Fig. 3 is a structural schematic diagram of a surface heat source comprising a plurality of intersecting carbon nanotube linear structures according to an embodiment of the present invention.

FIG. 4 is a schematic structural diagram of a surface heat source comprising a bent and coiled carbon nanotube linear structure according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of the structure of carbon nanotube segments in the carbon nanotube stretched film structure in the surface heat source of the embodiment of the present invention.

Fig. 6 is a scanning electron micrograph of the carbon nanotube drawn film structure in the surface heat source of the embodiment of the present invention.

Fig. 7 is a scanning electron micrograph of the carbon nanotube flocculated film structure in the surface heat source of the embodiment of the present invention.

Fig. 8 is a scanning electron microscope photo of carbon nanotubes arranged in different directions in the carbon nanotube rolling film structure in the surface heat source of the embodiment of the present invention.

Fig. 9 is a scanning electron microscope photo of carbon nanotubes arranged in the preferred orientation along the same direction in the carbon nanotube rolled film structure in the surface heat source of the embodiment of the present invention.

Fig. 10 is a scanning electron micrograph of non-twisted carbon nanotubes in a surface heat source according to an embodiment of the present invention.

Fig. 11 is a scanning electron micrograph of twisted carbon nanotubes in a surface heat source according to an embodiment of the present invention.

Fig. 12 is a scanning electron micrograph of a sectional surface of a heating element formed by compounding carbon nanotube stretched film and epoxy resin in the surface heat source of the embodiment of the present invention.

Fig. 13 is a structural schematic diagram of a surface heat source comprising a plurality of carbon nanotube structures spaced apart from each other according to an embodiment of the present invention.

FIG. 14 is a graph showing the temperature variation curves of the heating element in FIG. 12 under different voltages.

Fig. 15 is a schematic structural diagram of a surface heat source according to a second embodiment of the present invention.

Fig. 16 is a schematic cross-sectional view along line XVI-XVI of Fig. 15 .

Fig. 17 is a schematic structural diagram of a surface heat source according to a third embodiment of the present invention.

Fig. 18 is a flowchart of a method for preparing a surface heat source according to an embodiment of the present invention.

Fig. 19 is a photo of the carbon nanotube floc structure of the surface heat source preparation method according to the embodiment of the present invention.

Detailed ways

The surface heat source provided by the present invention will be described in detail below with reference to the drawings and specific embodiments.

Please refer to FIG. 1 and FIG. 2 , the first embodiment of the present invention provides a surface heat source 10 , the surface heat source 10 is a two-dimensional structure, that is, the surface heat source 10 is a structure extending along a two-dimensional direction. However, it should be pointed out that even if there is a two-dimensional structure with a certain thickness, the embodiment of the structure that is still regarded as or approximately regarded as two-dimensional structure macroscopically, such as: plate-shaped, film-shaped and other structures, should also be regarded as protected by the present invention scope.

The surface heat source 10 includes a heating element 16 , a first electrode 12 and a second electrode 14 . The heating element 16 is electrically connected to the first electrode 12 and the second electrode 14 , and is used to turn on the heating element 16 to flow current.

The heating element 16 includes a carbon nanotube composite structure, the carbon nanotube composite structure includes a matrix 162 and at least one carbon nanotube structure 164 is composited with the matrix 162 . Specifically, the carbon nanotube structure 164 includes a plurality of pores, and the material of the matrix 162 penetrates into the plurality of pores of the carbon nanotube structure 164 to form a carbon nanotube composite structure. When the volume of the matrix 162 is large, the carbon nanotube structure 164 is disposed in the matrix 162 and completely covered by the matrix 162 . The heating element 16 is a layered structure, specifically, the heating element 16 can be a planar structure or a curved structure. In this embodiment, the base 162 is a plate-shaped cuboid, and the carbon nanotube structure 164 is completely embedded in the base 162 .

The carbon nanotube structure 164 is a self-supporting structure. The so-called "self-supporting structure" means that the carbon nanotube structure 164 can maintain its own specific shape without being supported by a support. The carbon nanotube structure 164 of the self-supporting structure includes a plurality of carbon nanotubes, the plurality of carbon nanotubes attract each other through van der Waals force, thereby forming a network structure, and making the carbon nanotube structure 164 have a specific shape, so as to form a Integral self-supporting carbon nanotube structure. In this embodiment, the carbon nanotube structure 164 is a two-dimensional planar or one-dimensional linear structure. Since the carbon nanotube structure 164 is self-supporting, it can still maintain a planar or linear structure without being supported by the surface of the support. There are a lot of gaps between the carbon nanotubes in the carbon nanotube structure 164 , so that the carbon nanotube structure 164 has a lot of pores, and the matrix 162 material penetrates into the pores.

The carbon nanotube structure 164 includes a large number of uniformly distributed carbon nanotubes, and the carbon nanotubes are closely combined by van der Waals force. The carbon nanotubes in the carbon nanotube structure 164 are arranged in disorder or order. The disorder here means that the arrangement direction of the carbon nanotubes is irregular, and the order here means that the arrangement directions of at least most of the carbon nanotubes have certain rules. Specifically, when the carbon nanotube structure 164 includes disorderly arranged carbon nanotubes, the carbon nanotubes can be further intertwined, and the carbon nanotube structure 164 formed by the disorderly arranged carbon nanotubes is isotropic; when the carbon nanotubes When the structure 164 includes ordered arrangement of carbon nanotubes, the carbon nanotubes are preferentially oriented along one or more directions. The thickness of the carbon nanotube structure 164 is preferably 0.5 nm-1 mm. The carbon nanotubes in the carbon nanotube structure 164 include one or more of single-wall carbon nanotubes, double-wall carbon nanotubes and multi-wall carbon nanotubes. The single-walled carbon nanotubes have a diameter of 0.5 nm to 50 nm, the double-walled carbon nanotubes have a diameter of 1.0 nm to 50 nm, and the multi-walled carbon nanotubes have a diameter of 1.5 nm to 50 nm. Preferably, the carbon nanotube structure 164 includes ordered carbon nanotubes, and the carbon nanotubes are preferentially oriented along a fixed direction. It can be understood that the thermal response speed of the carbon nanotube structure 164 is related to its thickness. In the case of the same area, the larger the thickness of the carbon nanotube structure 164, the slower the thermal response speed; conversely, the smaller the thickness of the carbon nanotube structure 164, the faster the thermal response speed. Since the carbon nanotube structure 164 is composed of pure carbon nanotubes, the heat capacity per unit area of the carbon nanotube structure 164 is less than 2×10 ⁻⁴ joules per square centimeter Kelvin, preferably less than 1.7×10 ⁻⁶ joules per square centimeter Kelvin. The extremely small heat capacity per unit area makes the carbon nanotube structure 164 have a faster thermal response speed.

Specifically, the carbon nanotube structure 164 includes at least one carbon nanotube film, at least one carbon nanotube linear structure, or a composite structure composed of the carbon nanotube film and the linear structure. It can be understood that when the carbon nanotube structure 164 includes multiple carbon nanotube films, the multiple carbon nanotube films can be stacked or arranged side by side. Please refer to FIG. 3 , when the carbon nanotube structure 164 includes a plurality of carbon nanotube linear structures, the plurality of carbon nanotube linear structures can be arranged parallel to each other, side by side or crossed to form a two-dimensional carbon nanotube structure 164 or Intertwined or braided to form a two-dimensional carbon nanotube structure 164 . In addition, please refer to FIG. 4 , when the carbon nanotube structure 164 can be bent and coiled into a two-dimensional carbon nanotube structure 164 through a carbon nanotube linear structure.

The carbon nanotube film includes a carbon nanotube drawn film, a carbon nanotube flocculated film or a carbon nanotube rolled film. The carbon nanotube wire structure may include at least one carbon nanotube wire, a bundle structure composed of multiple carbon nanotube wires arranged in parallel, or a strand structure composed of multiple carbon nanotube wires twisted.

The carbon nanotube structure 164 may include at least one carbon nanotube drawn film, which is a self-supporting carbon nanotube film obtained by directly pulling from a carbon nanotube array. Each drawn carbon nanotube film includes a plurality of carbon nanotubes which are preferentially oriented in the same direction and arranged parallel to the surface of the drawn carbon nanotube film. The carbon nanotubes are connected end to end by van der Waals force to form an integral self-supporting carbon nanotube drawn film. Please refer to FIG. 5 and FIG. 6 , specifically, each drawn carbon nanotube film includes a plurality of continuous and aligned carbon nanotube segments 143 . The plurality of carbon nanotube segments 143 are connected end to end by van der Waals force. Each carbon nanotube segment 143 includes a plurality of parallel carbon nanotubes 145, and the plurality of parallel carbon nanotubes 145 are closely combined by van der Waals force. The carbon nanotube segment 143 has any width, thickness, uniformity and shape. The thickness of the drawn carbon nanotube film is 0.5 nanometers to 100 microns, the width is related to the size of the carbon nanotube array from which the drawn carbon nanotube film is drawn, and the length is not limited. When the carbon nanotube structure 164 is composed of a carbon nanotube drawn film, and the thickness of the carbon nanotube structure 164 is relatively small, such as less than 10 microns, the carbon nanotube structure 164 has good transparency, and its light transmittance can reach 90 %, can be used to create a transparent heat source.

When the carbon nanotube structure 164 includes multi-layer carbon nanotube drawn films stacked, a cross angle α is formed between carbon nanotubes arranged in preferred orientations in two adjacent layers of carbon nanotube drawn films, and α is greater than or equal to 0 degrees is less than or equal to 90 degrees (0°≤α≤90°). There is a certain gap between the plurality of carbon nanotube drawn films or between adjacent carbon nanotubes in a carbon nanotube drawn film, thereby forming a plurality of pores in the carbon nanotube structure 164, and the pore size of the pores is about less than 10 microns. For the specific structure and preparation method of the carbon nanotube stretched film, please refer to the CN101239712A Chinese mainland open patent application (carbon nanotube film) filed on February 9, 2007 by Fan Shoushan et al. Structure and preparation method, applicant: Tsinghua University, Hongfujin Precision Industry (Shenzhen) Co., Ltd.). To save space, it is only cited here, but all the technical disclosures of the above applications should also be regarded as a part of the technical disclosures of the present application.

The carbon nanotube structure 164 of the embodiment of the present invention includes a plurality of carbon nanotube stretched films stacked along the same direction, so that the carbon nanotubes in the carbon nanotube structure 164 are preferentially aligned along the same direction.

The carbon nanotube structure 164 may include at least one carbon nanotube flocculation film, and the carbon nanotube flocculation film includes intertwined and uniformly distributed carbon nanotubes. The length of the carbon nanotubes is greater than 10 microns, preferably 200-900 microns, so that the carbon nanotubes are entangled with each other. The carbon nanotubes attract and entangle with each other through van der Waals force to form a network structure, so as to form an integrated self-supporting carbon nanotube flocculation film. The carbon nanotube flocculation film is isotropic. The carbon nanotubes in the carbon nanotube flocculation film are evenly distributed and randomly arranged, forming a large number of pore structures, and the pore diameter is about less than 10 microns. The length and width of the carbon nanotube flocculated film are not limited. Please refer to Figure 7, because in the carbon nanotube flocculation film, the carbon nanotubes are intertwined with each other, so the carbon nanotube flocculation film has good flexibility, and is a self-supporting structure, which can be bent and folded into any shape Does not break. The area and thickness of the carbon nanotube flocculated film are not limited, and the thickness is 1 micron to 1 mm, preferably 100 microns. For the specific structure and preparation method of the carbon nanotube flocculation film, please refer to the Chinese mainland patent application No. 200710074027.5 (Method for preparing carbon nanotube film, applicant: Tsinghua University) filed by Fan Shoushan and others on April 13, 2007 , Hongfujin Precision Industry (Shenzhen) Co., Ltd.). To save space, it is only cited here, but all the technical disclosures of the above applications should also be regarded as a part of the technical disclosures of the present application.

The carbon nanotube structure 164 may include at least one carbon nanotube laminated film including uniformly distributed carbon nanotubes. The carbon nanotubes are disordered and preferentially aligned along the same direction or different directions. The carbon nanotubes in the carbon nanotube rolling film partially overlap each other, and are attracted to each other by van der Waals force, so that the carbon nanotube structure has good flexibility and can be bent and folded into any shape without breaking . Moreover, because the carbon nanotubes in the carbon nanotube rolling film are attracted to each other by van der Waals force, they are closely combined, so that the carbon nanotube rolling film is an integrated self-supporting structure. The carbon nanotube rolled film can be obtained by rolling a carbon nanotube array. The carbon nanotubes in the carbon nanotube rolling film form an angle β with the surface of the growth substrate forming the carbon nanotube array, where β is greater than or equal to 0 degrees and less than or equal to 15 degrees (0≤β≤15°) , the included angle β is related to the pressure exerted on the carbon nanotube array, the greater the pressure, the smaller the included angle, preferably, the carbon nanotubes in the carbon nanotube rolled film are arranged parallel to the growth substrate. The carbon nanotube rolling film is obtained by rolling a carbon nanotube array, and the carbon nanotubes in the carbon nanotube rolling film have different arrangements according to different rolling methods. Please refer to Fig. 8, when rolling along different directions, carbon nanotubes are preferentially aligned in different directions. Please refer to FIG. 9 , when rolled in the same direction, the carbon nanotubes are preferentially aligned along a fixed direction. In addition, when the rolling direction is perpendicular to the surface of the carbon nanotube array, the carbon nanotubes can be arranged randomly. The length of the carbon nanotubes in the carbon nanotube rolling film is greater than 50 microns.

The area and thickness of the carbon nanotube rolling film are not limited, and can be selected according to actual needs. The area of the carbon nanotube rolled film is substantially the same as the size of the carbon nanotube array. The thickness of the carbon nanotube rolling film is related to the height of the carbon nanotube array and the pressure of rolling, and can be 1 micron to 1 mm. It can be understood that the greater the height of the carbon nanotube array and the smaller the applied pressure, the greater the thickness of the prepared carbon nanotube laminated film; conversely, the smaller the height of the carbon nanotube array and the greater the applied pressure, the The thickness of the prepared carbon nanotube rolled film is smaller. There is a certain gap between adjacent carbon nanotubes in the carbon nanotube rolling film, so that a plurality of pores are formed in the carbon nanotube rolling film, and the diameter of the pores is less than about 10 microns. For the specific structure and preparation method of the carbon nanotube rolled film, please refer to the Chinese mainland patent application No. 200710074699.6 (Preparation method of carbon nanotube film, applicant: Tsinghua University) filed by Fan Shoushan and others on June 1, 2007 , Hongfujin Precision Industry (Shenzhen) Co., Ltd.). To save space, it is only cited here, but all the technical disclosures of the above applications should also be regarded as a part of the technical disclosures of the present application.

The carbon nanotube structure 164 may include at least one carbon nanotube wire. The carbon nanotube wire can be a non-twisted carbon nanotube wire or a twisted carbon nanotube wire. The non-twisted carbon nanotube wire is obtained by treating a drawn carbon nanotube film with an organic solvent. Please refer to FIG. 10 , the non-twisted carbon nanotube wire includes a plurality of carbon nanotubes arranged along the length direction of the carbon nanotube wire. Preferably, the carbon nanotubes are connected end to end. Specifically, the non-twisted carbon nanotube wire includes a plurality of carbon nanotube segments, the plurality of carbon nanotube segments are connected end to end by van der Waals force, and each carbon nanotube segment includes a plurality of carbon nanotube segments that are parallel to each other and closely combined by van der Waals force. nanotube. The carbon nanotube segment has any length, thickness, uniformity and shape. The length of the non-twisted carbon nanotubes is not limited, and the diameter is 0.5 nanometers to 100 microns. For the specific structure and preparation method of the carbon nanotube wire, please refer to the Chinese Patent No. CN100411979C filed on September 16, 2002 by Fan Shoushan et al. The Chinese patent application No. CN1982209A published on June 20, 2007. To save space, it is only cited here, but all the technical disclosures of the above applications should also be regarded as a part of the technical disclosures of the present application.

The twisted carbon nanotube wire is obtained by using a mechanical force to twist the two ends of the carbon nanotube film in opposite directions. Please refer to FIG. 11 , the twisted carbon nanotube wire includes a plurality of carbon nanotubes arranged helically around the carbon nanotube wire axis. Specifically, the twisted carbon nanotube wire includes a plurality of carbon nanotube segments, the plurality of carbon nanotube segments are connected end to end by van der Waals force, and each carbon nanotube segment includes a plurality of carbon nanotubes that are parallel to each other and closely combined by van der Waals force. Tube. The carbon nanotube segment has any length, thickness, uniformity and shape. The length of the twisted carbon nanotubes is not limited, and the diameter is 0.5 nanometers to 100 microns.

Further, the twisted carbon nanotubes can be treated with a volatile organic solvent. Under the effect of the surface tension generated when the volatile organic solvent volatilizes, the adjacent carbon nanotubes in the treated twisted carbon nanotubes are closely combined by van der Waals force, so that the diameter and specific surface area of the twisted carbon nanotubes are reduced. Increased density and strength.

Since the carbon nanotube wire is obtained by treating the above-mentioned carbon nanotube stretched film with an organic solvent or mechanical force, and the carbon nanotube stretched film is a self-supporting structure, the carbon nanotube wire is a self-supporting structure. The carbon nanotube wire is similar to the carbon nanotube stretched film, and a plurality of carbon nanotubes are connected end to end by van der Waals force to form an integral self-supporting carbon nanotube wire. In addition, there are gaps between adjacent carbon nanotubes in the carbon nanotube wire, so the carbon nanotube wire has a large number of pores, and the diameter of the pores is less than about 10 microns.

The material of the matrix 162 can be selected from polymer materials or inorganic non-metallic materials. The matrix 162 or the precursor forming the matrix 162 is liquid or gaseous at a certain temperature, so that the matrix 162 or the precursor of the matrix 162 can penetrate into the carbon nanometer during the preparation of the heating element 16 of the surface heat source 10. The gaps or pores of the tube structure 164 form a composite structure combining the solid matrix 162 and the carbon nanotube structure 164 . The material of the substrate 162 should have certain heat resistance, so that it will not be damaged by heat, deformed, melted, gasified or decomposed within the working temperature of the surface heat source 10 .

Specifically, the polymer material may include one or more of thermoplastic polymers or thermosetting polymers, such as cellulose, polyethylene terephthalate, acrylic resin, polyethylene, polypropylene, polystyrene, One or more of polyvinyl chloride, phenolic resin, epoxy resin, silica gel and polyester. The inorganic non-metallic material may include one or more of glass, ceramics and semiconductor materials. In the embodiment of the present invention, the material of the base body 162 is epoxy resin.

Please refer to FIG. 12 , since there are gaps between the carbon nanotubes in the carbon nanotube structure 164, a plurality of pores are formed in the carbon nanotube structure 164, and the matrix 162 or the precursor forming the matrix 162 is at a certain temperature. Liquid or gaseous, so that the matrix 162 can penetrate into the pores of the carbon nanotube structure 164 when it is combined with the carbon nanotube structure 164 . Figure 12 is a sectional photo of the heating element 16 obtained after stretching the heating element 16 parallel to the arrangement direction of the carbon nanotubes in the carbon nanotube film until the heating element 16 breaks. After recombination, the carbon nanotube structure 164 can still basically maintain the shape before recombination, and the carbon nanotubes are arranged in the same direction in the epoxy resin.

The matrix 162 can only be filled in the pores of the carbon nanotube structure 164 , or can further completely cover the entire carbon nanotube structure 164 as shown in FIG. 2 . Please refer to FIG. 13 , when the heating element 16 includes a plurality of carbon nanotube structures 164 , the plurality of carbon nanotube structures 164 may be disposed in the matrix 162 at intervals (or in contact with each other). When the carbon nanotube structure 164 is a two-dimensional structure, the two-dimensional structure can be arranged side by side or stacked in the matrix 162 at intervals or in contact with each other; when the carbon nanotube structure 164 is a linear structure, the linear The structures may be disposed in the matrix 162 at intervals or in contact with each other. When the carbon nanotube structures 164 are arranged at intervals in the matrix 162 , the amount of carbon nanotube structures 164 needed to prepare the heating element 16 can be saved. In addition, the carbon nanotube structure 164 can be arranged at a specific position of the substrate 162 according to actual needs, so that the heating element 16 has different heating temperatures at different positions.

It can be understood that the matrix 162 penetrates into the pores of the carbon nanotube structure 164, which can play a role in fixing the carbon nanotubes in the carbon nanotube structure 164, so that the carbon nanotubes in the carbon nanotube structure 164 can It will not fall off due to external friction or scratching. When the matrix 162 covers the entire carbon nanotube structure 164 , the matrix 162 can further protect the carbon nanotube structure 164 . When the base 162 is an insulating organic polymer material or an inorganic non-metallic material, the base 162 also ensures that the heating element 16 is insulated from the outside. In addition, the base 162 can further serve the purpose of conducting heat and making heat distribution uniform. Furthermore, when the temperature of the carbon nanotube structure 164 rises sharply, the matrix 162 can play a role of buffering heat, so that the temperature change of the heating element 16 is gentler. The material of the matrix 162 can be a flexible polymer material, so that the flexibility and toughness of the entire surface heat source 10 can be enhanced.

It can be understood that since the carbon nanotubes are evenly distributed in the carbon nanotube structure 164, the heating element 16 can be formed by directly combining the matrix 162 with the self-supporting carbon nanotube structure 164, so that the carbon nanotubes can be evenly distributed in the heating element 16 , and the content of carbon nanotubes reaches 99%, which improves the heating temperature of the heat source 10 . Since the carbon nanotube structure 164 is a self-supporting structure, and the carbon nanotubes are evenly distributed in the carbon nanotube structure 164, the self-supporting carbon nanotube structure 164 is directly compounded with the matrix 162, which can make the heating formed after the compounding The carbon nanotubes in the element 16 are still combined with each other to maintain the form of a carbon nanotube structure 164, so that the carbon nanotubes in the heating element 16 can be evenly distributed to form a conductive network, and are not limited by the concentration of the carbon nanotubes in the solution. The mass percentage of carbon nanotubes in the heating element 16 can reach 99%.

The first electrode 12 and the second electrode 14 are made of conductive materials, and the shapes of the first electrode 12 and the second electrode 14 are not limited, and may be conductive films, metal sheets or metal leads. Preferably, both the first electrode 12 and the second electrode 14 are a conductive film. When used in the micro surface heat source 10, the conductive film has a thickness of 0.5 nanometers to 100 micrometers. The material of the conductive film may be metal, alloy, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver glue, conductive polymer or conductive carbon nanotube, etc. The metal or alloy material can be aluminum, copper, tungsten, molybdenum, gold, titanium, neodymium, palladium, cesium or alloys in any combination thereof. In this embodiment, the material of the first electrode 12 and the second electrode 14 is metal palladium film with a thickness of 5 nanometers. The metal palladium and carbon nanotubes have better wetting effect, which is beneficial to form good electrical contact between the first electrode 12 and the second electrode 14 and the heating element 16, and reduce ohmic contact resistance.

The first electrode 12 and the second electrode 14 are directly electrically connected to the carbon nanotube structure 164 in the heating element 16 . Wherein, the first electrode 12 and the second electrode 14 are arranged at intervals, so that when the heating element 16 is applied to the surface heat source 10, a certain resistance value is connected to avoid short circuit phenomenon.

Specifically, when the matrix 162 of the heating element 16 is only filled in the pores of the carbon nanotube structure 164, since part of the carbon nanotubes in the carbon nanotube structure 164 are exposed on the surface of the heating element 16, the first electrode 12 And the second electrode 14 can be disposed on the surface of the heating element 16 , so that the first electrode 12 and the second electrode 14 are electrically connected with the carbon nanotube structure 164 . The first electrode 12 and the second electrode 14 can be arranged on the same surface of the heating element 16 or can be arranged on different surfaces of the heating element 16 . In addition, when the base 162 of the heating element 16 covers the entire carbon nanotube structure 164, in order to electrically connect the first electrode 12 and the second electrode 14 with the carbon nanotube structure 164, the first electrode 12 and the second The electrodes 14 may be disposed in the matrix 162 of the heating element 16 and directly contact the carbon nanotube structures 164 . At this time, in order to conduct the first electrode 12 and the second electrode 14 with the external power supply, the first electrode 12 and the second electrode 14 can be partially exposed outside the heating element 16; or, the heat source 10 can further include two Lead wires are electrically connected to the first electrode 12 and the second electrode 14 respectively, and lead out from the inside of the base body 162 .

When the carbon nanotubes in the carbon nanotube structure 164 are arranged in order, preferably, the arrangement direction of the carbon nanotubes extends from the first electrode 12 to the second electrode 14 . Specifically, when the carbon nanotube structure 164 includes at least one carbon nanotube drawn film, the first electrode 12 and the second electrode 14 are arranged at both ends of the carbon nanotube drawn film, so that the carbon nanotube drawn film The carbon nanotubes extend end to end from the first electrode 12 to the second electrode 14 . When the carbon nanotube structure 164 includes a plurality of carbon nanotube linear structures arranged in parallel, similar to a resistance wire, both ends of the carbon nanotube linear structure are electrically connected to the first electrode 12 and the second electrode 14 respectively.

The first electrode 12 and the second electrode 14 can be arranged on the surface of the heating element 16 or the carbon nanotube structure 164 through a conductive adhesive (not shown), and the conductive adhesive realizes the first electrode 12 and the second electrode. While the second electrode 14 is in electrical contact with the carbon nanotube structure 164 , the first electrode 12 and the second electrode 14 can be better fixed on the surface of the carbon nanotube structure 164 . Specifically, the conductive adhesive can be silver glue.

It can be understood that the structure and material of the first electrode 12 and the second electrode 14 are not limited, and the purpose of setting them is to make the carbon nanotube structure 164 in the heating element 16 flow current. Therefore, the first electrode 12 and the second electrode 14 only need to be electrically conductive, and forming electrical contact with the carbon nanotube structure 164 of the heating element 16 is within the protection scope of the present invention.

When the surface heat source 10 of the embodiment of the present invention is used, the first electrode 12 and the second electrode 14 of the surface heat source 10 can be connected to a wire first and then connected to a power source. After being powered on, the carbon nanotube structure 164 in the heat source 10 can radiate electromagnetic waves in a certain wavelength range. The surface heat source 10 may be in direct contact with the surface of the object to be heated. Alternatively, the surface heat source 10 may be arranged at a certain distance from the object to be heated.

The surface heat source 10 in the embodiment of the present invention can radiate electromagnetic waves in different wavelength ranges by adjusting the power supply voltage and the thickness of the carbon nanotube structure 164 when the area of the carbon nanotube structure 164 is constant. Specifically, the carbon nanotube structure 164 can generate an infrared thermal radiation. When the power supply voltage is constant, the thickness of the carbon nanotube structure 164 and the wavelength of the electromagnetic wave radiated from the surface heat source 10 have opposite changing trends. That is, when the power supply voltage is constant, the thicker the carbon nanotube structure 164 is, the shorter the wavelength of the electromagnetic wave radiated by the surface heat source 10 is; the thinner the carbon nanotube structure 164 is, the longer the wavelength of the electromagnetic wave radiated by the surface heat source 10 is. When the thickness of the carbon nanotube structure 164 is constant, the magnitude of the power supply voltage is inversely proportional to the wavelength of the electromagnetic wave radiated from the surface heat source 10 . That is, when the thickness of the carbon nanotube structure 164 is constant, the greater the power supply voltage, the shorter the wavelength of electromagnetic waves radiated by the surface heat source 10; the smaller the power supply voltage, the longer the wavelength of electromagnetic waves radiated by the surface heat source 10. It can be understood that the surface heat source 10 should limit the voltage applied to both ends of the first electrode 12 and the second electrode 14 through a circuit according to the material of the substrate 162 during application, so that the heating temperature of the carbon nanotube structure 164 is controlled within the temperature of the substrate 162. within the tolerable temperature range. For example, when the material of the matrix 162 is an organic polymer, the voltage range is 0-10 volts, and the heating temperature of the surface heat source 10 is below 120° C., which is lower than the melting point of the polymer. When the material of the base body 162 is ceramics, the voltage range is 10V-30V, and the heating temperature of the surface heat source 10 is 120°C-500°C. Please refer to FIG. 14 , the embodiment of the present invention measures the surface heat source 10 of the heating element 16 formed by laminating the carbon nanotube structure 164 formed by stacking 100 layers of carbon nanotube films and the epoxy resin matrix 162, and it can be found that the surface heat source 10, the higher the applied voltage, the faster the temperature of the surface heat source 10 rises, and the higher the heating temperature.

Carbon nanotubes have good electrical conductivity and thermal stability, and as an ideal black body structure, they have relatively high heat radiation efficiency. In another embodiment, when the substrate 162 is made of a heat-resistant material, the surface heat source 10 is exposed to an oxidizing gas or an atmospheric environment, wherein the carbon nanotube structure 164 has a thickness of 5 mm, and is heated by a voltage of 10 volts to 30 volts. By adjusting the power supply voltage, the surface heat source 10 can radiate electromagnetic waves with longer wavelengths. The temperature of the surface heat source 10 was found to be 50°C to 500°C by a temperature measuring instrument. For an object with a black body structure, when the corresponding temperature is 200°C to 450°C, it can emit thermal radiation (infrared rays) invisible to the human eye, and the thermal radiation at this time is the most stable and efficient. The surface heat source 10 made by using the carbon nanotube structure 164 can be applied to fields such as electric heaters, infrared therapeutic devices, electric blankets, and electric heaters.

In addition, when the thickness of the carbon nanotube structure 164 in the heating element 16 of the surface heat source 10 is small, which is a transparent carbon nanotube structure 164, and the material of the matrix 162 is a transparent organic or inorganic material, the surface heat source 10 is a transparent surface heat source 10. In addition, when the substrate 162 in the heating element 16 of the surface heat source 10 is made of flexible polymer material, the surface heat source 10 is a flexible surface heat source 10 . Further, since the matrix 162 of the polymer material can be formed into various shapes by molding, and the carbon nanotube wires can be woven into different shapes, the flexible surface heat source 10 can be used to manufacture self-heating heating clothes, heating gloves or Heating shoes, etc.

Please refer to FIG. 15 and FIG. 16 , the second embodiment of the present invention provides a surface heat source 20 , the surface heat source 20 includes a heating element 26 , a first electrode 22 and a second electrode 24 . The heating element 26 includes a matrix 262 and at least one carbon nanotube structure 264 disposed in the matrix 262 . The heating element 26 is a type of two-dimensional structure, that is, a two-dimensional structure with a certain thickness. Specifically, the heating element 26 can be a plane structure or a curved structure. The carbon nanotube structure 264 of the heating element 26 is electrically connected to the first electrode 22 and the second electrode 24 for enabling the heating element 26 to be powered on to flow current.

The structure of the surface heat source 20 is basically the same as the surface heat source 10 of the first embodiment, the difference is that the surface heat source 20 further includes a support 28 , a heat reflective layer 27 and a protective layer 25 . The heat reflective layer 27 is disposed on the surface of the support 28 . The heating element 26 is disposed on the surface of the heat reflective layer 27 . The first electrode 22 and the second electrode 24 are spaced apart from each other on the surface of the heating element 26 , and are in electrical contact with the heating element 26 , so as to allow current to flow through the heating element 26 . The protection layer 25 is disposed on the surface of the heating element 26 to prevent the heating element 26 from absorbing foreign impurities. The supporting body 28, the heat reflective layer 27 and the protective layer 25 are all optional structures. Further, the surface heat source 20 includes two electrode lead wires 29, which are respectively connected to the first electrode 22 and the second electrode 24, and drawn out from the first electrode 22 and the second electrode 24 embedded in the base body 262 to the outside of the base body 262. .

The shape of the support body 28 is not limited, and it has a surface for supporting the heating element 16 or the heat reflection layer 27 . The surface can be flat or curved. Preferably, the support body 28 is a plate-like structure, and its material can be hard materials, such as ceramics, glass, resin, quartz, etc., or flexible materials, such as plastics or resins. Wherein, the size of the support body 28 is not limited, and can be changed according to actual needs. The preferred support body 28 in this embodiment is a ceramic substrate.

The heat reflection layer 27 is used to reflect the heat generated by the heating element 26, so as to control the direction of heating, for single-sided heating, and to further improve the heating efficiency. The heat reflection layer 27 is made of a white insulating material, such as metal oxide, metal salt or ceramics. In this embodiment, the heat reflective layer 27 is an aluminum oxide layer with a thickness of 100 microns to 0.5 mm. The heat reflective layer 27 can be formed on the surface of the support 28 by sputtering or other methods. It can be understood that the heat reflection layer 27 can also be disposed on the surface of the support body 28 away from the heating element 26 , that is, the support body 28 is disposed between the heating element 26 and the heat reflection layer 27 . The heat reflective layer 27 is an optional structure. The heating element 26 can be directly arranged on the surface of the support body 28, at this time, the heating direction of the surface heat source 10 is not limited, and can be used for double-sided heating.

The protective layer 25 is an optional structure, and its material is an insulating material, such as plastic, rubber or resin. The thickness of the protective layer 25 is not limited, and can be selected according to actual conditions. The protective layer 25 covers the first electrode 22 , the second electrode 24 and the heating element 26 . In this embodiment, the material of the insulating protective layer 25 is heat-resistant rubber, and its thickness is 0.5-2 mm. The protective layer 25 can protect the heating element 26, especially when the matrix 262 in the heating element 26 is only filled in the pores of the carbon nanotube structure 264, the protective layer 25 can prevent the carbon nanotubes exposed on the surface of the heating element 26 from being damaged. In addition, the heating element 26 can be insulated from the outside except the first electrode 22 and the second electrode 24 .

Please refer to FIG. 17 , the third embodiment of the present invention provides a surface heat source 30 , the surface heat source 30 includes a heating element 36 , a first electrode 32 and a second electrode 34 . The heating element 36 is a two-dimensional structure, that is, a two-dimensional structure with a certain thickness. Specifically, the heating element 36 can be a plane structure or a curved structure. The heating element 36 is electrically connected to the first electrode 32 and the second electrode 34, and is used to make the carbon nanotubes in the heating element 36 be powered on to flow current.

The structure of the surface heat source 30 is basically the same as that of the surface heat source 10 of the first embodiment, the difference is that the heating element 36 includes a plurality of carbon nanotube linear composite structures 366 . The plurality of carbon nanotube linear composite structures 366 are interwoven to form a two-dimensional heating element 36 . The carbon nanotube linear composite structure 366 is obtained by compounding a carbon nanotube linear structure and a matrix material. The matrix material is filled in the pores of the carbon nanotube linear structure. The carbon nanotube composite wire structure 366 can be directly woven into heating elements 36 of various shapes conveniently. The matrix material is preferably a flexible polymer.

Please refer to Fig. 18, the embodiment of the present invention provides a method for preparing a surface heat source 10, which includes the following steps:

In step 1, a carbon nanotube structure 164 is provided, and the carbon nanotube structure 164 includes a plurality of pores.

According to the difference of the carbon nanotube structure 164, the preparation method of the carbon nanotube structure 164 includes: a direct film drawing method, a rolling method, a flocculation method and the like. In this embodiment, the carbon nanotube structure 164 can be a one-dimensional structure or a two-dimensional structure. The preparation methods of the above-mentioned several carbon nanotube structures 164 will be described separately below.

(1) When the carbon nanotube structure 164 includes at least one carbon nanotube drawn film, the preparation method of the carbon nanotube structure 164 specifically includes the following steps:

Firstly, a carbon nanotube array formed on a growth substrate is provided, and the array is a super-aligned carbon nanotube array.

The preparation method of the carbon nanotube array adopts the chemical vapor deposition method, and its specific steps include: (a) providing a flat growth substrate, the growth substrate can be a P-type or N-type silicon growth substrate, or a silicon oxide layer formed Growth substrate, the embodiment of the present invention preferably adopts a 4-inch silicon growth substrate; (b) uniformly form a catalyst layer on the surface of the growth substrate, the catalyst layer material can be iron (Fe), cobalt (Co), nickel (Ni) or any combination thereof; (c) anneal the above-mentioned growth substrate formed with the catalyst layer in air at 700°C to 900°C for about 30 minutes to 90 minutes; (d) place the treated growth substrate in the reaction In the furnace, heat to 500° C.-740° C. under a protective gas environment, and then pass through carbon source gas to react for about 5 minutes to 30 minutes, and grow to obtain a carbon nanotube array. The carbon nanotube array is a pure carbon nanotube array formed by a plurality of carbon nanotubes growing parallel to each other and perpendicular to the growth substrate. By controlling the growth conditions above, the aligned carbon nanotube array basically does not contain impurities, such as amorphous carbon or residual catalyst metal particles.

The carbon nanotube array provided in the embodiment of the present invention is one of a single-wall carbon nanotube array, a double-wall carbon nanotube array and a multi-wall carbon nanotube array. The diameter of the carbon nanotube is 1-50 nanometers, and the length is 50 nanometers-5 millimeters. In this embodiment, the length of the carbon nanotubes is preferably 100-900 microns.

In the embodiment of the present invention, the carbon source gas can be selected from acetylene, ethylene, methane and other chemically active hydrocarbons. The preferred carbon source gas in the embodiment of the present invention is acetylene; the protective gas is nitrogen or an inert gas, which is preferred in the embodiment of the present invention. The protective gas is argon.

It can be understood that the carbon nanotube array provided in the embodiment of the present invention is not limited to the above-mentioned preparation method, and may also be a graphite electrode constant current arc discharge deposition method, a laser evaporation deposition method, and the like.

Secondly, using a stretching tool to pull carbon nanotubes from the carbon nanotube array to obtain at least one carbon nanotube stretched film, which specifically includes the following steps: (a) selecting a carbon nanotube from the super-aligned carbon nanotube array Or a plurality of carbon nanotubes with a certain width. In this embodiment, an adhesive tape with a certain width, tweezers or clips are preferably used to contact the carbon nanotube array to select one or a plurality of carbon nanotubes with a certain width; (b) with Stretching the selected carbon nanotubes at a certain speed to form a plurality of carbon nanotube segments connected end to end, thereby forming a continuous carbon nanotube film. The pulling direction is substantially perpendicular to the growth direction of the carbon nanotube array.

During the above-mentioned stretching process, while the plurality of carbon nanotube segments are gradually detached from the growth substrate along the stretching direction under the action of tension, due to the van der Waals force, the selected plurality of carbon nanotube segments are separated from other carbon nanotube segments respectively. The fragments are pulled out continuously end to end, thereby forming a continuous, uniform carbon nanotube film with a certain width. The carbon nanotube film includes a plurality of carbon nanotubes connected end to end, and the carbon nanotubes are basically arranged along a stretching direction. Please refer to FIG. 5 and FIG. 6 , the carbon nanotube film includes a plurality of carbon nanotubes 145 arranged in preferred orientations. Further, the carbon nanotube film includes a plurality of carbon nanotube segments 143 connected end to end and arranged in an orientation, and the two ends of the carbon nanotube segments 143 are connected to each other by van der Waals force. The carbon nanotube segment 143 includes a plurality of carbon nanotubes 145 arranged parallel to each other. The method for obtaining the carbon nanotube film by direct stretching is simple and fast, and is suitable for industrial application.

The width of the carbon nanotube film is related to the size of the carbon nanotube array, and the length of the carbon nanotube film is not limited and can be produced according to actual needs. When the area of the carbon nanotube array is 4 inches, the width of the carbon nanotube film is 0.5 nanometers to 10 centimeters, and the thickness of the carbon nanotube film is 0.5 nanometers to 100 micrometers.

Finally, the carbon nanotube structure 164 is prepared by using the above-mentioned carbon nanotube drawn film.

The carbon nanotube stretched film can be used as a carbon nanotube structure 164 . Further, at least two drawn carbon nanotube films can also be laid in parallel without gaps or/and stacked to obtain a carbon nanotube structure 164 . Since the drawn carbon nanotube film has a larger specific surface area, the drawn carbon nanotube film has greater viscosity, so the multi-layered carbon nanotube films can be closely combined to form a carbon nanotube structure 164 . In the carbon nanotube structure 164, the number of layers of the carbon nanotube drawn film is not limited, and there is a cross angle α between two adjacent layers of the carbon nanotube drawn film, 0°≤α≤90°, which can be determined according to actual needs preparation. The carbon nanotube film can be laid along the direction from one electrode to the other electrode, so that the carbon nanotubes in the carbon nanotube film extend along the direction from one electrode to the other electrode

In this embodiment, the step of treating the carbon nanotube structure 164 with an organic solvent is further included. The organic solvent is a volatile organic solvent, and one or more mixtures of ethanol, methanol, acetone, dichloroethane and chloroform can be selected. , the organic solvent in the present embodiment adopts ethanol. The step of treating with an organic solvent is as follows: disposing the carbon nanotube structure 164 on a substrate surface or a frame structure, dripping the organic solvent on the surface of the carbon nanotube structure 164 through a test tube to infiltrate the entire carbon nanotube structure 164, Alternatively, the above-mentioned carbon nanotube structure 164 may also be soaked in a container containing an organic solvent. After the carbon nanotube structure 164 is infiltrated with an organic solvent, when the number of layers of the carbon nanotube film is small, under the action of surface tension, the adjacent carbon nanotubes in the carbon nanotube film will shrink into an interval distribution carbon nanotube wires. However, when the number of layers of the carbon nanotube film is large, the multilayer carbon nanotube film treated with the organic solvent has a uniform film structure. After the organic solvent treatment, the viscosity of the carbon nanotube structure 164 is reduced, making it easier to use.

(2) When the carbon nanotube structure 164 includes at least one carbon nanotube flocculated film, the preparation method of the carbon nanotube structure 164 includes the following steps:

First, a carbon nanotube raw material is provided.

The carbon nanotube raw material can be carbon nanotubes prepared by various methods such as chemical vapor deposition, graphite electrode constant current arc discharge deposition or laser evaporation deposition.

In this embodiment, a blade or other tool is used to scrape off the aligned carbon nanotube array from the substrate to obtain a carbon nanotube raw material. Preferably, in the carbon nanotube raw material, the length of the carbon nanotube is greater than 100 microns.

Secondly, adding the above-mentioned carbon nanotube raw material into a solvent and performing flocculation treatment to obtain a carbon nanotube floc structure, separating the above-mentioned carbon nanotube floc structure from the solvent, and finalizing the carbon nanotube floc structure processed to obtain a carbon nanotube film.

In the embodiment of the present invention, the solvent may be water, volatile organic solvent, or the like. The flocculation treatment can be carried out by means of ultrasonic dispersion treatment or high-intensity stirring. Preferably, the embodiment of the present invention adopts ultrasonic dispersion for 10 minutes to 30 minutes. Due to the large specific surface area of carbon nanotubes, there is a large van der Waals force between intertwined carbon nanotubes. The above flocculation treatment does not completely disperse the carbon nanotubes in the carbon nanotube raw material in the solvent, and the carbon nanotubes attract and entangle with each other through van der Waals force to form a network structure.

In the embodiment of the present invention, the method for separating the floc structure of carbon nanotubes specifically includes the following steps: pouring the solvent containing the floc structure of carbon nanotubes into a funnel with filter paper; An isolated carbon nanotube floc structure is obtained, and FIG. 19 is a photo of the carbon nanotube floc structure.

In the embodiment of the present invention, the shaping process of the carbon nanotube floc structure specifically includes the following steps: placing the carbon nanotube floc structure in a container; spreading the carbon nanotube floc structure according to a predetermined shape open; apply a certain pressure on the spread carbon nanotube floc structure; and, dry the residual solvent in the carbon nanotube floc structure or wait for the solvent to volatilize naturally to obtain a carbon nanotube floc film, as shown in Figure 7 Scanning electron micrograph of the carbon nanotube flocculation film.

It can be understood that in the embodiment of the present invention, the thickness and surface density of the carbon nanotube flocculation film can be controlled by controlling the spread area of the carbon nanotube flocculation structure. The larger the spread area of the carbon nanotube flocculation structure is, the smaller the thickness and surface density of the carbon nanotube flocculation film will be. For the carbon nanotube flocculated film obtained in the embodiment of the present invention, the thickness of the carbon nanotube flocculated film is 1 micrometer to 2 millimeters.

In addition, the above-mentioned steps of separating and shaping the carbon nanotube floc structure can also be directly realized by suction filtration, which specifically includes the following steps: providing a microporous filter membrane and a suction funnel; The solvent of the structure is poured into the suction funnel through the microporous filter membrane; a carbon nanotube flocculation membrane is obtained after suction filtration and drying. The microporous filter membrane is a filter membrane with a smooth surface and a pore size of 0.22 microns. Since the suction filtration method itself will provide a large air pressure to act on the carbon nanotube floc structure, the carbon nanotube floc structure will directly form a uniform carbon nanotube floc film after suction filtration. Moreover, since the surface of the microporous filter membrane is smooth, the carbon nanotube flocculation membrane is easy to peel off, and a self-supporting carbon nanotube flocculation membrane is obtained.

Please refer to Fig. 7, the above-mentioned carbon nanotube flocculated film includes intertwined carbon nanotubes, and the carbon nanotubes are mutually attracted and entangled by van der Waals force to form a network structure, so the carbon nanotube flocculated film has Very good toughness. In the carbon nanotube flocculation film, the carbon nanotubes are evenly distributed and randomly arranged.

It can be understood that the carbon nanotube flocculation film has a certain thickness, and its thickness can be controlled by controlling the spread area of the carbon nanotube flocculation structure and the pressure. Therefore, the carbon nanotube flocculation film can be directly used as a carbon nanotube structure 164 . In addition, at least two layers of carbon nanotube flocculation films can be stacked or arranged side by side to form a carbon nanotube structure 164 .

(3) When the carbon nanotube structure 164 includes at least one carbon nanotube rolled film, the preparation method of the carbon nanotube structure 164 includes the following steps:

Firstly, a carbon nanotube array formed on a growth substrate is provided, and the array is an aligned carbon nanotube array.

The carbon nanotube array is preferably a super-aligned carbon nanotube array. The preparation method of the carbon nanotube array is the same as that of the above-mentioned carbon nanotube array.

Secondly, a pressing device is used to extrude the above-mentioned carbon nanotube array to obtain a carbon nanotube rolling film, and the specific process is as follows:

The pressing device exerts a certain pressure on the carbon nanotube array. In the process of applying pressure, the carbon nanotube array will be separated from the growth substrate under the action of pressure, thereby forming a carbon nanotube rolling film with a self-supporting structure composed of a plurality of carbon nanotubes, and the plurality of carbon nanotubes The carbon nanotubes are substantially parallel to the surface of the carbon nanotube laminated film.

In the embodiment of the present invention, the pressing device is an indenter with a smooth surface, and the shape and extrusion direction of the indenter determine the arrangement of carbon nanotubes in the prepared carbon nanotube rolling film. Specifically, when a planar indenter is used to extrude in a direction perpendicular to the growth substrate of the above-mentioned carbon nanotube array, an isotropic carbon nanotube rolling film with disordered arrangement of carbon nanotubes can be obtained; When the indenter rolls along a fixed direction parallel to the substrate, a carbon nanotube rolled film with carbon nanotubes aligned along the fixed direction can be obtained; when a roller-shaped indenter is used to roll along different directions, the obtained Carbon nanotube laminated film in which carbon nanotubes are aligned in different directions.

It can be understood that when the above-mentioned carbon nanotube arrays are extruded in the above-mentioned different ways, the carbon nanotubes will fall under the action of pressure, and attract and connect with adjacent carbon nanotubes through van der Waals force to form a plurality of carbon nanotubes. A carbon nanotube laminated film with a self-supporting structure composed of tubes. The plurality of carbon nanotubes form an included angle β with the surface of the growth substrate, wherein β is greater than or equal to zero and less than or equal to 15 degrees (0°≤β≤15°). According to different rolling methods, as shown in FIG. 9 , the carbon nanotubes in the carbon nanotube rolling film can be preferentially aligned along a fixed direction; or, as shown in FIG. 8 , they can be preferentially aligned along different directions. In addition, under the action of pressure, the carbon nanotube array will be separated from the grown substrate, so that the rolled carbon nanotube film is easily detached from the substrate, thereby forming a self-supporting rolled carbon nanotube film.

Those skilled in the art should understand that the inclination degree (inclination angle) of the above-mentioned carbon nanotube array is related to the magnitude of the pressure, the greater the pressure, the greater the inclination angle. The inclination angle is the included angle between the carbon nanotubes in the carbon nanotube array and the substrate on which the carbon nanotube array grows. The thickness of the prepared carbon nanotube rolling film depends on the height of the carbon nanotube array and the pressure. The greater the height of the carbon nanotube array and the smaller the applied pressure, the greater the thickness of the prepared carbon nanotube rolling film; conversely, the smaller the height of the carbon nanotube array and the greater the applied pressure, the prepared carbon The thickness of the nanotube rolled film is smaller. The width of the carbon nanotube rolling film is related to the size of the substrate on which the carbon nanotube array grows. The length of the carbon nanotube rolling film is not limited and can be produced according to actual needs. In the carbon nanotube rolled film obtained in the embodiment of the present invention, the carbon nanotube rolled film has a thickness of 1 micron to 2 mm.

Finally, the carbon nanotube laminated film is lifted from the growth substrate to obtain a self-supporting carbon nanotube laminated film.

The above-mentioned carbon nanotube rolling film includes a plurality of carbon nanotubes arranged in the same direction or preferred orientation, and the carbon nanotubes are attracted to each other through van der Waals force, so the carbon nanotube rolling film has good toughness. In the carbon nanotube rolling film, the carbon nanotubes are evenly distributed and arranged regularly.

It can be understood that the carbon nanotube rolled film has a certain thickness, and its thickness can be controlled by the height of the carbon nanotube array and the pressure. Therefore, the carbon nanotube rolled film can be directly used as a carbon nanotube structure 164 . In addition, at least two carbon nanotube laminated films can be stacked or arranged side by side to form a carbon nanotube structure 164 .

(4) When the carbon nanotube structure 164 includes at least one carbon nanotube linear structure, the preparation method of the carbon nanotube structure 164 includes the following steps:

Firstly, at least one carbon nanotube drawn film is provided.

The method for forming the carbon nanotube drawn film is the same as the method for forming the carbon nanotube drawn film in (1).

Second, the carbon nanotube film is processed to form at least one carbon nanotube wire.

The step of treating the drawn carbon nanotube film may be to treat the drawn carbon nanotube film with an organic solvent to obtain a non-twisted carbon nanotube wire, or to use mechanical external force to twist the drawn carbon nanotube film to obtain a twisted carbon nanotube drawn film. carbon nanotube wires.

The step of using an organic solvent to treat the carbon nanotube drawn film is specifically: soak the entire surface of the carbon nanotube drawn film with an organic solvent, and under the action of the surface tension generated when the volatile organic solvent volatilizes, the carbon nanotube drawn film A plurality of carbon nanotubes parallel to each other are closely combined by van der Waals force, so that the stretched carbon nanotube film shrinks into a non-twisted carbon nanotube wire. The organic solvent is a volatile organic solvent, such as ethanol, methanol, acetone, dichloroethane or chloroform, and ethanol is used in this embodiment. Compared with the stretched carbon nanotube film without organic solvent treatment, the non-twisted carbon nanotube wire treated by organic solvent has a smaller specific surface area and lower viscosity. It can be understood that the method of using an organic solvent to treat the carbon nanotube film to form a non-twisted carbon nanotube wire is similar to the method of using an organic solvent to reduce the viscosity of the carbon nanotube film in (1). When twisting the carbon nanotube wire, the two ends of the carbon nanotube film are not fixed, that is, the carbon nanotube film is not arranged on the substrate surface or the frame structure.

The step of using external mechanical force to twist the carbon nanotube film is to use a mechanical force to twist the two ends of the carbon nanotube film in opposite directions. In the embodiment of the present invention, specifically, a spinning shaft whose tail can be stuck to the carbon nanotube drawn film can be provided. After the tail of the spinning shaft is combined with the drawn carbon nanotube film, the spinning shaft rotates the drawn carbon nanotube film in a rotating manner to form a twisted carbon nanotube wire. It can be understood that the rotation mode of the above-mentioned spinning shaft is not limited, and it can be forward rotation, reverse rotation, or a combination of forward rotation and reverse rotation.

Further, the twisted carbon nanotubes can be treated with a volatile organic solvent. Under the effect of the surface tension generated when the volatile organic solvent volatilizes, the adjacent carbon nanotubes in the treated twisted carbon nanotubes are closely combined by van der Waals force, so that the specific surface area of the twisted carbon nanotubes is reduced and the viscosity is reduced. , the density and strength of the twisted carbon nanotube wires without organic solvent treatment are increased.

Thirdly, at least one carbon nanotube wire structure is prepared by using the above carbon nanotube wire, and a carbon nanotube structure 164 is obtained.

The above-mentioned twisted carbon nanotube wire or non-twisted carbon nanotube wire is a self-supporting structure, which can be directly used as a carbon nanotube structure 164 . In addition, a plurality of carbon nanotube wires can be arranged in parallel to form a carbon nanotube wire structure in a bundle structure, or the carbon nanotube wires arranged in parallel can be twisted to obtain a stranded carbon nanotube wire structure. Further, the plurality of carbon nanotube wires or carbon nanotube wire-like structures can be arranged in parallel, intersected or braided to obtain a two-dimensional carbon nanotube structure 164 .

Step 2, forming a first electrode 12 and a second electrode 14 at two ends of the carbon nanotube structure 164 at intervals, and the first electrode 12 and a second electrode 14 are electrically connected to the carbon nanotube structure 164 .

The arrangement of the first electrode 12 and the second electrode 14 is related to the carbon nanotube structure 164 . When the carbon nanotubes in the carbon nanotube structure 164 are at least partially arranged in an orderly manner, such as the carbon nanotube structure 164 comprising a carbon nanotube stretched film, a carbon nanotube rolled film obtained by rolling along a fixed direction, or a carbon nanotube During the pipeline, that is, when most of the carbon nanotubes in the carbon nanotube structure 164 are aligned along the same direction, preferably, it should be ensured that some carbon nanotubes in the carbon nanotube structure 164 are aligned along the first electrode 12 to a second electrode. 14, so that the first electrode 12 and the second electrode 14 are arranged in the extending direction of the carbon nanotube. This arrangement can ensure that the carbon nanotube structure 164 has the best electrical conductivity, so that the heating element 16 has the best heating effect.

The first electrode 12 and a second electrode 14 can be arranged on the same surface of the carbon nanotube structure 164 or on different surfaces, or the first electrode 12 and a second electrode 14 can be arranged around the carbon nanotube structure 164 s surface. Wherein, the first electrode 12 and a second electrode 14 are spaced apart so that when the carbon nanotube structure 164 is applied to the linear heat source 10, a certain resistance value is connected to avoid short circuit. The carbon nanotube structure 164 itself has good adhesion and conductivity, so the first electrode 12 and a second electrode 14 can form good electrical contact with the carbon nanotube structure 164 .

The first electrode 12 and a second electrode 14 are conductive films, metal sheets or metal leads. The conductive film can be formed on the surface of the carbon nanotube structure 164 by electroplating, electroless plating, sputtering, vacuum evaporation, physical vapor deposition, chemical vapor deposition, direct coating or screen printing conductive paste or other methods. The metal sheet can be copper sheet or aluminum sheet or the like. The metal sheet or metal lead can be fixed on the surface of the carbon nanotube structure 164 by a conductive adhesive, or fixed on the carbon nanotube structure by screws, splints and the like. In the embodiment of the present invention, two palladium films are formed on both ends of the carbon nanotube structure 164 by a vacuum evaporation method as the first electrode 12 and the second electrode 14 .

The first electrode 12 and a second electrode 14 can also be a metallic carbon nanotube layer. The carbon nanotube layer is disposed on the surface of the carbon nanotube structure 164 . The carbon nanotube layer can be fixed on the surface of the carbon nanotube structure 164 by its own adhesive or conductive adhesive. The carbon nanotube layer includes aligned and uniformly distributed metallic carbon nanotubes. Specifically, the carbon nanotube layer includes at least one carbon nanotube film or at least one carbon nanotube wire. Preferably, at least part of the surface of the carbon nanotubes in the metallic carbon nanotube layer is coated with a metal layer, thereby improving the conductivity of the metallic carbon nanotube layer. The method of coating the metal layer on the surface of the carbon nanotubes in the carbon nanotube layer may be vacuum evaporation, plasma sputtering or physical vapor deposition.

It can be understood that after forming the first electrode 12 and a second electrode 14, two conductive leads can be further formed to be electrically connected to the ends of the first electrode 12 and the second electrode 14 respectively, and from the first electrode 12 and a second electrode 14 The two electrodes 14 are led out to an external power source.

In step 3, a matrix precursor is provided, and the matrix precursor is combined with the carbon nanotube structure 164 to form a heating element 16 .

The material of the matrix precursor is the material of the matrix, the solution formed of the matrix material or the precursor reactant for preparing the matrix material. The matrix precursor should be liquid or gaseous at a certain temperature.

The material of the matrix 162 includes polymer materials or inorganic non-metallic materials and the like. Specifically, the organic polymer material may include one or more of thermoplastic polymers or thermosetting polymers, so the matrix precursor material may be a polymer monomer solution that generates the thermoplastic polymers or thermosetting polymers, Or the mixed solution formed after the thermoplastic polymer or thermosetting polymer is dissolved in a volatile organic solvent. After the carbon nanotube structure 164 is directly soaked in the liquid matrix precursor, the matrix precursor is solidified to form a matrix 162 to be composited with the carbon nanotube structure 164 .

The inorganic non-metallic material can include one or more of glass, ceramics and semiconductor materials, so the matrix precursor can be a slurry made of inorganic non-metallic material particles, a reaction gas for preparing the inorganic non-metallic material or in the form of The inorganic non-metallic material in gaseous state. Specifically, vacuum evaporation, sputtering, chemical vapor deposition (CVD) and physical vapor deposition (PVD) methods can be used to form a gaseous matrix precursor, and the matrix precursor is deposited on the carbon nanotubes of the carbon nanotube structure 164. tube surface. In addition, a large number of inorganic non-metallic material particles can be dispersed in a solvent to form a slurry as the matrix precursor, and the carbon nanotube structure 164 is soaked in the slurry, and the solvent is evaporated, so that the matrix 162 and The carbon nanotube structure 164 is composited.

In a word, when the matrix precursor is in a liquid state, the third step specifically includes the steps of soaking the liquid matrix precursor into the carbon nanotube structure 164 and solidifying the matrix precursor, so that the matrix 162 penetrates into the carbon nanotube structure In the pores of 164, a heating element 16 is formed; when the matrix precursor is gaseous, the step three specifically includes the step of depositing the matrix precursor on the carbon nanotube surface of the carbon nanotube structure 164, so that the matrix 162 is filled with A heating element 16 is formed in the pores of the carbon nanotube structure 164 .

In this embodiment, the epoxy resin matrix material and the carbon nanotube structure 164 are compounded by the glue injection method to form a heating element 16, which specifically includes the following steps:

Step (1): providing a liquid thermosetting polymer material.

The viscosity of the liquid thermosetting polymer material is lower than 5 Pa·s, and can maintain the viscosity at room temperature for more than 30 minutes. In the embodiment of the present invention, it is preferred to prepare liquid thermosetting polymer materials with epoxy resin, which specifically includes the following steps:

First, put the mixture of glycidyl ether epoxy and glycidyl ester epoxy in a container, heat it to 30°C to 60°C, and place the glycidyl ether epoxy and glycidyl ester epoxy in the container The oxygen mixture was stirred for 10 minutes until the mixture of glycidyl ether epoxy and glycidyl ester epoxy was mixed uniformly.

Secondly, the aliphatic amine and diglycidyl ether are added to the uniformly stirred mixture of glycidyl ether type epoxy and glycidyl ester type epoxy to carry out chemical reaction.

Finally, the mixture of glycidyl ether epoxy and glycidyl ester epoxy is heated to 30° C. to 60° C. to obtain a liquid thermosetting polymer material containing epoxy resin.

Step (2): impregnating the carbon nanotube structure 162 with the liquid thermosetting polymer material.

In this embodiment, the method of using the liquid thermosetting polymer material to infiltrate the carbon nanotube structure 162 includes the following steps:

First, the carbon nanotube structure 162 is placed in a mold.

Second, the liquid thermosetting polymer material is injected into the mold to infiltrate the carbon nanotube structure 162 . In order to fully infiltrate the carbon nanotube structure 162 with the liquid thermosetting polymer material, the time for infiltrating the carbon nanotube structure 162 cannot be less than 10 minutes.

It can be understood that the method of infiltrating the carbon nanotube structure 162 with the liquid thermosetting polymer material is not limited to the injection method, and the liquid thermosetting polymer material can also be sucked into the carbon nanotube structure 162 through capillary action. , soaking the carbon nanotube structure 162, or soaking the carbon nanotube structure 162 in the liquid thermosetting polymer material.

Step (3): curing the carbon nanotube structure 162 infiltrated by the liquid thermosetting polymer material to obtain a carbon nanotube composite structure.

The curing method of the thermosetting polymer material containing epoxy resin in this embodiment specifically includes the following steps:

First, the mold is heated to 50°C to 70°C by a heating device, at which temperature the thermosetting polymer material containing epoxy resin is in a liquid state, and the temperature is maintained for 1 hour to 3 hours, so that the thermosetting polymer material continues to absorb heat to increase its cure.

Secondly, continue to heat the mold to 80° C. to 100° C., and maintain the temperature for 1 hour to 3 hours, so that the thermosetting polymer material continues to absorb heat to increase its curing degree.

Again, continue to heat the mold to 110° C. to 150° C., and maintain the temperature at this temperature for 2 hours to 20 hours, so that the thermosetting polymer material continues to absorb heat to increase its curing degree.

Finally, the heating is stopped, and after the mold is cooled down to room temperature, a carbon nanotube composite structure can be obtained by demoulding.

The specific steps for preparing the carbon nanotube composite structure above can be found in the Chinese mainland patent application "Preparation method of carbon nanotube composite material" with application number 200710125109.8 filed by Fan Shoushan et al. on December 14, 2007. To save space, it is only cited here, but all the technical disclosures of the above applications should also be regarded as a part of the technical disclosures of the present application.

It can be understood that the curing method of the above-mentioned thermosetting polymer material containing epoxy resin can also adopt the method of raising the temperature once, directly raising the temperature to 150° C., so that the thermosetting polymer material absorbs heat and cures.

It can be understood that the step of forming the first electrode 12 and a second electrode 14 in the above step 2 can be performed after forming the heating element 16 . When the matrix 162 is only filled in the pores of the carbon nanotube structure 164, so that the carbon nanotube part is exposed on the surface of the heating element 16, the first electrode 12 and a second electrode can be formed in the same way as step two. 14 is directly formed on the surface of the heating element 16 . When the matrix 162 completely covers the carbon nanotube structure 164, a step of exposing the carbon nanotube structure 164 on the surface of the heating element 16 is further included, and the first electrode 12 and the second electrode 14 are respectively connected with the exposed carbon nanotube structure 164. Nanotube structures 164 are electrically connected. Specifically, the heating element 16 can be cut by a cutting step to form a cutting surface, so that the carbon nanotube structure 164 is exposed to the cutting surface of the heating element 16, and then the first The electrode 12 and a second electrode 14 are formed on the cut surface of the heating element 16 to be electrically connected to the exposed carbon nanotube structure 164 .

It can be understood that when the carbon nanotube structure is linear, the method for forming the heating element 36 of the third embodiment may include the following steps:

First, compound the carbon nanotube linear structure with the matrix precursor to form a carbon nanotube linear composite structure 366;

Secondly, one or more carbon nanotube linear composite structures 366 are arranged to form a two-dimensional heating element 36 .

The carbon nanotube wire composite structure 366 can be interwoven, intersected, juxtaposed or coiled to form a two-dimensional heating element 36 . When the carbon nanotube wire-like composite structure 366 is interwoven, the heating element 36 can maintain a one-sided shape similar to a fabric. The interwoven heating elements 36 can be made into a heating pad, heating clothes, heating gloves and the like. When the carbon nanotube wire-like composite structures 366 are crossed, juxtaposed or coiled, the plurality of carbon nanotube wire-like structures 366 can be bonded by an adhesive, so that the heating element 36 maintains a planar shape.

The method of compounding the carbon nanotube linear structure and the matrix precursor is the same as the third step above.

The first electrode and the second electrode can be formed on the surface of the heating element 36 through the above-mentioned step two. Further, the carbon nanotube linear structure can be exposed on the surface of the heating element 36 through a cutting step, and then the first electrode and the second electrode can be formed on the exposed surface of the carbon nanotube structure, so that the first An electrode and a second electrode are electrically connected with the carbon nanotubes in the carbon nanotube composite structure.

It can be understood that the preparation method may further include the following optional steps, so as to prepare a surface heat source 20 with the second embodiment:

Step 4, providing a support 28 and forming a heat reflective layer 27 on the surface of the support 28 .

Forming a heat reflective layer 27 on the surface of the support body 28 can be realized by coating or coating. Specifically, when the material of the heat reflecting layer 27 is a metal salt or metal oxide, the particles of the metal salt or metal oxide can be dispersed in a solvent to form a slurry, and the slurry can be coated or silk The heat reflection layer 27 is formed by screen printing on the surface of the support body 28 . Depending on the metal salt or metal oxide, the solvent should not chemically react with the metal salt or metal oxide. In addition, the heat reflection layer 27 can also be formed by methods such as electroplating, electroless plating, sputtering, vacuum evaporation, chemical vapor deposition or physical vapor deposition. In the embodiment of the present invention, a layer of aluminum oxide is deposited on the surface of the ceramic substrate by physical vapor deposition as the heat reflection layer 27 .

Step five, disposing the heating element 26 on the surface of the heat reflection layer 27 .

The heating element 26 can be fixed on the surface of the heat reflection layer 27 by an adhesive. In addition, a mechanical fixing method can also be used, such as fixing devices such as screws and splints, to fix the four corners or four sides of the heating element 26 on the surface of the heat reflection layer 27 .

Step six, forming a protective layer 25 on the outer surface of the heating element 26 to form a heat source 20 .

The protection layer 25 can be directly fixed on the surface of the heating element 26 by an adhesive or a mechanical fixing method. In addition, when the material of the protective layer 25 is a thermoplastic polymer, the thermoplastic polymer can be coated or wrapped on the surface of the heating element 26 in a molten state at a high temperature, and solidified at a low temperature to form the protective layer 25 . In addition, when the protective layer 25 is a flexible polymer, such as a polyethylene terephthalate (PET) film, the protective layer 25 and the heating element 26 can be laminated and hot-pressed through a heat-pressing step. , so that the protective layer 25 is firmly combined with the heating element 26 .

The surface heat source and its preparation method have the following advantages: First, since the carbon nanotube structure is a self-supporting structure, and the carbon nanotubes are uniformly distributed in the carbon nanotube structure, the self-supporting carbon nanotube structure Direct compounding with the matrix can make the carbon nanotubes in the heating element formed after compounding still combine with each other to maintain the shape of a carbon nanotube structure, so that the carbon nanotubes in the heating element can be evenly distributed to form a conductive network without being affected by carbon nanotubes. The limitation of the dispersed concentration of the tubes in the solution enables the mass percentage of the carbon nanotubes in the heating element to reach 99%, so that the heat source has higher heating performance. In addition, the type of the matrix material is not limited to polymer, which makes the application range of the heat source more extensive. Second, because carbon nanotubes have better strength and toughness, the carbon nanotube structure has greater strength, better flexibility, and is not easy to break, so that it has a longer service life. In particular, when the carbon nanotube structure and When the flexible matrix is combined to form a heating element, a flexible heat source can be prepared, so that the heat source has a wider application range. Third, the carbon nanotubes in the carbon nanotube structure are evenly distributed, so they have uniform thickness and resistance, uniform heating, high electrothermal conversion efficiency of the carbon nanotube structure, and the heat capacity per unit area of the carbon nanotube structure is less than 2×10 -4 joules per square centimeter Kelvin, so the surface heat source has the characteristics of rapid temperature rise, small thermal hysteresis, fast thermal response speed, fast heat exchange speed and high radiation efficiency. Fourth, the diameter of the carbon nanotube is small, so that the carbon nanotube structure can have a small thickness, and a micro surface heat source can be prepared, which can be applied to the heating of micro devices. Fifth, when the carbon nanotube structure includes a carbon nanotube drawn film, the carbon nanotube drawn film can be obtained by pulling from a carbon nanotube array, the method is simple and is conducive to the production of a large-area surface heat source, and the carbon nanotube In the tube stretched film, the carbon nanotubes are preferentially oriented in the same direction, which has good electrical conductivity, so that the heat source has good heating performance. In addition, the carbon nanotube stretched film has a certain transparency, which can be used to prepare a transparent heat source . Sixth, the carbon nanotube wires can be used to weave heating elements of various shapes, thereby preparing surface heat sources of various shapes. Seventh, the carbon nanotube flocculation film and the carbon nanotube rolling film have good toughness, and the preparation method is simple. Eighth, the method of forming a self-supporting carbon nanotube structure and directly combining the carbon nanotube structure with a matrix to form a heating element is simple, and the content of carbon nanotubes in the heating element can be controlled conveniently. After compounding with the matrix, the carbon nanotube structure can still maintain the original shape, and has the same heat generation performance as the pure carbon nanotube structure. Ninth, the carbon nanotube structure can be selectively arranged at a certain position in a matrix with a specific shape, so as to realize local selective heating and meet the needs of different fields.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included within the scope of protection claimed by the present invention.

Claims (13)

1. A surface heat source, comprising: A heating element, the heating element includes a substrate and at least one integral self-supporting carbon nanotube structure, the carbon nanotube structure includes at least one layer of carbon nanotube rolling film, each layer of carbon nanotube rolling film Adjacent carbon nanotubes partially overlap each other, and are attracted to each other by van der Waals force, and are closely combined; and at least two electrodes are arranged at intervals and electrically connected to the heating element, It is characterized in that the at least one self-supporting carbon nanotube structure is embedded in the matrix and compounded with the matrix, and basically maintains the shape before compounding, the carbon nanotubes in the carbon nanotube structure are arranged in disorder, the The carbon nanotubes in the carbon nanotube structure are preferentially aligned along the same direction or the carbon nanotubes in the carbon nanotube structure are preferentially aligned along different directions. 2. The surface heat source according to claim 1, wherein the carbon nanotube structure comprises a plurality of carbon nanotube rolled films stacked or a plurality of carbon nanotube rolled films arranged side by side. 3. The surface heat source as claimed in claim 1, characterized in that, the carbon nanotube rolling film is obtained by rolling a carbon nanotube array, and the carbon nanotubes in the carbon nanotube rolling film are formed with The surface of the growth substrate of the carbon nanotube array forms an included angle β, wherein β is greater than or equal to 0 degrees and less than or equal to 15 degrees. 4. The surface heat source as claimed in claim 1, characterized in that, the carbon nanotubes in the carbon nanotube rolling film are aligned along the same direction, and the carbon nanotubes in the carbon nanotube rolling film in the surface heat source are Nanotubes extend from one electrode to the other. 5. The surface heat source according to claim 1, characterized in that the carbon nanotube rolled film has a thickness of 1 micron to 1 mm. 6 . The surface heat source according to claim 1 , wherein the heat capacity per unit area of the carbon nanotube structure is less than 2×10 ⁻⁴ joules per square centimeter Kelvin. 7. The surface heat source according to claim 1, wherein the at least two electrodes are respectively electrically connected to the carbon nanotube structure. 8 . The surface heat source according to claim 1 , wherein the heating element comprises a plurality of carbon nanotube structures arranged in the matrix at intervals or in contact with each other. 9. The surface heat source according to claim 1, characterized in that, the material of the substrate is an organic polymer material or an inorganic non-metallic material. 10. The surface heat source according to claim 1, characterized in that the surface heat source further comprises a support body, the heating element is at least partially supported by the support body, and the material of the support body is flexible material or hard material. 11. The surface heat source according to claim 10, characterized in that, the surface heat source further comprises a heat reflective layer, and the heat reflective layer is arranged between the heating element and the support or on the support Keep away from heating element surfaces. 12. A surface heat source comprising: A heating element and at least two electrodes are arranged at intervals and electrically connected to the heating element, characterized in that: the heating element includes at least one integral self-supporting carbon nanotube structure, and the matrix material is compounded in the carbon nanotube structure, The carbon nanotube structure includes at least one layer of carbon nanotube rolling film, and the adjacent carbon nanotubes in each layer of carbon nanotube rolling film partially overlap each other, and are attracted to each other by van der Waals force, and are tightly combined. The carbon nanotube structure in the element basically maintains the shape before compounding, the carbon nanotubes in the carbon nanotube structure are arranged in disorder, the carbon nanotubes in the carbon nanotube structure are arranged in the same direction, or the carbon nanotube structure The carbon nanotubes are preferentially oriented in different directions, the carbon nanotube structure has a plurality of micropores, and the matrix material is uniformly compounded in the micropores of the carbon nanotube structure. 13. The surface heat source according to claim 12, characterized in that, the diameter of the micropores is less than 10 microns.

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