Polyurea reinforcing method of hollow microspheres and modification equipment thereof

Abstract

The invention discloses a polyurea reinforcing method and modification equipment for hollow microbeads, and relates to the technical field of strength improvement of the hollow microbeads, and the method comprises the following steps: step 1, proportioning a dispersing agent and a polyurea component according to the component ratio of 1: (25-30), preheating to 40-70 DEG C, and setting the pressure of a dispersing agent spray gun and a polyurea spray gun to be 12-17MPa; secondly, the hollow microspheres are loaded into a stock bin, and the pressure of a hollow microsphere spray gun is set to range from 1 MPa to 3 MPa; and 3, starting the negative-pressure polyurea recovery device, the dispersing agent spray gun, the polyurea spray gun, the negative-pressure hollow microsphere recovery device and the hollow microsphere spray gun. According to the invention, by utilizing the characteristics of rapid curing and high strength of polyurea, the purpose of enhancing the strength of the hollow microspheres is achieved by coating the hollow microspheres; the modification equipment is simple in structure, low in cost and easy to install, and a polyurea spraying coating surface is formed through different component proportions and temperature control of the two-component spraying gun in cooperation with the negative pressure recovery device.

Description

Technical Field

[0001] The present invention relates to the technical field of hollow microsphere strength enhancement, and in particular to a polyurea reinforcement method for hollow microspheres and a modification device thereof. Background Art

[0002] Hollow microspheres are hollow, tiny spherical materials containing inert gas. Their density is generally 0.1-0.7g / cm3 and their particle size range is generally 5-200μm. Hollow microparticles are unique and stable. Due to their low density, low thermal conductivity, low dielectric constant, and chemical corrosion resistance, they are widely used in military, civilian, and other high-tech fields, such as solid buoyancy materials, petrochemicals, emulsion explosives, thermal insulation and fireproof materials, invisible sound-absorbing materials, advanced insulation materials, chemical product additives, and low-density ablative materials. However, with the continuous development of science and technology and the continuous development of new application areas, the performance requirements of hollow microspheres are becoming increasingly higher, especially the compressive strength. For example, when added to polymer materials to prepare low-density materials, especially solid buoyancy materials, the hollow microspheres are easily broken due to their relatively low compressive strength, resulting in a weak addition effect. Currently, commercial hollow microspheres are difficult to meet the requirements of ultra-high pressure and low density. Therefore, improving the strength of hollow microspheres will not only help expand the application field of hollow microspheres, but also help improve the overall performance of composite materials using hollow microspheres as additives. According to the compressive strength formula of hollow glass microspheres, the current domestic approach to preparing high-pressure resistant hollow glass microspheres is to increase the elastic modulus of glass.

[0003] Theoretical compressive strength calculation formula of hollow glass microspheres: (1) P—compressive strength of hollow glass microspheres, E—elastic modulus of glass, h—wall thickness of hollow glass microspheres, r—radius of hollow glass microspheres, µ—Poisson’s ratio of glass.

[0004] According to the theoretical calculation formula for hollow glass microspheres, increasing the elastic modulus E of the glass used to prepare hollow glass microspheres can effectively improve the compressive strength of the hollow glass microspheres. This is the main idea for preparing high-pressure resistant hollow glass microspheres in China. Chinese patent CN102320743B optimizes the design of glass composition, increases the elastic modulus of glass, and improves the chemical stability of glass to prepare high-pressure resistant hollow glass microspheres. The performance indicators of the microspheres reach a density of 0.2 to 0.6 g / cm3, a compressive strength of 3 to 130 MPa, and a particle size of ≤80 μm. Chinese patents CN106865992A and CN115925239A all use the same idea. However, this method has an upper limit on the level of improvement in the compressive strength of hollow glass microspheres. Research has found that the unevenness of the wall thickness and particle size distribution of the glass microspheres can cause changes in the strength of hollow glass microspheres. Without changing the original composition and elastic modulus of the hollow glass microspheres, traditional commercial hollow microspheres are mainly treated with silane coupling agents. This is done by introducing organic functional groups on the surface of the microspheres to form a bridging layer between the inorganic microspheres and the organic polymer, thereby improving the compatibility between the two. Surface-modified hollow microspheres generally exhibit better mechanical properties. Modification can also reduce the surface energy of the microspheres, reduce aggregation, and improve the fluidity and processing properties of the composite material. In addition, surface modification helps improve the heat resistance, chemical resistance, and aging resistance of the composite material. However, it has little effect on improving the strength of the hollow microspheres. How to enhance the overall strength of the hollow microspheres through surface improvement has become very urgent. Summary of the Invention

[0005] The present invention aims to provide a method for reinforcing hollow microspheres with polyurea and a modification device thereof. Polyurea is a high-performance polymer compound produced by the reaction of an isocyanate component and an amino compound component. Polyurea has excellent physical properties, including high tensile strength, elongation, tear strength, and abrasion resistance. It also has good chemical stability and can resist corrosion from a variety of acids, bases, and organic solvents. In addition, polyurea has good thermal stability and can maintain its performance at higher temperatures, and has good adhesion and can firmly adhere to the surfaces of various substrates. Because polyurea has a high tensile strength, which means it can withstand considerable tensile forces without breaking, it becomes practical to increase the strength of hollow glass microspheres by surface modification with polyurea.

[0006] Polyurea modification typically involves combining polyurea with other polymers or functional compounds to improve its original properties or impart new functionality. By blending polyurea with other polymers, the mechanical properties, heat resistance, and chemical resistance of the composite can be improved. Blending modification can be achieved through physical mixing or chemical reaction to form copolymers. The synthesis of polyurea typically involves the reaction of isocyanates with amines to form urea bonds. This reaction can be represented as: R−NCO+H₂N−R′→R−NH−CO−NH−R′, where R−NCO represents the isocyanate group and H₂N−R′ represents the amine compound.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A polyurea reinforcement method for hollow microspheres comprises the following steps: Step 1: Mix the dispersant and polyurea in a weight ratio of 1:25-30, preheat to 40°C-70°C, and set the pressure of the dispersant spray gun and the polyurea spray gun to between 12MPa-17MPa; Step 2: Load the hollow microspheres into the hopper and set the pressure of the hollow microsphere spray gun to between 1MPa and 3MPa; Step 3: Start the polyurea negative pressure recovery device, the dispersant spray gun, the polyurea spray gun, the hollow microsphere negative pressure recovery device and the hollow microsphere spray gun; At this time, the dispersant spray gun and polyurea spray gun drive the two-component materials under the action of the high-pressure pump, fully mix them at the nozzle, form a polyurea coating, and then coat the hollow microbeads; Step 4: The polyurea negative pressure recovery device collects the remaining polyurea, and the hollow microsphere negative pressure recovery device automatically unloads and air cools; Step 5: Detect the reinforcing effect of hollow microbead polyurea.

[0008] A device for modifying hollow microspheres reinforced with polyurea comprises a reaction tank, wherein a dispersant spray gun and a hollow microsphere spray gun are provided on one side of the middle portion of the reaction tank, and a polyurea negative pressure recovery device is provided on the other side of the middle portion of the reaction tank, wherein the polyurea negative pressure recovery device is used to recover polyurea under negative pressure; a hollow microsphere spray gun is provided at the bottom of the reaction tank, and a hollow microsphere negative pressure recovery device is provided at the top of the reaction tank, wherein the hollow microspheres are used to recover the hollow microspheres after polyurea modification.

[0009] As a further solution of the present invention: the polyurea spray gun and the dispersant spray gun are both connected to a metering pump and a high-pressure pump for controlling the ratio of the dispersant to the polyurea and controlling the speed and quality of the spraying by pressure.

[0010] As a further solution of the present invention: the hollow microsphere spray gun is connected to an air pressure pump to control the pressure spray speed to control the quality of the hollow microsphere modification.

[0011] As a further solution of the present invention: the polyurea negative pressure recovery device guides the direction and width of the polyurea spray coating surface through the combination of negative pressure and pressure of the polyurea spray gun.

[0012] As a further solution of the present invention: the hollow microsphere negative pressure recovery device adjusts the time for the hollow microspheres to pass through the polyurea coating surface by combining negative pressure with the pressure of the hollow microsphere spray gun.

[0013] As a further solution of the present invention: the injection ends of the polyurea spray gun and the dispersant spray gun both pass through a mixing tube, and the mixing tube is used to mix the polyurea and the dispersant.

[0014] As a further solution of the present invention: a spiral coil is provided on the outside of the mixing tube, a heat preservation tube is provided on the outside of the spiral coil, and hot air is passed into the spiral coil to heat the mixing tube.

[0015] As a further solution of the present invention: a telescopic tube is provided on one side of the upper end of the reaction tank, the telescopic tube is connected to the hollow microsphere negative pressure recovery device through a pipeline, and an electric telescopic rod is provided on the telescopic tube, which is used to drive the telescopic tube to extend and retract.

[0016] As a further solution of the present invention: the reaction tank includes an outer shell and an inner shell, a cavity is formed between the outer shell and the inner shell, two partitions are arranged inside the cavity, and the partitions divide the cavity into three areas, and the temperatures in the three areas are different.

[0017] Beneficial effects of the present invention: The present invention utilizes the characteristics of rapid curing and high strength of polyurea to coat hollow microspheres to achieve the purpose of enhancing the strength of hollow microspheres. The modification equipment of the present invention has a simple structure, low cost, and is easy to install. By using different component ratios and temperature control of a two-component spray gun and cooperating with a negative pressure recovery device, a polyurea spray coating surface is formed. The time of polyurea coating modification is controlled by the hollow microsphere spray gun and the negative pressure recovery device. By combining different parameters, accurate, stable, and appropriate polyurea modification can be provided for hollow powder sintering systems under different working conditions, thereby effectively improving the strength of the modified hollow microspheres. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is an electron microscope image of the thickness of the hollow microsphere polyurea reinforced according to the present invention; Figure 2 This is an electron microscope image of the batch polyurea-reinforced hollow microspheres of the present invention; Figure 3 It is a schematic diagram of the overall structure of the modification equipment of the present invention; Figure 4It is a side structural schematic diagram of the modification device of the present invention; Figure 5 Schematic diagram of the structure of the mixing tube of the present invention; Figure 6 Schematic diagram of the internal structure of the thermal insulation pipe of the present invention; Figure 7 It is a schematic diagram of the internal structure of the reaction tank of the present invention.

[0020] In the figure: 1. Polyurea spray gun; 2. Dispersant spray gun; 3. Hollow microbead spray gun; 4. Reaction tank; 5. Polyurea negative pressure recovery device; 6. Hollow microbead negative pressure recovery device; 7. Insulation tube; 71. Spiral coil; 8. Electric telescopic rod; 9. Telescopic tube; 10. Mixing tube; 41. Outer shell; 42. Inner shell; 43. Partition. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] See Figures 1 to 2 As shown, the present invention is a polyurea reinforcement method for hollow microspheres; Example 1 The density of the hollow microsphere raw powder was selected to be 0.38g / cm3, and the standard compressive strength was selected to be 3,800Psi (20% crushing rate). The dispersant and polyurea components were mixed in a weight ratio of 1:25. The preheating temperature was 40°C, the dual-gun pressure was set to 12MPa, and the hollow microsphere spray gun pressure was set to 1MPa. The polyurea negative pressure recovery device and the polyurea gun were started, and then the hollow microsphere negative pressure recovery device and the hollow microsphere spray gun were started. After continuing to operate for 60s, the collected polyurea modified hollow microspheres were air-cooled and tested for strength. The strength can be increased from 3,800Psi (20% crushing rate) to 8000Psi (20% crushing rate).

[0023] Example 2 The density of the hollow microsphere raw powder was selected to be 0.38g / cm3, and the standard compressive strength was selected to be 3,800Psi (20% crushing rate). The dispersant and polyurea components were mixed in a weight ratio of 1:30. The preheating temperature was 70°C, the dual-gun pressure was set to 12MPa, and the hollow microsphere spray gun pressure was set to 1MPa. The polyurea negative pressure recovery device and the polyurea gun were started, and then the hollow microsphere negative pressure recovery device and the hollow microsphere spray gun were started. After continuing to operate for 60s, the collected polyurea modified hollow microspheres were air-cooled and tested for strength. The strength can be increased from 3,800Psi (20% crushing rate) to 8500Psi (20% crushing rate).

[0024] Example 3: The density of the hollow microsphere raw powder was selected to be 0.38g / cm3, and the standard compressive strength was selected to be 3,800Psi (20% crushing rate). The dispersant and polyurea components were mixed in a weight ratio of 1:30. The preheating temperature was 70°C, the dual-gun pressure was set to 17MPa, and the hollow microsphere spray gun pressure was set to 1MPa. The polyurea negative pressure recovery device and the polyurea gun were started, and then the hollow microsphere negative pressure recovery device and the hollow microsphere spray gun were started. After continuing to operate for 60s, the collected polyurea modified hollow microspheres were air-cooled and tested for strength. The strength can be increased from 3,800Psi (20% crushing rate) to 10000Psi (20% crushing rate).

[0025] Example 4: The density of the hollow microsphere raw powder was selected to be 0.38g / cm3, and the standard compressive strength was 3,800Psi (20% crushing rate). The dispersant and polyurea components were mixed in a weight ratio of 1:30. The preheating temperature was 70°C, the dual-gun pressure was set to 17MPa, and the hollow microsphere spray gun pressure was set to 3MPa. The polyurea negative pressure recovery device and the polyurea gun were started, and then the hollow microsphere negative pressure recovery device and the hollow microsphere spray gun were started. After continuing to operate for 60s, the collected polyurea modified hollow microspheres were air-cooled and tested for strength. The strength can be increased from 3,800Psi (20% crushing rate) to 8000Psi (20% crushing rate).

[0026] The present invention mainly utilizes the characteristics of rapid curing and high strength of polyurea and achieves the purpose of enhancing the strength of hollow microspheres by coating the hollow microspheres.

[0027] Example 5 See Figures 3 to 7As shown, a polyurea-enhanced modification device for hollow microspheres includes a reaction tank 4, a dispersant spray gun 2 and a hollow microsphere spray gun 3 are provided on one side of the middle portion of the reaction tank 4, and a polyurea negative pressure recovery device 5 is provided on the other side of the middle portion of the reaction tank 4. The polyurea negative pressure recovery device 5 is used to recover polyurea under negative pressure; the hollow microsphere spray gun 3 is provided at the bottom of the reaction tank 4, and the hollow microsphere negative pressure recovery device 6 is provided at the top of the reaction tank 4 for recovering the hollow microspheres after polyurea modification.

[0028] The polyurea spray gun 1 and the dispersant spray gun 2 are both connected to a metering pump and a high-pressure pump to control the ratio of the dispersant to the polyurea and the speed and quality of the spraying by pressure. A high-precision metering pump or an air pressure control system can be used to adjust the mixing ratio of the two materials in real time (for example, from 1:1 to 10:1) to meet different modification requirements.

[0029] The hollow microsphere spray gun 3 is connected to an air pressure pump and is used to control the pressure spray speed to control the quality of the hollow microsphere modification.

[0030] The polyurea negative pressure recovery device 5 guides the direction and width of the polyurea spray coating surface by combining the negative pressure with the pressure of the polyurea spray gun 1 .

[0031] The hollow microbead negative pressure recovery device 6 adjusts the time for the hollow microbeads to pass through the polyurea coating surface by combining negative pressure with the pressure of the hollow microbead spray gun 3 to achieve the optimal coating modification effect.

[0032] The spraying ends of the polyurea spray gun 1 and the dispersant spray gun 2 both pass through a mixing tube 10 , and the mixing tube 10 is used to mix polyurea and dispersant.

[0033] The outside of the mixing tube 10 is provided with a spiral coil 71 , and the outside of the spiral coil 71 is provided with a heat preservation tube 7 . Hot air is passed into the spiral coil 71 to heat the mixing tube 10 , thereby ensuring the fluidity of the polyurea through temperature control.

[0034] A telescopic tube 9 is provided on one side of the upper end of the reaction tank 4. The telescopic tube 9 is connected to the hollow microsphere negative pressure recovery device 6 through a pipeline. An electric telescopic rod 8 is provided on the telescopic tube 9. The electric telescopic rod 8 is used to drive the telescopic tube 9 to extend and retract; the pressure adjustment of the hollow microsphere negative pressure recovery device 6 is coordinated by driving the telescopic tube 9 to adjust.

[0035] The reaction tank 4 includes an outer shell 41 and an inner shell 42, a cavity is formed between the outer shell 41 and the inner shell 42, and two partitions 43 are arranged inside the cavity. The partitions 43 divide the cavity into three areas. The setting of the partitions 43 ensures that the temperatures in the three areas are different, which are controlled by a temperature control device; low temperature is used at the inlet to prevent adhesion, high temperature is used in the middle to promote drying, and cooling and solidification are used at the outlet; it is set as an outer shell and an inner shell, on the one hand, for heating, and on the other hand, no structure is set inside the reaction tank 4, which is conducive to the modification of hollow microspheres.

[0036] Specific working process: Using a high-precision metering pump or air pressure control system, the mixing ratio of the two materials is adjusted in real time (for example, from 1:1 to 10:1) to meet different modification requirements. The dispersant and polyurea components are mixed in a ratio of 1:25-30, preheated to 40℃-70℃, and the pressure of dispersant spray gun 2 and polyurea spray gun 1 is set between 12MPa-17MPa. Hollow microbeads are loaded into the hopper, and the pressure of hollow microbead spray gun 3 is set between 1MPa-3MPa. The polyurea negative pressure recovery device 5 (adjusting the frequency converter to the specified frequency), dispersant spray gun 2, polyurea spray gun 1, hollow microbead negative pressure recovery device 6 (adjusting the frequency converter to the specified frequency), and hollow microbead spray gun 3 are activated. The dispersant spray gun 2 and polyurea spray gun 1 drive the two-component material under the action of a high-pressure pump (up to 5000psi) to ensure that the two components are fully mixed at the nozzle to form a uniform polyurea coating. High-pressure spraying not only improves the atomization effect of the material, but also adapts to long pipeline transportation and reduces material residue; the dispersant spray gun 2, polyurea spray gun 1 and hollow microbead spray gun 3 are all positive pressure; then under the action of negative pressure, the polyurea negative pressure recovery device collects the remaining polyurea, the hollow microbead negative pressure recovery device automatically unloads and air-cools, and the negative pressure in the hollow microbead negative pressure recovery device is less than that of the polyurea negative pressure recovery device; finally, the hollow microbead polyurea enhancement effect is tested.

[0037] In summary, the modifier of this invention utilizes two-component, two-fluid atomization technology, delivering two different modifying materials through independent pipelines and achieving instant mixing at the nozzle. High-pressure mixing technology is employed: the equipment uses a high-pressure pump (up to 5000 psi) to drive the two-component materials, ensuring thorough mixing of components A and B at the nozzle, forming a uniform polyurea coating. High-pressure spraying not only improves material atomization but also adapts to long pipeline transportation, reducing material residue.

[0038] The present invention uses a high-precision metering pump or an air pressure control system to adjust the mixing ratio of the two materials (for example, 1:1 to 10:1) in real time to meet different modification requirements.

[0039] The present invention can avoid pre-mixing failure: traditional pre-mixing may cause material denaturation (such as solvent volatilization and viscosity change), while instant mixing of two components can maintain material activity.

[0040] The present invention utilizes a heater, spiral coil 71, and mixing tube 10 to rapidly heat the material components and maintain a constant spray temperature. This design addresses the fluidity issues of high-viscosity materials at low temperatures while also preventing material degradation caused by high temperatures. It is particularly suitable for fast-curing materials such as polyurea.

[0041] The present invention adopts micro-droplet mixing technology: two materials are sheared by high-speed airflow during atomization to form nanometer / micrometer droplets, thereby improving mixing uniformity.

[0042] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A polyurea reinforcement method for hollow microspheres, characterized in that: The following steps are involved: Step 1: Mix the dispersant and polyurea in a weight ratio of 1:25-30, preheat to 40°C-70°C, and set the pressure of the dispersant spray gun and the polyurea spray gun to between 12MPa-17MPa; Step 2: Load the hollow microspheres into the hopper and set the pressure of the hollow microsphere spray gun to between 1MPa and 3MPa; Step 3: Start the polyurea negative pressure recovery device, the dispersant spray gun, the polyurea spray gun, the hollow microsphere negative pressure recovery device and the hollow microsphere spray gun; At this time, the dispersant spray gun and polyurea spray gun drive the two-component materials under the action of the high-pressure pump, fully mix them at the nozzle, form a polyurea coating, and then coat the hollow microbeads; Step 4: The polyurea negative pressure recovery device collects the remaining polyurea, and the hollow microsphere negative pressure recovery device automatically unloads and air cools; Step 5: Detect the reinforcing effect of hollow microbead polyurea.

2. A polyurea-enhanced modification device for hollow microspheres, characterized in that: The invention comprises a reaction tank (4), wherein a dispersant spray gun (2) and a hollow microsphere spray gun (3) are provided on one side of the middle of the reaction tank (4), and a polyurea negative pressure recovery device (5) is provided on the other side of the middle of the reaction tank (4), and the polyurea negative pressure recovery device (5) is used for negative pressure recovery of polyurea; a hollow microsphere spray gun (3) is provided at the lower part of the reaction tank (4), and a hollow microsphere negative pressure recovery device (6) is provided at the upper part of the reaction tank (4), and is used for recovering hollow microspheres modified by polyurea.

3. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: The polyurea spray gun (1) and the dispersant spray gun (2) are both connected to a metering pump and a high-pressure pump, and are used to control the ratio of the dispersant to the polyurea and to control the speed and quality of the spraying by pressure.

4. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: The hollow microsphere spray gun (3) is connected to an air pressure pump and is used to control the pressure spray speed to control the quality of the hollow microsphere modification.

5. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: The polyurea negative pressure recovery device (5) guides the direction and width of the polyurea spray coating surface by combining negative pressure with the pressure of the polyurea spray gun (1).

6. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: The hollow microbead negative pressure recovery device (6) adjusts the time it takes for the hollow microbeads to pass through the polyurea coating surface by combining the negative pressure with the pressure of the hollow microbead spray gun (3).

7. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: The spray ends of the polyurea spray gun (1) and the dispersant spray gun (2) both pass through a mixing tube (10), and the mixing tube (10) is used to mix the polyurea and the dispersant.

8. The polyurea-reinforced modification device for hollow microspheres according to claim 7, characterized in that: A spiral coil (71) is provided on the outside of the mixing tube (10), and a heat preservation tube (7) is provided on the outside of the spiral coil (71). Hot air is passed through the spiral coil (71) to heat the mixing tube (10).

9. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: A telescopic tube (9) is provided on one side of the upper end of the reaction tank (4), and the telescopic tube (9) is connected to the hollow microsphere negative pressure recovery device (6) through a pipeline. An electric telescopic rod (8) is provided on the telescopic tube (9), and the electric telescopic rod (8) is used to drive the telescopic tube (9) to extend and retract.

10. The polyurea-reinforced modification device for hollow microspheres according to claim 2, characterized in that: The reaction tank (4) comprises an outer shell (41) and an inner shell (42), wherein a cavity is formed between the outer shell (41) and the inner shell (42), and two partitions (43) are provided inside the cavity. The partitions (43) divide the cavity into three areas, and the temperatures in the three areas are different.

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