Preparation method of polymer-based composite material containing carbon nanotubes, composite material prepared by preparation method and product containing composite material

Abstract

The invention relates to a preparation method of a polymer-based composite material containing a carbon nanotube. The preparation method comprises the following steps: providing a carbon nanotube coated with a polymer monomer or a prepolymer; and mixing the polymer monomer or prepolymer coated carbon nanotube with a polymer matrix, and carrying out melt extrusion to obtain the polymer-based composite material containing the carbon nanotube, wherein the polymer monomer or prepolymer is a monomer or prepolymer of the polymer matrix. The invention also relates to the polymer-based composite material containing the carbon nanotubes prepared by the method and a cover plate product containing the composite material. The preparation method provided by the invention is beneficial to improving the dispersity of the carbon nanotubes in the polymer matrix, so that the polymer-based composite material in which the carbon nanotubes are uniformly dispersed can be obtained. The cover plate made of the composite material has better dielectric properties, can be used in a display module, and can effectively improve the touch signal-to-noise ratio, thereby improving the touch sensitivity.

Description

Technical Field

[0001] The present invention relates to the field of modified polymer-based composite materials, and more specifically to a method for preparing a polymer-based composite material containing carbon nanotubes, a composite material prepared thereby, and a product containing the composite material. Background Art

[0002] Modifying polymers through inorganic nanomaterials is one of the important ways to improve material properties. Since carbon nanotubes were discovered by S. Iijima in 1991, they have attracted widespread attention due to their quantum effects, large specific surface area, high mechanical strength, high electrical conductivity, and good heat resistance. As the preparation technology of carbon nanotubes matures and research gradually deepens, people are gradually interested in its practical application, especially as a modified material for polymers.

[0003] However, in the traditional melt processing of polymers, the melt viscosity is relatively high, the shear force during the melt blending process is relatively low, and the shear dispersion time is relatively short. Due to the high surface energy of carbon nanotubes, agglomeration is very likely to occur. Therefore, it is difficult for carbon nanotubes to be evenly dispersed in the matrix, which will eventually have an adverse effect on the comprehensive performance of the product. Therefore, how to enhance the interaction between the polymer matrix and carbon nanotubes, promote the uniform dispersion of carbon nanotubes, and construct a suitable carbon nanotube network in the polymer matrix, thereby improving the dielectric properties of the material, so as to obtain a composite material with excellent comprehensive performance, is a key issue that needs to be solved urgently.

[0004] CN101338073A discloses a method for preparing a PBO / single-walled carbon nanotube polymer, which uses a twin-screw extruder to solve the problems of high viscosity and difficult stirring of the polymer system, thereby preparing a PBO / single-walled carbon nanotube polymer with an intrinsic viscosity of 20-30dL / g. Specifically, the patent mixes a single-walled carbon nanotube monomer complex for PBO polymerization with polyphosphoric acid in a mass ratio of 1:3.2-4.5, then stirs for 12h-72h at a temperature below 80°C and under N2 protection, then adds P2O5 within 4h-24h, heats to 140°C-160°C under N2 gas protection, reacts for 2h-10h, and then in a twin-screw extruder, alternates between a feed tank and a receiving tank to perform polymerization reaction, thereby obtaining the target product. Summary of the invention

[0005] In the prior art, the dispersion of carbon nanotubes in a polymer matrix usually has the following problems:

[0006] Before carbon nanotubes are compounded with a polymer matrix, they usually need to be treated with a strong oxidant or a strong acid, and then ultrasonically dispersed in a solvent to make a pre-dispersion liquid. Then, the solvent of the pre-dispersion liquid will cause polymer degradation and release toxic substances during the melt processing, so solution casting and other methods are often used, which to a certain extent limits the application of polymer-carbon nanotubes in melt processing.

[0007] In the process of melt mixing, if you want to achieve a good dispersion effect, you often need to mix for a long time or perform melt mixing multiple times, which is not suitable for industrial continuous production processes. Moreover, long-term high temperature and shearing can easily cause polymer degradation, resulting in overall performance degradation.

[0008] After adding carbon nanotubes into the polymer matrix, the mechanical properties and transparency of the material itself are reduced due to the interfacial effect caused by the carbon nanotubes themselves being colored and incompatible with the matrix.

[0009] Existing organic-coated carbon nanotube masterbatches, such as polyol ester-coated single-walled carbon nanotube masterbatches, are often modified for general polymer materials. The masterbatch coating is not selected according to the structural characteristics of the actual polymer matrix molecular chain, and thus the modification effect of the carbon nanotubes cannot be maximized.

[0010] In order to solve the above problems, on the one hand, the present invention provides a method for preparing a polymer-based composite material containing carbon nanotubes, which comprises the following steps: providing carbon nanotubes coated with a polymer monomer or a prepolymer; mixing the carbon nanotubes coated with the polymer monomer or the prepolymer with a polymer matrix and then melt-extruding to obtain a polymer-based composite material containing carbon nanotubes; wherein the polymer monomer or the prepolymer is a monomer or prepolymer of the polymer matrix.

[0011] In one embodiment, the step of providing carbon nanotubes coated with polymer monomers or prepolymers includes: S100: dispersing carbon nanotube raw materials in a dispersion medium to obtain dispersion A; S200: subjecting dispersion A to density gradient centrifugation, taking out the top layer of dispersion to obtain dispersion B; S300: adding an activator and a dispersant to dispersion B and mixing them to obtain dispersion C; S400: mixing dispersion C with polymer monomers or prepolymers to obtain dispersion D, which contains carbon nanotubes coated with polymer monomers or prepolymers; S500: drying dispersion D to obtain carbon nanotubes coated with polymer monomers or prepolymers.

[0012] In one embodiment, in S100, the carbon nanotube raw material includes one or more carbon nanotubes selected from the following: carbon nanotubes with an outer diameter of 1 nm to 2 nm, a length of 1 μm to 30 μm, and a specific surface area of ​​550 to 1200 m2 ·g -1 Single-walled carbon nanotubes, and multi-walled carbon nanotubes with an outer diameter of 10nm-100nm and a length of 10μm-50μm.

[0013] In one embodiment, in S100, the dispersion medium includes water, C 1-5 Alcohol solvents, C 3-5 Ketone solvents, C 2-8 Ester solvents, C 2-4 Nitrile solvent or any combination thereof. In a preferred embodiment, the dispersion medium comprises water, ethanol, methanol, acetone or any combination thereof.

[0014] In one embodiment, in the polymer-based composite material containing carbon nanotubes, based on the total weight parts of the polymer matrix and the carbon nanotubes coated with the polymer monomer or prepolymer being 100 weight parts, the content of the carbon nanotubes is 0.01-1 weight part, the content of the polymer monomer or prepolymer is 1-5 weight parts, and the content of the polymer matrix is ​​95-99 weight parts.

[0015] In one embodiment, the polymer matrix comprises: bisphenol A-polycarbonate, isosorbide-based polycarbonate, polymethyl methacrylate, polylactic acid, polystyrene, polyimide or any blend or copolymer thereof, preferably isosorbide-based polycarbonate, polymethyl methacrylate or any blend or copolymer thereof.

[0016] In one embodiment, the polymer monomer or prepolymer includes: diphenol propane, isosorbide, mannitol, acrylate, styrene, lactide, fluorine-containing polyol, dopamine, ethylenediamine, pyromellitic dianhydride, oligomeric polymethyl methacrylate, oligomeric polylactic acid or any combination thereof, preferably isosorbide, oligomeric polymethyl methacrylate or any combination thereof.

[0017] In another aspect, the present application relates to a polymer-based composite material containing carbon nanotubes, which is prepared by the preparation method of the present application.

[0018] In yet another aspect, the present application relates to a polymer-based composite product, which comprises the polymer-based composite material containing carbon nanotubes of the present application.

[0019] In a preferred embodiment, the polymer-based composite product of the present application is a cover plate. In a more preferred embodiment, the polymer-based composite product of the present application is a display screen cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete understanding of the present invention, reference should now be made to the embodiments shown in more detail in the accompanying drawings and described below by way of example of the invention, in which:

[0021] Figure 1 :An exemplary embodiment of the display module of the present application.

[0022] Figure 2 : Scanning electron microscope image of the cover plate made from the composite material particle sample of Example 1 of the present application.

[0023] Figure 3 : Scanning electron microscope image of the cover plate made from the composite material particle sample of Comparative Example 1 of the present application.

[0024] Figure 4 : Scanning electron microscope image of the cover plate made from the composite material particle sample of Example 2 of the present application.

[0025] Figure 5 : Scanning electron microscope image of the cover plate made from the composite material particle sample of Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0026] General Definitions and Terminology

[0027] Unless otherwise indicated, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of a conflict, the definitions provided herein shall prevail.

[0029] Unless otherwise indicated, all percentages, parts, ratios, etc. are by weight.

[0030] When quantity, concentration or other value or parameter is given as range, preferred range or preferred upper limit and lower limit or specific value, it should be understood as specifically disclosing all ranges formed by paired values ​​from any upper limit range or preferred value and any lower limit range or preferred value, regardless of whether the range is disclosed separately. Unless otherwise stated, when numerical range is quoted herein, the range refers to including its endpoints and integers and fractions within all such ranges. The scope of the present invention is not limited to the specific numerical value quoted when defining the range. For example, "1-8" covers 1, 2, 3, 4, 5, 6, 7, 8 and any sub-range consisting of any two values ​​therein, such as 2-6, 3-5.

[0031] The terms "about" and "approximately" when used with a numerical variable generally refer to the value of that variable and all values ​​of that variable are within experimental error (e.g., within a 95% confidence interval for the mean) or within ±10% of the specified value, or a wider range.

[0032] The terms "comprises", "includes", "has", "contains" or "involves" and other variations thereof herein are inclusive or open-ended and do not exclude other unlisted elements or method steps. It will be understood by those skilled in the art that the above terms such as "comprising" encompass the meaning of "consisting of". The expression "consisting of" excludes any element, step or ingredient not specified. The expression "consisting essentially of" means that the scope is limited to the specified elements, steps or ingredients, plus the optional presence of elements, steps or ingredients that do not substantially affect the basic and novel features of the claimed subject matter. It will be understood that the expression "comprising" encompasses the expressions "consisting essentially of" and "consisting of".

[0033] The term "selected from..." means that one or more elements in the group listed later are independently selected and may include combinations of two or more elements.

[0034] When values ​​or end-points of a range are described herein, it should be understood that the disclosure includes the specific value or end-point cited.

[0035] As used herein, the terms "one or more" or "at least one" refer to one, two, three, four, five, six, seven, eight, nine or more.

[0036] Unless otherwise specified, the terms "combination thereof", "any combination thereof", "mixture thereof" and "blend thereof" mean a multi-component mixture of the elements, such as two, three, four and up to the maximum possible multi-component mixture.

[0037] In addition, if the number of parts or components of the present invention is not indicated before, it means that there is no limit to the number of occurrences (or existence) of the parts or components. Therefore, it should be interpreted as including one or at least one, and the singular form of the parts or components also includes the plural form, unless the numerical value obviously represents the singular.

[0038] As used herein, the term "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes both occurring and not occurring of said event or circumstance.

[0039] The term "C a-b " is used for compounds containing a to b carbon atoms. For example, "C 1-5 "Alcohol solvent" refers to alcohol compounds containing 1 to 5 carbon atoms, including but not limited to: methanol, ethanol, propanol, butanol, pentanol, etc. For example, "C 3-5 "Ketone solvent" refers to ketone compounds containing 3 to 5 carbon atoms, including but not limited to: acetone, butanone, etc. For example, "C 2-8"Ester solvent" refers to ester compounds containing 2 to 8 carbon atoms, including but not limited to: ethyl acetate, butyl acetate, etc. For example, "C 2-4 The term "nitrile solvent" refers to nitrile compounds containing 2 to 4 carbon atoms, including but not limited to acetonitrile.

[0040] The term "polymer monomer" used herein refers to a simple compound that can be synthesized into a high molecular compound through polymerization reaction or condensation reaction, and is a low molecular weight raw material used to synthesize a polymer.

[0041] The term "polymer prepolymer" used herein, which may also be referred to as "polymer prepolymer" or "polymer oligomer", refers to a polymer with a lower molecular weight having a degree of polymerization between that of a monomer and a final polymer.

[0042] When describing methods, components or steps, the use of letters or numbers is only for the purpose of distinction, and does not limit these methods, components or steps to be performed in the order or sequence of the identification. Those skilled in the art can make reasonable adjustments.

[0043] Method for preparing polymer-based composite material containing carbon nanotubes

[0044] On the one hand, the present application provides a method for preparing a polymer-based composite material containing carbon nanotubes, which includes the following steps: providing carbon nanotubes coated with a polymer monomer or a prepolymer; mixing the carbon nanotubes coated with the polymer monomer or the prepolymer with a polymer matrix and then melt-extruding to obtain a polymer-based composite material containing carbon nanotubes; wherein the polymer monomer or the prepolymer is a monomer or prepolymer of the polymer matrix.

[0045] The following is a detailed explanation with specific steps.

[0046] Provide polymer monomer or prepolymer coated carbon nanotubes

[0047] The carbon nanotube of the present application has the conventional definition in the art, that is, a one-dimensional nano material with a special structure, which is composed of several layers to tens of layers of coaxial circular tubes of carbon atoms arranged in a hexagonal shape. The diameter of the carbon nanotube is usually nanometer scale, and has a unique graphite structure, and its tube wall is a hexagonal grid structure similar to graphite formed by sp2 hybridization of carbon atoms. The carbon nanotube in the present application can be divided into single-walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT) according to the number of layers. The single-walled carbon nanotube is curled by a layer of graphite sheets, and the multi-walled carbon nanotube is nested by multiple concentric graphite tubes.

[0048] The polymer matrix may include: bisphenol A-polycarbonate, isosorbide-based polycarbonate, polymethyl methacrylate, polylactic acid, polystyrene, polyimide or any blend or copolymer thereof. Preferably, the polymer matrix of the present application includes isosorbide-based polycarbonate, polymethyl methacrylate or any combination thereof. Isosorbide-based polycarbonate and polymethyl methacrylate have excellent optical properties (such as transparency, low haze, etc.), good heat resistance, weather resistance, good strength, and excellent processing performance. In particular, isosorbide-based polycarbonate, as a bio-based material, has certain degradable properties, so there is an advantage of green environmental protection. The polymer matrix of the present application, especially the preferred polymer matrix, can make carbon nanotubes have excellent dispersibility therein through the method of the present application, and the corresponding composite material and product can obtain the desired excellent dielectric properties.

[0049] In the present application, the surface of the carbon nanotubes is first coated with a polymer monomer or a prepolymer, and then the carbon nanotubes coated with the polymer monomer or prepolymer are blended with a polymer matrix, melt extruded, and the like, wherein the polymer monomer or prepolymer used is a monomer or prepolymer of the polymer matrix used.

[0050] Compared with the prior art method of using organic-coated carbon nanotube masterbatch (for example, using polyol ester to coat single-walled carbon nanotube masterbatch), the present application uses monomers or prepolymers of a polymer matrix to coat carbon nanotubes, which can give full play to the modification effect of carbon nanotubes and thus obtain products with better performance. Without being bound by theory, the monomers or prepolymers of the polymer matrix of the present application, as coating materials for carbon nanotubes, have a structure similar to that of the polymer matrix, and can play an effect of interfacial volume expansion. In addition, the monomers or prepolymers of the polymer matrix can be combined with carbon nanotubes to generate crystals on the walls of carbon nanotubes. Nano-sized crystals can isolate carbon nanotubes to a certain extent, further reducing carbon nanotube agglomeration.

[0051] The polymer monomer or prepolymer includes: diphenol propane, isosorbide, mannitol, acrylate, styrene, lactide, fluorine-containing polyol, dopamine, ethylenediamine, pyromellitic dianhydride, oligomeric polymethyl methacrylate, oligomeric polylactic acid or any combination thereof, preferably isosorbide, oligomeric polymethyl methacrylate or any combination thereof.

[0052] The weight average molecular weight of the polymer prepolymer may be about 100-500 g / mol, for example, about 100 g / mol, about 200 g / mol, about 300 g / mol, about 400 g / mol, about 500 g / mol, and the like.

[0053] Those skilled in the art will understand that "a polymer monomer or prepolymer is a monomer or prepolymer of a polymer matrix" means: according to the type of the polymer matrix, the corresponding monomer or prepolymer is selected as the polymer monomer or prepolymer for coating the carbon nanotubes. For example, if the polymer matrix is ​​isosorbide-based polycarbonate, the polymer monomer may be isosorbide, and the polymer prepolymer may be an oligomeric isosorbide-based polycarbonate. For another example, if the polymer matrix is ​​polymethyl methacrylate, the polymer monomer may be methyl methacrylate, and the polymer prepolymer may be an oligomeric polymethyl methacrylate.

[0054] In a specific embodiment, the polymer matrix is ​​isosorbide-based polycarbonate, and the carbon nanotubes coated with the polymer monomer or prepolymer are isosorbide-coated carbon nanotubes.

[0055] In a specific embodiment, the polymer matrix is ​​polymethyl methacrylate, and the polymer monomer or prepolymer coated carbon nanotubes are oligomeric polymethyl methacrylate coated carbon nanotubes. Preferably, the weight average molecular weight of the oligomeric polymethyl methacrylate is about 200-400 g / mol, for example, about 200 g / mol, about 250 g / mol, about 300 g / mol, about 350 g / mol, about 400 g / mol, etc.

[0056] The coating of carbon nanotubes with a suitable amount of polymer monomers or prepolymers helps to optimize the performance of the obtained composite material. In one embodiment, in the carbon nanotubes coated with polymer monomers or prepolymers, the weight ratio of carbon nanotubes to polymer monomers or prepolymers is about (1:5) to about (1:20). If the weight ratio of carbon nanotubes to polymer monomers or prepolymers is too high, the coating of carbon nanotubes by polymer monomers or prepolymers may be insufficient, which is not conducive to interface volume expansion and reducing carbon nanotube agglomeration, and may cause the dispersion uniformity of carbon nanotubes in the composite material to decrease; if the weight ratio is too low, the coating process of carbon nanotubes becomes more difficult, which may increase the agglomeration effect of carbon nanotubes during the coating process.

[0057] In the polymer-based composite material containing carbon nanotubes of the present application, based on the total weight parts of the polymer matrix and the carbon nanotubes coated with the polymer monomer or prepolymer as 100 weight parts, the content of the carbon nanotubes is about 0.01-1 weight part, for example, 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 weight part, etc., the content of the polymer monomer or prepolymer is about 1-5 weight parts, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 weight parts, etc.; and the content of the polymer matrix is ​​about 95-99 weight parts, for example, 95, 96, 97, 98, 98.5, 98.8, 98.9, 99 weight parts, etc. The above amount not only helps to uniformly disperse the carbon nanotubes in the composite material, but also enables the polymer-based composite material to have desired properties (such as dielectric properties, optical properties, mechanical properties, etc.).

[0058] In the present application, the step of providing carbon nanotubes coated with polymer monomers or prepolymers may include:

[0059] S100: dispersing a carbon nanotube raw material in a dispersion medium to obtain a dispersion liquid A;

[0060] S200: After performing density gradient centrifugation on the dispersion A, taking out the top layer of the dispersion to obtain a dispersion B;

[0061] S300: adding an activator and a dispersant to the dispersion B and mixing them to obtain a dispersion C;

[0062] S400: mixing the dispersion C with a polymer monomer or a prepolymer to obtain a dispersion D containing carbon nanotubes coated with the polymer monomer or the prepolymer;

[0063] S500: Drying the dispersion D to obtain carbon nanotubes coated with polymer monomers or prepolymers.

[0064] S100: Dispersing the carbon nanotube raw material in a dispersion medium to obtain a dispersion A

[0065] By selecting specific carbon nanotubes as raw materials and screening and purifying the carbon nanotubes according to their size, carbon nanotubes of uniform size can be obtained. In the subsequent processing, by controlling the shear effect during the mixing process, the carbon nanotubes can be dispersed more evenly in the composite material.

[0066] In S100, the carbon nanotube raw material includes one or more carbon nanotubes selected from the following: carbon nanotubes with an outer diameter of about 1 nm to 2 nm, a length of about 1 μm to 30 μm, and a specific surface area of ​​about 550 to 1200 m 2 ·g -1Single-walled carbon nanotubes with an outer diameter of about 10nm-100nm and a length of about 10μm-50μm are used. Preferably, the carbon nanotube raw material is a single-walled carbon nanotube. Herein, the specific surface area of ​​a carbon nanotube refers to the total surface area of ​​a unit mass of carbon nanotubes. The specific surface area of ​​the single-walled carbon nanotubes of the present application can be about 550-1200m 2 ·g -1 , for example about 550m 2 ·g -1 、600m 2 ·g -1 、650m 2 ·g -1 、700m 2 ·g -1 、750m 2 ·g -1 、800m 2 ·g -1 、850m 2 ·g -1 、900m 2 ·g -1 、950m 2 ·g -1 , 1000m 2 ·g -1 、1050m 2 ·g -1 、1075m 2 ·g -1 、1100m 2 ·g -1 、1125m 2 ·g -1 、1150m 2 ·g -1 、1175m 2 ·g -1 、1200m 2 ·g -1 The specific carbon nanotube raw material of the present application can obtain carbon nanotubes of desired size and uniform size through the size screening process of the present application, which is beneficial to the dispersion of carbon nanotubes.

[0067] The dispersion medium refers to a liquid medium that can disperse carbon nanotubes and form a dispersion liquid. Polar medium is conducive to the dispersion effect of carbon nanotubes and subsequently added components (such as activators and dispersants). In one embodiment, in S100, the dispersion medium includes water, C 1-5 Alcohol solvents, C 3-5 Ketone solvents, C 2-8 Ester solvents, C 2-4Nitrile solvent or its arbitrary combination. In a preferred embodiment, the dispersion medium comprises water, ethanol, methanol, acetone or its arbitrary combination. The particularly preferred dispersion medium of the present application can make the carbon nanotubes well dispersed therein, and its boiling point has a certain gap with the polymer monomer or prepolymer, and can be easily removed from the system by drying (e.g., vacuum distillation) process, thereby avoiding the problem of polymer degradation and release of toxic substances due to the presence of dispersion medium in the melt processing process.

[0068] In S100, the weight ratio of the carbon nanotube raw material to the dispersion medium can be about (1:3) to about (1:10), for example, about 1:3, about 1:4, about 1:5, about 1:6, about 1:7, about 1:8, about 1:9, about 1:10, etc., which is conducive to forming a dispersion A with good performance.

[0069] Placing the carbon nanotube raw material in the dispersion medium at a suitable temperature is beneficial to improving the dispersion process efficiency and dispersion effect, and can also ensure that the structure of the carbon nanotubes is not destroyed. In S100, the carbon nanotube raw material can be dispersed in the dispersion medium at a temperature of about 20-40°C.

[0070] The carbon nanotube raw material can be dispersed in the dispersion medium by any dispersion method. For cost, dispersion effect, convenience, etc., in S100, the carbon nanotube raw material is dispersed in the dispersion medium by ultrasound. The ultrasonic time can be about 1-4 hours. The power of the ultrasonic equipment can be about 400-1000W. Such ultrasonic time and power can ensure the dispersion effect. In one embodiment, in S100, based on the weight of the dispersion A, the content of carbon nanotubes in the dispersion A is about 9wt% or more, for example, about 9wt% or more, about 10wt% or more, about 15wt% or more, about 20wt% or more, about 25wt% or more, etc. In one embodiment, in S100, based on the weight of the dispersion A, the content of carbon nanotubes in the dispersion A can be about 50wt% or less, for example, about 50wt% or less, about 40wt% or less, about 30wt% or less, etc. The appropriate content of carbon nanotubes in the dispersion A can simplify the difficulty of subsequent processing and obtain the desired treated dispersion. For example, when subsequent treatment is performed by density gradient centrifugation, the dispersion B obtained after the dispersion A having a suitable content of carbon nanotubes is treated can have uniform size and a desired content of carbon nanotubes.

[0071] S200: After performing density gradient centrifugation on dispersion A, the top layer of dispersion is taken out to obtain dispersion B

[0072] Density gradient centrifugation can be performed using conventional equipment in the art, such as a high-speed centrifuge. By subjecting dispersion A to density gradient centrifugation, the centrifugal force in the process promotes the layered distribution of carbon nanotubes in the density gradient. By taking out the dispersion of the top layer, the size of the carbon nanotubes can be further screened and the carbon nanotubes can have a more uniform size, which is beneficial to the uniformity of subsequent dispersion of the carbon nanotubes. In the present application, the "top layer of dispersion" refers to the dispersion portion that occupies a certain volume ratio from the top liquid surface of the dispersion to the bottom after density gradient centrifugation. The volume ratio described herein can be about 0.1, about 0.2, about 0.3, about 0.4, about 0.5 or higher.

[0073] In one embodiment, in S200, based on the weight of the dispersion B, the content of carbon nanotubes in the dispersion B is 5 wt% or more, for example, about 5 wt% or more, about 6 wt% or more, about 7 wt% or more, about 8 wt% or more, about 9 wt% or more, about 10 wt% or more, about 15 wt% or more, about 20 wt% or more, about 25 wt% or more, etc. In one embodiment, in S200, based on the weight of the dispersion B, the content of carbon nanotubes in the dispersion B may be about 50 wt% or less, for example, about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 25 wt% or less, about 20 wt% or less, about 15 wt% or less, etc. It is understood by those skilled in the art that after separation by density gradient centrifugation, the content of carbon nanotubes in the uppermost dispersion (i.e., dispersion B) is usually lower than the content of carbon nanotubes in the solution before separation.

[0074] S300: adding an activator and a dispersant to the dispersion B and mixing them to obtain a dispersion C.

[0075] The activator of the present application refers to a reagent that can activate the carbon nanotubes, and the activation treatment includes but is not limited to: removing metal elements in the carbon nanotubes, giving the carbon nanotubes more active functional groups, etc. The activators that can be used in the present application include but are not limited to: hydrochloric acid, nitric acid, concentrated sulfuric acid, hydrogen peroxide, sodium hydroxide or any combination thereof. In a specific embodiment, the activator is sodium hydroxide.

[0076] The amount of the activator can be about 1 wt%-10 wt% based on the weight of the dispersion B. A suitable amount of the activator can ensure the activation effect on the carbon nanotubes and avoid, for example, unavoidable excessive residual amount thereof, which may cause undesirable negative effects on the composite material in subsequent preparation, processing and related preparation.

[0077] The dispersant of the present application refers to an agent that can promote the uniform dispersion of solid particles in a dispersion medium to form a stable dispersion. The dispersant of the present application includes, but is not limited to, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, triethylhexyl phosphoric acid, sodium dodecyl sulfate, potassium dodecyl sulfate, sodium hexadecyl sulfate, potassium hexadecyl sulfate, sodium dodecyl sulfonate, potassium dodecyl sulfonate, sodium hexadecyl sulfonate, potassium hexadecyl sulfonate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, gum, polyethylene glycol fatty acid esters, sodium polyacrylate, polyvinyl alcohol, or any combination thereof. In a specific embodiment, the dispersant is sodium dodecyl sulfate.

[0078] The amount of the dispersant used can be about 0.1 wt%-1 wt% based on the weight of the dispersion B. A suitable amount of the dispersant can make the carbon nanotubes well dispersed in the dispersion medium and avoid undesirable negative effects on the subsequent preparation, processing and related preparation of the composite material due to, for example, an unavoidable high residual amount thereof.

[0079] By activating the carbon nanotubes of uniform size, more reactive functional groups can be introduced on the surface of the carbon nanotubes, which can increase the interaction with the monomer / prepolymer and alleviate the agglomeration effect. In addition, the combined action of the activator and the dispersant is more conducive to forming a uniform dispersion B. In one embodiment, in S300, based on the weight of the dispersion C, the content of the carbon nanotubes in the dispersion C is 3wt% or more.

[0080] S400: Mixing the dispersion C with the polymer monomer or prepolymer to obtain a dispersion D containing carbon nanotubes coated with the polymer monomer or prepolymer.

[0081] There is no particular limitation on the mixing method of the dispersion C with the polymer monomer or prepolymer, and it is only necessary to fully mix the two, for example, the mixing of the two can be achieved by stirring. The stirring and mixing can be completed by a high-speed stirrer. In one embodiment, in S400, the mixing of the dispersion C with the polymer monomer or prepolymer is carried out by stirring, and the stirring speed is about 3000-5000r / min. In one embodiment, in S400, the mixing time of the dispersion C with the polymer monomer or prepolymer is about 2-8 hours. Such a rotation speed and mixing time help the monomer or prepolymer to form a good coating effect on the carbon nanotube.

[0082] By controlling the weight ratio of the carbon nanotubes to the polymer monomer or prepolymer in the dispersion C in S400, the polymer monomer or prepolymer and the carbon nanotubes in the obtained polymer monomer or prepolymer-coated carbon nanotubes can have a desired ratio. In one embodiment, the weight ratio of the carbon nanotubes to the polymer monomer or prepolymer in the dispersion C can be about (1:5) to (1:20).

[0083] Compared with the polymer matrix, the melting point of the polymer monomer or prepolymer is relatively low, so the carbon nanotubes can be coated at a lower temperature and the carbon nanotubes can be dispersed at the same time. In addition, the dispersion medium can be removed later by utilizing the melting and boiling point difference between the polymer monomer or prepolymer and the dispersion medium.

[0084] In S400, the dispersion C is mixed with the polymer monomer or prepolymer at a temperature of about (T-5)°C to (T+5)°C, where T is the melting point of the polymer monomer or prepolymer. Such a temperature can melt the polymer monomer or prepolymer, thereby better coating the carbon nanotubes.

[0085] S500: Drying the dispersion D to obtain carbon nanotubes coated with polymer monomers or prepolymers

[0086] The drying process of the dispersion D refers to the process of removing the volatile phase (such as the dispersion medium) in the dispersion D. There are no special restrictions on the method and equipment of the drying process. Those skilled in the art can select the temperature of the drying process according to the volatile phase to be removed in the dispersion D (for example, according to the boiling point of the dispersion medium), but the temperature should not be too high to avoid decomposition of the components in the system or destruction of the coating structure. Removing the dispersion medium in the dispersion through the drying process not only prevents the release of harmful substances in the subsequent melt processing process, avoids inducing the decomposition of the polymer, but also reduces damage to the equipment.

[0087] From the perspective of drying effect, drying efficiency and avoiding undesirable negative changes in the system product, the drying process can be completed by vacuum distillation. The equipment for vacuum distillation can be, for example, a rotary evaporator. Vacuum distillation can reduce the temperature of the drying process, which is beneficial to avoid decomposition of the components in the system or destruction of the coating structure due to excessive temperature.

[0088] The polymer monomer or prepolymer coated carbon nanotubes are mixed with the polymer matrix and then melt extruded to obtain Polymer-based composite materials containing carbon nanotubes

[0089] Before melt extrusion, the polymer monomer or prepolymer coated carbon nanotubes are pre-mixed with the polymer matrix to optimize the dispersion effect and reduce agglomeration. The mixing process can be carried out by a temperature-controlled high-speed mixer. The mixing time can be, for example, about 5-30 minutes.

[0090] The mixing of the polymer monomer or prepolymer-coated carbon nanotubes with the polymer matrix can be carried out at a temperature near the melting point of the polymer monomer or prepolymer. In one embodiment, the mixing of the polymer monomer or prepolymer-coated carbon nanotubes with the polymer matrix can be carried out at a temperature of about (T-5)°C to (T+5)°C, where T is the melting point of the polymer monomer or prepolymer.

[0091] The mixing of the polymer monomer or prepolymer-coated carbon nanotubes with the polymer matrix can be performed under an inert gas environment (eg, under a nitrogen environment), which helps to avoid decomposition of the raw materials.

[0092] To prevent polymer degradation during mixing, an antioxidant can also be added to the system. In one embodiment, before the polymer monomer or prepolymer coated carbon nanotubes are mixed with the polymer matrix, an antioxidant is added to the polymer matrix. In a preferred embodiment, the antioxidant includes: hindered phenol antioxidants, phosphite antioxidants, thioester antioxidants or any combination thereof. Specifically, the antioxidant can be one or more of antioxidant 1010, antioxidant 168, antioxidant 300, and antioxidant 330. Based on the total weight of the polymer matrix contained in the system and the polymer monomer or prepolymer coated on the surface of the carbon nanotubes, the amount of the antioxidant can be about 0.1-0.3wt%.

[0093] Melt extrusion refers to the process of extruding after melting the raw materials, which can generally include the processes of feeding, conveying, melting, mixing, extruding, cooling, etc. In the melt extrusion process, the polymer monomer or prepolymer coating the carbon nanotubes and the polymer matrix are heated and melted, and then extruded. The melt extrusion process can be carried out using conventional equipment in the art, such as a screw extruder, preferably a twin-screw extruder.

[0094] After melt extrusion, a suitable subsequent process, such as granulation, can be selected according to actual needs. In one embodiment, the polymer monomer or prepolymer coated carbon nanotubes are mixed with a polymer matrix and then melt extruded and granulated to obtain polymer-based composite material particles containing carbon nanotubes.

[0095] Polymer-based composite materials and products containing carbon nanotubes

[0096] In another aspect, the present application relates to a polymer-based composite material containing carbon nanotubes, which is prepared by the preparation method of the present application.

[0097] In another aspect, the present application relates to a polymer-based composite product, which comprises the polymer-based composite material containing carbon nanotubes of the present application. In a specific embodiment, the polymer-based composite product is obtained by injection molding or compression injection molding the polymer-based composite particles containing carbon nanotubes of the present application.

[0098] In a preferred embodiment, the polymer-based composite product of the present application is a cover plate. In a more preferred embodiment, the polymer-based composite product of the present application is a display cover plate. The cover plate can be made by injection molding or compression injection molding. According to the actual scenario, for example, when used as a display cover plate, the cover plate thickness can be about 1mm-5mm, for example, about 1.5mm-2.5mm. The cover plate of the present application can have excellent dielectric properties, and its dielectric constant can be increased to about 3.3-4.8. The cover plate of the present application also has excellent optical properties, with high light transmittance and low haze. In one embodiment, the light transmittance of the cover plate can be 50%-80%. In one embodiment, the haze value of the cover plate can be about 2%-5%.

[0099] The cover plate made of the polymer-based composite material of the present application has excellent electrical and optical properties and is suitable for use as a display screen cover plate, especially a display screen cover plate in a display module with a touch function. The cover plate of the present application can be used as a display screen cover plate in various scenarios. As an example, the display screen cover plate of the present application can be used as a vehicle-mounted display screen cover plate.

[0100] Figure 1 An embodiment of a display module including a cover plate of the present application is shown. The display module 100 includes, in sequence: a display screen 11, an optical adhesive layer 12, and a cover plate 13 of the present application. Optionally, a surface of the cover plate 13 facing away from the optical adhesive layer 12 may have a coating 14. The display screen 11 may be an embedded display screen. The material of the optical adhesive layer 12 may be polymethyl methacrylate (PMMA) or polyurethane (PU). The coating 14 may be selected as needed, for example, it may be an anti-reflection-anti-fingerprint (AR-AF) coating.

[0101] Beneficial Effects

[0102] The preparation method of the present application is conducive to improving the dispersion of carbon nanotubes in a polymer matrix, thereby obtaining a polymer-based composite material with uniform dispersion of carbon nanotubes. The cover plate made from the composite material of the present application has better dielectric properties and can be used in display modules, which can effectively improve the touch signal-to-noise ratio and thus improve the touch sensitivity.

[0103] Example

[0104] The solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0105] It should be noted that the following embodiments are merely examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

[0106] Example 1

[0107] The sample of Example 1 was prepared by the following process:

[0108] The outer diameter is 1-2nm, the length is 5-30μm, and the specific surface area is 1075m 2 ·g -1 The single-walled carbon nanotubes were ultrasonicated at 25° C. for 1 hour to disperse the single-walled carbon nanotubes in acetone, thereby obtaining a dispersion A, wherein the content of the carbon nanotubes in the dispersion A was 10 wt % based on the weight of the dispersion A.

[0109] Subsequently, a gradient density centrifuge was used to perform four centrifugal operations, each centrifugal operation lasting 15 minutes, and the speed was set to 4000r / h, 8000r / h, 12000r / h and 15000r / h, respectively. After each centrifugation, the supernatant was extracted and used for the next centrifugation operation. After the four centrifugal operations, a dispersion system with different carbon nanotube contents from the top of the system liquid surface to the bottom of the system was obtained, and the uppermost dispersion was taken as dispersion B, wherein the content of carbon nanotubes in dispersion B was 6wt% based on the weight of dispersion B.

[0110] To dispersion B, add dispersant sodium dodecyl sulfate (in an amount of 1 wt% of the weight of dispersion B) and a NaOH activator with a concentration of 0.025 mol / L (in an amount of 1 wt% of the weight of dispersion B), transfer the system to a three-necked flask, control the temperature to 25±5°C and stir at a high speed of 2000 r / m for 2 hours to obtain dispersion C, wherein the content of carbon nanotubes in dispersion C is 4 wt% based on the weight of dispersion C.

[0111] Under stirring, isosorbide (polymer monomer) crystals (the amount of which is 5 times the weight of the carbon nanotubes contained in dispersion C) are added to dispersion C, and the system temperature is heated to 40°C. At the same time, acetone is dripped into the system to reduce the viscosity of isosorbide, thereby obtaining dispersion D containing isosorbide-coated single-walled carbon nanotubes.

[0112] The acetone in the dispersion D was removed by a rotary evaporator with the evaporation temperature set at 60° C. to obtain isosorbide-capped single-walled carbon nanotubes.

[0113] The prepared isosorbide-coated carbon nanotubes (1.8 parts by weight), isosorbide polycarbonate (98.1 parts by weight) and antioxidant 1010 (0.1 parts by weight) were placed in a high-speed mixer, mixed at a speed of 2000 r / m and a mixing temperature of 40°C for 5 minutes, and then fed into a twin-screw extruder, melt-extruded and granulated at a temperature of 230°C, thereby obtaining the composite material particle sample of Example 1.

[0114] Comparative Example 1

[0115] The sample of Comparative Example 1 was prepared by the following process:

[0116] Isosorbide polycarbonate has an outer diameter of 1-2nm, a length of 5-30μm, and a specific surface area of ​​1075m 2 ·g -1 The single-walled carbon nanotubes are directly physically blended and then extruded and granulated to obtain the composite material particle sample of Comparative Example 1, wherein the content of the carbon nanotubes is 0.3wt% based on the total weight of the composite material.

[0117] Example 2

[0118] The sample of Example 2 was prepared by the following process:

[0119] The outer diameter is 1-2nm, the length is 5-30μm, and the specific surface area is 1075m 2 ·g -1 The single-walled carbon nanotubes were ultrasonicated at 25° C. for 1 hour to disperse the single-walled carbon nanotubes in acetone, thereby obtaining a dispersion A, wherein the content of the carbon nanotubes in the dispersion A was 10 wt % based on the weight of the dispersion A.

[0120] Subsequently, a gradient density centrifuge was used to perform four centrifugal operations, each centrifugal operation lasting 15 minutes, and the speed was set to 4000r / h, 8000r / h, 12000r / h and 15000r / h, respectively. After each centrifugation, the supernatant was extracted and used for the next centrifugation operation. After the centrifugation operation, a dispersion system with different carbon nanotube contents from the top of the system liquid surface to the bottom of the system was obtained, and the uppermost dispersion was taken as dispersion B, wherein the content of carbon nanotubes in dispersion B was 6wt% based on the weight of dispersion B.

[0121] To dispersion B, add dispersant sodium dodecyl sulfate (in an amount of 1 wt% of the weight of dispersion B) and a NaOH activator with a concentration of 0.025 mol / L (in an amount of 1 wt% of the weight of dispersion B), transfer the system to a three-necked flask, control the temperature to 25±5°C and stir at a high speed of 2000 r / m for 2 hours to obtain dispersion C, wherein the content of carbon nanotubes in dispersion C is 3 wt% based on the weight of dispersion C.

[0122] Under stirring, oligomeric polymethyl methacrylate (polymer oligomer) (its amount is 5 times the weight of the carbon nanotubes contained in dispersion C) with a weight average molecular weight of about 300 g / mol is added to dispersion C, and the system temperature is heated to 40°C. At the same time, acetone is dripped into the system to reduce the viscosity of the oligomeric polymethyl methacrylate, thereby obtaining dispersion D containing single-walled carbon nanotubes coated with oligomeric polymethyl methacrylate.

[0123] The acetone in the dispersion D was removed by a rotary evaporator with the evaporation temperature set at 60° C. to obtain single-walled carbon nanotubes capped with oligomeric polymethyl methacrylate.

[0124] The prepared polymethyl methacrylate oligomer-coated carbon nanotubes (1.8 parts by weight), polymethyl methacrylate (98.1 parts by weight) and antioxidant 1010 (0.1 parts by weight) were placed in a high-speed mixer and mixed at a speed of 2000 r / m and a mixing temperature of 40°C for 5 minutes. They were then fed into a twin-screw extruder and melt-extruded and granulated at a temperature of 230°C to obtain the composite material particle sample of Example 2.

[0125] Comparative Example 2

[0126] The sample of Comparative Example 2 was prepared by the following process:

[0127] Polymethyl methacrylate and outer diameter of 1-2nm, length of 5-30μm, specific surface area of ​​1075m 2 ·g -1 The single-walled carbon nanotubes are directly physically blended and then extruded and granulated to obtain the composite material particle sample of Comparative Example 1, wherein the content of the carbon nanotubes is 0.3wt% based on the total weight of the composite material.

[0128] performance

[0129] The particle samples of the embodiment and the comparative example were respectively injection molded into cover plates with a thickness of 2 mm.

[0130] Reference Figure 1The cover plate sample prepared by the particle sample of the embodiment and the comparative example, the optical adhesive layer of PMMA material with a thickness of 0.25 mm and the In-cell (embedded) display screen are bonded together to obtain the display module samples of the embodiment and the comparative example.

[0131] Figure 2-5 Scanning electron microscope photos of cover plate samples made from the particle samples of the embodiment and the comparative example are shown respectively.

[0132] from Figure 2 and Figure 4 It can be seen that the cover plate made from the sample of the embodiment of the present application has good dispersion of carbon nanotubes and no agglomeration. Figure 3 and Figure 5 It can be seen that in the cover plate made of the sample of the comparative example, carbon nanotubes agglomeration sites appear, such as Figure 3 and Figure 5 The position shown in the circular box in .

[0133] Dielectric constant test: The dielectric constants of the cover plate samples of the embodiment and the comparative example were measured by NOVOCONTROL concept80 broadband dielectric spectrometer. The test results are shown in Table 1 below.

[0134] Touch signal-to-noise ratio test: The signal-to-noise ratio of the display module samples of the embodiment and the comparative example was tested by copper cylinders, and the test results are shown in Table 1 below.

[0135] Table 1

[0136] serial number Dielectric constant Touch signal-to-noise ratio Example 1 4.2 45 dB Comparative Example 1 3.0 34 dB Example 2 3.6 40 dB Comparative Example 2 2.8 32 dB

[0137] According to Table 1 above, compared with the comparative example, the cover plate sample of the embodiment of the present application has a higher dielectric constant and better dielectric performance. Compared with the comparative example, the display module sample of the embodiment of the present application has a higher touch signal-to-noise ratio and improved touch sensitivity.

[0138] It will be clear to those skilled in the art that many modifications and variations of the present invention may be made without departing from its spirit and scope. The specific embodiments described herein are provided only by way of example and are not intended to be limited in any way. The true scope and spirit of the present invention are shown by the appended claims, and the description and examples are merely exemplary.

Claims

1. A method for preparing a polymer-based composite material containing carbon nanotubes, comprising the following steps: Providing polymer monomer or prepolymer coated carbon nanotubes; The polymer monomer or prepolymer coated carbon nanotubes are mixed with a polymer matrix and then melt-extruded to obtain the polymer-based composite material containing carbon nanotubes; in, The polymer monomer or prepolymer is a monomer or prepolymer of the polymer matrix.

2. The preparation method according to claim 1, wherein The step of providing polymer monomer or prepolymer coated carbon nanotubes comprises: S100: dispersing a carbon nanotube raw material in a dispersion medium to obtain a dispersion liquid A; S200: After performing density gradient centrifugation on the dispersion A, taking out the top layer of the dispersion to obtain dispersion B; S300: adding an activator and a dispersant to the dispersion B and mixing them to obtain a dispersion C; S400: mixing the dispersion C with the polymer monomer or prepolymer to obtain a dispersion D, wherein the dispersion D contains carbon nanotubes coated with the polymer monomer or prepolymer; S500: drying the dispersion D to obtain the carbon nanotubes coated with the polymer monomer or prepolymer.

3. The preparation method according to claim 2, wherein In S100, The carbon nanotube raw material includes one or more carbon nanotubes selected from the following: carbon nanotubes with an outer diameter of 1nm-2nm, a length of 1μm-30μm, and a specific surface area of ​​550-1200m 2 ·g -1 Single-walled carbon nanotubes, and multi-walled carbon nanotubes with an outer diameter of 10nm-100nm and a length of 10μm-50μm; and / or The dispersion medium includes water, C 1-5 Alcohol solvents, C 3-5 Ketone solvents, C 2-8 Ester solvents, C 2-4 Nitrile solvent or any combination thereof; preferably, the dispersion medium comprises water, ethanol, methanol, acetone or any combination thereof; and / or The weight ratio of the carbon nanotube raw material to the dispersion medium is (1:3) to (1:10); and / or The content of the carbon nanotubes in the dispersion A is 9 wt % or more based on the weight of the dispersion A.

4. The preparation method according to claim 2, wherein In S100, The carbon nanotube raw material is dispersed in a dispersion medium at a temperature of 20-40° C.; and / or The carbon nanotube raw material is dispersed in the dispersion medium by ultrasound. Preferably, the ultrasound time is 1-4 hours and / or the power of the ultrasound equipment is 400-1000W.

5. The preparation method according to claim 2, wherein In S200, The content of the carbon nanotubes in the dispersion B is 5 wt % or more based on the weight of the dispersion B.

6. The preparation method according to claim 2, wherein In S300, The activator comprises: hydrochloric acid, nitric acid, concentrated sulfuric acid, hydrogen peroxide, sodium hydroxide or any combination thereof; and / or The dispersant comprises: sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, triethylhexyl phosphoric acid, sodium dodecyl sulfate, potassium dodecyl sulfate, sodium hexadecyl sulfate, potassium hexadecyl sulfate, sodium dodecyl sulfonate, potassium dodecyl sulfonate, sodium hexadecyl sulfonate, potassium hexadecyl sulfonate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum, polyethylene glycol fatty acid esters, sodium polyacrylate, polyvinyl alcohol or any combination thereof; and / or The content of the carbon nanotubes in the dispersion C is 3 wt % or more based on the weight of the dispersion C.

7. The preparation method according to claim 2, wherein: In S400, The weight ratio of the carbon nanotubes in the dispersion C to the polymer monomer or prepolymer is (1:5) to (1:20); and / or The mixing of the dispersion C and the polymer monomer or prepolymer is carried out at a temperature of (T-5)°C to (T+5)°C, wherein T is the melting point of the polymer monomer or prepolymer; and / or The dispersion C is mixed with the polymer monomer or prepolymer by stirring, and the stirring speed is 3000-5000 r / min; and / or The time for mixing the dispersion C with the polymer monomer or prepolymer is 2-8 hours.

8. The preparation method according to claim 1 or 2, wherein: In the carbon nanotubes coated with the polymer monomer or prepolymer, the weight ratio of the carbon nanotubes to the polymer monomer or prepolymer is (1:5) to (1:20); and / or In the polymer-based composite material containing carbon nanotubes, based on the total weight of the polymer matrix and the carbon nanotubes coated with the polymer monomer or prepolymer being 100 parts by weight, the content of the carbon nanotubes is 0.01-1 parts by weight, the content of the polymer monomer or prepolymer is 1-5 parts by weight, and the content of the polymer matrix is ​​95-99 parts by weight.

9. The preparation method according to claim 1 or 2, wherein: The polymer matrix comprises: bisphenol A-polycarbonate, isosorbide-based polycarbonate, polymethyl methacrylate, polylactic acid, polystyrene, polyimide or any blend or copolymer thereof, preferably isosorbide-based polycarbonate, polymethyl methacrylate or any blend or copolymer thereof; and / or The polymer monomer or prepolymer includes: diphenol propane, isosorbide, mannitol, acrylate, styrene, lactide, fluorine-containing polyol, dopamine, ethylenediamine, pyromellitic dianhydride, oligomeric polymethyl methacrylate, oligomeric polylactic acid or any combination thereof, preferably isosorbide, oligomeric polymethyl methacrylate or any combination thereof.

10. The preparation method according to claim 1 or 2, wherein: The mixing of the polymer monomer or prepolymer coated carbon nanotubes and the polymer matrix is ​​carried out at a temperature of (T-5)°C to (T+5)°C, wherein T is the melting point of the polymer monomer or prepolymer; and / or The mixing of the polymer monomer or prepolymer-coated carbon nanotubes and the polymer matrix is ​​carried out in an inert gas environment.

11. The preparation method according to claim 1 or 2, wherein: Before mixing the polymer monomer or prepolymer-coated carbon nanotubes with the polymer matrix, adding an antioxidant to the polymer matrix; Preferably, The antioxidant includes: hindered phenol antioxidant, phosphite antioxidant, thioester antioxidant or any combination thereof.

12. A polymer-based composite material containing carbon nanotubes, prepared by the method according to any one of claims 1 to 11.

13. A polymer-based composite product comprising the composite material according to claim 12, Preferably, The polymer-based composite material product is a cover plate, More preferably, The polymer-based composite material product is a display screen cover.

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