CN109280120B - Silica sol coated graphite/styrene copolymerized composite pellet and preparation method thereof - Google Patents
Silica sol coated graphite/styrene copolymerized composite pellet and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a graphite/styrene copolymerization composite pellet coated by silica sol and a preparation method thereof. The preparation method comprises the following steps: 1) preparing graphite coated by copolymerizable double-bond silica sol; 2) preparing graphite/styrene copolymerization composite balls coated by silica sol. The method solves the problem of polymerization inhibition of graphite in graphite/polystyrene synthesis from two aspects of physical shielding and chemical copolymerization reaction, and a compact physical shielding layer is formed on the surface of graphite micropowder by in-situ hydrolysis of tetraethoxysilane, so that polymerization inhibition groups on the surface of graphite are effectively shielded; on the other hand, the silica sol graphite powder containing double bonds is obtained by directly modifying the hydrophobic modifier containing the copolymerizable double bonds, and the double bonds on the surface of the graphite powder improve the activity of the copolymerization chemical reaction with the styrene monomer, so that the polymerization inhibition is eliminated on two layers of physical coating shielding polymerization inhibition and chemical copolymerization improvement.
Description
Technical Field
The invention belongs to the technical field of energy-saving heat-insulating materials, and particularly relates to a silica sol coated graphite/styrene copolymerized composite pellet and a preparation method thereof.
Background
In order to further improve the heat insulation and flame retardant properties of Expanded Polystyrene (EPS), graphite powder with heat insulation factors, infrared radiation reflection and heat conduction reduction properties is often introduced into EPS, so that a graphite EPS heat insulation material with excellent heat insulation properties is prepared. However, the graphite EPS thermal insulation material prepared by the suspension polymerization method has two problems. On one hand, the surface of the graphite contains quinoid groups such as benzoquinone and the like, and the quinoid groups are typical free radical trapping agents, so that the graphite has a remarkable polymerization inhibition phenomenon in the polymerization of vinyl monomers such as styrene and methyl methacrylate monomers, the polymerization time required by the graphite EPS is prolonged, the stability of a polymerization system is deteriorated, the product performance is also reduced, the difficulty and the generation cost of industrial large-scale production process control are increased, and the market popularization and application of high-performance graphite EPS products are hindered. On the other hand, the dispersibility of graphite in styrene monomer is also the most important factor for determining the performance of graphite EPS product, and the graphite has poor dispersibility in styrene monomer, serious agglomeration and poor dispersion stability, thus influencing the mechanical, heat insulation and flame retardant effects of graphite EPS.
Disclosure of Invention
The invention aims to solve the problems, namely the polymerization inhibition effect of the graphite in the synthesis of graphite polystyrene spheres by a physical shielding and chemical copolymerization double-layer shielding suspension polymerization method, and simultaneously solve the problems that the mechanical, heat insulation and flame retardant effects of a graphite polystyrene foam material are seriously influenced due to poor dispersibility, serious agglomeration and poor dispersion stability of the graphite in a styrene monomer.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing silica sol-coated graphite/styrene copolymerized composite beads, the method comprising:
1) preparation of copolymerizable double-bond silica sol coated graphite
Dissolving polyvinylpyrrolidone in absolute ethyl alcohol under stirring, and adding graphite, water and NH at one time3·H2O, performing first stirring, adding tetraethoxysilane once again, performing second stirring, adding a copolymerizable double-bond type hydrophobic modifier, continuously reacting, and performing solid-liquid separation, washing and drying to obtain the graphite coated by the copolymerizable double-bond type silica sol;
2) preparation of graphite/styrene copolymerization composite pellet coated by silica sol
Adding water, a water solution of a surfactant, a water solution of a first inorganic suspending agent and a water solution of a high-molecular suspending agent into a reaction container, uniformly stirring, then adding an oil phase consisting of a styrene monomer, an initiator and the graphite coated by the copolymerizable double-bond silica sol obtained in the step 1), heating the system under a stirring state, realizing copolymerization of the graphite coated by the copolymerizable double-bond silica sol and styrene monomer molecules through in-situ suspension polymerization, supplementing a second inorganic suspending agent in the reaction process, stopping heating after the styrene monomer is completely converted, and cooling to obtain the graphite/styrene copolymerization composite spheres coated by the silica sol.
As a preferred embodiment of the present invention,
in the step 1), the dosage of each component is based on absolute ethyl alcohol and relative to each 100mL of absolute ethyl alcohol:
0.1-1.0 g of polyvinylpyrrolidone, 1.0-20.0 g of graphite, 0.5-3.0 mL of water and NH3·H2O1-6.0 mL, tetraethoxysilane 0.5-7.0 mL and copolymerizable double bond type hydrophobic modifier 0.1-2.0 mL;
according to the invention, in step 1), graphite, water and NH are added in one step according to the above dosage3·H2And O and tetraethoxysilane are added at one time, so that the aim of controlling the hydrolysis time can be fulfilled, and the graphite coated by the copolymerizable double-bond silica sol is obtained.
In the step 2), based on water, the dosage of each component is as follows for every 100-200 mL of water: 1-8 mL of aqueous solution of a surfactant, 0.1-2 g of a first inorganic suspending agent, 5-10 mL of aqueous solution of a polymer suspending agent, 10-100 mL of a styrene monomer, 0.1-1.0 g of an initiator, 0.05-3.0 g of copolymerizable double bond silica sol and 0.1-2.0 g of a second inorganic suspending agent; wherein the mass fraction of the aqueous solution of the surfactant is 0.02-0.1 wt%, and the mass fraction of the aqueous solution of the polymer suspending agent is 4-10 wt%.
In a preferred embodiment of the present invention, the graphite has a flake structure and a particle diameter of 0.1 to 50 μm. The graphite with the flake structure and the particle size of 0.1-50 mu m is selected, so that the graphite powder is small in particle size, is beneficial to coating and modifying silica sol, and is beneficial to improving the dispersibility and stability of the graphite powder in styrene monomers, so that the graphite powder is uniformly dispersed in polystyrene spheres, and the flame retardance, heat insulation and mechanical properties of the graphite/styrene copolymer spheres coated with the silica sol are improved.
As a preferred embodiment of the present invention, in step 1), the copolymerizable double bond type hydrophobic modifier is selected from at least one of 3- (trimethoxysilyl) propyl methacrylate, vinyltrimethoxysilane and vinyltriethoxysilane.
As a preferred embodiment of the present invention, in the step 2), the surfactant is at least one selected from the group consisting of sodium dodecylbenzenesulfonate, sodium dodecylsulfate and nonylphenol polyoxyethylene ether.
As a preferred embodiment of the present invention, the inorganic suspending agent is selected from at least one of calcium phosphate, kaolin, barium sulfate and talc.
In a preferred embodiment of the present invention, the polymeric suspending agent is at least one selected from the group consisting of polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl methylcellulose, carboxymethyl cellulose and sodium polyacrylate.
As a preferred embodiment of the present invention, the initiator is azobisisobutyronitrile and/or benzoyl peroxide.
As a preferred embodiment of the present invention,
in the step 1), the first stirring time is 1-10 min; the second stirring time is 1-7 h; the continuous reaction time is 1-4 h;
in the step 2), the stirring speed is 100-300 r/min, and the heating is carried out until the temperature is 80-90 ℃.
The second aspect of the present invention provides silica sol-coated graphite/styrene copolymerized composite beads prepared by the above-described preparation method.
According to the invention, the solid-liquid separation can adopt the solid-liquid separation means which is conventionally adopted by the technical personnel in the field, including but not limited to suction filtration and centrifugation.
The invention has the beneficial effects that:
the method solves the problem of polymerization inhibition of graphite in graphite/polystyrene synthesis from two aspects of physical shielding and chemical copolymerization reaction, and a compact physical shielding layer is formed on the surface of the graphite through in-situ hydrolysis of tetraethoxysilane, so that polymerization inhibition groups on the surface of the graphite are effectively shielded; on the other hand, the silica sol coated graphite powder containing double bonds is obtained by directly modifying the hydrophobic modifier containing copolymerizable double bonds, and the double bonds on the surface of the graphite powder improve the activity of the copolymerization chemical reaction with styrene monomers, so that the polymerization inhibition is eliminated on two layers of physical coating shielding polymerization inhibition and chemical copolymerization improvement.
The invention can improve the dispersibility and stability of graphite in styrene monomer, improve the flame retardant property of composite material, and eliminate the polymerization inhibition effect in the synthesis of graphite polystyrene pellets. Specifically, on one hand, the nano-silica has better acid-base resistance and heat-resistant stability, and the silica can scatter ultraviolet rays and has better weather resistance, so that the graphite powder coated by the silica sol also has better acid-base resistance, heat-resistant stability and weather resistance. On the other hand, the silica sol on the surface of the graphite can be gathered on the surface of the molten polymer as a thermal isolation layer to reduce the contact of the polymer and the combustion flame, thereby improving the flame retardant property of the graphite/polystyrene material to a certain extent. In addition, most importantly, the color of the graphite powder is still maintained after the graphite powder is coated by the nano silicon dioxide, and the color of the graphite/styrene copolymerized composite pellet is not influenced while the graphite polymerization inhibition effect is shielded.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
FIG. 1 shows a scanning electron microscope image of 1000 times of copolymerizable double-bond silica sol coated graphite prepared by the present invention;
FIG. 2 shows a scanning electron microscope image of 30000 times of copolymerizable double-bond silica sol coated graphite prepared by the present invention;
FIG. 3 shows an elemental energy spectrum of a copolymerizable double bond type silica sol coated graphite prepared in accordance with the present invention;
FIG. 4 is a graph showing a comparison of dispersibility of copolymerizable double bond type silica sol coated graphite prepared in accordance with the present invention in styrene monomer;
FIG. 5 shows a photograph of silica sol coated graphite/styrene copolymer composite beads prepared according to the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Example 1
1) Preparation of copolymerizable double-bond type silica sol coated graphite
0.3g of polyvinylpyrrolidone was dissolved in 100mL of anhydrous ethanol under stirring, and 3.0g of graphite, 0.9mL of ultrapure water, and 2.0mL of NH were added all at once3·H2And O, stirring for 3min, adding 1.0mL of ethyl orthosilicate once again, reacting for 3.0h by magnetic stirring, directly adding 0.2mL of 3- (trimethoxysilyl) propyl methacrylate into the system, continuing to react for 2.0h, and performing suction filtration, washing and drying to obtain the hydrophobic copolymerizable double-bond silica sol coated graphite.
2) Synthesis of silica sol coated graphite/styrene copolymerized composite balls
Adding 110mL of distilled water, 5.5mL of sodium dodecyl benzene sulfonate aqueous solution with the mass fraction of 0.04%, 0.4g of calcium phosphate and 6mL of polyvinyl alcohol aqueous solution with the mass fraction of 6% into a four-mouth bottle provided with a mechanical stirring and condensing device, stirring at the rotating speed of 160 r/min, fully and uniformly stirring, adding an oil phase containing 40mL of styrene monomer, 0.4g of benzoyl peroxide and 0.4g of hydrophobic copolymerizable double bond type silica sol coated graphite into the reaction system, keeping the stirring at the rotating speed of 160 r/min, heating in a water bath to 85 ℃, supplementing 0.3g of calcium phosphate in the reaction process to keep the polymerization system stable, stopping heating after the monomer is completely converted, and cooling to obtain the silica sol coated graphite/styrene copolymerized composite spheres.
Example 2
1) Preparation of copolymerizable double-bond type silica sol coated graphite
0.5g of polyvinylpyrrolidone was dissolved in 100mL of anhydrous ethanol under stirring, and 6.0g of graphite, 2.0mL of ultrapure water, and 3.0mL of NH were added all at once3·H2And O, stirring for 4min, adding 2.0mL of ethyl orthosilicate once again, reacting for 3.5h by magnetic stirring, directly adding 0.3mL of 3- (trimethoxysilyl) propyl methacrylate into the system, continuing to react for 2.0h, and performing suction filtration, washing and drying to obtain the hydrophobic copolymerizable double-bond silica sol coated graphite.
2) Synthesis of silica sol coated graphite/styrene copolymerized composite balls
120mL of distilled water, 6.0mL of sodium dodecyl benzene sulfonate aqueous solution with the mass fraction of 0.04%, 0.6g of calcium phosphate and 7.0mL of hydroxypropyl methyl cellulose aqueous solution with the mass fraction of 7% are sequentially added into a four-mouth bottle provided with a mechanical stirring and condensing device, the stirring rotating speed is 180 r/min, after the mixture is fully stirred uniformly, an oil phase containing 40mL of styrene monomer, 0.4g of benzoyl peroxide and 0.6g of hydrophobic copolymerizable double bond type silica sol coated graphite is added into the reaction system, the stirring rotating speed is kept at 180 r/min, the temperature is raised to 85 ℃ in a water bath, 0.4g of calcium phosphate is supplemented in the reaction process to keep the polymerization system stable, after the monomer is completely converted, the heating is stopped, and the silica sol coated graphite/styrene copolymerized composite spheres are obtained after cooling.
Example 3
1) Preparation of copolymerizable double-bond type silica sol coated graphite
0.6g of polyvinylpyrrolidone was dissolved in 100mL of anhydrous ethanol under magnetic stirring, and 9.0g of graphite, 2.8mL of ultrapure water, and 4.0mL of NH were added in one portion3·H2O, stirring for 6min, adding 3.0mL of ethyl orthosilicate once again, reacting for 6.0h under magnetic stirring, directly adding 0.4mL of vinyltriethoxysilane into the system, continuing to react for 1.5h, performing suction filtration, washing and drying to obtain the hydrophobic copolymerizable double-bond silica sol packageAnd coating graphite.
2) Synthesis of silica sol coated graphite/styrene copolymerized composite balls
120mL of distilled water, 6.5mL of lauryl sodium sulfate aqueous solution with the mass fraction of 0.04%, 0.8g of kaolin and 7.0mL of carboxymethyl cellulose aqueous solution with the mass fraction of 5.5% are sequentially added into a four-mouth bottle provided with a mechanical stirring and condensing device, the stirring speed is 190 revolutions per minute, after the mixture is fully stirred uniformly, an oil phase containing 40mL of styrene monomer, 0.4g of azodiisobutyronitrile and 0.8g of hydrophobic copolymerizable double bond type silica sol coated graphite is added into the reaction system, the stirring speed is kept at 190 revolutions per minute, the temperature is raised to 85 ℃ in a water bath, 0.5g of kaolin is added in the reaction process to keep the polymerization system stable, after the monomer is completely converted, the heating is stopped, and the silica sol coated graphite/styrene copolymerized composite spheres are obtained after cooling.
Example 4
1) Preparation of copolymerizable double-bond type silica sol coated graphite
0.6g of polyvinylpyrrolidone was dissolved in 100mL of anhydrous ethanol under magnetic stirring, and 12.0g of graphite, 2.95mL of ultrapure water, and 5.0mL of NH were added in one portion3·H2And O, stirring for 8min, adding 4.0mL of ethyl orthosilicate once again, reacting for 5.0h by magnetic stirring, directly adding 0.6mL of vinyl triethoxysilane into the system, continuing to react for 1.5h, and performing suction filtration, washing and drying to obtain the hydrophobic copolymerizable double-bond silica sol coated graphite.
2) Synthesis of silica sol coated graphite/styrene copolymerized composite balls
160mL of distilled water, 6.0mL of lauryl sodium sulfate aqueous solution with the mass fraction of 0.06%, 0.9g of barium sulfate and 8.0mL of sodium polyacrylate aqueous solution with the mass fraction of 5.0% are sequentially added into a four-mouth bottle provided with a mechanical stirring and condensing device, the stirring rotating speed is 200 r/min, after the mixture is fully stirred uniformly, an oil phase containing 40mL of styrene monomer, 0.4g of benzoyl peroxide and 1.2g of hydrophobic copolymerizable double bond type silica sol coated graphite is added into the reaction system, the stirring rotating speed is kept at 200 r/min, the temperature is raised to 85 ℃ in a water bath, 0.55g of barium sulfate is added in the reaction process to keep the polymerization system stable, after the monomer is completely converted, the heating is stopped, and the silica sol coated graphite/styrene copolymerized composite spheres are obtained after cooling.
Example 5
1) Preparation of copolymerizable double-bond type silica sol coated graphite
0.6g of polyvinylpyrrolidone was dissolved in 100mL of anhydrous ethanol under magnetic stirring, and 16.0g of graphite, 2.95mL of ultrapure water, and 5.5mL of NH were added in one portion3·H2And O, stirring for 9min, adding 6.0mL of ethyl orthosilicate once again, reacting for 5.0h by magnetic stirring, directly adding 0.9mL of vinyltrimethoxysilane into the system, continuing to react for 3.0h, and performing suction filtration, washing and drying to obtain the hydrophobic copolymerizable double-bond silica sol coated graphite.
2) Synthesis of silica sol coated graphite/styrene copolymerized composite balls
170mL of distilled water, 7.0mL of a nonanol polyoxyethylene ether aqueous solution with the mass fraction of 0.04%, 0.8g of talcum powder and 9.0mL of a hydroxyethyl cellulose aqueous solution with the mass fraction of 4.0% are sequentially added into a four-mouth bottle provided with a mechanical stirring and condensing device, the stirring speed is 220 r/m, after the materials are fully stirred uniformly, an oil phase containing 40mL of a styrene monomer, 0.4g of azobisisobutyronitrile and 1.6g of hydrophobic copolymerizable double bond type silica sol coated graphite is added into the reaction system, the stirring speed is maintained at 220 r/m, the temperature is raised to 85 ℃ in a water bath, 0.6g of talcum powder is added in the reaction process to keep the polymerization system stable, after the monomer is completely converted, the heating is stopped, and the graphite/styrene copolymer composite coated with silica sol is obtained after cooling.
Comparative example (Synthesis of unmodified graphite expanded polystyrene Material)
160mL of distilled water, 6.0mL of lauryl sodium sulfate aqueous solution with the mass fraction of 0.06%, 0.9g of barium sulfate and 8.0mL of sodium polyacrylate aqueous solution with the mass fraction of 5.0% are added into a four-mouth bottle provided with a mechanical stirring and condensing device, the stirring speed is 200 r/min, after the mixture is fully stirred uniformly, an oil phase containing 40mL of styrene monomer, 0.4g of benzoyl peroxide and 1.2g of raw material graphite is added into the reaction system, the stirring speed is kept at 200 r/min, the water bath heating temperature is raised to 85 ℃, 0.65g of barium sulfate is supplemented in the reaction process to keep the polymerization system stable, after the monomer is completely converted, the heating is stopped, and the graphite/polystyrene spheres are obtained after cooling.
Under the condition that the monomers, the initiator and the polymerization temperature are consistent, the influence of the graphite coated by the hydrophobic copolymerizable double-bond silica sol and the raw material graphite on the polymerization time is examined by adopting the products prepared in the examples 1 to 5 and the comparative example, and the polymerization inhibition effect of the graphite in the process of synthesizing the graphite polystyrene spheres by the suspension polymerization method is effectively shielded by the method disclosed by the invention as shown by the time required by the polymerization reaction in the table 1.
TABLE 1
Remarks are as follows: the graphite used in the comparative example was unmodified raw material graphite.
FIG. 1 shows a scanning electron microscope picture of the copolymerizable double-bond silica sol-coated graphite prepared by the method under 1000 times, and the picture shows that the modified graphite has a sheet structure and has no obvious agglomeration phenomenon.
FIG. 2 shows a scanning electron microscope picture of graphite coated with copolymerizable double-bond silica sol prepared by the invention at 30000 times, and it can be observed from the picture that the modified graphite has a plurality of silica particles of 40-100 nm on the surface, and the particles form a compact coating layer.
Fig. 3 shows an element energy spectrum of the copolymerizable double bond type silica sol coated graphite prepared in the present invention, and only C, Si and O were observed in addition to the Au element introduced by the Au spraying pretreatment, which elements are derived from the graphite and silica components.
FIG. 4 is a graph showing the comparison of the dispersibility of the copolymerizable double bond type silica sol coated graphite prepared in the present invention in styrene monomer, and FIG. a is a photograph of the raw material graphite after being dispersed and left standing in styrene monomer for 5min, in which it can be found that the graphite is significantly precipitated. And the graph b shows graphite coated by silica sol, wherein the silica sol is rich in hydroxyl, has good hydrophilicity, cannot be dispersed in styrene monomers, and is basically completely settled at the bottom after standing for 5 min. And the picture c is a picture of the graphite coated by hydrophobic copolymerizable double-bond silica sol after being dispersed and kept stand for 5min in styrene monomer, and the silica sol is grafted with a hydrophobic modifier to show hydrophobicity, so that the graphite coated by the silica sol and the styrene copolymerized composite spheres have better compatibility and dispersion stability in the styrene monomer and provide guarantee for the next step of suspension polymerization for preparing the graphite/styrene copolymerized composite spheres coated by the silica sol.
FIG. 5 is a photograph showing the graphite/styrene copolymer beads coated with silica sol prepared according to the present invention, in which it can be seen that the composite beads have a uniform particle size, an average particle size of about 1.1mm, and the original color of graphite is maintained after the silica sol is coated with graphite.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (9)
1. A preparation method of graphite/styrene copolymerization composite balls coated by silica sol is characterized by comprising the following steps:
1) preparation of copolymerizable double-bond silica sol coated graphite
Dissolving polyvinylpyrrolidone in absolute ethyl alcohol under stirring, and adding graphite, water and NH at one time3·H2O, performing first stirring, adding tetraethoxysilane once again, performing second stirring, adding a copolymerizable double-bond type hydrophobic modifier, continuously reacting, and performing solid-liquid separation, washing and drying to obtain the graphite coated by the copolymerizable double-bond type silica sol;
2) preparation of graphite/styrene copolymerization composite pellet coated by silica sol
Adding water, a water solution of a surfactant, a first inorganic suspending agent and a water solution of a high-molecular suspending agent into a reaction container, uniformly stirring, then adding an oil phase consisting of a styrene monomer, an initiator and the graphite coated by the copolymerizable double-bond silica sol obtained in the step 1), heating the system under a stirring state, realizing copolymerization of the graphite coated by the copolymerizable double-bond silica sol and styrene monomer molecules through in-situ suspension polymerization, supplementing a second inorganic suspending agent in the reaction process, stopping heating after the styrene monomer is completely converted, and cooling to obtain graphite/styrene copolymerization composite spheres coated by the silica sol;
in the step 1), the dosage of each component is, based on absolute ethyl alcohol, relative to each 100mL of absolute ethyl alcohol: 0.1-1.0 g of polyvinylpyrrolidone, 1.0-20.0 g of graphite, 0.5-3.0 mL of water and NH3·H2O1-6.0 mL, tetraethoxysilane 0.5-7.0 mL and copolymerizable double bond type hydrophobic modifier 0.1-2.0 mL;
in the step 2), based on water, the dosage of each component is as follows for every 100-200 mL of water: 1-8 mL of aqueous solution of a surfactant, 0.1-2 g of a first inorganic suspending agent, 5-10 mL of aqueous solution of a polymer suspending agent, 10-100 mL of a styrene monomer, 0.1-1.0 g of an initiator, 0.05-3.0 g of copolymerizable double bond silica sol and 0.1-2.0 g of a second inorganic suspending agent; wherein the mass fraction of the aqueous solution of the surfactant is 0.02-0.1 wt%, and the mass fraction of the aqueous solution of the polymer suspending agent is 4-10 wt%.
2. The method according to claim 1, wherein the graphite has a flake structure and a particle size of 0.1 to 50 μm.
3. The method of claim 1, wherein the copolymerizable double bond type hydrophobic modifier is at least one selected from the group consisting of 3- (trimethoxysilyl) propyl methacrylate, vinyltrimethoxysilane and vinyltriethoxysilane in the step 1).
4. The preparation method according to claim 1, wherein in the step 2), the surfactant is selected from at least one of sodium dodecylbenzenesulfonate, sodium dodecylsulfate and nonylphenol polyoxyethylene ether.
5. The method according to claim 1, wherein the inorganic suspending agent is selected from at least one of calcium phosphate, kaolin, barium sulfate, and talc.
6. The method according to claim 1, wherein the polymeric suspending agent is at least one selected from the group consisting of polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, and sodium polyacrylate.
7. The production method according to claim 1, wherein the initiator is azobisisobutyronitrile and/or benzoyl peroxide.
8. The production method according to claim 1,
in the step 1), the first stirring time is 1-10 min; the second stirring time is 1-7 h; the continuous reaction time is 1-4 h;
in the step 2), the stirring speed is 100-300 r/min, and the heating is carried out until the temperature is 80-90 ℃.
9. Silica sol coated graphite/styrene copolymer composite beads prepared by the method of any one of claims 1 to 8.
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