阅读说明：本技术 一种导热聚合物材料用高导热填料的制备方法 (Preparation method of high-thermal-conductivity filler for thermal-conductivity polymer material ) 是由 赵方伟 王纲 马洁 任仰省 李响 冯继凡 程路路 于 2019-10-10 设计创作，主要内容包括：一种导热聚合物材料用高导热填料的制备方法,包括步骤：将球形氮化硼分散到极性溶剂中,加入偶联剂进行改性,得到改性球形氮化硼；将纳米碳材料与极性溶剂分散混合,得到分散液；将改性氮化硼超声分散到分散液中,超声处理；将制得的物料经水热还原,然后冷冻干燥,得到碳纳米材料-改性球形氮化硼核壳结构的填充颗粒；将制得的填充颗粒与导热填料填充到聚合物中。本发明公开的高导热填料的制备方法解决了石墨烯添加量高会在制备复合材料时团聚的问题,提高了导热性。解决了石墨烯添加量高会使材料在使用时流动性差,因团聚加工困难的问题。制备方法简单；所采用的溶剂种类及用量少,对基体的污染小；制备出的高导热填料应用范围广泛,效果好。(A preparation method of a high thermal conductive filler for a thermal conductive polymer material comprises the following steps: dispersing spherical boron nitride into a polar solvent, and adding a coupling agent for modification to obtain modified spherical boron nitride; dispersing and mixing the nano carbon material and a polar solvent to obtain a dispersion liquid; ultrasonically dispersing the modified boron nitride into the dispersion liquid, and ultrasonically treating; carrying out hydrothermal reduction on the prepared material, and then freeze-drying to obtain filling particles of a carbon nano material-modified spherical boron nitride core-shell structure; the prepared filled particles and the heat-conducting filler are filled into a polymer. The preparation method of the high-thermal-conductivity filler disclosed by the invention solves the problem that the graphene is agglomerated when the composite material is prepared due to high addition amount of the graphene, and improves the thermal conductivity. The method solves the problems that due to the high addition amount of graphene, the material has poor fluidity when in use and is difficult to process due to agglomeration. The preparation method is simple; the types and the dosage of the adopted solvents are less, and the pollution to the matrix is less; the prepared high-heat-conductivity filler has wide application range and good effect.)

1. The preparation method of the high-thermal-conductivity filler for the thermal-conductive polymer material is characterized by comprising the following components in parts by mass:

nano-carbon material: 2.5 to 20;

spherical boron nitride: 9 to 45;

polar solvent (amount of spherical boron nitride used is 1): 10-50;

coupling agent (based on the amount of spherical boron nitride used as 1): 0.05 to 0.5;

heat-conducting filler: 1 to 5;

base material: 100.

2. a preparation method of a high-thermal-conductivity filler for a thermal-conductive polymer material is characterized by comprising the following preparation steps:

s1, modification of spherical boron nitride: dispersing spherical boron nitride into a polar solvent, and adding a coupling agent for modification to obtain modified spherical boron nitride;

s2, dispersing and mixing the nano carbon material and a polar solvent to obtain a dispersion liquid;

s3, ultrasonically dispersing the modified boron nitride obtained after the modification of the S1 into the dispersion liquid prepared by the S2, and ultrasonically treating for 5-30 minutes;

s4, carrying out hydrothermal reduction on the material prepared in the step S3, and then carrying out freeze drying for 24-48 hours to obtain filling particles of the carbon nano material-modified spherical boron nitride core-shell structure;

s5, filling the filling particles prepared in the S4 and the heat-conducting filler into a corresponding polymer matrix according to a certain proportion.

3. The method for preparing a high thermal conductive filler for a thermal conductive polymer material according to claim 1, wherein the carbon nanomaterial is at least one selected from graphene, graphene oxide and graphene derivatives, and is preferably graphene.

4. The method of claim 1, wherein the spherical boron nitride particles have a size of 1 μm to 20 μm.

5. The method for preparing a high thermal conductive filler for thermal conductive polymer material according to claim 1, wherein the polar solvent is at least one selected from ethanol, toluene, acetone, and isopropanol, preferably ethanol.

6. The method of claim 5, wherein the concentration of ethanol is 0.5-5 mol/L.

7. The method of claim 1, wherein the coupling agent is at least one selected from a group consisting of a titanic acid coupling agent and a silane coupling agent.

8. The method of claim 1, wherein the thermally conductive filler is at least one selected from the group consisting of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, and silicon carbide.

9. The method of claim 1, wherein the matrix material is at least one selected from the group consisting of Polystyrene (PS) and polypropylene (PP).

Technical Field

The invention relates to the field of composite polymer heat conduction materials, in particular to a high heat conduction filler containing high-addition-amount graphene, which is used for a heat conduction polymer material.

Background

The thermal conductivity of the polymer matrix itself is currently generally very low (about 0.2 W.m.)^-1·K^-1) If a high thermal conductivity (1-5 W.m) is to be achieved^-1·K^-1) It is usually necessary to fill 50-80 vol% of conventional thermally conductive filler. The high filler addition amount can lead to the fact that the modified composite high polymer material is heavy in weight, the excellent mechanical property of the polymer is reduced, and meanwhile, the processing difficulty is increased, so that the practical application of the current heat-conducting polymer material is limited.

For the heat-conducting composite high polymer material, the formation of the heat-conducting network can greatly reduce the interface thermal resistance and improve the heat conductivity of the composite material. Graphene not only has extremely highThermal conductivity (up to 5300 W.m)^-1·K^-1) In addition, other properties of graphene, such as mechanical properties, are also very excellent compared to conventional thermally conductive fillers, such as metal fillers, inorganic fillers, carbon materials. It is therefore a promising thermally conductive filler. However, the effect of forming the thermally conductive network merely by increasing the content of the thermally conductive filler is not obvious. Although the graphene has high thermal conductivity, the graphene serving as a nano material is easy to agglomerate under the condition of high content, so that the thermal conductivity of the graphene is influenced; on the other hand, the total addition amount is small (the addition amount is generally about 1-3 vol%), an effective heat conducting network structure cannot be constructed, and the addition amount of the graphene exceeding 1vol% can cause agglomeration phenomenon, and the graphene exceeding 3vol% can cause serious agglomeration. And too much graphene can quickly increase the viscosity of the system, increase the preparation difficulty and easily generate bubbles. Therefore, how to prepare the graphene composite heat conduction material with high content, difficult agglomeration and good dispersion effect is a difficult point of current research.

Disclosure of Invention

The invention aims to solve the problems and provides a preparation method of a high-thermal-conductivity filler for a thermal-conductivity polymer material. The high-thermal-conductivity filler solves the problems of overhigh filler addition amount, poor overall fluidity and difficult later-stage processing in the traditional preparation method of the thermal conductive material, and also solves the problems that the graphene addition amount of the graphene thermal conductive material in the preparation process cannot be too high, and the graphene thermal conductive material can not be agglomerated and cannot give full play to the advantages of the graphene. The filler can contain high-content graphene (the maximum addition amount can reach 40 wt%), and the heat-conducting property of the matrix material can be greatly improved. Moreover, micron-sized spherical boron nitride is innovatively used in the invention and is combined with graphene under pi-pi acting force, so that the prepared filler has larger specific surface area than a sheet material. The utilization rate is improved, the theory of the heat conducting network is better met, and the heat conducting performance is further broken through.

The preparation method of the high-thermal-conductivity filler for the thermal-conductive polymer material comprises the following components in parts by mass:

nano-carbon material: 2.5 to 20;

spherical boron nitride: 9- -45

Polar solvent (amount of spherical boron nitride used is 1): 10-50;

coupling agent (based on the amount of spherical boron nitride used as 1): 0.05 to 0.5;

heat-conducting filler: 1 to 5;

base material: 100.

the invention relates to a preparation method of a high-thermal-conductivity filler for a thermal-conductivity polymer material, which comprises the following preparation steps:

s1, modification of spherical boron nitride: dispersing spherical boron nitride into a polar solvent, and adding a coupling agent for modification to obtain modified spherical boron nitride;

s2, dispersing and mixing the nano carbon material and a polar solvent to obtain a dispersion liquid;

s3, ultrasonically dispersing the modified boron nitride obtained after the modification of the S1 into the dispersion liquid prepared by the S2, and ultrasonically treating for 5-30 minutes;

s4, carrying out hydrothermal reduction on the material prepared in the step S3, and then carrying out freeze drying for 24-48 hours to obtain filling particles of the carbon nano material-modified spherical boron nitride core-shell structure;

s5, filling the filling particles prepared in the S4 and the heat-conducting filler into a corresponding polymer matrix according to a certain proportion.

Further, the carbon nanomaterial is at least one selected from graphene, graphene oxide, and a graphene derivative, and is preferably graphene.

Furthermore, the particle size of the spherical boron nitride is between 1 and 20 mu m.

Further, the polar solvent is selected from at least one of ethanol, toluene, acetone and isopropanol, and preferably ethanol.

Further, the ethanol concentration is between 0.5 and 5 mol/L.

Further, the coupling agent is at least one selected from a titanic acid coupling agent and a silane coupling agent.

Further, the heat conducting filler is selected from at least one of alumina, magnesia, zinc oxide, aluminum nitride and silicon carbide.

Further, the matrix material is selected from at least one of Polystyrene (PS) and polypropylene (PP).

In order to better illustrate the technical problems to be solved and the technical means adopted by the invention, the prior technical scheme and the defects thereof are provided as follows:

1. an intercalation assembly boron nitride-graphene composite material, application and a preparation method thereof are disclosed in Chinese patent (CN 201610310346.0). In the disclosure, graphene sheets and a hexagonal boron nitride film layer intercalated between the graphene layers, the hexagonal boron nitride film layer connects the graphene sheets between graphene interatomic layers to form an intercalation structure of graphene/boron nitride in a sandwich form.

However, the boron nitride used in the method is a sheet layer, namely, a 2D structure, and it is known that when graphene exists in a sheet layer structure, stacking and agglomeration are very easy to occur. Further, it is clearly proposed in a document (anfei. construction of three-dimensional graphene thermal conductive network and study of its thermal conductive composite [ D ]. 2018) published thereafter: the graphene with lower content can not be in complete contact, and the sheets can be separated by the low-heat-conduction matrix and are diffused, so that phonon scattering and interface thermal resistance are increased. When the content is higher, the contact between the graphene sheet layers is increased to form a heat conducting network, so that heat conduction is facilitated.

In addition, the invention adopts a liquid phase stripping technology for preparing the lamellar boron nitride, uses a large amount of solvent, has complex process and has no specific parameter description on the heat-conducting property.

2. Chinese patent (CN 201410220107.7) discloses a water-based heat-dissipating coating and a preparation method thereof. According to the invention, nano carbon material coated boron nitride composite powder is added into aqueous dispersion of matrix resin as a coating filler. But the boron nitride and the nano-carbon material coated on the outer layer are dispersed in aqueous dispersion, the application field of the dispersion medium is determined, so the boron nitride and the nano-carbon material can only be used as paint, and the carbon nano-material is at most 10wt%, and the thermal conductivity is 1.54 W.m^-1·K^-1The heat conduction effect is not obvious。

The high-thermal-conductivity filler prepared by the preparation method disclosed by the invention has the following characteristics:

1. solves the problem that the graphene with high addition amount can be agglomerated during the preparation of the composite material, and further improves the thermal conductivity (5 W.m)^-1·K^-1). On one hand, graphene and spherical boron nitride are combined in the form of hydrogen bonds and/or pi-pi bonds, and the thin graphene is adsorbed on the outer surface of the boron nitride, so that the dispersed graphene materials are separated in the form of the spherical boron nitride, and the phenomenon of graphene agglomeration is reduced. On the other hand, the synergistic effect between the monolithic layer graphene and the boron nitride can promote the formation of a more effective interconnection structure and a heat conduction network, and the heat conduction effect is better achieved. And through the secondary matching with the heat-conducting filler, the coating can be formed on the outer side of the graphene again in a hydrogen bond mode, and a three-layer coating structure of the heat-conducting filler, graphene and modified spherical boron nitride from outside to inside is formed, so that the dispersion of the graphene is more uniform, and meanwhile, the heat-conducting efficiency of the graphene is correspondingly improved under the action of the outer-layer heat-conducting filler.

2. The method solves the problems that due to the high addition amount of graphene, the material has poor fluidity when in use and is difficult to process due to agglomeration. The prepared graphene/boron nitride filler is spherical, and the particle fluidity is good in the plasticizing stage in the matrix. The high filling and high utilization of graphene can be realized, and the problem that the graphene is agglomerated when the addition amount of the graphene is 2wt% in general research is solved.

3. The high-thermal-conductivity filler has wide application range, and can be randomly blended with high-molecular substrates such as plastics, rubber and the like on one hand because of being in solid particles; on the other hand, the modified. The polymer heat conduction material provided by the invention can be applied to the fields of electric heating devices, aerospace, communication electronics and the like.

Detailed Description

The present invention will be further described with reference to specific embodiments. Meanwhile, it is to be understood that, in order to ensure the comparability of the embodiments and the influence of the variable factors reduced as much as possible on the experimental results in the experimental process, especially, the influence of different thermally conductive fillers and polymer matrix materials on the experimental results in the present invention is relatively large, so some limitations need to be made (it is clear that the limitations made in the following embodiments do not affect the technical content disclosed in the present invention, do not limit the technical scope of the present invention, and the highly thermally conductive fillers disclosed in the present invention also have universality in other polymer matrices based on the universality of the polymer materials). In the following examples and comparative examples, ethanol was used as the polar solvent, aluminum nitride was used as the thermally conductive filler, and polystyrene was used as the matrix material.