CN111205558B

CN111205558B - Graphene-reinforced heat-conducting polymer composite material, preparation method thereof and heat-conducting product

Info

Publication number: CN111205558B
Application number: CN202010131661.3A
Authority: CN
Inventors: 徐欢; 徐玮彤; 郭晓然; 张新和; 张志博; 刘耘成; 朱亚坤; 李金来
Original assignee: Enn Inner Mongolia Graphene Materials Co ltd
Current assignee: Inner Mongolia Xinminhui Nanotechnology Co ltd
Priority date: 2020-02-28
Filing date: 2020-02-28
Publication date: 2023-04-28
Anticipated expiration: 2040-02-28
Also published as: CN111205558A

Abstract

The invention discloses a graphene reinforced heat-conducting polymer composite material, a preparation method thereof and a heat-conducting product, and relates to the technical field of heat-conducting materials. The preparation method of the graphene reinforced heat-conducting polymer composite material comprises the following steps: carrying out liquid phase stripping on graphite to obtain graphene dispersion liquid; mixing a modifier with the graphene dispersion liquid by a mill to obtain a modified graphene dispersion liquid; separating the modified graphene from the modified graphene dispersion liquid to obtain modified graphene; and (3) melting and blending the modified graphene, the heat-conducting filler, the polymer matrix and the processing aid to obtain the graphene reinforced heat-conducting polymer composite material. The graphene reinforced heat-conducting polymer composite material is prepared by the preparation method of the graphene reinforced heat-conducting polymer composite material. The heat conducting material comprises the graphene reinforced heat conducting polymer composite material.

Description

Graphene-reinforced heat-conducting polymer composite material, preparation method thereof and heat-conducting product

Technical Field

The invention relates to the technical field of heat conducting materials, in particular to a graphene reinforced heat conducting polymer composite material, a preparation method thereof and a heat conducting product.

Background

The graphene has a unique two-dimensional periodic honeycomb lattice structure, and the stable carbon six-membered ring in the structural unit of the graphene endows the graphene with excellent high heat conductivity (5000W/m.K), so that the graphene has better heat conductivity, mechanical property and electric conductivity, and therefore, the graphene reinforced heat-conducting polymer composite material obtained by mixing the graphene and the polymer matrix has good heat conductivity.

However, as the surface energy of the graphene is extremely large and the scattering degree of phonons at the interface of the graphene and the polymer matrix is high, the graphene in the graphene reinforced heat-conducting polymer composite material obtained by mixing the graphene and the polymer matrix is unevenly dispersed, so that the heat-conducting property of the graphene reinforced heat-conducting polymer composite material is reduced.

Disclosure of Invention

The invention aims to provide a graphene reinforced heat-conducting polymer composite material, a preparation method thereof and a heat-conducting product, so that the dispersibility of graphene in the graphene reinforced heat-conducting polymer composite material is improved, and the graphene reinforced heat-conducting polymer composite material has good heat-conducting property.

In order to achieve the above purpose, the invention provides a preparation method of a graphene reinforced heat-conducting polymer composite material. The preparation method of the graphene reinforced heat-conducting polymer composite material comprises the following steps:

Step 1): and (3) carrying out liquid phase stripping on the graphite to obtain graphene dispersion liquid.

Step 2): carrying out mill mixing on the first modifier and the graphene dispersion liquid, so that the first modifier is attached to the surface of graphene to obtain modified graphene dispersion liquid, wherein the mass ratio of the first modifier to the graphene is 1: (1-10).

Step 3): separating the modified graphene from the modified graphene dispersion liquid to obtain modified graphene; and

step 4): and (3) melting and blending 1-40 parts by weight of modified graphene, 1-55 parts by weight of heat conducting filler, 30-75 parts by weight of polymer matrix and 10-20 parts by weight of optional processing aid, and then performing optional granulation treatment to obtain the graphene reinforced heat conducting polymer composite material.

Compared with the prior art, in the preparation method of the graphene reinforced heat-conducting polymer composite material, the liquid phase stripping method is adopted to perform the first-step shearing stripping on the graphite, so that the graphene dispersion liquid with higher concentration can be obtained, and meanwhile, the graphene can be uniformly dispersed in the graphene dispersion liquid. The grinding machine mixing can perform second-step shearing stripping on graphene in the graphene dispersion liquid, so that the graphene dispersing time is saved, the in-situ modification of the graphene is realized, and the preparation and modification period of the graphene is shortened. Meanwhile, the second step of shearing and stripping can avoid the agglomeration phenomenon caused by higher graphene concentration in the graphene dispersion liquid, so that the modifier can be fully contacted with the surface of the graphene, and the modifier is promoted to be attached to the surface of the graphene. At this time, when the modified graphene is melt blended with the polymer matrix and the heat conducting filler, the first modifier on the surface of the modified graphene can reduce the surface tension between the graphene and the heat conducting filler and between the modified graphene and the polymer matrix, so that the uniformity of mixing of the graphene, the polymer matrix and the heat conducting filler is ensured. And the graphene and the heat-conducting filler in the graphene reinforced heat-conducting polymer composite material are mutually overlapped, and a three-dimensional heat-conducting structure which is mutually communicated is constructed in the graphene reinforced heat-conducting polymer composite material, so that the graphene reinforced heat-conducting polymer composite material has good heat-conducting property and mechanical property.

From the above, in the preparation method of the graphene reinforced heat-conducting polymer composite material provided by the embodiment of the invention, the graphite is treated by adopting a two-step shearing and stripping method, so that the preparation and surface modification period of graphene can be shortened, the modified graphene dispersion liquid with good surface modification and higher concentration can be obtained, and the preparation and modification period of graphene can be improved. Meanwhile, the modified graphene and the heat-conducting filler can be uniformly filled between polymer matrixes to form a three-dimensional heat-conducting network, so that the heat-conducting property and the mechanical property of the graphene reinforced heat-conducting polymer composite material are improved.

The invention also provides a graphene reinforced heat-conducting polymer composite material, which is prepared by the preparation method of the graphene reinforced heat-conducting polymer composite material.

Compared with the prior art, the graphene reinforced heat-conducting polymer composite material has the same beneficial effects as the graphene reinforced heat-conducting polymer composite material, and the description is omitted herein.

The embodiment of the invention also provides a heat conduction product. The heat conduction product comprises the graphene reinforced heat conduction polymer composite material.

Compared with the prior art, the beneficial effects of the heat conduction product provided by the invention are the same as those of the graphene reinforced heat conduction polymer composite material, and are not repeated here.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

fig. 1 is a preparation flow chart of a preparation method of a graphene reinforced heat-conducting polymer composite material provided by an embodiment of the invention;

fig. 2 is a transmission electron microscope image of modified graphene obtained in the fourth embodiment of the present invention;

fig. 3 is a transmission electron microscope image of modified graphene obtained in the fifth embodiment of the invention;

fig. 4 is an impact cross-sectional morphology diagram of a graphene reinforced heat-conducting polymer composite material obtained in the sixth embodiment of the present invention;

fig. 5 is an impact cross-sectional morphology diagram of a graphene reinforced heat-conducting polymer composite material obtained in the seventh embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In order to meet the heat dissipation requirements of structures such as electronic equipment and electronic components produced in the electronic industry, heat conducting polymers with light weight, easy processing, high strength, high heat conductivity and low cost are widely used in the electronic industry. For example: polyamide-6 (PA-6) and Polycarbonate (PC) are widely used in electronic devices such as transformer inductors, electronic component heat dissipation, special cables, electronic packages, and heat conduction potting in civil, aviation, and building material fields.

However, with the rapid development of the electronic information industry (especially, high-power electronic devices), the assembly density and the assembly integration level of the structures such as electronic equipment and electronic components produced in the electronic industry are higher and higher, so that the heat dissipation effect requirements of the structures such as the sub-equipment and the electronic components are higher and higher. In order to meet the development requirements of high density and high integration of electronic industry products, the requirements of heat conduction performance of materials applied to the electronic industry are also higher and higher. At present, the polymer matrix and the heat conducting material with better heat conducting performance can be mixed to prepare the material applied to the electronic industry, and the heat conducting performance of the material applied to the electronic industry can be improved, so that the heat radiating effect of the electronic industry product is ensured. For example: the thermal conductivity of pure PA-6 is only 0.338W/mK. The thermal conductivity of the alumina-polymer composite material obtained by filling 50% of alumina into pure PA-6 was 1.57 times that of pure PA-6. The thermal conductivity of the zinc oxide-polymer composite material obtained by filling 25% of zinc oxide into pure PA-6 is improved by 3 times compared with that of pure PA-6.

The graphene has a unique two-dimensional periodic honeycomb lattice structure, and the stable carbon six-membered ring in the structural unit of the graphene endows the graphene with excellent high heat conductivity coefficient (> 5000W/m.K), so that the graphene and a polymer matrix can be mixed to prepare the graphene reinforced heat-conducting polymer composite material with good heat conductivity. At this time, the thermal conductivity of the graphene reinforced heat-conducting polymer composite material is 4.11W/m.K, which is improved by more than 15 times compared with that of pure PA-6, so that the heat dissipation efficiency of electronic industry products can be greatly improved by the graphene reinforced heat-conducting polymer composite material.

However, in the prior art, graphene is generally prepared by adopting a method of oxidizing and peeling a graphite sheet, but in the process of preparing the graphene by adopting the preparation method, the problems of large environmental hazard, high potential safety hazard coefficient, long production period, low yield, defects of the graphene and the like exist, so that the graphene is difficult to continuously produce in a large scale. Meanwhile, the surface energy of graphene is extremely large, and the scattering degree of phonons at the interface of the graphene and the heat-conducting polymer is high, so that the graphene is unevenly distributed in the graphene reinforced heat-conducting polymer composite material, and therefore, the graphene is required to be subjected to surface modification. However, the existing polar modification of graphene generally requires a large amount of chemical reagents and complex treatment process, and is difficult to adapt to clean, mass and continuous production.

For example: tao Yu of Hezhou Herun New Material science and technology Co., ltd.) takes natural graphite powder or graphite oxide as a raw material, and obtains graphene through ball milling for a long time (80-240 h), then the graphene is heated in an aqueous solution containing a coupling agent for reaction, and is subjected to suction filtration and drying to obtain modified graphene, and finally the modified graphene is introduced into epoxy resin through mechanical stirring to obtain the heat-conducting adhesive (Chinese patent application No. CN 102433098A).

However, when graphene is prepared by the method, there are problems of long production period, low yield and many defects of graphene. Meanwhile, when the graphene is modified by the method, the graphene is easy to agglomerate in an aqueous solution containing the coupling agent, and the coupling agent is difficult to coat on the surfaces of all the graphene, so that the graphene is unevenly dispersed in the heat-conducting adhesive, the heat-conducting adhesive is insufficient in heat conductivity and low in heat conductivity, and the wider application of the heat-conducting adhesive in the fields of energy sources, electrons, LED display and the like is limited.

Example 1

In order to shorten the preparation period of the graphene reinforced heat-conducting polymer composite material and ensure the dispersion uniformity of graphene in the graphene reinforced heat-conducting polymer, the embodiment of the invention provides the graphene reinforced heat-conducting polymer composite material and a preparation method thereof. Referring to fig. 1, the preparation method of the graphene-reinforced heat-conducting polymer composite material includes:

Step 1): and (3) carrying out liquid phase stripping on the graphite to obtain graphene dispersion liquid. It should be noted that the graphite may be selected according to practical situations, as long as the graphite has a relatively high fixed carbon content. For example: the graphite may be at least one of flake graphite, spheroidal graphite, graphite oxide, expandable graphite, and expanded graphite.

Step 2): and carrying out mill mixing on the first modifier and the graphene dispersion liquid to enable the first modifier to be modified and attached to the surface of graphene, thereby obtaining the graphene dispersion liquid, wherein the mass ratio of the first modifier to the graphene is 1: (1-10).

Step 3): and separating the modified graphene from the modified graphene dispersion liquid to obtain the modified graphene. There are various methods for separating the modified graphene from the modified graphene dispersion liquid, for example: and filtering or suction filtering the modified graphene dispersion liquid, and drying filter residues to obtain the modified graphene. Or centrifugally separating the modified graphene dispersion liquid to obtain the modified graphene.

Step 4): 1 to 40 parts by weight of modified graphene, 1 to 55 parts by weight of heat conducting filler, 30 to 75 parts by weight of polymer matrix and 10 to 20 parts by weight of optional processing aid are melt blended, and then optional granulation treatment is carried out, so that the graphene reinforced heat conducting polymer composite material is obtained.

According to the preparation method of the graphene reinforced heat-conducting polymer composite material, provided by the embodiment of the invention, the graphite is sheared and stripped in the first step by adopting the liquid phase stripping method, so that the graphene dispersion liquid with higher concentration can be obtained, and meanwhile, the graphene can be uniformly dispersed in the graphene dispersion liquid. The grinding machine mixing can perform second-step shearing stripping on graphene in the graphene dispersion liquid, so that the first modifier can be fully contacted with the surface of the graphene, and the first modifier is attached to the surface of the graphene, so that in-situ modification of the graphene is realized, the graphene dispersing time can be saved, and the preparation and modification period of the graphene is shortened. Meanwhile, the second step of shearing and stripping can avoid the agglomeration phenomenon caused by higher graphene concentration, and the modification effect of the graphene is ensured. At this time, when the modified graphene is melt blended with the polymer matrix and the heat conducting filler, the first modifier on the surface of the modified graphene can reduce the surface tension between the modified graphene and the heat conducting filler as well as between the modified graphene and the polymer matrix, so that the uniformity of mixing of the graphene, the polymer matrix and the heat conducting filler is ensured. And moreover, graphene and a heat-conducting filler in the graphene reinforced heat-conducting polymer composite material are mutually overlapped, and a three-dimensional heat-conducting structure which is mutually communicated is constructed in the graphene reinforced heat-conducting polymer composite material, so that the graphene reinforced heat-conducting polymer composite material has good heat-conducting performance and mechanical property.

From the above, in the preparation method of the graphene reinforced heat-conducting polymer composite material provided by the embodiment of the invention, the graphene is prepared by adopting a two-step shearing and stripping method, and the graphene is modified, so that the preparation and modification period of the graphene can be shortened. Meanwhile, the modified graphene and the heat-conducting filler can be uniformly filled between polymer matrixes to form a three-dimensional heat-conducting network, so that the heat-conducting property and the mechanical property of the graphene reinforced heat-conducting polymer composite material are improved.

As one possible implementation, in step 4) above, melt blending the modified graphene, the thermally conductive filler, the polymer matrix, and the optional processing aid comprises:

uniformly mixing the modified graphene, the heat-conducting filler, the polymer matrix and the optional processing aid to obtain a uniformly mixed material;

and (3) carrying out melt blending on the uniformly mixed materials through two-stage mixing treatment.

Wherein, melt blending the uniformly mixed materials through two-stage mixing treatment comprises:

and (3) carrying out first-stage mixing treatment on the uniformly mixed materials, so that the uniformly mixed materials are melted and then uniformly mixed, and extruding to obtain the master batch. The first-stage mixing time can be selected according to actual requirements and equipment characteristics, and the mixing materials can be melted and uniformly mixed. For example, the first-stage kneading is continuous kneading, and the time of the first-stage kneading is not less than 30 seconds.

And then carrying out second-stage mixing treatment on the masterbatch, and further shearing and dispersing the masterbatch to ensure that the graphene with higher mass fraction is well peeled off and uniformly dispersed in the heat-conducting polymer, so that the limit filling quantity of the modified graphene in the heat-conducting polymer is improved, and the graphene reinforced heat-conducting polymer composite material is ensured to have good heat-conducting property, mechanical property and processing property. The second-stage mixing time can be selected according to practical situations, so long as the graphene with high mass fraction can be well peeled off and uniformly dispersed in the heat-conducting polymer. For example, the second-stage kneading is also continuous kneading, and the time of the second-stage kneading is not less than 30 seconds.

In the embodiment of the invention, when the uniformly mixed materials are subjected to melt blending through two-stage mixing treatment, the first-stage mixing treatment is required to be carried out on the uniformly mixed materials, and then the second-stage treatment operation is carried out. The first section of mixing treatment can be used for evenly mixing the evenly mixed materials after melting, and extruding to obtain the master batch. And, the second stage mixing treatment can further shear and disperse the masterbatch.

After the first-stage kneading treatment is completed, the extruded masterbatch may be cooled and then subjected to the second-stage kneading treatment, or the extruded masterbatch may be directly subjected to the second-stage kneading treatment.

The kneading apparatus of the above-described first-stage kneading treatment includes, as examples, at least one of a roll-over type internal mixer, a continuous type internal mixer, a twin-screw extruder, a single-screw extruder, a planetary screw extruder, and a reciprocating extruder.

The mixing equipment for the second-stage mixing treatment comprises at least one of a turnover internal mixer, a continuous internal mixer, a double-screw extruder, a single-screw extruder, a planetary screw extruder and a reciprocating extruder.

Specifically, in order to ensure that the polymer matrix in the uniformly mixed material is sufficiently melted during the two-stage mixing treatment, the temperature of the first-stage mixing treatment and the second-stage mixing treatment is 100-400 ℃.

Illustratively, when the modified graphene, the heat-conducting filler, the polymer matrix and the optional processing aid are uniformly mixed, at least one of a conical mixer, a high-speed mixer, an open mill, a roll-over internal mixer, a continuous internal mixer, a Z-type kneader, a screw kneader, a vacuum kneader and a horizontal double-screw mixer is used as the uniformly mixing equipment.

Specifically, the mixing temperature is 20-90 ℃, and the mixing time is 10-120 min.

As a possible implementation manner, in the step 4), the heat conductive filler is at least one of an insulating heat conductive filler and an electric conductive heat conductive filler. At this time, different heat conducting fillers are selected, and the graphene reinforced heat conducting polymer composite material has different electric conductivity.

For example: if the graphene-reinforced thermally conductive polymer composite is required to have good electrical conductivity, the thermally conductive filler includes only an electrically conductive thermally conductive filler. At the moment, the three-dimensional heat conduction network formed by the heat conduction filler and the graphene also has good electric conduction performance, so that the graphene reinforced heat conduction polymer composite material has good electric conduction performance and good heat conduction performance. If the graphene-reinforced thermally conductive polymer composite material is required to be an insulating material, the thermally conductive filler only includes an insulating thermally conductive filler. At this time, the electrical resistance of the three-dimensional heat conduction network is increased by utilizing the insulation performance of the heat conduction filler, so that the graphene reinforced heat conduction polymer composite material is an insulation material. If the graphene-reinforced thermally conductive polymer composite material has low requirements on electrical conductivity, the thermally conductive filler includes an insulating thermally conductive filler and an electrically conductive thermally conductive filler.

The above-mentioned conductive heat conductive filler may be selected according to practical requirements, for example. For example: the insulating heat conductive filler may be at least one of silicon carbide, magnesium borate, aluminum borate, magnesium carbonate, magnesium oxide, magnesium hydroxide, calcium carbonate, calcium sulfate, wollastonite, boron nitride, zinc oxide, and aluminum oxide, but is not limited thereto.

The above-mentioned conductive heat conductive filler may be selected according to actual needs. For example: the conductive heat conductive filler may be at least one of carbon fiber, carbon nanotube, crystalline flake graphite, ultrafine graphite, expanded graphite and graphite oxide, but is not limited thereto.

The processing aid in the step 4) is at least one of a second modifier, a toughening agent, a flow modifier, a coupling agent, an antioxidant and a stabilizer. When the processing aid is used in the graphene reinforced heat-conducting polymer composite material, the second modifier can be used for carrying out surface modification on the polymer matrix and the heat-conducting filler, so that the contact effect of the modified graphene and the heat-conducting filler in the polymer matrix is ensured, and the modified graphene and the heat-conducting filler can be uniformly filled in the polymer matrix. The toughening agent can improve the toughness of the polymer matrix, so that the binding force between the polymer matrix and the graphene and the heat-conducting filler is enhanced, and the mechanical property of the graphene-enhanced heat-conducting polymer composite material is further improved. The flow modifier can improve the rheological properties of the polymer matrix, the heat conducting filler and the graphene, so that the heat conducting filler and the graphene are easier to fill in the polymer matrix, and the content of the graphene in the graphene reinforced heat conducting polymer is increased, thereby enhancing the heat conducting performance of the graphene reinforced heat conducting polymer. The antioxidant can improve the antioxidant properties of the graphene-reinforced thermally conductive polymer. The stabilizer can increase the stability of the polymer matrix, the graphene and the heat conducting filler, and prevent the heat conducting polymer from aging and decomposing.

The polymer matrix in step 4) may be at least one of Polyethylene (PE), polypropylene (PP), polybutylene (PB), polyvinylchloride (Polyvinyl chloride), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (Polyvinylidene fluoride, PVDF), polystyrene (Expandable Polystyrene, EPS), acrylonitrile-butadiene-styrene copolymer (Acrylonitrile butadiene Styrene copolymers, ABS), polyamide (Polyamide, PA), polyphenylene sulfide (Polyphenylene sulfide, PPs), polycarbonate (PC), polybutylene terephthalate (Polybutylene terephthalate, PBT), polyethylene terephthalate (polyethylene glycol terephthalate, PET), and linear low density polyethylene (Linear low density polyethylene, LLDPE), but is not limited thereto. At the moment, the heat conducting polymer has better heat conducting property, and the graphene reinforced heat conducting polymer composite material can be guaranteed to have better heat conducting property.

As a possible implementation manner, in step 1), the liquid phase exfoliation of the graphite includes:

And (3) carrying out mill mixing on the dispersion liquid containing graphite and the stripping agent to obtain graphene dispersion liquid. In this case, the stripping agent acts on the surface of the graphite, and the sheet layer on the surface of the graphite can be stripped. Meanwhile, the grinding machine can fully shear graphite, so that graphene obtained by stripping the surface of the graphite is dispersed in a solvent, and graphene dispersion liquid with higher concentration can be obtained, and the preparation efficiency of the graphene is further improved.

Illustratively, to ensure that the stripping agent can sufficiently strip the graphite, the mass ratio of the stripping agent to the graphite is 1: (1-10). Meanwhile, in order to ensure that the graphite can be sufficiently peeled, the mass fraction of the graphite in the dispersion liquid containing the graphite and the dispersing agent is 1-10%.

Preferably, in order to increase the production efficiency of the graphene-reinforced thermally conductive polymer composite material, the dispersion liquid containing graphite and the exfoliating agent is mill-mixed using a sand mill. At this time, the sand mill can carry out continuous sand milling to the dispersion liquid containing graphite and stripping agent to can improve the production efficiency of graphite dispersion liquid, and then improve the production efficiency of graphite reinforcing heat conduction polymer composite.

Specifically, the sand milling mixing medium of the sand feeding mill is oxidized steel balls or zirconia balls with the diameter of 0.8-2.0 mm, the mixing time of the mill is 0.5-2 h, and the mixing temperature of the mill is 10-80 ℃.

Preferably, in step 1), before the liquid phase exfoliation, graphite is added to a solvent containing a exfoliating agent, and mixed and dispersed to obtain the dispersion liquid containing graphite and exfoliating agent.

As a possible implementation manner, in the step 1), the graphite is expanded graphite. The stripping agent is at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium dodecyl sulfonate, polyoxyethylene octyl phenol ether-10 and octyl phenol polyoxyethylene ether. The solvent is at least one of water and lower alcohol.

Specifically, the fixed carbon content of the expanded graphite is 85% -99%, the expansion ratio of the expanded graphite is 100-500 times, and the size of the expanded graphite is 10-2000 mu m. The lower alcohol is one of ethanol, ethylene glycol and isopropanol.

As a possible implementation, the graphene dispersion is mill mixed with the first modifier using a sand mill in step 2) above.

Illustratively, the media for sand milling and mixing of the sand mill is 0.1mm to 0.4mm, the time for mill mixing is 0.5h to 6h, and the temperature for mill mixing is 10 ℃ to 80 ℃.

Meanwhile, the first modifier in the step 2) is a coupling agent.

Further, the coupling agent is at least one of titanate coupling agent and aluminate coupling agent, and the mass fraction of the coupling agent is 1/100-5/100 of that of graphite.

Example two

The embodiment of the invention provides a graphene reinforced heat-conducting polymer composite material. The graphene reinforced heat-conducting polymer composite material is prepared by the preparation method of the graphene reinforced heat-conducting polymer composite material.

The technical effects of the graphene-reinforced heat-conducting polymer composite material provided by the embodiment of the invention are the same as those of the preparation method of the graphene-reinforced heat-conducting polymer composite material, and are not repeated herein.

Illustratively, the graphene-highly thermally conductive polymer composite described above includes the following components: 30-75 parts by mass of a polymer matrix, 1-40 parts by mass of modified graphene, 1-55 parts by mass of a heat conducting filler, and 10-20 parts by mass of a processing aid.

Specifically, the thermal conductivity coefficient of the graphene reinforced thermal conductive polymer composite material is 2.8W/mK-15.1W/mK.

Example III

The present embodiment provides a thermally conductive product. The heat conduction product comprises the graphene reinforced heat conduction polymer composite material.

Specifically, the heat conduction product can be a heat dissipation base of the LED electronic lamp.

Example IV

The embodiment of the invention provides a preparation method of a graphene reinforced heat-conducting polymer composite material. The preparation method of the graphene reinforced heat-conducting polymer composite material comprises the following steps:

the first step: 100g of expanded graphite (produced in Qingdao Nikkera graphite works, fixed carbon content: 95%, expansion ratio: 250, average size: 1000 μm), 5g of sodium dodecyl sulfate and 5g of polyoxyethylene octyl phenol ether-10 were added to 9890g of water at 20℃and mixed and stirred to obtain a dispersion containing graphite and a stripping agent. The dispersion containing graphite and a stripping agent was transferred to a pin-type sand mill (manufactured by Dongguan diamond mechanical equipment Co., ltd.) in which stainless steel balls were used as a sand medium with a diameter of 0.8mm, and mixed for 2 hours by a first mill to obtain a graphene dispersion.

And a second step of: 1g of titanate coupling agent is added into the graphene dispersion liquid at the temperature of 40 ℃, mixed and dispersed, and then transferred into a rod pin type sand mill with a sand grinding medium of zirconia beads with the diameter of 0.4mm for secondary mill mixing for 0.5h, so as to obtain the modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and sufficiently drying filter residues until the water content is lower than 0.1%, thereby obtaining 100.6g modified graphene.

Fourth step: at a temperature of 60 ℃, the mass ratio is 30:1:40:14:15 polypropylene, modified graphene, magnesium oxide, wollastonite and a processing aid are mixed in a conical mixer for 10min to obtain a uniformly mixed material. Wherein, the processing aid comprises the following components in percentage by mass: 5:2:0.5: MAH-g-EV, white oil, EBS, antioxidant, and silane coupling agent at 0.5.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 200 ℃ and extruding to obtain the master batch. And (3) carrying out second-stage mixing treatment on the masterbatch in a single screw extruder at 220 ℃, cooling the extruded material, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

The extrusion material of the second mixing operation was dried at 100℃for 1 to 2 hours, and then a test sample was molded using an injection molding machine equipped with a standard test bar mold. Wherein the test samples comprise 5 tensile test bars, 5 impact test bars, 3 thermal conductivity test plates and 3 volume resistivity test plates.

Example five

The first step: 1000g of expanded graphite (produced in Qingdao Nikkera graphite works, fixed carbon content 85%, expansion ratio 150, average size 2000 μm), 200g of sodium dodecylbenzenesulfonate and 300g of octylphenol polyoxyethylene ether were added to 8500g of water at 40℃and stirred and mixed to obtain a dispersion containing graphite and a stripping agent. The dispersion containing graphite and a stripping agent was transferred to a pin-type sand mill (available from Dongguan Langmuir mechanical equipment Co., ltd.) in which zirconia beads having a diameter of 2.0mm as a sand medium, and mixed for 0.5 hours by a first mill to obtain a graphene dispersion.

And a second step of: at the temperature of 80 ℃, 10g of aluminate coupling agent is added into the graphene dispersion liquid, mixed and dispersed, then transferred into a rod pin type sand mill with a sand grinding medium of stainless steel balls with the diameter of 0.3mm, and mixed for 6 hours by a second mill, so as to obtain the modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and fully drying filter residues until the water content is lower than 0.1 g to obtain 1002.7g of modified graphene.

Fourth step: at a temperature of 80 ℃, the mass ratio is 44:40:1:15 (produced by zilupetrifaction corporation), modified graphene, alumina (produced by beijing gallery bridge materials technologies limited) and processing aids are mixed in a high speed mixer for 120 minutes, obtaining a uniformly mixed material. Wherein the processing aid is prepared from the following components in percentage by mass: 5:2:2:0.5:0.5.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 190 ℃ to obtain the masterbatch. And then, at the temperature of 180 ℃, carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder, cooling the extruded material, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

The extruded material of the second mixing operation was dried at 100℃for 1 to 2 hours, and then a test sample was molded using an injection molding machine equipped with a standard test bar mold. Wherein the test samples comprise 5 tensile test bars, 5 impact test bars, 3 thermal conductivity test plates and 3 volume resistivity test plates.

Example six

the first step: 200g of expanded graphite (produced in Qingdao Nikkera graphite works, fixed carbon content: 99%, expansion ratio: 250, average size: 1000 μm), 100g of sodium dodecylbenzenesulfonate and 100g of octylphenol polyoxyethylene ether were mixed with 9600g of water at 50℃and dispersed by stirring to obtain a dispersion liquid containing graphite and a stripping agent. The dispersion liquid containing graphite and a stripping agent was transferred to a pin-type sand mill in which zirconia beads were 1.0mm in sand medium, and mixed for 0.5 hours in the first mill to obtain a graphene dispersion liquid.

And a second step of: 2g of silane coupling agent is added into graphene dispersion liquid at the temperature of 90 ℃, mixed and dispersed, and then transferred into a rod pin type sand mill with stainless steel balls with the sand grinding medium of 0.1mm for secondary mill mixing for 3 hours, so as to obtain modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and sufficiently drying filter residues until the water content is less than 0.1%, thereby obtaining 201.4g modified graphene.

Fourth step: at a temperature of 90 ℃, the mass ratio is 45:5:30:20 PS, modified graphene, crystalline flake graphite (mesh number is 200 mesh, fixed carbon content is 95%) and processing aid are mixed in a horizontal double-screw mixer for 65min, and a uniformly mixed material is obtained. Wherein, the processing aid is 10 in mass ratio: 5:2:2:0.5:0.5 MAH-g-SEBS, white oil, PE wax, EBS, antioxidant and aluminate coupling agent.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a pressurized internal mixer at the temperature of 220 ℃ to obtain the master batch. And (3) carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder at the temperature of 210 ℃, cooling the extruded material, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

The extrusion material of the second stage mixing treatment is dried for 1 to 2 hours at the temperature of 100 ℃, and then a test sample is molded by using an injection molding machine provided with a standard test spline mold. Wherein the test samples comprise 5 tensile test bars, 5 impact test bars, 3 thermal conductivity test plates and 3 volume resistivity test plates.

Example seven

the first step: 500g of expanded graphite (fixed carbon content: 95%, expansion ratio: 300 times, average size: 20 μm), ten 50g of sodium dialkylsulfonate and 100g of sodium dodecylsulfate were mixed with 9350g of water at a temperature of 20℃and dispersed with stirring to obtain a dispersion liquid containing graphite and a stripping agent. The dispersion liquid containing graphite and a stripping agent was transferred to a pin-type sand mill with stainless steel balls having a sand grinding medium of 2.0mm, and mixed by a first mill to obtain a graphene dispersion liquid.

And a second step of: and adding 25g of silane coupling agent into the graphene dispersion liquid at the temperature of 50 ℃ for mixing and dispersing, and then transferring the mixture into a rod pin type sand mill with a sand grinding medium of 0.2mm stainless steel balls for secondary mill mixing for 3.5 hours to obtain the modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and fully drying filter residues until the water content is 0.1%, so as to obtain 503.3g of modified graphene.

Fourth step: at a temperature of 90 ℃, the mass ratio is 45:5:30:20, modified graphene, carbon fiber (average diameter of 7 μm) and a processing aid are mixed in a Z-type kneader for 90min to obtain a uniformly mixed material. Wherein, the processing aid comprises the following components in percentage by mass: 3:4:2:0.5:0.5 MAH-g-EPDM, white oil, chlorinated paraffin, EBS, antioxidant and silane coupling agent.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 310 ℃ to obtain the masterbatch. And (3) carrying out second-stage mixing treatment on the masterbatch in a single screw extruder at the temperature of 330 ℃, and cooling and granulating the extruded material to obtain the graphene reinforced heat-conducting polymer composite material.

And drying the extruded material melt material subjected to the second-stage mixing treatment at the temperature of 100 ℃ for 1-2 hours, and then forming a test sample by using an injection molding machine provided with a standard test spline mold. Wherein the test samples comprise 5 tensile test bars, 5 impact test bars, 3 thermal conductivity test plates and 3 volume resistivity test plates.

Example nine

the first step: after 800g of expanded graphite (fixed carbon content: 90%, expansion ratio: 200, average size: 50 μm), 300g of sodium dodecyl sulfate and 200g of polyoxyethylene octyl phenol ether-10 and 8700g of water were mixed at a temperature of 70℃to obtain a dispersion liquid containing graphite and a stripping agent. The dispersion liquid containing graphite and a stripping agent was transferred to a pin type sand mill in which zirconia beads were 0.8mm in sand medium, and mixed for 2 hours by a first mill to obtain a graphene dispersion liquid.

And a second step of: at 60 ℃, 16g of carbonate coupling agent is added into the graphene dispersion liquid for mixed dispersion, and then the mixture is transferred into a pin type sand mill of zirconia beads with a grinding medium of 0.4mm for secondary mill mixing for 1h, so as to obtain the modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and fully drying filter residues until the water content is 0.1%, thereby obtaining 806.1g of modified graphene.

Fourth step: at a temperature of 50 ℃, the mass ratio is 10:30:10:40: and uniformly mixing the PA-6, the PA-66, the modified graphene, the silicon carbide and the processing aid in a horizontal double-screw mixer to obtain a uniformly mixed material. Wherein, the processing aid comprises the following components in percentage by mass: 2:2:0.5:0.5 MAH-g-POE, white oil, zinc stearate, antioxidants and silane coupling agents.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 310 ℃ to obtain the masterbatch. And (3) carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder at the temperature of 320 ℃, cooling the extruded material, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

Example nine

the first step: at a temperature of 50℃300g of expanded graphite (available from Nikkera graphite works in Qingdao, fixed carbon content: 93%, expansion ratio: 280, average size: 300 μm), 100g of sodium dodecyl sulfate and 200g of polyoxyethylene octyl phenol ether-10 were added to 9400g of water, and mixed and dispersed to obtain a dispersion liquid containing expanded graphite and a stripping agent. The dispersion containing the expanded graphite and the release agent was transferred to a pin-type sand mill (available from Dongguan diamond mechanical equipment Co., ltd.) in which zirconia beads were 2.0mm in sand medium, and mixed for 1 hour by a first mill to obtain a graphene dispersion.

And a second step of: at the temperature of 85 ℃, 10g of titanate coupling agent is added into the graphene dispersion liquid, after mixing and dispersing, the graphene dispersion liquid is transferred into a pin type sand mill of zirconia beads with the grinding medium of 0.3mm for secondary mill mixing for 2 hours, and the modified graphene dispersion liquid is obtained.

And a third step of: and filtering the modified graphene dispersion liquid, and sufficiently drying filter residues until the water content is 0.1%, so as to obtain 302.9g of modified graphene.

Fourth step: the mass ratio is 30 at 60 ℃:30:10:20:10, mixing PC, ABS, modified graphene, carbon nano tube and processing aid in a high-speed mixing agent for 45min to obtain a uniformly mixed material. Wherein, the processing aid comprises the following components in percentage by mass: 2:2:0.5: MAH-g-SBS of 0.5, white oil, MBS, antioxidants and silane coupling agents.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a single-screw mixer at the temperature of 280 ℃ to obtain the master batch. And (3) carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder at the temperature of 260 ℃, cooling the extruded material, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

Examples ten

The first step: 600g of expanded graphite (fixed carbon content 98% available from Nikkera graphite works in Qingdao, expansion ratio 350, average size 1500 μm) and 200g of polyoxyethylene octyl phenol ether-10 were added to 9600g of water at a temperature of 30℃and mixed and stirred to obtain a dispersion containing expanded graphite and a stripping agent. The dispersion containing the expanded graphite and the exfoliating agent was transferred to a pin-type sand mill (available from Dongguan diamond mechanical equipment Co., ltd.) in which zirconia beads having a diameter of 2.0mm as a sand medium, and mixed for 1 hour by a first mill to obtain a graphene dispersion.

And a second step of: after 10g of a carbonate coupling agent was added to the graphene dispersion at a temperature of 80 ℃ and mixed, the mixture was transferred to a pin type sand mill for a second time of 2 hours in which zirconia beads with a sand medium of 0.3mm were milled, to obtain a modified graphene dispersion.

And a third step of: and filtering the modified graphene dispersion liquid, and fully drying filter residues until the water content is 0.1%, so as to obtain 302.9g of modified graphene.

Fourth step: at a temperature of 20 ℃, the mass ratio is 40:10:20:30:10, mixing PC, modified graphene, boron nitride, calcium sulfate and a processing aid in a vacuum kneader for 80min to obtain a uniformly mixed material. Wherein the processing aid comprises the following components in percentage by mass: 1:1:0.5:0.5 MAH-g-SBS, white oil, PETS, antioxidants and silane coupling agents.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 270 ℃ to obtain the masterbatch. And (3) carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder at the temperature of 260 ℃, and cooling and granulating after extrusion to obtain the graphene reinforced heat-conducting polymer composite material.

Example eleven

the first step: 600g of flake graphite (available from Nikkera graphite works in Qingdao, fixed carbon content 95%, average size 200 μm) and 200g of polyoxyethylene octyl phenol ether-10 were added to 9600g of ethanol at a temperature of 30℃and mixed and stirred to obtain a dispersion containing flake graphite and a stripping agent. The dispersion containing the flake graphite and the exfoliating agent was transferred to a pin-type sand mill (Dongguan Langmuir equipment Co., ltd.) in which zirconia beads having a diameter of 2.0mm as a sand medium, and mixed for 1 hour by a first mill to obtain a graphene dispersion.

Fourth step: at a temperature of 100 ℃, the mass ratio is 75:10:10:45:10 (linear low density polyethylene, jilin petrochemical), modified graphene, boron nitride, calcium sulfate and a processing aid are mixed in a vacuum kneader for 80 minutes to obtain a uniformly mixed material. Wherein the processing aid comprises the following components in percentage by mass: 1:1:0.3:0.7 MAH-g-SBS, white oil, PETS, antioxidants and silane coupling agents.

Fifth step: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 100 ℃ to obtain the masterbatch. And (3) carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder at the temperature of 400 ℃, and cooling and granulating after extrusion to obtain the graphene reinforced heat-conducting polymer composite material.

Comparative example one

The comparative example provides a preparation method of a graphene reinforced heat-conducting polymer composite material. The preparation method of the graphene reinforced heat-conducting polymer composite material comprises the following steps:

the first step: the mass ratio is 30:40:15:15, magnesium oxide, wollastonite and a processing aid are uniformly mixed in a conical mixer to obtain a uniformly mixed material. Wherein, the processing aid comprises the following components in percentage by mass: 5:2:0.5:0.5 MAH-g-EVA, white oil, EBS, antioxidants and silane coupling agents.

And a second step of: and (3) carrying out first-stage mixing treatment on the uniformly mixed materials in a double-screw extruder at the temperature of 200 ℃ to obtain the masterbatch. And (3) at 220 ℃, carrying out second-stage mixing treatment on the masterbatch in a single-screw extruder, extruding, cooling and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

And drying the extruded material after the second-stage mixing treatment at the temperature of 100 ℃ for 1-2 hours, and then forming a test sample by using an injection molding machine with a standard test spline mold. Wherein the test samples comprise 5 tensile test bars, 5 impact test bars, 3 thermal conductivity test plates and 3 volume resistivity test plates.

Comparative example two

The present comparative example provides a method of preparing a polymer composite. The preparation method of the graphene reinforced heat-conducting polymer composite material comprises the following steps:

the first step: 1000g of expanded graphite (fixed carbon content: 85% in Nikka graphite works purchased from Qingdao, expansion ratio: 150, average size: 2000 μm), 200g of sodium dodecylbenzenesulfonate, 300g of octylphenol polyoxyethylene ether were added to 8500g of water at a temperature of 40℃and mixed uniformly, and then transferred to a rod pin type sand mill (available from Toguan's Langmuir mechanical equipment Co., ltd.) having a diameter of 2.0mm as a sand medium, followed by mixing for 0.5 hours by a first mill to obtain a graphene dispersion.

And a second step of: at 90 ℃, 10g of aluminate coupling agent is added into the graphene dispersion liquid, mixed and dispersed, then transferred into a rod pin type sand mill with a sand grinding medium of 0.3mm stainless steel balls, and mixed for 6 hours by a second mill, so as to obtain the modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and then sufficiently drying filter residues until the water content is less than 0.1 percent to obtain 1002.7g modified graphene.

Fourth step: at a temperature of 80 ℃, the mass ratio is 44:40:1:15, the PE, the modified graphene, the alumina and the processing aid are uniformly mixed in a high-speed mixer to obtain a uniformly mixed material. Wherein, the processing aid comprises the following components in percentage by mass: 5:2:2:0.5: POE 0.5, white oil, PE wax, EBS, antioxidants and aluminate coupling agents.

Fifth step: and (3) mixing the uniformly mixed materials in a double-screw extruder at the temperature of 180 ℃, cooling the extruded materials, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

The above molten mass was dried at 100 ℃ for 1 to 2 hours, and then a test sample was molded using an injection molding machine equipped with a standard test strip mold. Wherein the test samples comprise 5 tensile test bars, 5 impact test bars, 3 thermal conductivity test plates and 3 volume resistivity test plates.

Comparative example three

the first step: 200g of expanded graphite (fixed carbon content: 99% in Nikka graphite works available in Qingdao, expansion ratio: 250, average size: 1000 μm), 100g of sodium dodecylbenzenesulfonate, and 100g of octylphenol polyoxyethylene ether were added to 9600g of water at 20℃and stirred and mixed, and then transferred to a pin type sander (available from Toguan mechanical equipment Co., ltd.) in which zirconia beads having a diameter of 1.0mm were used as a sanding medium, and mixed for 0.5 hours by a first mill to obtain a graphene dispersion.

And a second step of: at 90 ℃, adding 2g of silane coupling agent into the graphene dispersion liquid, mixing and dispersing, transferring into a rod pin type sand mill with a sand grinding medium of stainless steel balls with the diameter of 0.1mm, and carrying out secondary mill mixing to obtain the modified graphene dispersion liquid.

And a third step of: and filtering the modified graphene dispersion liquid, and fully drying filter residues until the water content is lower than 0.1%, thereby obtaining 201.4g modified graphene.

Fourth step: at a temperature of 90 ℃, the mass ratio is 75:5:20:0.05 PS, modified graphene and processing aid are uniformly mixed in a horizontal double-screw mixer to obtain a uniformly mixed material. Wherein the processing aid comprises the following components in percentage by mass: 5:2:2:0.5:0.5 MAH-g-SEBS, white oil, PE wax, EBS, antioxidant and aluminate coupling agent.

Fifth step: and (3) carrying out primary mixing operation on the uniformly mixed materials in a pressurized internal mixer at the temperature of 220 ℃ to obtain the master batch. And (3) carrying out second-stage mixing treatment on the masterbatch in a double-screw extruder at the temperature of 210 ℃, cooling the extruded material, and granulating to obtain the graphene reinforced heat-conducting polymer composite material.

The modified graphene obtained in example four and example five were observed by high power projection electron microscopy (HR-TEM, available in japan), respectively, and a transmission electron microscope picture of the graphene obtained in example four was shown in fig. 2, and a transmission electron microscope picture of the graphene obtained in example five was shown in fig. 3. As can be seen from fig. 2 and 3, the graphene with a lower layer number can be obtained under wider experimental conditions by adopting the two-step shearing and stripping method, so that good heat conduction performance and mechanical property can be given to the graphene reinforced heat conduction polymer composite material.

The impact cross-sectional morphology of the graphene-reinforced thermally conductive polymer composites obtained in examples six and seven was observed by a field emission scanning electron microscope (SEM, available from FEI, finland), the SEM pictures obtained in example six are shown in fig. 4, and the SEM pictures obtained in example seven are shown in fig. 5. As can be seen from fig. 4 and fig. 5, in the graphene reinforced heat-conducting polymer composite material obtained by the preparation method of the graphene reinforced heat-conducting polymer composite material provided by the invention, the two-stage mixing method can promote the graphene to be fully peeled off and uniformly dispersed in the graphene reinforced heat-conducting polymer composite material. The heat conducting filler can promote mutual lap joint between graphenes and the heat conducting filler to construct a heat conducting three-dimensional network which is mutually communicated, and the heat conducting performance and the mechanical performance of the graphene reinforced heat conducting polymer composite material can be improved.

Mass distribution tables of the kinds of the respective components in the graphene-reinforced thermally conductive polymer composite materials of the above-described fourth to eleventh examples and comparative examples one to third examples are shown in table 1. The polymer graphene reinforced heat-conducting polymer composite materials obtained in the fourth to tenth examples and the first to third comparative examples were subjected to electric conductivity test, heat conductivity test and mechanical property test, and the test results are shown in table 2.

The electrical conductivity test of the graphene reinforced heat-conducting polymer composite material can be realized through the volume resistivity test of the graphene reinforced heat-conducting polymer composite material. The volume resistivity test is: the volume resistivity of the graphene reinforced thermally conductive polymer composite was tested using a digital high resistance meter according to the standard of GB/T1410-2006. At least 5 random positions were tested for each group and the results averaged.

The mechanical property test is as follows: the tensile properties of the graphene reinforced thermally conductive polymer composites were tested using a universal stretcher (model 5900) from Instron, usa, ASTM D638-2003, according to the plastic tensile properties test standard in the american society for testing and materials. At least 5 replicates per group were secured for tensile testing and the results averaged. According to the test standard of the cantilever beam impact strength in the national standard GB/T1843-2008, the impact strength of the composite material at 25 ℃ is tested. At least 5 replicates per group were tested by impact and the results averaged.

And (3) heat conduction coefficient test: and according to the thermal conductivity coefficient test standard in GB/T10297-2015, performing performance evaluation on the graphene reinforced thermal conductive polymer composite material by using a heat conductivity coefficient tester of a Hunan pool instrument factory. At least 3 replicates per group were tested and the results averaged.

TABLE 1 Components types and Mass Allocation Table

Table 2 results of performance testing of graphene-reinforced thermally conductive polymer composites

From the fifth example, the second comparative example and Table 1, it can be seen that the fifth example and the second comparative example differ only in that the two-stage kneading method was used to knead the kneaded material in the fifth example, and the one-stage kneading method was used to knead the kneaded material in the second comparative example. As can be seen from table 2, the graphene-reinforced thermally conductive polymer composite material obtained in example five has a thermal conductivity coefficientReaches 15.1W/m.K, and the heat conductivity coefficient of the graphene reinforced heat-conducting polymer composite material obtained in the second comparative example is improved by 110%. In the fifth embodiment, the tensile strength of the graphene reinforced heat-conducting polymer composite material reaches 28.2MPa, and the tensile strength of the graphene reinforced heat-conducting polymer composite material is improved by 16% compared with that of the graphene reinforced heat-conducting polymer composite material obtained in the second comparative embodiment. The impact strength of the graphene reinforced heat-conducting polymer composite material obtained in the fifth embodiment reaches 16.7kJ/m ² Compared with the graphene reinforced heat-conducting polymer composite material obtained in the second comparative example, the impact strength of the graphene reinforced heat-conducting polymer composite material is improved by 101%. Therefore, the two-step mixing method can realize good stripping and uniform dispersion of the modified graphene in the heat-conducting polymer, promote the modified graphene and the heat-conducting filler to form a three-dimensional heat-conducting structure in the heat-conducting polymer, and ensure that the graphene reinforced heat-conducting polymer composite material has good heat-conducting property and mechanical property.

And the synergistic effect of the heat conducting filler and the modified graphene on the spatial scale can construct a stable three-dimensional heat conducting network structure, so that the heat conducting performance of the graphene reinforced heat conducting high-grouping polymer composite material is remarkably improved. For example: the difference between the seventh embodiment and the third embodiment is that the conductive filler in the third embodiment does not include crystalline flake graphite. In the third embodiment, when the crystalline flake graphite as the heat conducting filler is not added, the heat conductivity coefficient of the graphene reinforced heat conducting high-grouping polymer composite material is only 2.2W/m.K, but in the sixth embodiment, after 30 parts of crystalline flake graphite is added, the heat conductivity coefficient of the graphene reinforced heat conducting high-grouping polymer composite material is sharply increased to 8.6W/m.K, and the lifting amplitude is close to 3 times, so that when the types of the heat conducting fillers are different, the heat conductivity of the graphene reinforced heat conducting high-polymer composite material is also different.

Meanwhile, the graphene reinforced heat-conducting polymer composite material can well meet the requirement of regulating and controlling the electric conductivity of the graphene reinforced heat-conducting polymer composite material. For example: as can be seen from table 1, the difference between the sixth embodiment and the seventh embodiment is that the heat conductive filler in the sixth embodiment is crystalline flake graphite, and the graphene-reinforced heat conductive polymer composite material in the seventh embodiment is carbon fiber, but the volume resistivity of the graphene-reinforced heat conductive polymer composite material in the sixth embodiment is 3.5E03, the volume resistivity of the graphene-reinforced heat conductive polymer composite material in the seventh embodiment is 2.6E02, and the volume resistivity of the graphene-reinforced heat conductive polymer composite material in the sixth embodiment is an order of magnitude higher than the volume resistivity of the graphene-reinforced heat conductive polymer composite material in the eighth embodiment. Therefore, the electric conductivity of the graphene reinforced heat-conducting polymer composite material can be controlled by adding different types of heat-conducting fillers.

Meanwhile, in the eighth embodiment, the volume resistivity of the graphene reinforced heat-conducting polymer composite material obtained by using silicon carbide as the heat-conducting filler is 6.8E11. At this time, the graphene reinforced heat-conducting polymer composite material is close to an insulation grade, and the volume resistivity of the graphene reinforced heat-conducting polymer composite material obtained in the sixth embodiment exceeds the measurement range, and the graphene reinforced heat-conducting polymer composite material is completely insulated. From the above, by controlling the types and parts of the graphene reinforced heat-conducting polymer composite material in the graphene reinforced heat-conducting polymer composite material, the electric conductivity of the graphene reinforced heat-conducting polymer composite material can be regulated and controlled, and even the graphene reinforced heat-conducting polymer composite material of a theatre can be obtained. The graphene reinforced heat-conducting polymer composite material with adjustable electric conductivity has good application effects in the scenes of capacitance and inductance, heat dissipation of electronic components, electronic packaging and the like.

In the description of the above embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The preparation method of the graphene reinforced heat-conducting polymer composite material is characterized by comprising the following steps of:

step 1): carrying out liquid phase stripping on graphite to obtain graphene dispersion liquid;

step 2): carrying out mill mixing on a modifier and the graphene dispersion liquid, so that the modifier is attached to the surface of graphene to obtain modified graphene dispersion liquid, wherein the mass ratio of the modifier to the graphene is 1: (1-10);

step 4): melting and blending 1-40 parts by weight of modified graphene, 1-55 parts by weight of heat conducting filler, 30-75 parts by weight of polymer matrix and 10-20 parts by weight of optional processing aid, and then performing optional granulation treatment to obtain a graphene reinforced heat conducting polymer composite material; wherein in step 4), melt blending the modified graphene, the thermally conductive filler, the polymer matrix, and optionally the processing aid comprises:

carrying out the melt blending on the uniformly mixed materials through two-stage mixing treatment;

wherein the melt blending of the blend material by a two-stage compounding process comprises:

carrying out first-stage mixing treatment on the uniformly mixed materials, and then carrying out second-stage mixing treatment;

the modifier is a coupling agent.

2. The method for preparing a graphene-reinforced thermally conductive polymer composite material according to claim 1, wherein the mixing equipment of the first-stage mixing treatment comprises: at least one of a roll-over internal mixer, a continuous internal mixer, a twin-screw extruder, a single-screw extruder, a planetary screw extruder and a reciprocating extruder;

the mixing equipment for the second-stage mixing treatment comprises: at least one of a roll-over internal mixer, a continuous internal mixer, a twin-screw extruder, a single-screw extruder, a planetary screw extruder and a reciprocating extruder;

the temperature of the first-stage mixing treatment and the second-stage mixing treatment is 100-400 ℃.

3. The method of preparing a graphene-reinforced thermally conductive polymer composite material according to claim 1, wherein in the step 1), the liquid-phase exfoliation of the graphite comprises: carrying out mill mixing on the dispersion liquid containing the graphite and the stripping agent to obtain graphene dispersion liquid;

In the step 1), the graphite is added into a solvent containing the stripping agent before liquid phase stripping, and the graphite and the stripping agent are mixed and dispersed to obtain a dispersion liquid containing the graphite and the stripping agent.

4. The method for preparing a graphene-reinforced thermally conductive polymer composite material according to claim 3, wherein a mass ratio of the exfoliating agent to the graphite is 1: (1-10) the mass fraction of graphite in the dispersion liquid containing the graphite and the stripping agent is 1-10%;

mill mixing the dispersion containing the graphite and a stripping agent using a sand mill; the sand grinding mixing medium of the sand grinding machine is oxidized steel balls or zirconia balls with the diameter of 0.8-2.0 mm, the mixing time of the sand grinding machine is 0.5-2 h, and the mixing temperature of the sand grinding machine is 10-80 ℃.

5. The method of preparing a graphene-reinforced thermally conductive polymer composite material according to claim 3, wherein in the step 1), the graphite is expanded graphite; and/or the stripping agent is at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium dodecyl sulfonate, polyoxyethylene octyl phenol ether-10 and octyl phenol polyoxyethylene ether; and/or the solvent is at least one of water and lower alcohol;

The lower alcohol is one of ethanol, glycol and isopropanol.

6. The method for preparing a graphene reinforced heat-conducting polymer composite material according to claim 5, wherein the fixed carbon content of the expanded graphite is 85% -99%, the expansion ratio of the expanded graphite is 100-500 times, and the size of the expanded graphite is 10-2000 μm.

7. The method of preparing a graphene-reinforced thermally conductive polymer composite material according to claim 1, wherein in the step 4), the thermally conductive filler is at least one of an insulating thermally conductive filler and an electrically conductive thermally conductive filler; and/or the processing aid is at least one of a toughening agent, a flow modifier, a coupling agent, an antioxidant and a stabilizer; and/or the polymer matrix is at least one of polyethylene, polypropylene, polybutene, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyamide, polyphenylene sulfide, polycarbonate, polybutylene terephthalate and polyethylene terephthalate; and/or

In the step 4), the mixing equipment used when the modified graphene, the heat-conducting filler, the polymer matrix and the optional processing aid are uniformly mixed is at least one of a conical mixer, a high-speed mixer, an open mill, a roll-over internal mixer, a continuous internal mixer, a Z-type kneader, a screw kneader, a vacuum kneader and a horizontal double-screw mixer.

8. The preparation method of the graphene reinforced heat-conducting polymer composite material according to claim 7, wherein the mixing temperature is 20-90 ℃ and the mixing time is 10-120 min;

the insulating heat-conducting filler comprises at least one of silicon carbide, magnesium borate, aluminum borate, magnesium carbonate, magnesium oxide, magnesium hydroxide, calcium carbonate, calcium sulfate, wollastonite, boron nitride, zinc oxide and aluminum oxide; and/or the conductive heat-conducting filler comprises at least one of carbon fiber, carbon nano tube, crystalline flake graphite, ultrafine graphite, expanded graphite and graphite oxide.

9. The method for preparing a graphene-reinforced thermally conductive polymer composite material according to claim 1, wherein in the step 2), the mass fraction of the modifier is 1/100 to 5/100 of that of graphite; and/or

The graphene dispersion is mill mixed with a modifier by using a sand mill.

10. The method for preparing the graphene reinforced heat-conducting polymer composite material according to claim 9, wherein the coupling agent is at least one of a titanate coupling agent and an aluminate coupling agent, the medium for sand milling and mixing of the sand mill is 0.1-0.4 mm, the time for mixing of the sand mill is 0.5-6 h, and the temperature for mixing of the sand mill is 10-80 ℃.

11. The method of preparing a graphene-reinforced thermally conductive polymer composite material according to claim 1, wherein the modified graphene obtained in the step 3) has a thickness of 1.5nm to 15nm and/or the modified graphene has a maximum radial dimension of 2 μm to 40 μm and a moisture content of less than 0.1%.

12. A graphene-reinforced thermally conductive polymer composite material, characterized in that it is prepared by the preparation method of a graphene-reinforced thermally conductive polymer composite material according to any one of claims 1 to 11.

13. The graphene-reinforced thermally conductive polymer composite material according to claim 12, comprising the following components: 30-75 parts by mass of the polymer matrix, 1-40 parts by mass of the modified graphene, 1-55 parts by mass of the heat conductive filler, and 10-20 parts by mass of the processing aid.

14. The graphene-reinforced thermally conductive polymer composite material according to claim 13, wherein the graphene-reinforced thermally conductive polymer composite material has a thermal conductivity of 2.8W/m-K to 15.1W/m-K.

15. A thermally conductive product, characterized in that it comprises a graphene-reinforced thermally conductive polymer composite according to any one of claims 12-14.