阅读说明：本技术 一种隔热微球及其制备方法 (A kind of heat-insulated microballoon and preparation method thereof ) 是由 韩金 沈宇鹏 陈钦越 冯祎平 马佳奇 钟明强 于 2019-07-08 设计创作，主要内容包括：本发明公开了一种隔热微球及其制备方法,属于新材料领域,该隔热微球通过在惰性气体的氛围下,将氧化石墨烯微球置于1300℃以上的温度下进行烧结5min以上；再将烧结后的石墨烯微球分散正硅酸乙酯中,以分散有石墨烯微球的正硅酸乙酯为前驱体,在搅拌条件下,采用溶胶凝胶法在石墨烯微球外包覆二氧化硅层；停止搅拌,收集浮于反应液表面的包覆有二氧化硅的石墨烯微球。该微球以石墨烯为模板,制备超低密度石墨烯基二氧化硅微球,该微球热导率降低到0.02W/m.K以下,具有绝佳的隔热作用。(The invention discloses a kind of heat-insulated microballoons and preparation method thereof, belong to field of new materials, and the heat-insulated microballoon is by graphene oxide microballoon being placed at a temperature of 1300 DEG C or more and is sintered 5min or more under the atmosphere of inert gas；Sintered graphene microballoon is dispersed in ethyl orthosilicate again, to be dispersed with the ethyl orthosilicate of graphene microballoon as presoma, under agitation, using sol-gal process in graphene microballoon outer cladding silicon dioxide layer；Stop stirring, collects the graphene microballoon being coated with silicon oxide for floating on the surface of the reaction solution.The microballoon prepares the graphene-based silicon dioxide microsphere of extremely-low density using graphene as template, which is reduced to 0.02W/m.K hereinafter, having excellent heat-blocking action.)

1. a kind of preparation method of heat-insulated microballoon, which is characterized in that the method are as follows:

(1) under the atmosphere of inert gas, graphene oxide microballoon is placed at a temperature of 1300 DEG C or more and is sintered 5min More than；

(2) the sintered graphene microballoon of step 1 is dispersed in ethyl orthosilicate, to be dispersed with the positive silicic acid second of graphene microballoon Ester is presoma, under agitation, using sol-gal process in graphene microballoon outer cladding silicon dioxide layer；

(3) stop stirring, collect the graphene microballoon being coated with silicon oxide for floating on the surface of the reaction solution.

2. preparation method according to claim 1, which is characterized in that the sol-gal process of the step 2 specifically: stirring Under the conditions of mixing, the ethyl orthosilicate for being dispersed with graphene microballoon is added drop-wise in the mixed solution of ethyl alcohol and ammonium hydroxide, the ethyl alcohol In the mixed solution of ammonium hydroxide, the volumetric concentration of ethyl alcohol is 2-10%, and the pH of mixed solution is 8-10；Reaction temperature is 10-40 DEG C, the reaction time is 2-7 hours.

3. according to the method described in claim 2, it is characterized in that, mass volume ratio of the graphite microspheres in ethyl orthosilicate is small In 10mg/mL.

4. preparation method according to claim 1, which is characterized in that the collection method of the step 3 is filtering.

5. preparation method according to claim 1, which is characterized in that the diameter of the graphene microballoon is 5-20 μm, stone The wall thickness of black alkene microballoon is 2-5nm.

6. preparation method according to claim 5, which is characterized in that the graphene microballoon the preparation method is as follows: matching The graphene oxide solution for setting 2-6mg/mL, spray drying obtains graphene oxide microballoon at 200 DEG C, and graphene oxide is micro- Ball is sintered 5min or more at a temperature of being placed in 1300 DEG C or more.

7. a kind of heat-insulated microballoon, which is characterized in that the titanium dioxide including hollow plumbago alkene microballoon and cladding hollow plumbago alkene microballoon Silicon layer.

8. heat-insulated microballoon according to claim 7, which is characterized in that the thickness 5-10nm of the silicon dioxide layer, graphite The diameter of alkene microballoon is 5-20 μm, and the wall thickness of graphene microballoon is 2-5nm.

Technical field

The invention belongs to field of new materials, more particularly to a kind of graphene-based heat-insulated microballoon and preparation method thereof.

Background technique

Building heat-insulation and heat-preservation is energy saving, improvement living environment and an importance using function.Build energy Consumption proportion in the entire energy consumption of the mankind therefore is built generally in 30-40%, the mostly energy consumption of heating and air-conditioning Energy-saving significance is great.Traditional heat preserving and insulating material is to reduce based on density of material and the coefficient of conductivity, to reduce unit bodies Phonon number and heat radiation site in product.Aether Reflection and Heat Insulation Coatings pass through the ceramic spherical particles hollow material of application and are applying The vacuum cavity layer formed in layer, constructs effective thermodynamic barrier, not only itself thermal resistance is big, and thermal coefficient is low, and heat reflectivity Height reduces absorption of the building to solar radiant heat, reduces coating surface and interior space temperature, therefore it is unanimously public by expert Think promising one of energy-efficient material.

Currently used is the silicon dioxide microsphere of high porosity high reflectance.Its thermal conductivity can be reduced to 0.08W/ (K m).The nineties in last century, the scientific research personnel of US National Aeronautics and Space Administration (NASA) are to solve aerospace craft heat transfer control to ask It inscribes and researches and develops a kind of novel space insulation reflection enamel coating (Therma-Cover) used, which is to be suspended in inertia by some What the small ceramic particle in latex was constituted, it has the heat such as high reflectance, high radiant rate, low thermal conductivity, low heat storage coefficient Work performance has the function of brilliant heat insulating reflecting.This hitech materials promote the use of the people by space industry in foreign countries, are used for In building and industrial plants, and China is exported to, in some large scale industry facilities.

But it is currently used be high porosity high reflectance silicon dioxide microsphere, wall thickness is big, density is big, is not able to satisfy Higher insulation requirement.In view of this, being badly in need of a kind of stabilization prepares extremely-low density, the method for heat-insulated silicon dioxide hollow microsphere.

Summary of the invention

The purpose of the present invention is in the prior art since silicon dioxide microsphere wall thickness is big, the big caused heat-insulated effect of density The relatively poor problem of fruit provides a kind of graphene-based heat-insulated microballoon and preparation method thereof.

The present invention adopts the following technical scheme: a kind of heat-insulated microballoon, including hollow plumbago alkene microballoon and cladding hollow plumbago The silicon dioxide layer of alkene microballoon.Graphene microballoon has smaller density as support frame, compared to silicon dioxide microsphere And wall thickness, the silicon dioxide layer of external sheath reflect heat as radiating layer.

The present invention also provides the method for preparing above-mentioned heat-insulated microballoon, specifically:

(1) under the atmosphere of inert gas, graphene oxide microballoon is placed at a temperature of 1300 DEG C or more and is sintered 5min or more forms hollow ball-shape structure so that surface of graphene oxide functional group acutely discharges, and the sizing of graphene microballoon is kept away Exempt from its dissociate in the next steps and spherical structure collapse.A large amount of defect sites are formed on surface simultaneously.

(2) the sintered graphene microballoon of step 1 is dispersed in ethyl orthosilicate, to be dispersed with the positive silicon of graphene microballoon Acetoacetic ester is presoma, under agitation, using sol-gal process in graphene microballoon outer cladding silicon dioxide layer；It is sintered The defects of journey site forms the active site for silica nucleation in sol-gel process, so that silica is in stone Clad is formed outside black alkene microballoon.Wherein, some pore defects are unavoidably had in graphene ball preparation process, but by In the presence of the high surface tension of ethyl orthosilicate, prevent liquid to the infiltration inside graphene ball, inside graphene ball Almost without silica nucleation.

(3) stop stirring, collect the graphene microballoon being coated with silicon oxide for floating on the surface of the reaction solution.

Above-mentioned sol-gal process specifically: under agitation, the ethyl orthosilicate for being dispersed with graphene microballoon is added dropwise To in the mixed solution of ethyl alcohol and ammonium hydroxide, in the mixed solution of the ethyl alcohol and ammonium hydroxide, the volumetric concentration of ethyl alcohol is 2-10%, is mixed The pH for closing solution is 8-10；Reaction temperature is 10-40 DEG C, and the reaction time is 2-7 hours.

Mass volume ratio of the graphite microspheres in ethyl orthosilicate is less than 10mg/mL, so that graphene microballoon is fully dispersed, It avoids reuniting.

The graphene microballoon the preparation method is as follows: configuration 2-6mg/mL graphene oxide solution, sprayed at 200 DEG C Mist is dried to obtain graphene oxide microballoon, graphene oxide microballoon is placed at a temperature of 1300 DEG C or more be sintered 5min with On, the diameter of obtained graphene microballoon is 5-20 μm, and the wall thickness of graphene microballoon is 2-5nm.

The parameters such as reaction time, temperature by adjusting solgel reaction are the thickness of adjustable silicon dioxide layer, thick Degree can select within the scope of 5-10nm.

The beneficial effects of the present invention are: using graphene as template, prepare the graphene-based silicon dioxide microsphere of extremely-low density. Wherein, graphene plays the role of bracket, supports silicon dioxide microsphere；Additionally as template, the thickness of silica is reduced, thus Reduce the density of whole microballoon.Prepared microballoon, extexine have fine and close silicon dioxide layer, can reflect 90% or more heat Amount.And the reduction density that graphene microballoon is played the role of, so that microballoon thermal conductivity itself is reduced to 0.02W/m.K or less. The two collective effect, so that graphene-based silicon dioxide microsphere has excellent heat-blocking action.

Detailed description of the invention

Fig. 1 is the shape appearance figure of graphene oxide microballoon；

Fig. 2 is 1300 DEG C of sintered shape appearance figures；

Fig. 3 is the shape appearance figure for the graphene microballoon being coated with silicon oxide.

Specific embodiment