阅读说明：本技术 一种碳纳米复合薄膜的制备方法及用途 (Preparation method and application of carbon nano composite film ) 是由 刘伟 马江将 贾琨 王东红 马晨 于 2020-06-20 设计创作，主要内容包括：本发明涉及电磁防护和热管理技术领域,更具体而言,涉及一种碳纳米复合薄膜的制备方法及用途,将碳纳米复合薄膜先将聚氨酯单体与碳纳米管混合,通过原位聚合反应获得复合材料,极大地提高了碳纳米管的分散性,使复合材料中碳纳米管的含量大大增加,显著地提升了复合材料的导热、导电及电磁屏蔽性能。采用涂料涂覆方式成膜,所制备的薄膜厚度小(50-100μm),为自支撑的薄膜,使用过程无需载体,适用于柔性电子器件。所制备的复合薄膜具有较高的热导率和电导率,可同时作为热界面材料及电磁屏蔽材料使用,可节省更多空间。生产过程环保,不会对人体和环境造成危害。(The invention relates to the technical field of electromagnetic protection and thermal management, in particular to a preparation method and application of a carbon nano composite film. The coating is adopted to form a film, the prepared film has small thickness (50-100 mu m), is a self-supporting film, does not need a carrier in the using process, and is suitable for flexible electronic devices. The prepared composite film has higher thermal conductivity and electrical conductivity, can be used as a thermal interface material and an electromagnetic shielding material at the same time, and can save more space. The production process is environment-friendly, and does not cause harm to human bodies and the environment.)

1. A preparation method of a carbon nano composite film is characterized by comprising the following steps:

s1, adding the carbon nano tube into an acetone solution, and performing ultrasonic dispersion to obtain a carbon nano tube dispersion liquid;

s2, transferring the carbon nano tube dispersion liquid prepared in the S1 into a four-neck flask with a thermometer, a condenser and a stirrer, adding oligomer polyol and diisocyanate, and continuously stirring and reacting for 1-3 hours at the temperature of 70-90 ℃ under the protection of inert gas;

s3, adding a chain extender into the flask S3, continuously stirring and reacting at the temperature of 70-90 ℃ for 2-5 hours to obtain a polyurethane prepolymer, and adding triethylamine after the solution is cooled to room temperature;

s4, adding distilled water into the solution obtained in the step S3, and removing acetone in the solution in a distillation mode to obtain an aqueous carbon nano tube/polyurethane prepolymer dispersion liquid;

s5, transferring the aqueous carbon nanotube/polyurethane prepolymer dispersion liquid prepared in the S4 into a ball milling tank, adding hydrazine or polyethylene polyamine organic matters, and performing ball milling at room temperature to obtain a carbon nanotube/aqueous polyurethane coating;

s6, coating the carbon nanotube/waterborne polyurethane coating prepared in the S5 on a glass substrate to form a film; and after the film is completely dried, peeling the film from the glass substrate to obtain the carbon nano composite film.

2. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the carbon nano tube, acetone, oligomer polyol, diisocyanate, a chain extender, triethylamine, hydrazine or polyethylene polyamine and water are prepared according to the following parts by weight: 10-100: 1000-1500: 50-100: 20-50: 4-10: 2-5: 1-3: 500-1200.

3. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the oligomer polyalcohol is one or more of polycaprolactone dihydric alcohol, polytetramethylene glycol, polycarbonate dihydric alcohol and polyether dihydric alcohol; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate; the chain extender is one or more of dihydroxybutyric acid, dihydroxypropionic acid and 2, 4-dihydroxyvaleric acid; the polyethylene polyamine organic matter is one or more of ethylenediamine, diethylenetriamine, triethylene tetramine and tetraethylenepentamine; the inert gas is one of nitrogen, helium and argon or a mixed gas of the nitrogen, the helium and the argon.

4. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the stirring rate in the step S2 is 200-500 rpm.

5. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the stirring rate in the step S3 is 200-500 rpm.

6. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the distillation temperature in the step S4 is 60-90 ℃.

7. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the ball milling speed in the step S5 is 500-1000rpm, and the ball milling time is 4-8 h.

8. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the coating manner in step S6 includes, but is not limited to, knife coating, spray coating, screen printing, spin coating.

9. The method for preparing a carbon nanocomposite film according to claim 1, characterized in that: the drying temperature of the film in the step S6 is room temperature or 50-80 ℃.

10. Use of the carbon nanocomposite film produced by the production method according to any one of claims 1 to 9, characterized in that: the carbon nano composite film is used for heat dissipation and electromagnetic shielding of a flexible device.

Technical Field

The invention relates to the technical field of electromagnetic protection and thermal management, in particular to a preparation method and application of a carbon nano composite film.

Background

With the rapid development of modern science and technology, the miniaturization and function integration of electronic equipment become for the development trend, and various flexible devices such as wearable electronic equipment and foldable electronic equipment bring very big convenience for people's work and life. However, electromagnetic radiation is inevitably generated in the operation process of the electronic components, which not only threatens the health of human beings, but also causes mutual interference among the components and influences the normal operation of equipment; on the other hand, as the power of the electronic device is higher and higher, the electronic device generates more heat in the working process, which causes over-high temperature and seriously affects the working performance and the service life of the device. Meanwhile, as the volume of the flexible devices is greatly reduced compared with the prior art, in order to save the internal space, the multifunctional interface material is favored by the flexible devices. Therefore, flexible interface materials with heat dissipation and electromagnetic shielding functions have attracted much attention.

Thermal interface materials are typically located between a heat source (e.g., a CPU) and a heat sink to conduct heat from the heat source to the heat sink. The interface of hard material inevitably generates air gap, and the heat conductivity of the interface is seriously influenced because the air has low heat conductivity. Therefore, soft polymer matrix composites are the first choice for thermal interface materials. For electromagnetic shielding, highly conductive metals are the most commonly used electromagnetic shielding materials, but the metal density is largeAnd is susceptible to corrosion, has poor flexibility and is difficult to apply to flexible electronic devices. The polymer-based electromagnetic shielding material can make up the defects of metal materials and is widely concerned by scientific researchers. However, the polymer itself does not have the function of heat conduction or electromagnetic shielding, and a filler (such as metal powder, ceramic powder, graphite, and the like) with the function of heat conduction or electromagnetic shielding needs to be added into the polymer matrix to obtain the heat conduction or electromagnetic shielding composite material. Carbon nanotubes are a new type of carbon nanomaterial with low density, high aspect ratio and extremely high thermal conductivity (C)>3000W/mK) and conductivity (10)⁶S/cm) is a heat conduction/shielding dual-function filler with extremely high potential.

The heat conduction and electromagnetic shielding performance of the polymer-based composite material is in direct proportion to the loading capacity of the functional filler. However, since the carbon nanomaterial has a large specific surface area, the nanoparticles are easily agglomerated, resulting in poor dispersibility of the carbon nanomaterial in the polymer matrix. The existing preparation method of polymer-based composite materials (such as the application patents with publication numbers of CN110564335A and CN 109729707A) is to mix carbon nanotubes and high molecular polymers directly in a solution or melting manner, and the load capacity of carbon nanofillers in the obtained composite materials is very low, which seriously affects the heat conduction and electromagnetic shielding performance of the composite materials. On the other hand, the existing polymer-based carbon nano functional material is generally a single functional material, or is used for interface heat conduction or electromagnetic shielding, has a large thickness (> 0.5 mm), occupies a large space in an electronic device, and cannot meet the use requirement of an interface material in a flexible device.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a preparation method of a carbon nano composite film for heat dissipation and electromagnetic shielding of a flexible device.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a preparation method of a carbon nano composite film comprises the following steps:

s1, adding the carbon nano tube into an acetone solution, and performing ultrasonic dispersion to obtain a carbon nano tube dispersion liquid;

s2, transferring the carbon nano tube dispersion liquid prepared in the S1 into a four-neck flask with a thermometer, a condenser and a stirrer, adding oligomer polyol and diisocyanate, and continuously stirring and reacting for 1-3 hours at the temperature of 70-90 ℃ under the protection of inert gas;

s3, adding a chain extender into the flask S3, continuously stirring and reacting at the temperature of 70-90 ℃ for 2-5 hours to obtain a polyurethane prepolymer, and adding triethylamine to neutralize acid components in the solution after the solution is cooled to room temperature;

s4, adding distilled water into the solution obtained in the step S3, and removing acetone in the solution in a distillation mode to obtain an aqueous carbon nano tube/polyurethane prepolymer dispersion liquid;

s5, transferring the aqueous carbon nanotube/polyurethane prepolymer dispersion liquid prepared in the S4 into a ball milling tank, adding hydrazine or polyethylene polyamine organic matters, and performing ball milling at room temperature to obtain a carbon nanotube/aqueous polyurethane coating;

s6, coating the carbon nanotube/waterborne polyurethane coating prepared in the S5 on a glass substrate to form a film; and after the film is completely dried, peeling the film from the glass substrate to obtain the carbon nano composite film.

Further, the carbon nano tube, acetone, oligomer polyol, diisocyanate, a chain extender, triethylamine, hydrazine or polyethylene polyamine and water are prepared according to the following parts by weight: 10-100: 1000-1500: 50-100: 20-50: 4-10: 2-5: 1-3: 500-1200.

Further, the oligomer polyol is one or more of polycaprolactone diol, polytetramethylene glycol, polycarbonate diol and polyether diol; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate; the chain extender is one or more of dihydroxybutyric acid, dihydroxypropionic acid and 2, 4-dihydroxyvaleric acid; the polyethylene polyamine organic matter is one or more of ethylenediamine, diethylenetriamine, triethylene tetramine and tetraethylenepentamine; the inert gas comprises one of nitrogen, helium and argon or a mixed gas thereof.

Further, the stirring speed in the step S2 is 200-500 rpm.

Further, the stirring speed in the step S3 is 200-500 rpm.

Further, the distillation temperature in the step S4 is 60-90 ℃.

Further, the ball milling speed in the step S5 is 500-.

Further, the coating manner in step S6 includes, but is not limited to, knife coating, spray coating, screen printing, spin coating.

Further, the drying temperature of the film in the step S6 is room temperature or 50-80 ℃.

The carbon nano composite film prepared by the preparation method is used for heat dissipation and electromagnetic shielding of flexible devices.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a preparation method and application of a carbon nano composite film, firstly, polyurethane monomers (oligomer polyol and diisocyanate) and carbon nano tubes are mixed, and a composite material is obtained through in-situ polymerization reaction. Compared with polyurethane resin or prepolymer, the viscosity of the polyurethane monomer is obviously reduced, so that the carbon nano tubes are dispersed in the polyurethane more uniformly, the loading capacity of the carbon nano tubes in the composite film is greatly improved, and the formation of a cross-linked three-dimensional carbon nano tube electric conduction and heat conduction network is facilitated; on the other hand, the carbon nano tube used in the invention is not treated by acid or surfactant, has a perfect crystal structure, has less defects or impurities, reduces the scattering frequency of electrons and phonons, retains the intrinsic high electrical conductivity and thermal conductivity of the carbon nano tube, and obviously improves the thermal conductivity and the electric conductivity of the composite film. The excellent conductivity of the carbon nano composite film increases the impedance mismatching degree of the film surface and the air, and improves the reflection capability of the film on electromagnetic waves; meanwhile, the electromagnetic wave and the carbon nanotube network are coupled to generate eddy current loss, and finally the eddy current loss is lost in the form of heat energy, so that the electromagnetic shielding performance of the composite film is remarkably improved. The coating is adopted to form a film, the prepared film has small thickness (50-100 mu m), is a self-supporting film, does not need a carrier in the using process, and is suitable for flexible electronic devices. The prepared composite film has higher thermal conductivity and electrical conductivity, can be used as a thermal interface material and an electromagnetic shielding material at the same time, and can save more space. The production process is environment-friendly, and does not cause harm to human bodies and the environment.

Drawings

FIG. 1 is an SEM front view of a carbon nanotube composite film prepared according to the present invention;

FIG. 2 is a side view of SEM of a carbon nanotube composite film prepared according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.