Preparation and application of hollow glass microsphere precursor microparticles with porous structure

Abstract

The application discloses a kind of porous structure's hollow glass microsphere precursor microparticle preparation and application, comprising: mixing silica sol with water, then under magnetic stirring, add water glass, obtain mixed solution;Metal acetate and boric acid are dissolved into saturated aqueous solution, under magnetic stirring, add to mixed solution, with acetic acid adjustment pH, obtain white emulsion, after stirring by homogenizer, carry out spray drying, obtain porous structure's hollow glass microsphere precursor microparticle.The microporous of porous structure's hollow glass microsphere precursor microparticle inside has been replaced with the bubble nucleation process of microparticle in the process of foaming into ball in the process of foaming into ball, shorten foaming into ball time, eliminate the bubble that ball wall is not coalesced, reduce the particle of incomplete foaming, improve the yield and performance of hollow glass microsphere.The application uses crosslinking incomplete silica sol as raw material, with chemical bonding replaces the traditional soft chemical method preparation microparticle's cohesive aggregation, enhances the pressure strength of precursor microparticle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hollow glass microsphere precursor particle preparation, and more particularly, the present application relates to a preparation and application of a porous hollow glass microsphere precursor particle. BACKGROUND

[0002] Hollow glass microspheres are spherical hollow glass powders with a diameter of about 5-200 μm, which have the advantages of low density, good stability, high strength, good fluidity, etc. Through material component design and microsphere structure regulation, it can also have the functions of radiation resistance, sound insulation, heat insulation, insulation, etc. Therefore, hollow glass microspheres are widely used as fillers in the fields of national defense technology and petrochemical industry.

[0003] The industrial production process of hollow glass microspheres has two main processes: one is the preparation of precursor particles; the other is the foaming of precursor particles into balls at high temperature. The precursor particles obtained in the first process have a decisive influence on the efficiency of the second process of foaming into balls and the performance of the product, and are the decisive link of hollow glass microsphere production. There are two methods for producing precursor particles: one is the glass powder method, which mainly mixes glass raw materials and foaming agents uniformly, then melts into glass liquid at high temperature, and then performs water quenching, drying, crushing and other processes to obtain precursor particles with a given composition. The hollow glass microspheres prepared by the glass powder method have high chemical stability and high pressure resistance, but this method requires high-temperature melting, grinding, and classification processes, resulting in high energy consumption and low particle foaming efficiency. The other is a soft chemical method, which first disperses silica powder, metal inorganic salt, foaming agent and stable dispersing agent in water to form a slurry, and then sprays and dries to obtain precursor particles. In the precursor particles prepared by the soft chemical method, the components are aggregated into particles under the binding action of the stable dispersing agent, and there is no chemical bonding between the components, so the strength of the precursor particles is low and they are easy to break.

[0004] Fluid mechanics simulation studies show that the whole process of foaming precursor particles into balls can be divided into four stages: encapsulation, foaming, refining, and cooling and solidification. The foaming stage can be divided into four processes: bubble nucleation, growth, coalescence and integration. The precursor particles undergo morphological evolution from solid particles, porous particles, core-shell particles to hollow microspheres. The precursor particles obtained by the glass powder method and the soft chemical method are solid particles, and there is a problem of incomplete foaming in the process of high-temperature vitrification into balls. SUMMARY

[0005] An object of the present application is to solve at least the above problems and / or deficiencies, and to provide at least the advantages described later.

[0006] In order to achieve these objects and other advantages of the present application, a method for preparing a porous hollow glass microsphere precursor particle is provided, which comprises the following steps:

[0007] Step one, mix silica sol with water, then add water glass under magnetic stirring, get the mixture;

[0008] Step two, dissolve metal acetate and boric acid into saturated aqueous solution, add it into the mixture from step one under magnetic stirring, adjust pH with acetic acid, get the white emulsion;

[0009] Step three, spray dry the white emulsion from step two after stirring by homogenizer, get the porous hollow glass microsphere precursor particles.

[0010] Preferably, in step one, the silica content in silica sol is 20-40%, and the particle size is 5-10nm.

[0011] Preferably, in step one, the volume ratio of silica sol to water is 1:0.8-1.2.

[0012] Preferably, in step one, the modulus of water glass is 3.1-3.4; the amount of water glass is calculated according to the mass ratio of Na2O in target hollow glass microsphere.

[0013] Preferably, in step one, the stirring speed under magnetic stirring is 500-700rpm.

[0014] Preferably, in step two, the metal acetate includes lithium acetate, potassium acetate, magnesium acetate, calcium acetate, aluminum acetate and zinc acetate.

[0015] Preferably, in step two, the amount of metal acetate and boric acid is calculated according to the mass ratio of corresponding oxide in target hollow glass microsphere.

[0016] Preferably, in step two, adjust pH with acetic acid to 5.5-7.

[0017] Preferably, in step three, the stirring speed of homogenizer is 10000-20000rpm, and the stirring time is 2-5min; the inlet temperature of spray drying is 180-400℃, the feeding rate is 5-10%, the inlet air volume is 60-80%, and the air flow is 500-700L / h.

[0018] Preferably, in step two, it also includes different frequency electromagnetic treatment to the obtained white emulsion: put the white emulsion in low frequency electromagnetic oscillation field for 5-15min, then in high frequency electromagnetic oscillation field for 5-10min.

[0019] Preferably, the frequency of low frequency electromagnetic oscillation field is 10-20Hz; the frequency of high frequency electromagnetic oscillation field is 50-100Hz.

[0020] Use of the porous hollow glass microsphere precursor particle prepared by the preparation method as described above in the preparation of hollow glass microspheres.

[0021] The present application at least includes the following beneficial effects: the micropores in the porous hollow glass microsphere precursor particle prepared by the present application replace the bubble nucleation process of the particle in the foaming and ball forming process, shortens the foaming and ball forming time, eliminates the uncoalesced bubbles in the wall of the hollow glass microsphere, reduces the particles with incomplete foaming, and improves the yield and performance of the hollow glass microspheres.

[0022] The present application uses incompletely crosslinked silica sol as the main raw material, and completes the silicate formation and partial crosslinking reaction in the solution doping and spray drying process, without adding a stabilizing dispersant, and uses chemical bonding instead of the traditional soft chemical method of preparing particles to replace the cohesive aggregation of the particles, thereby enhancing the pressure resistance of the precursor particles. The present application uses nanoscale silica sol as the raw material, improves the doping uniformity of the precursor particles, further improves the uniformity of the glass material after foaming and ball forming, and improves the product performance.

[0023] The present application uses different frequency electromagnetic waves to treat the emulsion, which can make the material mixing more uniform, improve the uniformity of the porous hollow glass microsphere precursor particles obtained subsequently, and promote the incompletely crosslinked silica sol to complete the partial silicate formation and crosslinking reaction in the process, thereby further improving the yield and performance of the hollow glass microspheres.

[0024] Other advantages, objects, and features of the present application will be apparent from the following description, and will be understood by those skilled in the art upon reading and understanding the specification. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Scanning electron microscope of the porous hollow glass microsphere precursor particles prepared for Example 1;

[0026] Figure 2 Scanning electron microscope of the internal cross section of the porous hollow glass microsphere precursor particles prepared for Example 1 after grinding and crushing;

[0027] Figure 3 Scanning electron microscope of the hollow glass microspheres prepared for the solid structure hollow glass microsphere precursor particles of Comparative Example 1;

[0028] Figure 4 Simulation of the bubble growth and coalescence and the evolution of the particle morphology in the foaming and ball forming process of the precursor particles;

[0029] Figure 5 Foaming time of the hollow glass microsphere precursor particles with different porosities. DETAILED DESCRIPTION

[0030] The application will be further described in detail below with reference to the accompanying drawings so that those skilled in the art can carry out the application according to the description.

[0031] It should be understood that the terms such as "have", "contain" and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0032] In the following examples, the silica content of the silica sol used is 30±1%, and the particle size is 5-10 nm.

[0033] Example 1

[0034] A method for preparing a porous hollow glass microsphere precursor particle, comprising the following steps:

[0035] Step one, mix 12 mL of silica sol with 12 mL of water, then add 3 mL of water glass with a silica content of 28.56% and a modulus of 3.3 under magnetic stirring at 600 rpm to obtain a mixed solution;

[0036] Step two, dissolve metal acetate (aluminum acetate dihydrate: 0.2927 g; calcium acetate monohydrate: 1.9832 g; magnesium acetate tetrahydrate: 1.4144 g; lithium acetate: 0.8805 g; potassium acetate: 0.2775 g; zinc acetate dihydrate: 0.3585 g) and 0.7082 g of boric acid in 48 mL of water, and add it to the mixed solution obtained in step one under magnetic stirring at 600 rpm, and adjust the pH to 6.5 with acetic acid to obtain a white emulsion;

[0037] Step three, the white emulsion obtained in step two is stirred by a homogenizer at 10000 rpm for 3 min, and then spray dried to obtain a porous hollow glass microsphere precursor particle; wherein the specific conditions of spray drying are: inlet air temperature is 180℃, feeding rate is 7%, inlet air flow is 70%, and air flow is 600 L / h.

[0038] The porous hollow glass microsphere precursor particle prepared in this example and the internal cross section after grinding and crushing are characterized by scanning electron microscopy, and the results are shown in Figures 1-2 It can be seen that the porous hollow glass microsphere precursor particle prepared in this example forms a certain density of micropores inside, indicating that the porous hollow glass microsphere precursor particle is successfully prepared.

[0039] Comparative Example 1

[0040] A method for preparing a solid hollow glass microsphere precursor particle, comprising the following steps:

[0041] Step one, 7.7g white carbon black and 25ml water were mixed, and a solution A was obtained by stirring for 5min at 10000rpm using a homogenizer;

[0042] Step two, metal acetate (aluminum acetate dihydrate: 0.2927g; calcium acetate monohydrate: 1.9832g; magnesium acetate tetrahydrate: 1.4144g; lithium acetate: 0.8805g; sodium acetate trihydrate: 2.1592g; potassium acetate: 0.2775g; zinc acetate dihydrate: 0.3585g) and 0.7082g boric acid were dissolved in 48ml water, which was added to solution A under stirring at 10000rpm using a homogenizer to obtain a doped emulsion;

[0043] Step three, the doped emulsion was continuously stirred at 10000rpm using a homogenizer for 5min, and then spray dried to obtain solid-structured hollow glass microsphere precursor particles; wherein the specific conditions of spray drying were: inlet air temperature was 180℃, feeding rate was 7%, inlet air volume was 70%, and air flow was 600L / h.

[0044] The solid-structured hollow glass microsphere precursor particles prepared in the present example were foamed into balls at 1200℃, wherein the feeding rate was 15kg / h, and hollow glass microspheres were prepared, the scanning electron microscope image is shown in Figure 3 It can be seen that there are incomplete foaming particles in the hollow glass microspheres prepared from the solid-structured hollow glass microsphere precursor particles, and there are uncoalesced bubbles in the ball wall.

[0045] Figure 4 For the simulation of bubble growth and coalescence and the morphology evolution of the precursor particles in the process of foaming the precursor particles into balls, in the process of melting and foaming, the gas generated by the decomposition of the foaming agent gathers into nuclei, which is the first important process, and there is a critical value of the bubble diameter in the melt, when the bubble diameter is greater than the critical value, the bubble can continue to grow, if it is less than the critical value, the bubble collapses. The foaming time of hollow glass microsphere precursor particles with different porosities was studied by fluid mechanics simulation, and the results are shown in Figure 5 It can be seen that the pre-formed micro-pores in the precursor particles of the present application can significantly shorten the bubble nucleation time and improve the foaming efficiency.

[0046] Example 2

[0047] A method for preparing a porous hollow glass microsphere precursor particle, comprising the following steps:

[0048] Step one, 12mL silica sol and 12mL water were mixed, and then 3mL water glass with a silica content of 28.56% and a modulus of 3.3 was added under magnetic stirring at 600rpm to obtain a mixed solution;

[0049] Step two, dissolve the metal acetate (aluminum diacetate: 0.2927g; calcium acetate monohydrate: 1.9832g; magnesium acetate tetrahydrate: 1.4144g; lithium acetate: 0.8805g; potassium acetate: 0.2775g; zinc acetate dihydrate: 0.3585g) and 0.7082g boric acid in 48mL water, and add it to the mixture obtained in step one under 600rpm magnetic stirring, adjust the pH to 6.5 with acetic acid, to obtain a white emulsion, then subject the obtained white emulsion to different frequency electromagnetic treatment: place the white emulsion in a low frequency electromagnetic oscillation field for 10min, and then in a high frequency electromagnetic oscillation field for 7min; wherein the low frequency electromagnetic oscillation field has a frequency of 15Hz, and the high frequency electromagnetic oscillation field has a frequency of 50Hz;

[0050] Step three, spray dry the white emulsion after treatment in step two after stirring for 3min at 10000rpm by a homogenizer, to obtain the porous hollow glass microsphere precursor particles; wherein the specific conditions of spray drying are: the inlet air temperature is 180℃, the feeding rate is 7%, the inlet air volume is 70%, and the air flow is 600L / h.

[0051] Grind the porous hollow glass microsphere precursor particles prepared in this embodiment by rolling, the particles have less breakage, high strength, and uniform internal micropore distribution, which shows that the treatment of the emulsion by different frequency electromagnetic in this embodiment can make the material mixing more uniform, improve the uniformity of the porous hollow glass microsphere precursor particles obtained subsequently, and promote the formation of part of silicates and crosslinking reaction of the incompletely crosslinked silica sol in this process, thereby improving the performance of the prepared precursor particles.

[0052] Although the embodiments of the present application have been disclosed as above, it is not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily realized by those skilled in the art, therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A method for producing a porous hollow glass microsphere precursor particle, characterized by, The method comprises the following steps: Step one, mixing silica sol with water, then adding water glass under magnetic stirring to obtain a mixed solution; wherein the volume ratio of silica sol to water is 1:0.8-1.2; the modulus of the water glass is 3.1-3.4; the amount of water glass is calculated according to the mass ratio of Na2O in the target hollow glass microsphere; Step two, dissolving metal acetate and boric acid into a saturated aqueous solution, adding the solution to the mixed solution obtained in step one under magnetic stirring, and adjusting the pH with acetic acid to obtain a white emulsion; wherein the metal acetate is lithium acetate, potassium acetate, magnesium acetate, calcium acetate, aluminum acetate and zinc acetate; Step three, stirring the white emulsion obtained in step two by a homogenizer, and then performing spray drying to obtain hollow glass microsphere precursor particles with a porous structure; In step two, the obtained white emulsion is further subjected to different frequency electromagnetic treatment: the white emulsion is placed in a low-frequency electromagnetic oscillation field for 5-15 min, and then is placed in a high-frequency electromagnetic oscillation field for 5-10 min; wherein the frequency of the low-frequency electromagnetic oscillation field is 10-20 Hz; the frequency of the high-frequency electromagnetic oscillation field is 50-100 Hz.

2. A method of producing hollow glass microbead precursor particles of porous structure according to claim 1, characterized by, In step one, the silica content in the silica sol is 20-40%, and the particle size is 5-10 nm.

3. The method for preparing porous hollow glass microsphere precursor particles as described in claim 1, characterized in that, In step one, the magnetic stirring speed is 500-700 rpm.

4. The method for preparing porous hollow glass microsphere precursor particles as described in claim 1, characterized in that, In step two, the amount of metal acetate and boric acid is calculated according to the mass ratio of the corresponding oxide in the target hollow glass microsphere.

5. The method for preparing porous hollow glass microsphere precursor particles as described in claim 1, characterized in that, In step two, the pH is adjusted to 5.5-7 with acetic acid.

6. The method for preparing porous hollow glass microsphere precursor particles as described in claim 1, characterized in that, In step three, the stirring speed of the homogenizer is 10,000-20,000 rpm, and the stirring time is 2-5 min; the inlet air temperature of the spray drying is 180-400℃, the feeding rate is 5-10%, the inlet air volume is 60-80%, and the air flow is 500-700 L / h.

7. Use of the hollow glass microsphere precursor particles with a porous structure prepared by the method of any one of claims 1-6 in the preparation of hollow glass microspheres.

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