CN114988375B - Heat-conducting microsphere, preparation method thereof and polymer composite material - Google Patents
Heat-conducting microsphere, preparation method thereof and polymer composite material Download PDFInfo
- Publication number
- CN114988375B CN114988375B CN202210631136.7A CN202210631136A CN114988375B CN 114988375 B CN114988375 B CN 114988375B CN 202210631136 A CN202210631136 A CN 202210631136A CN 114988375 B CN114988375 B CN 114988375B
- Authority
- CN
- China
- Prior art keywords
- heat
- microsphere
- conducting
- sol
- thermally conductive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
- C01B21/0726—Preparation by carboreductive nitridation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
- C01B21/0648—After-treatment, e.g. grinding, purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
- C01B21/0728—After-treatment, e.g. grinding, purification
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/28—Nitrogen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/38—Boron-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
- C01P2004/32—Spheres
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
- C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/28—Nitrogen-containing compounds
- C08K2003/282—Binary compounds of nitrogen with aluminium
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/38—Boron-containing compounds
- C08K2003/382—Boron-containing compounds and nitrogen
- C08K2003/385—Binary compounds of nitrogen with boron
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention discloses a heat-conducting microsphere, a preparation method thereof and a polymer composite material, and relates to the technical field of heat-conducting materials, wherein the heat-conducting microsphere comprises a first heat-conducting phase and a second heat-conducting phase; wherein the first heat conducting phase is boron nitride; the second heat conducting phase is selected from aluminum nitride and/or silicon nitride; the filling amount of the heat-conducting microspheres in the polymer matrix can reach 70%, and a high-efficiency heat-conducting network can be constructed in the polymer matrix, so that the heat-conducting performance of the polymer is effectively improved.
Description
Technical field:
the invention relates to the technical field of heat conducting materials, in particular to a heat conducting microsphere, a preparation method thereof and a polymer composite material.
The background technology is as follows:
with the development of microelectronic integration technology, microelectronic devices are increasingly highly integrated and often used under conditions of high power and high frequency, so that a large amount of heat is generated when the microelectronic devices are in operation, and if the heat is not timely dissipated, the microelectronic devices are damaged, and the service lives of the microelectronic devices are seriously affected.
The electronic packaging material is used for sealing protection, heat dissipation, shielding and the like of electronic components, and is a sealing body of an integrated circuit. Polymers are widely used in electronic packaging materials due to their light weight, ease of processing, low cost, and electrical insulation, but pure polymers have a thermal conductivity of about 0.1-0.3W/(m·k), which greatly limits their use in electronic packaging materials that require heat dissipation. At present, the heat conductivity of the polymer is generally improved by filling a large amount of filler with high heat conductivity and good insulation property in the polymer.
The morphology of the filler plays a critical role in the viscosity and flowability of the thermally conductive composite material when other influencing factors are the same. In the same manner, the spherical filler fills the composite with the lowest viscosity and the best flowability compared with other fillers with other shapes. At the same particle size, the spherical filler has a higher filling amount in the polymer because the specific surface area is smaller than that of the non-spherical filler, so the spherical heat-conducting filler is preferable in application.
Aluminum nitride and hexagonal boron nitride are widely used as filler materials for polymer encapsulation materials due to their high thermal conductivity and insulation. However, both aluminum nitride and platelet-shaped hexagonal boron nitride cause a significant increase in the viscosity of the polymer material at very small loadings, with a maximum loading in the polymer of about 50-60%, resulting in limited thermal conductivity enhancement of the polymer.
Patent CN114044681a discloses a boron nitride composite microsphere and a preparation method thereof, the coefficient of thermal conductivity of the boron nitride/alumina microsphere prepared by the method is 1.9-4.5W/(m·k), and the improvement of thermal conductivity of the polymer is limited, but the surface density of the boron nitride/alumina microsphere prepared by the method is high, so that in carbothermic reduction reaction, aluminum oxide in the microsphere is difficult to completely nitride, and the improvement of thermal conductivity of the polymer is limited.
The national institute of Miss and university's paper for preparation of epoxy resin based composite materials and study of heat conducting property discloses that spherical aluminum nitride with particle size of 100nm and hexagonal boron nitride with particle size of 1-3 μm are compounded and filled in epoxy resin, and although the compounded filler shows better heat conducting property than single filler in the composite material, the maximum filling amount of the compounded filler in the epoxy resin can only reach 40%, and the heat conductivity of the filled epoxy resin composite material is 1.1W/(m.K) at most, so that further improvement of the heat conductivity of the polymer material is necessary.
The invention comprises the following steps:
the invention aims to solve the technical problem that the existing heat conducting filler has limited improvement on the heat conducting performance of a polymer, and provides a heat conducting microsphere, a preparation method thereof and a polymer composite material.
In order to achieve the above object, one of the objects of the present invention is to provide a thermally conductive microsphere comprising a first thermally conductive phase and a second thermally conductive phase; wherein the first heat conducting phase is boron nitride; the second thermally conductive phase is selected from aluminum nitride and/or silicon nitride.
Another object of the present invention is to provide a method for preparing the heat conductive microsphere, comprising the steps of:
(1) Uniformly mixing a surfactant, boron nitride and sol in water to obtain sol A; wherein the sol is selected from aluminum sol and/or silica sol;
(2) Mixing a dispersing agent with the sol A to obtain a suspension B;
(3) Dropwise adding the suspension B into an oily solvent to obtain a mixed system; then, the mixed system is dehydrated to obtain a precipitate C;
(4) The sediment C is sintered at low temperature in an oxygen-containing atmosphere, and then sintered at high temperature in a protective gas to obtain a precursor;
(5) And in a nitrogen atmosphere, mixing the precursor with graphite powder, and performing carbothermic reduction reaction to obtain the heat-conducting microsphere.
The third object of the present invention is to provide a polymer composite material, comprising a polymer matrix and a heat conductive filler, wherein the heat conductive filler comprises the heat conductive microsphere or the heat conductive microsphere prepared by the method.
The beneficial effects of the invention are as follows: the filling amount of the heat-conducting microspheres in the polymer matrix can reach 70%, and a high-efficiency heat-conducting network can be constructed in the polymer matrix, so that the heat-conducting performance of the polymer is effectively improved.
Description of the drawings:
FIG. 1 is an SEM image of thermally conductive microspheres prepared according to example 1 of the invention;
FIG. 2 is an enlarged view of a portion of the portion A1 of FIG. 1 in accordance with the present invention;
FIG. 3 is an SEM image of thermally conductive microspheres prepared according to example 2 of the invention;
FIG. 4 is an SEM image of thermally conductive microspheres prepared according to example 3 of the invention;
FIG. 5 is an SEM image of the thermally conductive powder obtained in comparative example 3 of the present invention;
fig. 6 is an XRD pattern of the thermally conductive microspheres prepared in example 1, example 9, example 10 and comparative example 4 according to the present invention.
The specific embodiment is as follows:
the invention is further described below with reference to specific embodiments and illustrations in order to make the technical means, the creation features, the achievement of the purpose and the effect of the implementation of the invention easy to understand.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
Microspheres in the present invention refer to particles that are nearly or nearly spherical, but may also be spheroid, and should not be construed as geometrically spherical.
As described above, the present invention provides a thermally conductive microsphere comprising a first thermally conductive phase and a second thermally conductive phase; wherein the first heat conducting phase is boron nitride; the second thermally conductive phase is selected from aluminum nitride and/or silicon nitride. Specifically, the heat-conducting microsphere can be BN/AlN composite microsphere, BN/Si 3 N 4 Composite microsphere or BN/AlN/Si 3 N 4 Composite microspheres.
Preferably, the weight ratio of the second heat conduction phase to the first heat conduction phase is 1 (0.25-5); for example, it may be 1:0.25, 1:0.5, 1:0.75, 1:1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or any value in the range of any two ratios described above; preferably 1 (0.5-3); more preferably 1 (0.8-1.5).
Under the preferred conditions of the invention, the particle size of the heat-conducting microsphere is 30-100 mu m.
The invention also provides a method for preparing the heat-conducting microsphere, which comprises the following steps:
(1) Uniformly mixing a surfactant, boron nitride and sol in water to obtain sol A; wherein the sol is selected from aluminum sol and/or silica sol;
(2) Mixing a dispersing agent with the sol A to obtain a suspension B;
(3) Dropwise adding the suspension B into an oily solvent to obtain a mixed system; then, the mixed system is dehydrated to obtain a precipitate C;
(4) The sediment C is sintered at low temperature in an oxygen-containing atmosphere firstly, and then sintered at high temperature in a protective gas to obtain a precursor;
(5) And in a nitrogen atmosphere, mixing the precursor with graphite powder, and performing carbothermic reduction reaction to obtain the heat-conducting microsphere.
In the invention, sol is adopted as an adhesive to bond and agglomerate flaky boron nitride, then a spherical precipitate C (the main component is boron nitride/oxide, the oxide is alumina and/or silicon dioxide) is formed by adopting a ball drop method, the oxide in the precipitate C can form nitride through roasting and carbothermic reduction reaction, thus forming the heat-conducting microsphere (BN/AlN composite microsphere or BN/Si) 3 N 4 Composite microsphere or BN/AlN/Si 3 N 4 Composite microsphere), the heat conduction microsphere has high heat conduction coefficient, stable structure under the action of external force, difficult disassembly, and the filling amount in the polymer can reach 70 percent, thereby effectively improving the heat conduction performance of the polymer.
In the step (1) of the invention, the proportion of the oxide and the boron nitride in the sol is controlled within a reasonable range, and the excessive use amount of the boron nitride can lead to the poor sphericity of the product heat-conducting microspheres and easy disintegration, so that the maximum filling amount of the product in a polymer matrix is reduced; preferably, the sol is calculated as oxide, and the weight ratio of the sol to the boron nitride is 1 (0.25-5); for example, it may be 1:0.25, 1:0.5, 1:0.75, 1:1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or any value in the range of any two ratios described above; preferably 1 (0.5-3).
In the present invention, when the sol is an alumina sol, the oxide therein refers to alumina; when the sol is a silica sol, the oxide therein is referred to as silica.
The particle size of the alumina in the alumina sol is 10-300nm, for example, the particle size can be any value in the range of 10nm, 20nm, 50nm, 100nm, 150nm, 200nm, 250nm and 300nm or any two ratio of the above values; the solid content of the aluminum sol in the invention is 10-30wt%.
The particle size of the silicon dioxide in the silica sol is 10-300nm, for example, the particle size can be any value in the range of 10nm, 20nm, 50nm, 100nm, 150nm, 200nm, 250nm and 300nm or any two ratio of the above values; the solid content of the silica sol in the invention is 10-30wt%.
In one embodiment of the present invention, the aluminum sol and the silica sol may be used simultaneously, that is, the aluminum sol and the silica sol may be mixed in any ratio in the step (1), and the product obtained by the above method is BN/AlN/Si 3 N 4 Composite microspheres.
Preferably, the boron nitride is flaky hexagonal boron nitride with the particle size of 1-10 mu m; for example, it may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value in the range of any two values mentioned above; preferably 1-5 μm.
Preferably, the surfactant of the present invention is at least one selected from cationic surfactants, anionic surfactants and nonionic surfactants, preferably anionic surfactants; the anionic surfactant includes, but is not limited to, at least one of carboxylate, sulfonate, sulfate, and phosphate.
In the invention, the dispersing agent can uniformly disperse the boron nitride, thereby improving the stability of the suspension B and reducing or avoiding the generation of precipitation; preferably, the dispersing agent in the step (2) is at least one selected from polyethylene glycol, polyvinyl alcohol and polyvinylpyrrolidone.
In the invention, in order to make the boron nitride and sol mixed more uniformly; preferably, the method further comprises: ball milling the suspension B, wherein the ball milling conditions comprise: the speed is 200-400r/min, and the time is 3-30min.
In some preferred embodiments of the present invention, in step (3), the oily solvent is a water-insoluble solvent, and the kind of oily solvent may be known to those skilled in the art, including but not limited to at least one of silicone oil, fatty acid, and hydrocarbon solvent; for example, it may be at least one of paraffin oil, oleic acid and simethicone.
In the step (3), the water removal is carried out by reacting the mixed system for 2-5h at 100-200 ℃; under the conditions, the water in the mixed system can be volatilized; further, the temperature of the water removal should be not lower than the boiling point of water (100 ℃) and not higher than the boiling point of the oily solvent; therefore, the temperature of the water removal can be adjusted according to the type of the oily solvent; the time for water removal can be adjusted according to the amount of water used.
Impurities in the precipitate can be removed by sintering in the step (4) to obtain a component of BN/Al 2 O 3 Or BN/SiO 2 Or BN/Al 2 O 3 /SiO 2 Is a precursor of (a); in the invention, the roasting process is very critical, and impurities possibly remain in the obtained precursor when the sintering temperature is too low or the sintering time is too short; the sintering temperature is too high or the sintering time is too long, and precursor dispersion can be caused, so that a spherical product can not be obtained; therefore, the invention adopts the process of low-temperature sintering and then high-temperature sintering so as to obtain the precursor with high sphericity and low impurity content.
Preferably, the low temperature sintering conditions in step (4) include: the temperature is 400-750 ℃ and the time is 1-12h; the low temperature sintering temperature can be 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃ or any value in the range of any two values, preferably 600-700 ℃; the low-temperature sintering time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or any value in the range of any two values, and is preferably 3-5h.
Preferably, the high temperature sintering conditions in step (4) include: the temperature is 900-1600 ℃ and the time is 1-12h; the high temperature sintering temperature can be 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃, 1450 ℃, 1500 ℃, 1550 ℃, 1600 ℃ or any value in the range of any two values, preferably 1000-1500 ℃; the high-temperature sintering time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or any value in the range of any two values, and is preferably 6-10h.
The shielding gas in step (4) of the present invention may be known to those skilled in the art, including but not limited to nitrogen and/or inert gases; preferably nitrogen.
In the step (5), the oxide in the precursor can be reduced by carbothermal reduction reaction to obtain the heat-conducting microsphere (BN/AlN composite microsphere or BN/Si) 3 N 4 Composite microsphere or BN/AlN/Si 3 N 4 Composite microspheres); the carbothermic reaction conditions can be known to those skilled in the art, and exemplary carbothermic reaction conditions include: the temperature is 900-1600 ℃ and the time is 1-12h.
Preferably, the weight ratio of the precursor to the graphite powder is (0.5-4) 1; preferably (0.8-3): 1; more preferably (1-1.5): 1. The inventors found that too low a proportion of graphite powder during carbothermic reaction does not allow complete nitridation of the oxides (alumina and/or silica) in the precursor, resulting in poor thermal conductivity of the thermally conductive microspheres; the excessive proportion of graphite powder can cause a large amount of graphite powder to remain in the heat-conducting microspheres, so that the insulation property of the heat-conducting microspheres is poor.
The invention also provides a polymer composite material, which comprises a polymer matrix and a heat-conducting filler, wherein the heat-conducting filler is the heat-conducting microsphere or the heat-conducting microsphere prepared by the method.
Preferably, the polymer composite comprises 1 to 75wt% of the thermally conductive filler and 25 to 99wt% of the polymer matrix, based on the total weight of the polymer composite. The thermally conductive filler may be present in an amount of 1wt%, 2wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, based on the total weight of the polymer composite, and the polymer matrix may be present in an amount of 99wt%, 98wt%, 95wt%, 90wt%, 85wt%, 80wt%, 75wt%, 70wt%, 65wt%, 60wt%, 55wt%, 50wt%, 45wt%, 40wt%, 35wt%, 30wt%, 25wt%, respectively.
In some preferred embodiments of the present invention, the polymer matrix is selected from at least one of polypropylene resin, polyethylene vinyl acetate, polyvinyl chloride resin, polystyrene resin, polyphenylene ether resin, polyamide resin, polycarbonate, epoxy resin, polyurethane, acrylic resin, polyacrylonitrile resin, polyvinyl alcohol resin, bismaleimide resin, polyimide resin, cyanate ester resin, natural rubber, polyisoprene rubber, ethylene propylene rubber, styrene butadiene rubber, fluoro rubber, neoprene rubber, nitrile rubber, silicone rubber, and fluorosilicone rubber; preferably, the polymer matrix is selected from at least one of epoxy, polyurethane and silicone rubber.
The present invention will be described in detail by examples.
Aluminum sol: the solid content is 20%, and the grain diameter of alumina in the alumina sol is 100nm;
the particle size of the flaky hexagonal boron nitride (h-BN) powder is 2 μm; aluminum nitride (AlN) powder having a particle size of 100nm; graphite powder: particle size 2 μm;
liquid paraffin oil: the density is 0.84-0.86g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the Polyethylene glycol: average molecular weight (Mn) =6000;
epoxy resin: the epoxy equivalent is 210-230g/mol and the softening point is 14-23 ℃.
The testing method comprises the following steps:
content ratio of compounds in the product: the peak intensity of each phase in the XRD pattern is calculated by the jade software;
thermal conductivity: the method is obtained by testing a Hot disk thermal constant analyzer (polyimide film probe, model number is 7577), the testing temperature is 20 ℃, the testing depth is 2mm, the sample thickness is 3mm, the length and width are 4cm respectively, each sample is tested 5 times, and the average value is obtained.
The structural stability test method of the spherical powder product comprises the following steps: the product obtained in the example was added to ethanol, and the mixture was mechanically stirred at a rotation speed of 500r/min for 5min, and the product was observed for dispersion into flakes and stability was measured.
Example 1
Adding 10 parts of aluminum sol (with the solid content of 20 percent), 2 parts of boron nitride and sodium dodecyl benzene sulfonate (accounting for 0.05 percent of the weight of the boron nitride) into 20 parts of deionized water by weight, and uniformly dispersing by ultrasonic to obtain a solution A;
adding 2 parts of polyethylene glycol into the solution A, uniformly mixing, then placing into a ball mill, and ball milling for 10min at a rotating speed of 250r/min to obtain a suspension B;
adding the liquid paraffin oil with the volume 4 times of that of the deionized water into a three-neck flask, stirring and heating to 55 ℃, then adding the suspension B into the flask dropwise, heating to 100 ℃ for reaction for 3 hours, naturally cooling after the reaction is finished, and then centrifugally separating reactants to obtain white precipitate C;
sintering the precipitate C at 700 ℃ for 4 hours in an air atmosphere to remove organic matters, and then sintering the precipitate C at 1400 ℃ for 8 hours in a nitrogen atmosphere to obtain a spherical precursor;
and mixing the spherical precursor and graphite powder in a weight ratio of 1:1, and then sintering for 7 hours at 1600 ℃ in a nitrogen atmosphere to obtain the heat-conducting microsphere B1 (BN/AlN composite microsphere).
As can be seen from fig. 6, the main components of the thermally conductive microsphere B1 prepared in this example are aluminum nitride and boron nitride; the peak intensity of each phase in the XRD pattern is calculated by the jade software: in the heat-conducting microsphere B1, the weight ratio of the boron nitride to the aluminum nitride is 1.2:1.
FIG. 1 is an SEM image of thermally conductive microspheres prepared according to example 1 of the invention; fig. 2 is a partial enlarged view of a portion A1 in fig. 1. As can be seen from fig. 1 and 2: the product prepared in this example was a composite microsphere of BN/AlN with a diameter of 80. Mu.m, and the composite microsphere was packed with flaky boron nitride.
Examples 2 to 4 and comparative example 1
The procedure of example 1 was followed, except that: the weight ratio of the aluminum sol (in terms of alumina) to boron nitride is shown in table 1.
Experimental example:
the heat conductive microspheres prepared in examples 1 to 4 and comparative example 1 were filled into epoxy resin, and the heat conductive properties of the obtained epoxy resin composite material are shown in table 1.
TABLE 1
Fig. 3 is an SEM image of the thermally conductive microsphere prepared in example 2 of the present invention, and fig. 4 is an SEM image of the thermally conductive microsphere prepared in example 3 of the present invention. As can be seen by comparing fig. 1, 3 and 4, the sphericity of the thermally conductive microsphere B2 prepared in example 2 and the sphericity of the thermally conductive microsphere B3 prepared in example 3 are deteriorated with respect to the thermally conductive microsphere B1.
Examples 5 to 8 and comparative examples 2 to 3
The procedure of example 1 was followed, except that: the sintering process in step 4 is shown in table 2, and the thermal conductivity of the resulting epoxy resin composite is shown in table 2.
TABLE 2
Fig. 5 is an SEM image of the heat conductive powder C3 obtained in comparative example 3. As can be seen from fig. 5, although boron nitride in the heat conductive powder C3 is agglomerated, the agglomerates are irregularly blocky.
Examples 9 to 10
The procedure of example 1 was followed, except that: in carbothermic reaction: the weight ratios of the spherical precursor and graphite powder are shown in table 3.
Experimental example: the heat conductive microspheres prepared in examples 9 to 10 were filled into epoxy resin, and the heat conductivity coefficients of the obtained epoxy resin composites are shown in table 3.
TABLE 3 Table 3
As can be seen from fig. 6, the XRD pattern of the thermally conductive microsphere B9 obtained in example 9 shows peaks of alumina, which indicates that excessive use of the precursor during carbothermic reaction may result in incomplete nitridation of alumina.
Statistical calculation was performed on peak intensities of phases in the XRD pattern of the thermally conductive microsphere B10 obtained in example 10 by using the jade software: the thermally conductive microsphere B10 prepared in example 10 contained 49.5wt% BN, 40.2wt% AlN and 10.4wt% graphite; the heat-conducting microsphere B10 also contains graphite, which indicates that when the graphite is excessively used in the carbothermic reaction process, the graphite in the product cannot be completely removed, so that the heat-conducting property of the heat-conducting microsphere is affected, the insulativity of the heat-conducting microsphere is reduced, and the epoxy resin composite material filled with the heat-conducting microsphere is not suitable for being applied to electronic packaging materials.
Comparative example 4
Preparation of BN/Al according to the method of CN114044681A example 1 2 O 3 The method comprises the steps of carrying out a first treatment on the surface of the Followed by the BN/Al 2 O 3 Mixing the powder with graphite powder in a weight ratio of 1:1, and then sintering the mixture for 7 hours at 1600 ℃ in a nitrogen atmosphere to obtain the heat conduction powder C4.
As can be seen from fig. 6, the XRD pattern of the thermally conductive powder C4 prepared in comparative example 4 shows peaks of alumina; illustrating the presence of a large amount of alumina in the thermally conductive powder C4, further illustrating BN/Al obtained in comparative example 4 2 O 3 The precursor cannot be completely nitrided, probably because of the BN/Al 2 O 3 The surface density of the microsphere is high, which leads to Al in the microsphere 2 O 3 Cannot be completely nitrided.
Comparative example 5
Reference to "preparation of composite material" section 3.2.3 in "preparation of epoxy resin-based composite material and study of thermal conductivity"; wherein the particle size of the AlN raw material is 100nm, and the heat conduction powder C5 is obtained.
Uniformly dispersing a heat-conducting filler (BN: alN=4:1, the particle size of boron nitride is 3-5 mu m, and the particle size of aluminum nitride is 100 nm) with the volume fraction of 4:1 in a proper amount of acetone solution (the volume ratio of the heat-conducting filler is 3:1) under the ultrasonic condition, and continuously stirring for 40min to obtain heat-conducting powder C5 (BN-AlN); then adding the epoxy resin, heating, pouring and curing.
Application example 1
Filling the epoxy resin with heat-conducting microspheres B1 and flaky h-BN (particle size of 2 mu m) respectively to obtain an epoxy resin composite material; the filling amount of the heat conductive filler (heat conductive microspheres B1 or flake h-BN) and the heat conductivity coefficient of the obtained epoxy resin composite are shown in table 4.
TABLE 4 Table 4
As can be seen from table 4: the filling amount of the heat-conducting microsphere B1 in the epoxy resin is up to 70%, and the heat conductivity coefficient of the obtained epoxy resin composite material can be up to 5.6W/(m.K) which is 26.7 times that of the pure epoxy resin; the filling amount of the h-BN in the epoxy resin can only reach 40% at maximum, and the heat conductivity coefficient of the obtained epoxy resin composite material can only reach 1.64W/(m.K) at maximum.
Application example 2
Filling epoxy resin by using the heat-conducting microspheres B1 to B10 and the heat-conducting powder C1 to C5 respectively to obtain an epoxy resin composite material; the maximum filling amount of the heat conductive filler and the heat conductivity coefficient of the obtained epoxy resin composite material are shown in table 5.
TABLE 5
From comparison of application example 1, application example 2 and application example 3, it can be seen that: the maximum filling amount of the heat-conducting microspheres B2 and the heat-conducting microspheres B3 in the epoxy resin is reduced relative to that of the heat-conducting microspheres B1, so that the heat conductivity coefficient of the epoxy resin composite material is correspondingly reduced.
As can be seen from the comparison of application example 1 and application example 14: the thermal conductivity of the epoxy resin filled with the thermally conductive microspheres C4 is at most 3.53W/(mK).
As can be seen from the comparison of application example 1 and application example 15: the maximum filling amount of the heat conduction powder C5 in the epoxy resin can only reach 40wt percent, and the heat conduction coefficient of the obtained epoxy resin composite material can only reach 1.7W/(m.K) at most.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (23)
1. A method of preparing thermally conductive microspheres comprising the steps of:
(1) Uniformly mixing a surfactant, boron nitride and sol in water to obtain sol A; wherein the sol is selected from aluminum sol and/or silica sol;
(2) Mixing a dispersing agent with the sol A to obtain a suspension B;
(3) Dropwise adding the suspension B into an oily solvent to obtain a mixed system; then, the mixed system is dehydrated to obtain a precipitate C;
(4) The sediment C is sintered at low temperature in an oxygen-containing atmosphere, and then sintered at high temperature in a protective gas to obtain a precursor;
(5) And in a nitrogen atmosphere, mixing the precursor with graphite powder, and performing carbothermic reduction reaction to obtain the heat-conducting microsphere.
2. The method according to claim 1, characterized in that: in the step (1), the weight ratio of the sol to the boron nitride is 1 (0.25-5) in terms of oxide.
3. The method according to claim 2, characterized in that: in the step (1), the weight ratio of the sol to the boron nitride is 1 (0.5-3) in terms of oxide.
4. The method according to claim 1, characterized in that: in the step (1), the particle size of the oxide in the sol is 10-300nm, and the solid content is 10-30wt%.
5. The method according to claim 1, characterized in that: in the step (1), the boron nitride is flaky hexagonal boron nitride, and the particle size is 1-10 mu m.
6. The method according to claim 1, characterized in that: in the step (1), the surfactant is at least one selected from the group consisting of cationic surfactants, anionic surfactants and nonionic surfactants.
7. The method according to claim 1, characterized in that: in the step (2), the dispersing agent is at least one selected from polyethylene glycol, polyvinyl alcohol and polyvinylpyrrolidone.
8. The method according to claim 1, characterized in that: step (2) further comprises: ball milling the suspension B, wherein the ball milling conditions comprise: the speed is 200-400r/min, and the time is 3-30min.
9. The method according to claim 1, characterized in that: in the step (3), the oily solvent is at least one of silicone oil, fatty acid and hydrocarbon solvent.
10. The method according to claim 1, characterized in that: in the step (3), the water removal is carried out by reacting the mixed system at 100-200 ℃ for 2-5 h.
11. The method according to claim 1, characterized in that: in the step (4), the low-temperature sintering condition includes: the temperature is 400-750 ℃ and the time is 1-12h.
12. The method according to claim 1, characterized in that: in the step (4), the high-temperature sintering conditions include: the temperature is 900-1600 ℃ and the time is 1-12h.
13. The method according to claim 1, characterized in that: in the step (4), the shielding gas is nitrogen and/or inert gas.
14. The method according to claim 1, characterized in that: in step (5), the carbothermic reaction conditions include: the temperature is 900-1600 ℃ and the time is 1-12h.
15. The method according to claim 1, characterized in that: in the step (5), the weight ratio of the precursor to the graphite powder is (0.5-4): 1.
16. A thermally conductive microsphere prepared according to the method of any one of claims 1-15.
17. The thermally conductive microsphere of claim 16, wherein: comprises a first heat conduction phase and a second heat conduction phase; wherein the first heat conducting phase is boron nitride; the second thermally conductive phase is selected from aluminum nitride and/or silicon nitride.
18. The thermally conductive microsphere of claim 17, wherein: the weight ratio of the second heat conduction phase to the first heat conduction phase is 1 (0.25-5).
19. The thermally conductive microsphere of claim 18, wherein: the weight ratio of the second heat conduction phase to the first heat conduction phase is 1 (0.5-3).
20. The thermally conductive microsphere of claim 16, wherein: the particle size of the heat-conducting microsphere is 30-100 mu m.
21. A polymer composite comprising a polymer matrix and a thermally conductive filler, characterized in that: the heat conductive filler is the heat conductive microsphere of any one of claims 16-20.
22. The polymer composite of claim 21 wherein: the polymer composite comprises 1-75wt% thermally conductive filler and 25-99wt% polymer matrix, based on the total weight of the polymer composite.
23. The polymer composite of claim 22 wherein: the polymer matrix is at least one selected from polypropylene resin, polyethylene vinyl acetate, polyvinyl chloride resin, polystyrene resin, polyphenyl ether resin, polyamide resin, polycarbonate, epoxy resin, polyurethane, acrylic resin, polyacrylonitrile resin, polyvinyl alcohol resin, bismaleimide resin, polyimide resin, cyanate resin, natural rubber, polyisoprene rubber, ethylene propylene rubber, styrene butadiene rubber, fluororubber, chloroprene rubber, nitrile rubber, silicone rubber and fluorosilicone rubber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210631136.7A CN114988375B (en) | 2022-06-06 | 2022-06-06 | Heat-conducting microsphere, preparation method thereof and polymer composite material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210631136.7A CN114988375B (en) | 2022-06-06 | 2022-06-06 | Heat-conducting microsphere, preparation method thereof and polymer composite material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114988375A CN114988375A (en) | 2022-09-02 |
| CN114988375B true CN114988375B (en) | 2023-07-28 |
Family
ID=83033493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210631136.7A Active CN114988375B (en) | 2022-06-06 | 2022-06-06 | Heat-conducting microsphere, preparation method thereof and polymer composite material |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114988375B (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6950148B2 (en) * | 2016-03-31 | 2021-10-13 | 三菱ケミカル株式会社 | Aluminum Nitride-Boron Nitride Composite Agglomerated Particles and Their Manufacturing Methods |
| CN109181134A (en) * | 2018-09-05 | 2019-01-11 | 南京工业大学 | A kind of thermal-conductive polymer matrix composites and preparation method thereof |
| JP7187919B2 (en) * | 2018-09-20 | 2022-12-13 | 株式会社豊田中央研究所 | Thermally conductive composite material and manufacturing method thereof |
| CN110054864B (en) * | 2018-12-25 | 2020-09-01 | 上海交通大学 | High-thermal-conductivity composite filler and preparation method of polymer-based composite material thereof |
| CN109868118B (en) * | 2019-03-01 | 2020-12-25 | 安徽壹石通金属陶瓷有限公司 | Preparation method of aluminum nitride-aluminum oxide core-shell structure with high thermal conductivity |
| CN113956683B (en) * | 2020-07-21 | 2023-02-21 | 国家能源投资集团有限责任公司 | Heat-conducting insulating filler, preparation method thereof and heat-conducting insulating composite material |
| CN114804041B (en) * | 2022-05-12 | 2024-04-26 | 安徽壹石通材料科技股份有限公司 | Hexagonal boron nitride and preparation method thereof, and heat conducting rubber |
-
2022
- 2022-06-06 CN CN202210631136.7A patent/CN114988375B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN114988375A (en) | 2022-09-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112961469B (en) | Epoxy resin-based high-thermal-conductivity insulating material and preparation method thereof | |
| WO2017143625A1 (en) | High thermal conductive composite material, thermal conductive sheet prepared from material, and preparation method therefor | |
| CN110922719A (en) | High-thermal-conductivity boron nitride/epoxy resin composite material and preparation method and application thereof | |
| TW201827383A (en) | Boron nitride aggregated grain, method for producing same, and thermally conductive resin composition using same | |
| WO2016086587A1 (en) | Thermally conductive and insulating epoxy resin composition and preparation method therefor and use thereof | |
| CN112724677A (en) | Dopamine modified boron nitride heat-conducting silicone grease and preparation method thereof | |
| CN112063020B (en) | Core-shell spherical heat-conducting filler and preparation method and application thereof | |
| CN111777840A (en) | Epoxy resin micro-nano blending composite material for packaging power electronic high-power device and preparation method thereof | |
| CN109206853A (en) | A kind of high-thermal-conductivity epoxy resin based composites, and its preparation method and application | |
| CN110713721A (en) | Preparation method of high-thermal-conductivity silicone rubber | |
| CN112225186B (en) | Preparation method of spherical boron nitride | |
| CN111286213A (en) | Chemical and physical treatment method of high-thermal-conductivity filler | |
| CN110760189A (en) | Different layer type Ti3C2Filled high-thermal-conductivity silicone grease thermal interface material and preparation method thereof | |
| CN112646552A (en) | Efficient heat-conducting silicone grease and preparation method thereof | |
| CN113930050A (en) | High-thermal-conductivity low-viscosity epoxy plastic packaging material and preparation method thereof | |
| CN113754925B (en) | Insulating base material-carbon nano tube hybrid material and preparation method and application thereof | |
| CN109659281B (en) | High-thermal-conductivity electronic packaging composite material and preparation method thereof | |
| CN111393856A (en) | Graphene-based high-thermal-conductivity low-thermal-resistance thermal conductive paste and preparation method thereof | |
| CN111826132A (en) | High-thermal-conductivity composite gel and preparation method thereof | |
| CN114988375B (en) | Heat-conducting microsphere, preparation method thereof and polymer composite material | |
| CN114525100A (en) | High-thermal-conductivity low-viscosity epoxy pouring sealant and preparation method thereof | |
| CN112908956A (en) | Metal oxide/graphene composite fluid and preparation method and application thereof | |
| CN116715938A (en) | Dielectrophoresis force orientation-based epoxy resin composite insulating material and preparation method thereof | |
| CN111349270A (en) | Filler composition modified by solvents with different polarities, preparation method and application | |
| CN115746799A (en) | Preparation method of single-component heat-conducting gel with high heat conductivity |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |