High-strength hollow glass bead and preparation method thereof

Abstract

The invention discloses a high-strength hollow glass microsphere and a preparation method thereof. The method comprises the following steps: 1) synthesizing a feed liquid system of the hollow glass microsphere; 2) synthesizing precursor particles; and 3) vitrification sintering: conveying the precursor particles by adopting a low-airflow double-plunger pump, and carrying out vitrification sintering to prepare the hollow glass microspheres. According to the method, a low-airflow double-plunger pump is adopted to replace a Venturi jet pump to convey precursor particles, the product with the strength remarkably improved is prepared, and the strength of the product is improved by at least 7% and can be improved by 13% at most.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic fillers and preparation thereof, and particularly relates to high-strength hollow glass microspheres and a preparation method thereof. Background Art

[0002] Hollow glass microspheres are composed of silicate glass system. They are hollow, lightweight micron-sized spherical particles with excellent properties such as low density, high strength, low thermal conductivity, sound insulation, wear resistance, corrosion resistance, radiation protection, low water absorption, strong chemical stability, and good fluidity. At present, the technology for the industrial production of hollow glass microspheres is mainly the solid-phase glass powder method adopted by 3M Company in the United States. The main process technology route is: first, the solid-phase raw materials of the glass system are melted with a foaming agent at high temperature, then quenched with water, ground and crushed, sieved and graded to obtain a coarse product, and then foamed at high temperature to form hollow glass microspheres. The required high temperature is 1200-1600℃, the production energy consumption is large, the process cycle is long, and the particle size distribution is difficult to control. In contrast, the soft chemical method can overcome the potential barriers in the solid-phase reaction through chemical reactions, carry out chemical reactions at lower temperatures and in a gentle reaction process, and then granulate and sinter to achieve the industrial production of hollow glass microspheres. It has the characteristics of low energy consumption, short process flow, low cost, and high yield.

[0003] Hollow glass microspheres are widely used in marine buoyancy materials, paint coating materials, lightweight structural materials, automotive parts materials, thermal insulation materials, composite materials, etc. In recent years, with the rapid development of technology in various industries, higher requirements have been placed on the strength of composite materials and hollow glass microspheres. How to ensure the low density of hollow glass microspheres while improving their strength has become a problem that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing hollow glass microspheres based on a soft chemical method. The hollow glass microspheres prepared by the method have significantly improved strength compared with the conventional soft chemical method, and at the same time have the advantages of high hollow rate, relatively low cost, adjustable performance, and wide sources.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A method for preparing hollow glass microspheres, the method comprising:

[0007] 1) Liquid system for synthesizing hollow glass microspheres;

[0008] 2) synthesizing precursor particles;

[0009] 3) Vitrification and sintering: using a low-gas flow double-plunger pump to transport the precursor particles, and vitrification and sintering to prepare the hollow glass microspheres.

[0010] According to an embodiment of the present invention, the hollow glass microspheres prepared in step 3) have a strength increased by at least 7% compared to the hollow glass microspheres prepared by using a Venturi jet pump.

[0011] According to the embodiment of the present invention, the hollow glass microspheres prepared in step 3) can have a strength that is increased by up to 13%, for example, by up to 12.09%, compared to the hollow glass microspheres prepared by using a Venturi jet pump.

[0012] According to an embodiment of the present invention, the composition of the hollow glass microspheres prepared in step 3) comprises 60-70% SiO2, 8-12% B2O3, 8-12% Na2O, 6-11% CaO, 0.5-2% MgO and 0.5-2% Al2O3, based on a mass ratio of 100%.

[0013] According to an embodiment of the present invention, in step 1), the liquid system includes silicon dioxide, borax, sodium sulfate, sodium nitrate, calcium nitrate, sodium aluminate and magnesium chloride.

[0014] According to an embodiment of the present invention, in step 1), the added content of silicon dioxide, borax, sodium sulfate, sodium nitrate, calcium nitrate, sodium aluminate and magnesium chloride is added according to the component proportion of the hollow glass microspheres prepared in step 3).

[0015] According to an embodiment of the present invention, in step 1), the feed liquid system is evenly dispersed in a homogeneous dispersion system.

[0016] According to an embodiment of the present invention, in step 2), the synthesis temperature of the precursor particles is 350-400 degrees Celsius.

[0017] According to an embodiment of the present invention, in step 3), the powder delivery rate of the low airflow double plunger pump is 20-40 g / min.

[0018] According to an embodiment of the present invention, in step 3), the powder delivery airflow of the low airflow double plunger pump is 0.05-0.35m 3 / h, for example 0.1-0.35m 3 / h, 0.1m 3 / h、0.2m 3 / h、0.3m 3 / h or 0.135m 3 / h.

[0019] According to an embodiment of the present invention, in step 3), the air and gas flow rates of the low airflow dual plunger pump are 16-25m 3 / h.

[0020] The present invention also provides a hollow glass microsphere, which has a strength increased by at least 7% compared with the hollow glass microsphere prepared by using a Venturi jet pump.

[0021] According to the embodiment of the present invention, compared with the hollow glass microspheres prepared by using a Venturi jet pump, the strength can be increased by up to 13%, for example, up to 12.09%.

[0022] According to an embodiment of the present invention, the composition of the hollow glass microspheres, based on a mass ratio of 100%, includes 60-70% SiO2, 8-12% B2O3, 8-12% Na2O, 6-11% CaO, 0.5-2% MgO and 0.5-2% Al2O3.

[0023] According to an embodiment of the present invention, the hollow glass microspheres are prepared by the above-mentioned method for preparing hollow glass microspheres.

[0024] Beneficial effects of the present invention:

[0025] Powder delivery is a key part of the vitrification sintering process. The stability, speed and powder / gas ratio of powder precursor particle delivery have a great influence on the performance of the final product. In the present invention, a low-gas flow double-plunger pump is used to replace the Venturi jet pump to deliver the precursor particles, and a product with significantly improved strength is prepared, and its strength is increased by at least 7% and up to 13%. The strength is calculated by volume survival rate (1-breakage rate N p ), specifically tested by the industry standard JC / T2285-2014 using an isostatic pressure test system.

[0026] The Venturi jet pump requires a large amount of airflow to generate negative pressure vacuum suction to transport the precursor particles, while the double plunger pump only needs a small amount of air, and the negative pressure vacuum suction generated by the plunger is used to transport the precursor particles. Therefore, the Venturi jet pump needs to adjust the pumping rate of the powder by the size of the airflow, while the plunger pump can adjust the pumping rate of the powder by the speed of the plunger movement, and only a small amount of airflow is needed to transport the powder. As the powder delivery speed increases, the powder delivery airflow of the Venturi jet pump increases, while the powder delivery speed of the double plunger pump is not related to the air flow. Therefore, under the condition of the same powder delivery amount, the Venturi jet pump has a larger airflow, which makes the particles move faster, the low-density particles stay in the high-temperature zone for a short time, and the spherical shell is not completely vitrified, resulting in poor strength and low volume survival rate. In addition, the atmospheric flow of the Venturi jet pump causes some small particles in the high-temperature zone to become solid beads, which increases the density. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0028] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0029] Example 1

[0030] The hollow glass microspheres of the present invention are composed of: a silicon dioxide content of 67% (weight ratio, the same below) silicon dioxide is dispersed in an aqueous solution with a solid content of 18%, and soluble salts equivalent to 11% B2O3, 12% Na2O, 8% CaO, 1% MgO and 1% Al2O3 of glass matrix material are added in sequence under stirring, including borax, sodium sulfate, sodium nitrate, calcium nitrate, sodium aluminate and magnesium chloride, and after stirring for 30 minutes, the mixture is sent into an AB double reactor and switched to a homogenous dispersion system for dispersion for 60 minutes to perform homogenization and dispersion treatment of the slurry.

[0031] The dispersed slurry is transported to the high-speed atomizer through a diaphragm pump, and after contacting the co-current high-temperature drying medium (350-400 degrees Celsius), it is dried into precursor particles in a few seconds.

[0032] Subsequently, the dried precursor particles are fed into the spray gun nozzle through a low-airflow double-plunger pump and then enter the in-situ vitrification gasification furnace to obtain hollow glass microspheres; wherein the powder amount of the low-airflow double-plunger pump is listed in Table 2.

[0033] The prepared hollow glass microspheres were tested for density using a true density meter, and the pressure test was performed using an isostatic pressure test system according to the industry standard JC / T2285-2014. Specifically, the hollow glass microspheres will break under isostatic pressure P, and the density change before and after breakage is measured using a gas comparative pycnometer, and then the volume change is obtained by dividing the mass by the density. The volume change rate of the hollow glass microspheres under the isostatic pressure P reflects the breakage rate N. p The isostatic pressure here is the pressure at which the hollow glass microsphere breaks at the breakage rate N p The isostatic pressure under isostatic pressure is, therefore, determined by the volume survival rate (1-N p ) can reflect the strength of hollow glass microspheres.

[0034] Embodiment 2-6

[0035] The difference between Examples 2-6 and Example 1 is that the powder amount, powder delivery airflow and air flow rate are different, which are specifically listed in Table 2.

[0036] Comparative Examples 1-6

[0037] The other steps are the same as those in Example 1, except that the dried precursor particles are subsequently fed into the spray gun nozzle through a venturi jet pump and then into an in-situ vitrification gasification furnace to obtain hollow glass microspheres. The specific powder amount, powder feeding airflow and air flow are listed in Table 1.

[0038] Table 1 and Table 2 also list the test results of the hollow glass microspheres of Examples 1-6 and Comparative Examples 1-6.

[0039] Table 1 Properties of hollow glass microspheres prepared by Venturi jet pumping powder

[0040]

[0041] Table 2 Properties of hollow glass microspheres prepared by low pressure double plunger pumping powder

[0042]

[0043]

[0044] In Table 1 or Table 2, volume survival rate = 1 - damage rate.

[0045] In Table 2, taking Example 1 as an example, its strength improvement (%) relative to the comparative example refers to comparative example 1; taking Example 2 as an example, its strength improvement (%) relative to the comparative example refers to comparative example 2.

[0046] The difference between a Venturi jet pump and a low-airflow dual-plunger pump is that a Venturi jet pump requires a large amount of airflow to generate negative pressure vacuum suction to transport precursor particles, while a dual-plunger pump only requires a small amount of air, and the negative pressure vacuum suction generated by the plunger to transport precursor particles. Therefore, a Venturi jet pump needs to adjust the powder pumping rate by the size of the airflow, while a plunger pump can adjust the powder pumping rate by the speed of the plunger movement, and only a small amount of airflow is needed to transport the powder.

[0047] The above is an exemplary description of the embodiments of the present invention. However, the protection scope of the present invention is not limited to the above embodiments. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing hollow glass microspheres, characterized in that: The method comprises: 1) Liquid system for synthesizing hollow glass microspheres; 2) synthesizing precursor particles; 3) Vitrification and sintering: using a low-gas flow double-plunger pump to transport the precursor particles, and vitrification and sintering to prepare the hollow glass microspheres.

2. The method according to claim 1, characterized in that Step 3) The components of the hollow glass microspheres prepared, based on a mass ratio of 100%, include 60-70% SiO2, 8-12% B2O3, 8-12% Na2O, 6-11% CaO, 0.5-2% MgO and 0.5-2% Al2O3.

3. The method according to claim 1 or 2, characterized in that: In step 1), the liquid system includes silicon dioxide, borax, sodium sulfate, sodium nitrate, calcium nitrate, sodium aluminate and magnesium chloride.

4. The method according to claim 3, characterized in that In step 1), the added content of silicon dioxide, borax, sodium sulfate, sodium nitrate, calcium nitrate, sodium aluminate and magnesium chloride is added according to the component proportion of the hollow glass microspheres prepared in step 3).

5. The method according to any one of claims 1 to 4, characterized in that: In step 2), the synthesis temperature of the precursor particles is 350-400 degrees Celsius.

6. The method according to any one of claims 1 to 5, characterized in that: In step 3), the powder delivery rate of the low airflow double plunger pump is 20-40 g / min.

7. The method according to any one of claims 1 to 6, characterized in that: In step 3), the powder delivery airflow of the low airflow double plunger pump is 0.05-0.35m 3 / h.

8. The method according to any one of claims 1 to 7, characterized in that: In step 3), the air and gas flow rates of the low-flow dual-piston pump are 16-25m 3 / h.

9. A hollow glass microsphere, characterized in that: The hollow glass microspheres are prepared according to the method according to any one of claims 1-8.

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