A microcapsule coating process and preparation method for rubber foaming agent

Abstract

This invention relates to the field of rubber additive preparation technology, and provides a microcapsule for rubber foaming agents. By weight, it comprises the following raw materials: core material: 50-80 parts chemical foaming agent, 1-5 parts dispersant, and 100-200 parts deionized water; wall material: 20-40 parts methyl methacrylate monomer, 10-30 parts ethylene-octene copolymer emulsion grafted with maleic anhydride, 0.5-2 parts initiator, and an appropriate amount of pH adjuster. The apparatus includes a premixing tank, a main reactor, a secondary reactor, a dehydration chamber, a heating tank, and a heat exchange tank, all connected in series via a diaphragm pump. By employing a double-layer composite wall material—an inner layer of rigid and tough barrier and an outer layer of flexible and compatible material—the problem of easy breakage during mixing of traditional single-layer brittle wall materials is solved. The 70°C hot water discharged from the main reactor is cooled to 50°C by the heat exchange tank and supplied to the secondary reactor, achieving cascaded utilization of thermal energy. A reversing component allows for switching between heating, water replenishment, and cleaning pipelines, resulting in a compact structure and simple operation.

Description

Technical Field

[0001] This invention relates to the field of rubber additive preparation technology, specifically to a microcapsule encapsulation process and preparation method for rubber foaming agents. Background Technology

[0002] Rubber foam materials are widely used in automotive sealing strips, building seals, and sporting goods due to their excellent shock absorption, sound insulation, and lightweight properties. The foaming agent is the core additive in the rubber foaming process; its decomposition temperature and rate directly determine the uniformity of the cell structure and the physical properties of the finished product. Commonly used chemical foaming agents, such as azodicarbonamide and 4,4'-oxobisbenzenesulfonyl hydrazine, typically have decomposition temperatures between 160 and 210°C, while the vulcanization temperature of most rubbers is in the range of 140 to 180°C. This mismatch between the foaming agent's decomposition temperature and the rubber's vulcanization temperature is the fundamental reason for uneven cell structure and difficulty in controlling the foaming ratio.

[0003] To address this issue, industrially, foaming agents are typically microencapsulated. The physical isolation provided by the wall material delays or regulates the decomposition temperature of the foaming agent. However, existing microencapsulation technologies often use single wall materials such as melamine resin and urea-formaldehyde resin, which suffer from low encapsulation rates, brittle wall materials prone to breakage during mixing, and poor compatibility between the wall material and the rubber matrix leading to uneven dispersion. Furthermore, existing encapsulation processes are mostly intermittent operations, with each step running independently, resulting in significant batch-to-batch quality variations and failing to meet the stability requirements of large-scale production. Additionally, the inner and outer layer encapsulation require different temperatures, and traditional heating systems with independent temperature control suffer from low thermal efficiency and high energy consumption. Therefore, a microencapsulation process and preparation method for rubber foaming agents are needed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a microcapsule encapsulation process and preparation method for rubber foaming agents. This solves the problems of existing microcapsule encapsulation technologies, such as the use of a single brittle wall material that is easily broken during mixing, leading to uncontrolled foaming; batch-to-batch quality instability due to independent operation of each step in the encapsulation process; and low thermal energy utilization due to independent temperature control of the inner and outer layers.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A microcapsule for a rubber foaming agent, comprising, by weight, the following raw materials:

[0007] Core material: 50-80 parts chemical foaming agent, 1-5 parts dispersant, 100-200 parts deionized water;

[0008] Wall material: 20-40 parts methyl methacrylate monomer, 10-30 parts ethylene-octene copolymer emulsion grafted with maleic anhydride, 0.5-2 parts initiator, and appropriate amount of pH adjuster;

[0009] The preparation steps of the microcapsules for the rubber foaming agent are as follows:

[0010] Step 1, Premixing and Dispersion: Add the foaming agent to a premixing tank containing deionized water, add the dispersant simultaneously, and start the stirring roller and ultrasonic stirrer to disperse the particles and prepare a uniform and stable foaming agent suspension.

[0011] Step 2, Inner Layer Coating: The suspension obtained in Step 1 is transported to the main reactor through a pipeline. High-purity nitrogen is introduced to replace the air in the reactor and an inert atmosphere is maintained. Methyl methacrylate monomer is added and thoroughly mixed. Under the protection of inert gas, the temperature is raised to 60-80°C and stirred to allow the monomer to reach adsorption equilibrium on the surface of the foaming agent particles. Then, an initiator solution is slowly added dropwise to allow polymethyl methacrylate to deposit on the surface of the foaming agent particles to form the inner wall material, thus obtaining an inner layer coated microcapsule suspension.

[0012] Step 3, outer coating: The inner coating microcapsule suspension obtained in Step 2 is transported to the outer coating vessel through a pipeline. The pH value is adjusted to 8-10, and an ethylene-octene copolymer emulsion grafted with maleic anhydride is added. Physical fusion and hydrogen bond-assisted coating are carried out under stirring conditions at 40-60℃ for 1-3 hours, so that the outer wall material is uniformly coated on the surface of the inner wall material, resulting in a double-layer coated microcapsule suspension.

[0013] Step 4, Post-processing: The double-layer coated microcapsule suspension obtained in Step 3 is temporarily stored for precipitation and kept in suspension by low-speed stirring. Then, it is sent to a horizontal spiral sedimentation centrifuge for solid-liquid separation by diaphragm pump. The filter cake is then sent to a vacuum drying oven and vacuum dried at 40-60℃ for 12-24 hours to finally obtain the finished product microcapsules for rubber foaming agent.

[0014] A microcapsule encapsulation device for a rubber foaming agent, comprising:

[0015] A premixing tank is equipped with a motor-driven stirring roller at the top center of the premixing tank for macroscopic mixing and circulation of the foaming agent suspension. Ultrasonic stirrers are arranged around the stirring roller for microscopic dispersion of foaming agent agglomerates in the high-concentration zone at the bottom of the tank. The stirring roller and the ultrasonic stirrers work together to achieve uniform suspension of the foaming agent in the aqueous medium.

[0016] The main reactor is used for in-situ polymerization and coating of the inner layer of PMMA. A secondary reactor is arranged side by side on its right side for electrostatic adsorption and physical fusion coating of the outer layer of POE-g-MAH. The inner walls of the main reactor and the secondary reactor are fixedly connected to inner tanks. The inner walls of the inner tanks are equipped with stirring components. The premixing tank, the main reactor, and the secondary reactor are connected in series in sequence through connecting pipes with diaphragm pumps. Spray heads for cleaning the inside of the tanks are fixedly connected to the top and rear of the premixing tank, the main reactor, and the secondary reactor.

[0017] The dehydration chamber has its input end connected to the output end of the secondary reactor via a connecting pipe with a diaphragm pump. The inner wall of the dehydration chamber is equipped with a dehydration component driven by a motor, which is used to perform solid-liquid separation on the double-layer coated microcapsule suspension.

[0018] A heating tank is located behind the main reactor and is used to provide 70°C circulating hot water to the device. A temperature sensor is installed on the front top of the heating tank to monitor the water temperature in real time. Multiple heating tubes are installed at the bottom of the heating tank. The top of the heating tank is connected to the main reactor via a reversing assembly to deliver hot water to the heating tubes of the main reactor to heat the materials inside. The output end of the heating tubes in the secondary reactor is connected to a water supply pipe via a heat exchange assembly to return the cooled water to the reactor for replenishment.

[0019] Preferably, the stirring assembly includes a stirring shaft driven by a motor at the top of the inner tank. Impellers are fixedly connected to the top and middle of the stirring shaft to generate axial circulating flow to uniformly mix the materials in the tank. Stirring blades are fixedly connected to the bottom of the stirring shaft. Multiple scrapers are fixedly connected to the outer wall of the stirring blades to rotate close to the inner wall of the inner tank to scrape off the materials adhering to the wall.

[0020] Preferably, the dehydration assembly includes a separation tank mounted on the inner wall of the dehydration chamber via a bracket. A solid treatment pipe for discharging the dehydrated solid filter cake is fixedly connected to the left side of the separation tank, and a liquid discharge pipe for discharging the clarified liquid is fixedly connected to the right side of the separation tank. A transport roller is coaxially arranged on the inner wall of the separation tank. The outer edge of the spiral blades of the transport roller is close to the inner wall of the separation tank to push the deposited solid filter cake toward the solid treatment pipe. A rotating shaft is rotatably connected to the outer wall of the input end of the transport roller. The input end of the rotating shaft is connected to the output end of the secondary reactor to introduce the suspension into the interior of the transport roller.

[0021] Preferably, the reversing assembly includes an adjusting pipe located at the top of the heating tank. A partition ring is fixedly connected to the inner wall of the right side of the adjusting pipe, dividing the inner cavity of the adjusting pipe into a water supply chamber and a water drain chamber. A reversing rod is rotatably connected to the inner wall of the partition ring. The reversing rod is a hollow cavity with water inlets around its central perimeter for introducing hot water from the heating tank into the inner cavity of the reversing rod. A reversing block is fixedly connected to the outer wall of the reversing rod, and an outlet is provided on the bottom outer wall of the reversing block for guiding the hot water to different downstream pipelines. A piston block is fixedly connected to the right end of the reversing rod to block the water supply line when water is discharged. A connecting block is fixedly connected to the left end of the reversing rod. A drive rod driven by a cylinder is rotatably connected to the end of the connecting block. A connecting sleeve is fitted on the outer wall of the connecting block. A guide groove is opened on the outer wall of the connecting sleeve. A protrusion embedded in the groove of the connecting sleeve is fixedly connected to the outer wall of the connecting block. By extending and retracting the drive rod, the reversing rod can be driven to perform a compound motion of axial movement and circumferential rotation under the constraint of the guide groove of the connecting sleeve, so as to realize the switching of the hot water delivery channel.

[0022] Preferably, the right end of the regulating pipe is connected to the water supply pipe, the bottom middle of the drain chamber of the regulating pipe is connected to the heating tank, the bottom left side of the drain chamber of the regulating pipe is connected to the input end of the heating pipe in the main reactor through a connecting pipe, and the bottom left side of the regulating pipe is connected to the spray head through a connecting pipe.

[0023] Preferably, a connecting frame is fixedly connected to the outer wall of the drive rod, and the connecting frame is slidably connected to a bracket on which an air pump is installed. A drive shaft is installed on the outer wall of the connecting frame, and a drive shaft driven by a motor is connected to the outer wall of the drive shaft through two meshing gears. The rotation of the drive shaft can drive the drive shaft to rotate synchronously.

[0024] Preferably, both ends of the drive shaft are fixedly connected to connecting discs. A lever is fixedly connected to the outer wall of the connecting disc. A drive rod is provided on the outer wall of the connecting disc. Two protrusions are fixedly connected to the outer wall of the drive rod. The bottom of the drive rod is connected to a drive rod two via two meshing gears. The end of the drive rod two is connected to a drive shaft two via two meshing bevel gears. A drive chamber is provided at the end of the drive shaft two. Two meshing gears are rotatably connected to the inner wall of the drive chamber. The drive shaft two can drive the gears to rotate to achieve quantitative pumping of water flow. One of the drive chambers is connected to a connecting pipe connected to a heating pipe, and the other drive chamber is connected to a connecting pipe connected to a spray head.

[0025] Preferably, the heat exchange assembly includes a heat exchange tank located at the output end of the heating tube in the secondary reactor. The heat exchange tank is fixedly connected to partitions on both its upper and lower sides, dividing it into a heat exchange chamber and two cooling chambers. A connecting pipe connects the two cooling chambers. The top cooling chamber of the heat exchange tank is connected to the output end of the heating tube in the secondary reactor, the bottom cooling chamber is connected to a water supply pipe, the top of the heat exchange chamber is connected to the input end of the heating tube in the secondary reactor, and the bottom of the heat exchange chamber is connected to the output end of the heating tube in the main reactor.

[0026] Preferably, the top of the premixing tank, the main reactor, and the secondary reactor are all fixedly connected with multiple addition pipes for connecting additives. The output ends of the premixing tank, the main reactor, and the secondary reactor are all equipped with reversing valves. One output end of the reversing valve is connected to a connecting pipe for conveying materials to the next process, and the other output end is connected to a drain pipe for discharging cleaning wastewater.

[0027] Working principle:

[0028] In the premixing and dispersion stage, firstly, the foaming agent powder and dispersant are added to the deionized water in the premixing tank. The motor at the top center of the premixing tank drives the stirring roller to rotate. The stirring roller drives the material in the tank to circulate macroscopically and prevents particles from depositing on the tank wall and bottom. At the same time, the ultrasonic stirrers around the stirring roller are started and work in an intermittent mode, with 30 seconds of ultrasonic stirring followed by 30 seconds of pause, and the operation is repeated. The amplitude rod of the ultrasonic stirrer is inserted into the tank from the top at an angle and downwards. In the high concentration area at the bottom of the tank, the foaming agent agglomerates are broken up one by one. Through the coordinated action of the stirring roller and the ultrasonic stirrer in space and time, the macroscopic mixing and microscopic dispersion of the foaming agent particles can be completed to form a uniform and stable foaming agent suspension.

[0029] During the inner coating stage, after premixing and dispersion, the suspension is pumped into the inner tank of the main reactor through a diaphragm pump and conveying pipeline connected to the bottom outlet of the premixing tank. The main reactor is used for in-situ polymerization and coating of the inner PMMA layer. The stirring assembly inside the reactor is started, and the motor at the top of the inner tank drives the stirring shaft to rotate. The impeller at the top and middle of the stirring shaft generates an axial circulation flow to uniformly mix the materials in the reactor. The stirring blades at the bottom of the stirring shaft and multiple scrapers fixed to the outer wall rotate close to the inner wall of the inner tank to scrape off the material adhering to the wall and prevent scaling. After all the suspension has been pumped in, high-purity nitrogen is introduced into the reactor. The air is replaced with gas to maintain an inert atmosphere and prevent oxygen inhibition of polymerization. Methyl methacrylate monomer is added through an addition tube, the temperature is raised to 70°C and stirred at a constant temperature to allow the monomer to reach adsorption equilibrium on the surface of the foaming agent particles. Then, the initiator solution is slowly added in two batches. During this process, methyl methacrylate undergoes in-situ polymerization under the action of the initiator. The generated polymethyl methacrylate molecular chains are gradually deposited on the surface of the foaming agent particles, so that polymethyl methacrylate is deposited on the surface of the foaming agent particles to form the inner wall material, resulting in an inner layer coated microcapsule suspension.

[0030] In the outer coating stage, after the inner coating is completed, the suspension is transported through a diaphragm pump connected to the bottom outlet of the main reactor to the inner tank of the secondary reactor via pipeline. The secondary reactor is used for the outer POE-g-MAH electrostatic adsorption and physical fusion coating. The heating medium for the outer coating reactor comes from the hot water discharged from the heating pipe of the main reactor, which is cooled by the heat exchange components. The bottom of the heat exchange chamber of the heat exchange tank is connected to the output end of the heating pipe in the main reactor, receiving the 70℃ hot water discharged from the main reactor as a heat source. The top of the heat exchange chamber is connected to the input end of the heating pipe in the secondary reactor. The hot water is cooled to 50℃ in the heat exchange chamber and then sent to the heating pipe of the secondary reactor. The materials in the reactor were heated, and after the suspension was completely transferred to the secondary reactor, the stirring assembly was turned on. Sodium carbonate solution was added dropwise through the addition tube to adjust the pH of the suspension to 9. Then, an ethylene-octene copolymer emulsion grafted with maleic anhydride was added. Physical fusion and hydrogen bond-assisted coating were carried out under stirring at 50°C. During this process, positively charged emulsion particles were adsorbed onto the surface of negatively charged PMMA microcapsules under electrostatic attraction, and physical fusion and chain entanglement occurred under thermal motion to form a uniform and dense outer wall material. After the reaction was completed, heating was stopped, stirring was continued, and the mixture was naturally cooled to room temperature to obtain a double-layer coated microcapsule suspension.

[0031] In the solid-liquid separation and washing stage, after the outer coating is completed, the double-layer coated microcapsule suspension is sent to the dehydration chamber through a diaphragm pump connected to the output end of the secondary reactor for solid-liquid separation. The suspension enters the coaxially arranged transport roller inside the separation tank via a rotating shaft. The transport roller is driven by a motor to rotate. Under the action of centrifugal force, the solid microcapsule particles are deposited on the inner wall of the separation tank to form a filter cake layer. The clarified liquid is discharged from the liquid outlet pipe on the right side of the separation tank. The outer edge of the spiral blades of the transport roller rotates close to the inner wall of the separation tank, pushing the deposited solid filter cake towards the solid processing pipe on the left side and discharging it. The process requires multiple washing and circulating centrifugation. Subsequently, the dried filter cake is sent to a vacuum drying oven for drying. After drying, the powdered product is taken out, which is the finished microcapsule product for rubber foaming agent.

[0032] During the hot water supply and reversing phase, the heating tank provides 70℃ circulating hot water to the entire system. Multiple electric heating tubes installed at the bottom of the heating tank heat the water stored inside. A temperature sensor on the top front side monitors the water temperature in real time. When the water temperature reaches 70℃, a cylinder at the top of the heating tank drives a drive rod to extend or retract. The end of the drive rod is connected to a reversing rod via a connecting block. A protrusion on the outer wall of the connecting block is embedded in a guide groove of the connecting sleeve. The extension and retraction of the drive rod drives the reversing rod to perform a combined axial movement and circumferential rotation under the constraint of the guide groove of the connecting sleeve, thus switching the hot water delivery channel. Hot water enters the regulating pipe through the middle of the bottom of the drain chamber, and then enters the inner cavity of the reversing rod through the inlet. When the reversing rod rotates to the heating position, the outlet is aligned with the connecting pipe on the left side of the bottom of the drain chamber, delivering 70℃ hot water to the heating pipe of the main reactor. When the reversing rod rotates to the water replenishment position, the piston block at the right end of the reversing rod opens the water replenishment pipe, and water flows through the water replenishment chamber to replenish softened water to the heating tank. When the reversing rod rotates to the cleaning position, the outlet is aligned with the connecting pipe connected to the spray head, delivering cleaning hot water to the spray heads at the top of the premixing tank, the main reactor, and the secondary reactor to clean the inside of the tanks.

[0033] In the stage of cascaded utilization of thermal energy, the 70°C hot water discharged after heat exchange in the heating tubes of the main reactor enters the bottom of the heat exchange chamber of the heat exchange tank, serving as a heat source to flow through the heat exchange chamber and heat the fluid in the cooling chamber on the other side. The top cooling chamber of the heat exchange tank is connected to the output end of the heating tubes in the secondary reactor, receiving the low-temperature hot water discharged from the secondary reactor. The low-temperature hot water flows into the bottom cooling chamber through the connecting pipe. During this process, it absorbs heat from the heat exchange chamber and rises in temperature. Then, it flows back to the heating tank for water replenishment through the water supply pipe. The top of the heat exchange chamber of the heat exchange tank sends hot water cooled to 50°C into the heating tubes of the secondary reactor to provide constant temperature heating for the outer coating. Through heat exchange between the heat exchange chamber and the cooling chamber of the heat exchange tank, the waste heat of the high-temperature hot water discharged from the main reactor is fully recovered and utilized. At the same time, the softened water in the water supply pipe is preheated before being sent into the heating tank, realizing cascaded utilization of thermal energy and significantly reducing heating energy consumption.

[0034] During the cleaning phase, after each production batch is completed, the pipelines at the output ends of each reactor are switched using a reversing valve, changing the output end from the connecting pipe to the drain pipe. The heating tank delivers cleaning hot water to the spray head at the top of each reactor through the reversing assembly. The spray head evenly sprays the cleaning hot water onto the inner wall of the reactor and the stirring assembly. At the same time, the stirring assembly rotates to assist in the cleaning. The cleaning wastewater is discharged from the bottom of the reactor and discharged into the wastewater treatment system through the drain pipe connected to the reversing valve. After cleaning, the reactors are purged and dried with nitrogen, and each reactor returns to the standby state, ready for the next production batch.

[0035] This invention provides a microcapsule encapsulation process and preparation method for rubber foaming agents. It has the following beneficial effects:

[0036] 1. This invention employs a double-layer composite coating structure with PMMA as the inner wall material and POE-g-MAH as the outer wall material. The inner PMMA layer provides a rigid skeleton and excellent gas barrier properties, effectively isolating the foaming agent from external contact and delaying the decomposition temperature. The outer POE-g-MAH layer is flexible and elastic, and is not easily broken under the high shear force of rubber compounding. At the same time, the maleic anhydride groups form hydrogen bonds or chemical bonds with the rubber matrix, significantly improving the dispersion uniformity and interfacial bonding of microcapsules in rubber. This fundamentally solves the problem of easy breakage and uncontrolled foaming caused by traditional single-layer brittle wall materials during processing.

[0037] 2. This invention uses a heat exchange tank connected in series between the main reactor and the secondary reactor to cool the 70°C hot water discharged from the main reactor to 50°C and supply it to the secondary reactor. At the same time, the low-temperature hot water discharged from the secondary reactor and the room-temperature softened water in the water supply pipe absorb heat from the heat exchange tank in the cooling chamber and then heat up and flow back to the water supply. This heat energy cascade utilization design allows the energy of the same stream of hot water to serve the inner layer polymerization and outer layer coating processes successively. Waste heat is fully recovered and used for water supply preheating, which greatly reduces the overall heating energy consumption and achieves efficient energy utilization.

[0038] 3. This invention achieves automatic switching of hot water between three channels: heating the main reactor, replenishing water circulation, and cleaning spraying, by using the extension and retraction of the drive rod in the reversing assembly to drive the reversing rod to perform a composite motion of axial movement and circumferential rotation under the constraint of the guide groove of the connecting sleeve. The purely mechanical reversing structure eliminates the need for multiple independent valves and complex electronic control, and the switching action is precise and reliable. It integrates the three pipelines of hot water supply, replenishing water circulation, and online cleaning into one, simplifying the pipeline layout and operation process. Attached Figure Description

[0039] Figure 1 This is a perspective view of the present invention;

[0040] Figure 2 This is a schematic diagram of the heating tank of the present invention;

[0041] Figure 3 This is a schematic diagram of the premix tank of the present invention;

[0042] Figure 4 This is a schematic diagram of the interior of the premix tank of the present invention;

[0043] Figure 5 This is a schematic diagram of the reaction vessel of the present invention;

[0044] Figure 6 This is a schematic diagram of the inner tank of the present invention;

[0045] Figure 7 This is a schematic diagram of the interior of the inner tank of the present invention;

[0046] Figure 8 This is a schematic diagram of the dehydration chamber of the present invention;

[0047] Figure 9 This is a schematic diagram of the interior of the dehydration chamber of the present invention;

[0048] Figure 10 This is a schematic diagram of the transport roller of the present invention;

[0049] Figure 11 This is a schematic diagram of the interior of the heat exchange tank of the present invention;

[0050] Figure 12 This is a schematic diagram of the interior of the heating tank of the present invention;

[0051] Figure 13 This is a schematic diagram of the regulating tube of the present invention;

[0052] Figure 14 This is a schematic diagram of the inside of the regulating tube of the present invention;

[0053] Figure 15 This is a schematic diagram of the drive shaft of the present invention;

[0054] Figure 16 This is a schematic diagram of the interior of the drive compartment of the present invention.

[0055] The components include: 1. Premixing tank; 2. Main reactor; 3. Secondary reactor; 4. Dehydration chamber; 5. Heating tank; 6. Heat exchange tank; 7. Stirring roller; 8. Ultrasonic stirrer; 9. Spray head; 10. Inner tank; 11. Heating tube; 12. Stirring shaft; 13. Impeller; 14. Stirring blade; 15. Scraper; 16. Separation tank; 17. Conveying roller; 18. Solids processing pipe; 19. Liquid discharge pipe; 20. Rotating shaft; 21. 21. Regulating pipe; 22. Water supply pipe; 23. Temperature sensor; 24. Heating element; 25. Partition plate; 26. Connecting pipe; 27. Separating ring; 28. Reversing rod; 29. ​​Reversing block; 30. Connecting block; 31. Connecting sleeve; 32. Drive rod; 33. Connecting frame; 34. Drive compartment; 35. Drive shaft; 36. Drive shaft one; 37. Connecting plate; 38. Drive rod one; 39. Drive rod two; 40. Drive shaft two. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Example:

[0058] As one aspect of this application, embodiments of the present invention provide microcapsules for rubber foaming agents, comprising, by weight, the following raw materials:

[0059] Core material: 65 parts chemical foaming agent, 3.5 parts dispersant, 150 parts deionized water;

[0060] Wall material: 30 parts methyl methacrylate monomer, 15 parts ethylene-octene copolymer emulsion grafted with maleic anhydride, 1.2 parts initiator, and appropriate amount of pH adjuster;

[0061] A method for preparing a rubber foaming agent by microcapsule encapsulation, the specific steps of which are as follows:

[0062] Step 1, Premixing and Dispersion: Add the foaming agent to a premixing tank containing deionized water, add the dispersant simultaneously, and start the stirring roller and ultrasonic stirrer to disperse the particles and prepare a uniform and stable foaming agent suspension.

[0063] Step 2, Inner Layer Coating: The suspension obtained in Step 1 is transported to the main reactor through a pipeline. High-purity nitrogen is introduced to replace the air in the reactor and an inert atmosphere is maintained. Methyl methacrylate monomer is added and thoroughly mixed. Under the protection of inert gas, the temperature is raised to 70°C and stirred to allow the monomer to reach adsorption equilibrium on the surface of the foaming agent particles. Then, an initiator solution is slowly added dropwise to allow polymethyl methacrylate to deposit on the surface of the foaming agent particles to form the inner wall material, thus obtaining an inner layer coated microcapsule suspension.

[0064] Step 3, outer coating: The inner coating microcapsule suspension obtained in Step 2 is transported to the outer coating vessel through a pipeline, the pH value is adjusted to 9, and the ethylene-octene copolymer emulsion grafted with maleic anhydride is added. Physical fusion and hydrogen bond-assisted coating are carried out under stirring at 50°C for 2 hours, so that the outer wall material is uniformly coated on the surface of the inner wall material, and a double-layer coated microcapsule suspension is obtained.

[0065] Step 4, Post-processing: The double-layer coated microcapsule suspension obtained in Step 3 is temporarily stored for precipitation and kept in suspension by low-speed stirring. Then, it is sent to a horizontal spiral sedimentation centrifuge for solid-liquid separation by diaphragm pump. The filter cake is then sent to a vacuum drying oven and vacuum dried at 50°C for 18 hours to finally obtain the finished rubber foaming agent microcapsules.

[0066] Based on the above-described method for preparing microcapsule coatings for rubber foaming agents, as another aspect of this application, a microcapsule coating apparatus for rubber foaming agents includes:

[0067] Please see the appendix Figure 1 -Appendix Figure 3 The premix tank 1 has a motor-driven stirring roller 7 installed at the top center for macroscopic mixing and circulation of the foaming agent suspension. Ultrasonic stirrers 8 are installed around the stirring roller 7 to microscopically disperse the foaming agent agglomerates in the high concentration zone at the bottom of the tank. The stirring roller 7 and the ultrasonic stirrers 8 work together to achieve uniform suspension of the foaming agent in the aqueous medium.

[0068] Specifically, during premixing and dispersion, the foaming agent powder and dispersant are added to the deionized water in the premixing tank 1. The motor drives the stirring roller 7 to rotate, causing the material in the tank to circulate macroscopically and prevent particle deposition. At the same time, the ultrasonic stirrer 8 operates in intermittent mode, with its amplitude rod inserted from the top of the tank at an angle downwards to break up the foaming agent agglomerates in the high concentration area at the bottom of the tank. Through the synergistic action of the stirring roller 7 and the ultrasonic stirrer 8, a uniform and stable foaming agent suspension is formed.

[0069] Please see the appendix Figure 2 Appendix Figure 5 and attached Figure 6The main reactor 2 is used for in-situ polymerization and coating of the inner PMMA layer. A secondary reactor 3 is arranged side-by-side on its right side for electrostatic adsorption and physical fusion coating of the outer POE-g-MAH layer. Both the main reactor 2 and the secondary reactor 3 have inner tanks 10 fixedly connected to their inner walls. A stirring assembly is installed on the inner wall of the inner tank 10. The premixing tank 1, the main reactor 2, and the secondary reactor 3 are connected in series via a connecting pipe equipped with a diaphragm pump. Spray heads 9 for cleaning the interior of the premixing tank 1, the main reactor 2, and the secondary reactor 3 are fixedly connected to their top rear sides. The stirring assembly includes a motor-driven stirring shaft 12 at the top of the inner tank 10. Impellers 13 are fixedly connected to the middle part of the vessel to generate axial circulation flow to uniformly mix the materials in the vessel. Stirring blades 14 are fixedly connected to the bottom of the stirring shaft 12. Multiple scrapers 15 are fixedly connected to the outer wall of the stirring blades 14 to rotate close to the inner wall of the inner tank 10 to scrape off the materials adhering to the wall. Multiple addition pipes for connecting additives are fixedly connected to the top of the premixing tank 1, the main reactor 2, and the secondary reactor 3. Reversing valves are installed at the output ends of the premixing tank 1, the main reactor 2, and the secondary reactor 3. One output end of the reversing valve is connected to the connecting pipe to transport the material to the next process, and the other output end is connected to the drain pipe to discharge the cleaning wastewater.

[0070] Specifically, the foaming agent suspension dispersed in the premix tank 1 is pumped into the inner tank 10 of the main reactor 2 via a diaphragm pump connected to the bottom outlet of the tank. The stirring assembly inside the reactor is then activated, with the stirring shaft 12 driven by a motor to rotate. The impeller 13, fixed at its top and middle, generates an axial circulation flow to uniformly mix the materials inside the reactor. The scraper 15 on the outer wall of the bottom stirring blades 14 rotates close to the inner wall of the inner tank 10, scraping away adhering materials to prevent scaling. After all the suspension has been pumped in, methyl methacrylate monomer and initiator are added to the reactor through an addition pipe. Simultaneously, high-purity nitrogen is introduced to remove oxygen and maintain an inert atmosphere. The heating tank 5 delivers 70°C hot water to the heating pipe 11 of the main reactor 2 via a reversing assembly, heating the materials inside the reactor at a constant temperature of 70°C. The reaction proceeds as follows: polymethyl methacrylate (PMMA) is deposited on the surface of the foaming agent particles to form the inner wall material. After the reaction is complete, heating is stopped, and the mixture is stirred and allowed to cool naturally to room temperature to obtain an inner layer microcapsule suspension. The inner layer microcapsule suspension is then switched to the connecting pipe channel through the bottom reversing valve of the main reactor 2 and pumped to the inner tank 10 of the secondary reactor 3 via a diaphragm pump. The heating medium of the heating pipe 11 of the secondary reactor 3 is provided by the hot water discharged from the main reactor 2 after being cooled to 50°C by the heat exchange component. After all the suspension has been transferred, the stirring component is turned on, and sodium carbonate solution is added dropwise through the adding tube to adjust the pH value to 9. Then, POE-g-MAH emulsion is added, and the reaction is carried out at 50°C with stirring for 2 hours to make the outer wall material uniformly coat the surface of the inner wall material, thus obtaining a double-layer microcapsule suspension.

[0071] Please see the appendix Figure 7 -Appendix Figure 9The input end of the dehydration chamber 4 is connected to the output end of the secondary reactor 3 via a connecting pipe with a diaphragm pump. The inner wall of the dehydration chamber 4 is equipped with a dehydration assembly driven by a motor, which is used to perform solid-liquid separation on the double-layer coated microcapsule suspension. The dehydration assembly includes a separation tank 16 mounted on the inner wall of the dehydration chamber 4 via a bracket. A solid treatment pipe 18 for discharging the dehydrated solid filter cake is fixedly connected to the left side of the separation tank 16, and a liquid discharge pipe 19 for discharging the clarified liquid is fixedly connected to the right side of the separation tank 16. A transport roller 17 is coaxially arranged on the inner wall of the separation tank 16. The outer edge of the spiral blades of the transport roller 17 is close to the inner wall of the separation tank 16, which is used to push the deposited solid filter cake toward the solid treatment pipe 18. A rotating shaft 20 is rotatably connected to the outer wall of the input end of the transport roller 17. The input end of the rotating shaft 20 is connected to the output end of the secondary reactor 3, which is used to guide the suspension into the interior of the transport roller 17.

[0072] Specifically, after the reaction in the secondary reactor 3 is completed, the double-layer coated microcapsule suspension is switched to the connecting pipe channel via a reversing valve and pumped into the dehydration chamber 4 by a diaphragm pump. The suspension enters the interior of the coaxially arranged transport roller 17 inside the separation tank 16 via the rotating shaft 20. The motor drives the transport roller 17 to rotate. Under the action of centrifugal force, the solid microcapsule particles are deposited on the inner wall of the separation tank 16 to form a filter cake layer. The clarified liquid is discharged from the liquid outlet pipe 19 on the right side of the separation tank 16. The outer edge of the spiral blades of the transport roller 17 rotates close to the inner wall of the separation tank 16, pushing the deposited solid filter cake towards the solid treatment pipe 18 on the left side of the separation tank 16 and discharging it into the external washing container. After the filter cake is washed with water and repeatedly dehydrated, the final dehydrated wet filter cake is collected. Then, the final dehydrated wet filter cake is spread flat on a stainless steel tray and sent into a vacuum drying oven. It is dried in a vacuum environment for 18 hours. After drying, the powdered product is taken out, which is the finished microcapsule product for rubber foaming agent.

[0073] Please see the appendix Figure 11 Appendix Figure 13 and attached Figure 14The heating tank 5 is located behind the main reactor 2 and is used to provide 70°C circulating hot water to the device. A temperature sensor 23 is installed on the front top of the heating tank 5 to monitor the water temperature inside the tank in real time. Multiple heating tubes 24 for heating are installed at the bottom of the heating tank 5. The top of the heating tank 5 is connected to the main reactor 2 through a reversing assembly to deliver hot water to the heating tubes 11 of the main reactor 2 to heat the materials inside the reactor. The output end of the heating tubes 11 in the secondary reactor 3 is connected to a water supply pipe through a heat exchange assembly. 22, used to return the cooled warm water to the replenishment water, the reversing assembly includes a regulating pipe 21 located at the top of the heating tank 5, a partition ring 27 fixedly connected to the inner wall of the right side of the regulating pipe 21, the partition ring 27 dividing the inner cavity of the regulating pipe 21 into a replenishment chamber and a drain chamber, a reversing rod 28 rotatably connected to the inner wall of the partition ring 27, the reversing rod 28 is a hollow cavity, with water inlets on all four sides of its middle part, used to introduce hot water from the heating tank 5 into the inner cavity of the reversing rod 28, and a reversing... The reversing block 29 has an outlet on its bottom outer wall to direct hot water to different downstream pipelines. The right end of the reversing rod 28 is fixedly connected to a piston block to block the water supply line when water is discharged. The left end of the reversing rod 28 is fixedly connected to a connecting block 30. The end of the connecting block 30 is rotatably connected to a cylinder-driven drive rod 32. The outer wall of the connecting block 30 is fitted with a connecting sleeve 31. The outer wall of the connecting sleeve 31 has a guide groove. The outer wall of the connecting block 30 is fixedly connected to a protrusion embedded in the groove of the connecting sleeve 31. The extension and retraction of the drive rod 32 can drive the reversing rod 28 to perform a compound motion of axial movement and circumferential rotation under the constraint of the guide groove of the connecting sleeve 31, thereby realizing the switching of the hot water delivery channel. The right end of the regulating pipe 21 is connected to the water supply pipe 22. The bottom middle of the drain chamber of the regulating pipe 21 is connected to the heating tank 5. The bottom left side of the drain chamber of the regulating pipe 21 is connected to the input end of the heating pipe 11 in the main reaction vessel 2 through a connecting pipe. The bottom left side of the regulating pipe 21 is connected to the spray head 9 through a connecting pipe.

[0074] Specifically, multiple heating elements 24 at the bottom of the heating tank 5 are energized to heat the water stored inside. A temperature sensor 23 monitors the water temperature in real time. When the water temperature reaches 70℃, the reversing assembly is activated, and a cylinder drives the drive rod 32 to extend and retract. The end of the drive rod 32 is connected to the reversing rod 28 via a connecting block 30. A protrusion on the outer wall of the connecting block 30 is embedded in a guide groove on the outer wall of the connecting sleeve 31. The extension and retraction of the drive rod 32 drives the reversing rod 28 to perform a combined axial movement and circumferential rotation under the constraint of the guide groove in the connecting sleeve 31. When the reversing rod 28 rotates to the heating position, the hot water in the heating tank 5 enters the regulating pipe 21 through the middle of the bottom of the drain chamber, and then... Water enters the inner cavity of the reversing rod 28 and exits through the outlet at the bottom of the reversing block 29. It is then transported along the connecting pipe on the left side of the bottom of the drainage chamber of the regulating pipe 21 to the input end of the heating pipe 11 of the main reactor 2 to heat the material inside the main reactor 2. When the reversing rod 28 rotates to the water replenishment position, the piston block at the right end of the reversing rod 28 exits the separator ring 27 pipeline. Softened water enters the heating tank 5 for water replenishment through the channel connected to the water replenishment pipe 22 at the right end of the regulating pipe 21. When the reversing rod 28 rotates to the cleaning position, the outlet of the reversing block 29 is aligned with the connecting pipe of the spray head 9. Hot water is transported through this pipeline to the spray head 9 at the top of the premix tank 1, the main reactor 2, and the secondary reactor 3 to clean the inside of the tanks.

[0075] Please see the appendix Figure 13 Appendix Figure 15 and attached Figure 16 A connecting frame 33 is fixedly connected to the outer wall of the drive rod 32. The connecting frame 33 is slidably connected to a bracket on which an air pump is mounted. A drive shaft 36 is mounted on the outer wall of the connecting frame 33. The outer wall of the drive shaft 36 is connected to a drive shaft 35 driven by a motor through two meshing gears. The rotation of the drive shaft 35 can drive the drive shaft 36 to rotate synchronously. Connecting discs 37 are fixedly connected to both ends of the drive shaft 36. A lever is fixedly connected to the outer wall of the connecting disc 37. A drive rod 38 is provided on the outer wall of the connecting disc 37. The outer wall of the drive rod 38 is fixedly connected to... There are two protrusions. The bottom of the transmission rod 38 is connected to the transmission rod 39 via two meshing gears. The end of the transmission rod 39 is connected to the transmission shaft 40 via two meshing bevel gears. The end of the transmission shaft 40 is provided with a drive chamber 34. The inner wall of the drive chamber 34 is rotatably connected to two meshing gears. The transmission shaft 40 can drive the gears to rotate to realize the quantitative pumping of water flow. One drive chamber 34 is connected to the connecting pipe of the heating pipe 11, and the other drive chamber 34 is connected to the connecting pipe of the spray head 9.

[0076] Specifically, the motor drives the drive shaft 35 to rotate. The drive shaft 35 drives the transmission shaft 36 to rotate synchronously through two meshing gears. The connecting discs 37 at both ends of the transmission shaft 36 rotate with the shaft. The paddles on the outer wall of the connecting discs 37 periodically actuate the two protrusions on the outer wall of the transmission rod 38, converting the continuous rotational motion into the intermittent rotational motion of the transmission rod 38. The transmission rod 38 drives the transmission rod 39 to rotate through the bottom meshing gear. The transmission rod 39 drives the transmission shaft 40 to rotate through the bevel gear transmission. The transmission shaft 40 drives the two meshing gears in the drive chamber 34 to rotate, realizing the quantitative pumping of water. One drive chamber 34 is connected in series to the connecting pipe connected to the heating pipe 11, and quantitatively pumps hot water to the heating pipe 11 of the main reactor 2 or the secondary reactor 3; the other drive chamber 34 is connected in series to the connecting pipe connected to the spray head 9, and quantitatively pumps the cleaning hot water to the spray head of each reactor.

[0077] Please see the appendix Figure 10 and attached Figure 12 The heat exchange assembly includes a heat exchange tank 6 located at the output end of the heating pipe 11 inside the secondary reactor 3. The heat exchange tank 6 is fixedly connected to both the upper and lower sides by partitions 25, which divide the heat exchange tank 6 into a heat exchange chamber and two cooling chambers. A connecting pipe 26 is provided between the two cooling chambers and they are connected through the connecting pipe 26. The top cooling chamber of the heat exchange tank 6 is connected to the output end of the heating pipe 11 inside the secondary reactor 3, and the bottom cooling chamber of the heat exchange tank 6 is connected to the water supply pipe 22. The top of the heat exchange chamber of the heat exchange tank 6 is connected to the input end of the heating pipe 11 inside the secondary reactor 3, and the bottom of the heat exchange chamber of the heat exchange tank 6 is connected to the output end of the heating pipe 11 inside the main reactor 2.

[0078] Specifically, the 70°C hot water discharged after heat exchange in the heating tube 11 of the main reactor 2 enters the bottom of the heat exchange chamber of the heat exchange tank 6 and flows through the heat exchange chamber as a heat source. The low-temperature hot water discharged after heat exchange in the heating tube 11 of the secondary reactor 3 enters the top cooling chamber of the heat exchange tank 6 and flows into the bottom cooling chamber through the connecting pipe 26. During the flow of the low-temperature hot water between the two cooling chambers, it exchanges heat with the high-temperature heat source in the heat exchange chamber through the partition 25, absorbs heat and rises in temperature, and flows back to the heating tank 5 to replenish water through the water replenishment pipe 22. The hot water in the heat exchange chamber cools down to 50°C after releasing heat and is discharged from the top of the heat exchange chamber and sent to the input end of the heating tube 11 of the secondary reactor 3 to provide constant temperature heating for the outer coating. The heat exchange tank 6 realizes the heat exchange between the high-temperature hot water discharged from the main reactor 2 and the low-temperature hot water discharged from the secondary reactor 3 and the replenishment water, so as to achieve the purpose of cascade utilization of thermal energy.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A microcapsule for a rubber foaming agent, comprising, by weight, the following raw materials: Core material: 50-80 parts chemical foaming agent, 1-5 parts dispersant, 100-200 parts deionized water; Wall material: 20-40 parts methyl methacrylate monomer, 10-30 parts ethylene-octene copolymer emulsion grafted with maleic anhydride, 0.5-2 parts initiator, and appropriate amount of pH adjuster; The preparation steps of the microcapsules for the rubber foaming agent are as follows: Step 1, Premixing and Dispersion: Add the foaming agent to a premixing tank containing deionized water, add the dispersant simultaneously, and start the stirring roller and ultrasonic stirrer to disperse the particles and prepare a uniform and stable foaming agent suspension. Step 2, Inner Layer Coating: The suspension obtained in Step 1 is transported to the main reactor through a pipeline. High-purity nitrogen is introduced to replace the air in the reactor and an inert atmosphere is maintained. Methyl methacrylate monomer is added and thoroughly mixed. Under the protection of inert gas, the temperature is raised to 60-80°C and stirred to allow the monomer to reach adsorption equilibrium on the surface of the foaming agent particles. Then, an initiator solution is slowly added dropwise to allow polymethyl methacrylate to deposit on the surface of the foaming agent particles to form the inner wall material, thus obtaining an inner layer coated microcapsule suspension. Step 3, outer coating: The inner coating microcapsule suspension obtained in Step 2 is transported to the outer coating vessel through a pipeline. The pH value is adjusted to 8-10, and an ethylene-octene copolymer emulsion grafted with maleic anhydride is added. Physical fusion and hydrogen bond-assisted coating are carried out under stirring conditions at 40-60℃ for 1-3 hours, so that the outer wall material is uniformly coated on the surface of the inner wall material, resulting in a double-layer coated microcapsule suspension. Step 4, Post-processing: The double-layer coated microcapsule suspension obtained in Step 3 is temporarily stored for precipitation and kept in suspension by low-speed stirring. Then, it is sent to a horizontal spiral sedimentation centrifuge for solid-liquid separation by diaphragm pump. The filter cake is then sent to a vacuum drying oven and vacuum dried at 40-60℃ for 12-24 hours to finally obtain the finished product microcapsules for rubber foaming agent.

2. A microcapsule encapsulation process for a rubber foaming agent, used to prepare the microcapsules for the rubber foaming agent as described in claim 1, characterized in that, include: A premixing tank (1) is equipped with a motor-driven stirring roller (7) at the top center of the premixing tank (1) for macroscopic mixing and circulation of the foaming agent suspension. Ultrasonic stirrers (8) are provided around the stirring roller (7) for microscopic dispersion of foaming agent agglomerates in the high concentration zone at the bottom of the tank. The stirring roller (7) and the ultrasonic stirrer (8) work together to achieve uniform suspension of the foaming agent in the aqueous medium. The main reactor (2) is used for in-situ polymerization coating of the inner layer PMMA. A secondary reactor (3) is arranged side by side on its right side for electrostatic adsorption and physical fusion coating of the outer layer POE-g-MAH. The inner walls of the main reactor (2) and the secondary reactor (3) are fixedly connected to an inner tank (10). The inner wall of the inner tank (10) is equipped with a stirring assembly. The premix tank (1), the main reactor (2) and the secondary reactor (3) are connected in series through a connecting pipe with a diaphragm pump. The top rear side of the premix tank (1), the main reactor (2) and the secondary reactor (3) are fixedly connected to a spray head (9) for cleaning the inside of the tank. The dehydration chamber (4) has its input end connected to the output end of the secondary reactor (3) via a connecting pipe with a diaphragm pump. The inner wall of the dehydration chamber (4) is provided with a dehydration component driven by a motor, which is used to perform solid-liquid separation on the double-layer coated microcapsule suspension. Heating tank (5) is located on the rear side of the main reactor (2) and is used to provide 70°C circulating hot water to the device. A temperature sensor (23) is installed on the front top of the heating tank (5) to monitor the water temperature in the tank in real time. Multiple electric heating tubes (24) for heating are installed at the bottom of the heating tank (5). The top of the heating tank (5) is connected to the main reactor (2) through a reversing assembly to deliver hot water to the heating tube (11) of the main reactor (2) to heat the material in the reactor. The output end of the heating tube (11) in the secondary reactor (3) is connected to a water supply pipe (22) through a heat exchange assembly to return the warm water after heat exchange and cooling to the water supply.

3. The microcapsule encapsulation device for rubber foaming agent according to claim 2, characterized in that, The stirring assembly includes a stirring shaft (12) driven by a motor at the top of the inner tank (10). Impellers (13) are fixedly connected to the top and middle of the stirring shaft (12) to generate axial circulation flow to uniformly mix the materials in the tank. Stirring blades (14) are fixedly connected to the bottom of the stirring shaft (12). Multiple scrapers (15) are fixedly connected to the outer wall of the stirring blades (14) to rotate close to the inner wall of the inner tank (10) to scrape off the materials adhering to the wall.

4. The microcapsule encapsulation device for rubber foaming agent according to claim 2, characterized in that, The dehydration assembly includes a separation tank (16) mounted on the inner wall of the dehydration chamber (4) via a bracket. A solid processing pipe (18) for discharging the dehydrated solid filter cake is fixedly connected to the left side of the separation tank (16), and a liquid discharge pipe (19) for discharging the clarified liquid is fixedly connected to the right side of the separation tank (16). A transport roller (17) is coaxially arranged on the inner wall of the separation tank (16). The outer edge of the spiral blade of the transport roller (17) is close to the inner wall of the separation tank (16) to push the deposited solid filter cake toward the solid processing pipe (18). A rotating shaft (20) is rotatably connected to the outer wall of the input end of the transport roller (17). The input end of the rotating shaft (20) is connected to the output end of the secondary reactor (3) to introduce the suspension into the interior of the transport roller (17).

5. The microcapsule encapsulation device for rubber foaming agent according to claim 2, characterized in that, The reversing assembly includes an adjusting pipe (21) located at the top of the heating tank (5). A partition ring (27) is fixedly connected to the inner wall of the right side of the adjusting pipe (21). The partition ring (27) divides the inner cavity of the adjusting pipe (21) into a water supply cavity and a drainage cavity. A reversing rod (28) is rotatably connected to the inner wall of the partition ring (27). The reversing rod (28) is a hollow cavity with water inlets around its center for introducing hot water from the heating tank (5) into the inner cavity of the reversing rod (28). A reversing block (29) is fixedly connected to the outer wall of the reversing rod (28). A water outlet is provided on the bottom outer wall of the reversing block (29) for guiding hot water to different downstream pipelines. A piston block is fixedly connected to the right end of the rod (28) for blocking the water supply line when water is discharged. A connecting block (30) is fixedly connected to the left end of the reversing rod (28). A cylinder-driven driving rod (32) is rotatably connected to the end of the connecting block (30). A connecting sleeve (31) is sleeved on the outer wall of the connecting block (30). A guide groove is opened on the outer wall of the connecting sleeve (31). A protrusion embedded in the groove of the connecting sleeve (31) is fixedly connected to the outer wall of the connecting block (30). The reversing rod (28) can be driven to make a composite motion of axial movement and circumferential rotation under the constraint of the guide groove of the connecting sleeve (31) by the extension and retraction of the driving rod (32), so as to realize the switching of the hot water delivery channel.

6. The microcapsule encapsulation device for rubber foaming agent according to claim 5, characterized in that, The right end of the regulating pipe (21) is connected to the water supply pipe (22), the middle of the bottom of the drain chamber of the regulating pipe (21) is connected to the heating tank (5), the left side of the bottom of the drain chamber of the regulating pipe (21) is connected to the input end of the heating pipe (11) in the main reactor (2) through the connecting pipe, and the left side of the bottom of the regulating pipe (21) is connected to the spray head (9) through the connecting pipe.

7. The microcapsule encapsulation device for rubber foaming agent according to claim 5, characterized in that, The outer wall of the drive rod (32) is fixedly connected to a connecting frame (33), which is slidably connected to a bracket on which an air pump is installed. The outer wall of the connecting frame (33) is supported by a drive shaft (36), and the outer wall of the drive shaft (36) is connected to a drive shaft (35) driven by a motor through two meshing gears. The drive shaft (36) can be driven to rotate synchronously by the rotation of the drive shaft (35).

8. The microcapsule encapsulation device for rubber foaming agent according to claim 7, characterized in that, Both ends of the first drive shaft (36) are fixedly connected to a connecting plate (37). A lever is fixedly connected to the outer wall of the connecting plate (37). A first drive rod (38) is provided on the outer wall of the connecting plate (37). Two protrusions are fixedly connected to the outer wall of the first drive rod (38). The bottom of the first drive rod (38) is connected to a second drive rod (39) through two meshing gears. The end of the second drive rod (39) is connected to a second drive shaft (40) through two meshing bevel gears. The end of the second drive shaft (40) is provided with a drive chamber (34). Two meshing gears are rotatably connected to the inner wall of the drive chamber (34). The second drive shaft (40) can drive the gears to rotate to realize the quantitative pumping of water flow. One of the drive chambers (34) is connected to the connecting pipe of the heating pipe (11), and the other drive chamber (34) is connected to the connecting pipe of the spray head (9).

9. A microcapsule encapsulation device for a rubber foaming agent according to claim 2, characterized in that, The heat exchange assembly includes a heat exchange tank (6) located at the output end of the heating tube (11) inside the secondary reactor (3). The heat exchange tank (6) is fixedly connected to both the upper and lower sides by partitions (25). The partitions (25) divide the heat exchange tank (6) into a heat exchange chamber and two cooling chambers. A connecting pipe (26) is provided between the two cooling chambers and they are connected through the connecting pipe (26). The top cooling chamber of the heat exchange tank (6) is connected to the output end of the heating tube (11) inside the secondary reactor (3). The bottom cooling chamber of the heat exchange tank (6) is connected to the water supply pipe (22). The top of the heat exchange chamber of the heat exchange tank (6) is connected to the input end of the heating tube (11) inside the secondary reactor (3). The bottom of the heat exchange chamber of the heat exchange tank (6) is connected to the output end of the heating tube (11) inside the main reactor (2).

10. A microcapsule encapsulation device for a rubber foaming agent according to claim 2, characterized in that, The top of the premix tank (1), the main reactor (2) and the secondary reactor (3) are all fixedly connected with multiple addition pipes for connecting additives. The output ends of the premix tank (1), the main reactor (2) and the secondary reactor (3) are all equipped with reversing valves. One output end of the reversing valve is connected to the connecting pipe for conveying the material to the next process, and the other output end is connected to the drain pipe for discharging cleaning wastewater.

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