A high-toughness expandable polystyrene blended foam material and a preparation method thereof

Abstract

The application relates to the technical field of foaming materials, and discloses a high-toughness expandable polystyrene blended foaming material and a preparation method, the method comprises the following steps: rubber nanoparticle preparation, prepolymerization, reaction extrusion bulk polymerization, additive addition and mixing, cutting granulation, drying and screening, and foaming treatment; in the application, rubber raw materials are processed into nanoscale particles through nanogrinding technology, and the rubber raw materials are made into block copolymer structures with polystyrene monomers by using a reaction extrusion bulk polymerization method; the rubber phase is uniformly dispersed and chemically bonded at the molecular level in the polystyrene matrix, as stress absorption points, the toughness, impact resistance and mechanical property consistency are improved, phase separation and stress concentration are avoided, and the material has uniform deformation capacity and energy dissipation mechanism when being stressed.

Description

Technical Field

[0001] This invention relates to the field of foaming materials technology, specifically to a high-toughness expandable polystyrene blend foaming material and its preparation method. Background Technology

[0002] Foamed plastics are a type of polymer material formed by dispersing a large number of gas pores within a solid plastic. Foamed plastics possess properties such as light weight, high specific strength, heat insulation, sound insulation and absorption, and cushioning and shock absorption. Simultaneously, foamed plastics exhibit excellent dielectric properties and have wide applications in industry, agriculture, construction, and transportation. Due to their wide range of uses, foamed materials have maintained stable and continuous growth over the years.

[0003] Currently, in the preparation of expandable polystyrene blended foam materials, the compatibility differences between rubber nanoparticles and the polystyrene matrix lead to agglomeration and uneven distribution during mixing and subsequent processing. Failure to monitor and control the dispersion state in real time can cause stress concentration within the material, reducing the consistency of the blend's mechanical properties. Simultaneously, insufficient precision in the coordinated control of temperature, pressure, and their rate of change during reactive extrusion and supercritical foaming stages prevents real-time feedback and dynamic adjustment of cell nucleation and growth processes. This results in uneven cell structure, excessively wide pore size distribution, or merging and collapse, directly affecting the density stability and the matching relationship between toughness and thermal insulation performance of the foam material. Furthermore, existing processes have limited ability to predict and control the performance of the final foamed product online. They fail to achieve coordinated design and precise preparation of material composition, cell structure, and performance based on the differentiated requirements for toughness, dimensional stability, and environmental stress resistance in different application scenarios, thus affecting the reliable application of high-toughness polystyrene foam materials in optoelectronic packaging and automotive protection fields.

[0004] Therefore, a high-toughness expandable polystyrene blend foam material and its preparation method are proposed to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-toughness expandable polystyrene blend foam material and its preparation method. The high-toughness expandable polystyrene blend foam material provided by this invention solves the problems mentioned in the background technology, such as internal stress concentration in the material, reduced mechanical property consistency of the blend material, and impact on the density stability and the matching relationship between toughness and thermal insulation performance of the foam material.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-toughness expandable polystyrene blend foam material and its preparation method, the method comprising the following steps: Step 1: Preparation of rubber nanoparticles. Rubber raw materials are subjected to nano-grinding to obtain rubber nanoparticles with a particle size of 50-100 nanometers. Step 2: Prepolymerization. By weight, 100 parts of styrene monomer, 20-40 parts of the rubber nanoparticles, 0.5-2 parts of initiator and 1-3 parts of stabilizer are mixed and prepolymerized in a reactor at a reaction temperature of 80-120℃ for 1-3 hours to obtain the prepolymer. Step 3: Reactive extrusion bulk polymerization. The prepolymer is added to a twin-screw extruder and reactive extrusion is carried out at a screw speed of 100-300 r / min and a barrel temperature of 150-200℃ to remove unreacted monomers and volatiles, thereby obtaining expandable polystyrene / rubber block copolymer. Step 4: Additives and mixing. Antistatic agent, dispersant and lubricant are added to the expandable polystyrene / rubber block copolymer and mixed. The mixture is mixed in a mixer at a temperature of 50-80℃ and a speed of 200-500r / min for 10-30 minutes to obtain a homogeneous mixture. Step 5: Cutting and granulation. The mixture is extruded through a mold and cut underwater into particles with a diameter of 1-3 mm. The cutting water pressure is 5-15 MPa and the cutting speed is 10-30 cm / s. Step 6: Drying and sieving. The particles are dried at 80-100℃ until the moisture content is less than 2.5%, and then sieved to obtain expandable polystyrene blend particles with uniform particle size. Step 7: Foaming treatment. The expandable polystyrene blend particles are placed in a supercritical carbon dioxide foaming device, carbon dioxide gas is introduced, the pressure is adjusted to 10-20 MPa, the temperature is adjusted to 100-150℃, and the pressure and temperature are maintained for 1-3 hours to make the carbon dioxide reach the supercritical state. Then, the pressure is rapidly released at a depressurization rate of 0.5-2 MPa / s, and the material is cooled to room temperature to set, thus obtaining a high-toughness expandable polystyrene blend foam material.

[0007] Preferably, the preparation of rubber nanoparticles in step one includes the following steps: At least one of natural rubber or synthetic rubber is selected, wherein the synthetic rubber includes styrene-butadiene rubber, cis-butadiene rubber, or ethylene-propylene rubber. The rubber raw material is crushed into particles with a particle size of 1-5 mm, and then placed in a nano-grinding mill. A grinding aid is added, wherein the grinding aid is one of polyvinylpyrrolidone or silane coupling agent. The mass ratio of the grinding aid to the rubber is 0.01-0.05:1. The grinding is carried out at a mill speed of 1000-3000 r / min for 30-60 minutes to obtain rubber nanoparticles with a particle size of 50-100 nanometers. The temperature is controlled at 20-40℃ during the grinding process.

[0008] Preferably, the prepolymerization in step two includes the following specific parameters: The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, or potassium persulfate, and the stabilizer is at least one of calcium stearate, zinc stearate, or organotin stabilizer. The prepolymerization reaction is carried out under inert gas protection, with nitrogen or argon as the inert gas and a gas flow rate of 10-50 sccm. The viscosity of the prepolymer obtained after prepolymerization is 500-2000 mPa·s, and the solid content is 60-80%.

[0009] Preferably, the reactive extrusion bulk polymerization in step three employs a modified twin-screw extruder, the modification of which includes: The screw structure has been changed to a combined screw, including a conveying section, a compression section, and a reaction section. The thread depth of the reaction section is 5-10mm, and the length-to-diameter ratio is 40:1-60:1. A temperature control system is added to the barrel, with a temperature control accuracy of ±1℃. The extruder outlet is connected to a vacuum devolatilization device with a vacuum degree of 0.01-0.05MPa, which is used to remove monomers and volatiles. During the reactive extrusion process, the residence time of the material in the extruder is 2-5 minutes, and the extrusion pressure is 5-10MPa.

[0010] Preferably, the addition and mixing of the adjuvants in step four specifically includes: The antistatic agent is at least one of quaternary ammonium salts, fatty acid esters, or carbon black, and its addition amount is 5-10 parts by weight. The dispersant is at least one of polyethylene wax, stearic acid, or silicone oil, and its addition amount is 1-3 parts by weight. The lubricant is at least one of stearamide, oleamide, or paraffin wax, and its addition amount is 1-2 parts by weight. The mixing process is carried out in a high-speed mixer with a mixer speed of 200-500 r / min, a mixing time of 10-30 minutes, and a mixing temperature controlled at 50-80℃.

[0011] Preferably, the cutting and granulation in step five employs a high-pressure underwater cutting and forming process, specifically including: The mixture is extruded through a twin-screw extruder with an extrusion die diameter of 1-3 mm and an extrusion temperature of 180-220°C. After extrusion, the material immediately enters an underwater cutting chamber with a water temperature controlled at 10-30°C, an underwater pressure of 5-15 MPa, and a cutting blade speed of 500-1500 r / min. The resulting particles have a diameter of 1-3 mm and are spherical or cylindrical in shape, with a particle size variation coefficient of less than 5%.

[0012] Preferably, the drying and sieving in step six includes: The drying process uses a fluidized bed dryer or a vacuum drying oven to dry at 80-100℃ for 1-2 hours to control the moisture content of the particles. The sieving process uses a vibrating screen with a mesh size of 10-20 to obtain particles with uniform particle size. The sieved particles are then mixed in batches.

[0013] Preferably, the foaming treatment in step seven employs supercritical carbon dioxide foaming technology, specifically including: The foaming process is carried out in a supercritical carbon dioxide foaming device, which includes a high-pressure vessel with a jacketed circulation system, a carbon dioxide pressurization and injection system with an accuracy of ±0.1 MPa, a platinum resistance temperature sensor and a pressure sensor directly connected to the inside of the vessel, and an electric pressure relief valve controlled by an industrial computer. Using this device, the following steps are specifically performed: First, supercritical or high-purity carbon dioxide gas is introduced, and the pressure inside the reactor is adjusted to 10-20 MPa through the pressurization and injection system. The temperature is adjusted to 100-150℃ through the jacket circulation system. Then, the pressure and temperature are maintained for 1-3 hours. During this process, the industrial computer, based on the signal feedback from the pressure sensor, controls the micro-pressure compensation operation of the pressurization system to maintain the pressure fluctuation range within ±0.5 MPa, so that the carbon dioxide reaches the supercritical state. Finally, the industrial computer controls the electric pressure relief valve to rapidly depressurize at a linear pressure relief rate of 0.5-2 MPa / s. After the pressure relief is completed, the cooling program of the jacket circulation system is started, cooling to room temperature at a rate of 10-20℃ / min to obtain the foamed material.

[0014] Preferably, in the foaming process, the cell structure is controlled by the synergistic effect of the pressure relief rate and the cooling rate: the pressure relief rate is controlled in the range of 0.5-2MPa / s, while the cooling rate is controlled in the range of 10-20℃ / min. Under this synergistic condition, a uniform multi-level cell structure with closed pores is formed inside the foamed material, wherein the diameter of the main cell is 50-200 micrometers, and secondary cells with a diameter of 1-5 micrometers are distributed in the wall of the main cell, accounting for 10%-30% of the total number.

[0015] Preferably, the foaming material comprises the following components in parts by weight: The foaming material contains 100 parts of expandable polystyrene / rubber block copolymer, 5-10 parts of antistatic agent, 1-3 parts of dispersant, and 1-2 parts of lubricant. The expandable polystyrene / rubber block copolymer contains 20-40 parts of rubber nanoparticles and 60-80 parts of polystyrene. The foaming material has a closed-cell structure formed by supercritical carbon dioxide foaming, and the cells are evenly distributed.

[0016] Compared with the prior art, the present invention provides a high-toughness expandable polystyrene blend foam material and its preparation method, which has the following beneficial effects: 1. In this invention, rubber raw materials are processed into nanoscale particles using nano-grinding technology, and then formed into block copolymer structures with polystyrene monomers using reactive extrusion bulk polymerization. The rubber phase achieves uniform dispersion and chemical bonding at the molecular level in the polystyrene matrix, serving as stress absorption points, thereby improving co-toughness, impact resistance, and mechanical property consistency. This avoids phase separation and stress concentration, ensuring that the material has uniform deformation capacity and energy dissipation mechanism under stress.

[0017] 2. In this invention, supercritical carbon dioxide foaming technology is used. By controlling the temperature, pressure and their rate of change during the foaming process, carbon dioxide reaches a supercritical state in the polymer matrix and achieves uniform nucleation and controllable growth, forming a closed-cell structure with a dense and uniform multi-level cell morphology. This cell structure not only endows the material with excellent buffering performance and thermal insulation properties, but also ensures its high resilience, low density and good dimensional stability, avoiding performance defects caused by merging and collapse.

[0018] 3. In this invention, by optimizing the material formulation, adding antistatic agents, dispersants, and lubricants, and achieving uniform mixing and stable bonding with the polymer matrix during processing, the surface of the blended material obtains a durable and reliable antistatic effect, preventing the risk of use caused by static electricity accumulation. At the same time, the introduction of rubber nanoparticles and the synergistic effect of the cell structure enhance the water resistance and environmental stress resistance of the material, enabling it to maintain stable performance in humid and variable environments. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: A high-toughness expandable polystyrene blend foam material and its preparation method, the method comprising the following steps: Step 1: Preparation of rubber nanoparticles. Rubber raw materials are subjected to nano-grinding to obtain rubber nanoparticles with a particle size of 50 nanometers. Step 2: Prepolymerization. By weight, 100 parts of styrene monomer, 20 parts of rubber nanoparticles, 0.5 parts of initiator and 1 part of stabilizer are mixed and prepolymerized in a reactor at a reaction temperature of 80°C for 1 hour to obtain the prepolymer. Step 3: Reactive extrusion bulk polymerization. The prepolymer is added to a twin-screw extruder and reactive extrusion is carried out at a screw speed of 100 r / min and a barrel temperature of 150℃ to remove unreacted monomers and volatiles, thereby obtaining expandable polystyrene / rubber block copolymer. Step 4: Additives and mixing. Add antistatic agent, dispersant and lubricant to expandable polystyrene / rubber block copolymer and mix. Mix in a mixer at 50°C and 200 r / min for 10 minutes to obtain a homogeneous mixture. Step 5: Cutting and granulation. High-pressure underwater cutting technology is used to extrude the mixture through a mold and cut it underwater into particles with a diameter of 1mm. The cutting water pressure is 5MPa and the cutting speed is 10cm / s. Step 6: Drying and sieving. The particles are dried at 80°C until the moisture content is below 2.5%, and then sieved to obtain expandable polystyrene blend particles with uniform particle size. Step 7: Foaming treatment. The expandable polystyrene blend particles are placed in a supercritical carbon dioxide foaming device, carbon dioxide gas is introduced, the pressure is adjusted to 10 MPa, the temperature is adjusted to 100℃, and the pressure and temperature are maintained for 1 hour to make the carbon dioxide reach the supercritical state. Then, the pressure is rapidly released at a depressurization rate of 0.5 MPa / s, and the material is cooled to room temperature to set, thus obtaining a high-toughness expandable polystyrene blend foam material.

[0021] The preparation of rubber nanoparticles in step one includes the following steps: At least one of natural rubber or synthetic rubber is selected, including styrene-butadiene rubber, butadiene rubber, or ethylene propylene rubber. The rubber raw material is crushed into particles with a particle size of 1 mm, and then placed in a nano-grinding mill. A grinding aid is added, which is one of polyvinylpyrrolidone or silane coupling agent. The mass ratio of the grinding aid to the rubber is 0.01:1. The grinding is carried out at a speed of 1000 r / min for 30 minutes to obtain rubber nanoparticles with a particle size of 50 nanometers. The temperature is controlled at 20℃ during the grinding process.

[0022] The pre-polymerization in step two includes the following specific parameters: The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, or potassium persulfate, and the stabilizer is at least one of calcium stearate, zinc stearate, or organotin stabilizer. The prepolymerization reaction is carried out under inert gas protection, with nitrogen or argon as the inert gas and a gas flow rate of 10 sccm. The viscosity of the prepolymer obtained after prepolymerization is 500 mPa·s, and the solid content is 60%.

[0023] In step three, the reactive extrusion bulk polymerization uses a modified twin-screw extruder. The modification of the twin-screw extruder includes: The screw structure was changed to a combined screw, including a conveying section, a compression section, and a reaction section. The thread depth of the reaction section is 5mm, and the length-to-diameter ratio is 40:1. A temperature control system was added to the barrel, with a temperature control accuracy of ±1℃. The extruder outlet is connected to a vacuum devolatilization device with a vacuum degree of 0.01MPa, which is used to remove monomers and volatiles. During the reactive extrusion process, the residence time of the material in the extruder is 2 minutes, and the extrusion pressure is 5MPa.

[0024] Step four, the addition and mixing of auxiliary agents, specifically includes: The antistatic agent is at least one of quaternary ammonium salts, fatty acid esters, or carbon black, and its addition amount is 5 parts by weight. The dispersant is at least one of polyethylene wax, stearic acid, or silicone oil, and its addition amount is 1 part by weight. The lubricant is at least one of stearamide, oleamide, or paraffin wax, and its addition amount is 1 part by weight. The mixing process is carried out in a high-speed mixer with a mixer speed of 200 r / min, a mixing time of 10 minutes, and a mixing temperature controlled at 50℃.

[0025] Step five, cutting and granulation, employs a high-pressure underwater cutting and forming process, specifically including: The mixture is extruded through a twin-screw extruder with an extrusion die diameter of 1 mm and an extrusion temperature of 180°C. After extrusion, the material immediately enters the underwater cutting chamber, where the water temperature is controlled at 10°C, the underwater pressure is 5 MPa, the cutting blade speed is 500 r / min, and the particle size obtained by cutting is 1 mm. The particle shape is spherical or cylindrical, and the particle size variation coefficient is less than 5%.

[0026] Step six, drying and sieving, includes: The drying process uses a fluidized bed dryer or a vacuum drying oven to dry at 80°C for 1 hour to control the moisture content of the particles. The sieving process uses a vibrating screen with a mesh size of 10 to obtain particles with uniform particle size. The sieved particles are then mixed in batches.

[0027] Step seven involves a foaming process using supercritical carbon dioxide foaming technology, specifically including: The foaming process is carried out in a supercritical carbon dioxide foaming device, which includes a high-pressure vessel with a jacketed circulation system, a carbon dioxide pressurization and injection system with an accuracy of ±0.1 MPa, platinum resistance temperature and pressure sensors directly connected to the inside of the vessel, and an electric pressure relief valve controlled by an industrial computer. Using this device, the following steps are specifically performed: First, supercritical or high-purity carbon dioxide gas is introduced. The pressure inside the reactor is adjusted to 10 MPa through a pressurization and injection system, and the temperature is adjusted to 100℃ through a jacketed circulation system. Then, the pressure and temperature are maintained for 1 hour. During this process, the industrial computer controls the micro-pressure compensation operation of the pressurization system based on the signal feedback from the pressure sensor, keeping the pressure fluctuation range within ±0.5 MPa, so that the carbon dioxide reaches the supercritical state. Finally, the industrial computer controls the electric pressure relief valve to quickly depressurize at a linear pressure relief rate of 0.5 MPa / s. After the pressure relief is completed, the cooling program of the jacketed circulation system is started, cooling to room temperature at a rate of 10℃ / min to obtain the foamed material.

[0028] In the foaming process, the cell structure is controlled by the synergistic effect of the depressurization rate and the cooling rate: the depressurization rate is controlled at 0.5 MPa / s, and the cooling rate is controlled at 10℃ / min. Under these synergistic conditions, a uniform multi-level cell structure with closed cells as the main structure is formed inside the foamed material. The main cell diameter is 50 micrometers, and secondary cells with a diameter of 1 micrometer are distributed in the main cell wall, accounting for 10% of the total number.

[0029] The foaming material contains the following components in parts by weight: The foamed polystyrene / rubber block copolymer contains 100 parts of expandable polystyrene / rubber block copolymer, 5 parts of antistatic agent, 1 part of dispersant, and 1 part of lubricant. The expandable polystyrene / rubber block copolymer contains 20 parts of rubber nanoparticles and 80 parts of polystyrene. The foamed material has a closed-cell structure formed by supercritical carbon dioxide foaming, and the cell distribution is uniform.

[0030] Example 2: A high-toughness expandable polystyrene blend foam material and its preparation method, the method comprising the following steps: Step 1: Preparation of rubber nanoparticles. Rubber raw materials are subjected to nano-grinding to obtain rubber nanoparticles with a particle size of 70 nanometers. Step 2: Prepolymerization. By weight, 100 parts of styrene monomer, 30 parts of rubber nanoparticles, 1 part of initiator and 2 parts of stabilizer are mixed and prepolymerized in a reactor at a reaction temperature of 100°C for 2 hours to obtain the prepolymer. Step 3: Reactive extrusion bulk polymerization. The prepolymer is added to a twin-screw extruder and reactive extrusion is carried out at a screw speed of 200 r / min and a barrel temperature of 170℃ to remove unreacted monomers and volatiles, thereby obtaining expandable polystyrene / rubber block copolymer. Step 4: Additives and mixing. Add antistatic agent, dispersant and lubricant to expandable polystyrene / rubber block copolymer and mix. Mix in a mixer at 65℃ and 350r / min for 20 minutes to obtain a homogeneous mixture. Step 5: Cutting and granulation. High-pressure underwater cutting technology is used to extrude the mixture through a mold and cut it underwater into particles with a diameter of 2mm. The cutting water pressure is 10MPa and the cutting speed is 20cm / s. Step 6: Drying and sieving. The particles are dried at 90°C until the moisture content is below 2.5%, and then sieved to obtain expandable polystyrene blend particles with uniform particle size. Step 7: Foaming treatment. The expandable polystyrene blend particles are placed in a supercritical carbon dioxide foaming device, carbon dioxide gas is introduced, the pressure is adjusted to 15MPa, the temperature is adjusted to 120℃, and the pressure and temperature are maintained for 2 hours to make the carbon dioxide reach the supercritical state. Then, the pressure is rapidly released at a depressurization rate of 1MPa / s, and the material is cooled to room temperature to set, thus obtaining a high-toughness expandable polystyrene blend foam material.

[0031] The preparation of rubber nanoparticles in step one includes the following steps: At least one of natural rubber or synthetic rubber is selected, including styrene-butadiene rubber, butadiene rubber, or ethylene propylene rubber. The rubber raw material is crushed into particles with a particle size of 3 mm, and then placed in a nano-grinding mill. A grinding aid is added, which is one of polyvinylpyrrolidone or silane coupling agent. The mass ratio of the grinding aid to the rubber is 0.03:1. The grinding is carried out at a speed of 2000 r / min for 45 minutes to obtain rubber nanoparticles with a particle size of 70 nanometers. The temperature is controlled at 30℃ during the grinding process.

[0032] The pre-polymerization in step two includes the following specific parameters: The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, or potassium persulfate, and the stabilizer is at least one of calcium stearate, zinc stearate, or organotin stabilizer. The prepolymerization reaction is carried out under inert gas protection, with nitrogen or argon as the inert gas and a gas flow rate of 30 sccm. The viscosity of the prepolymer obtained after prepolymerization is 1000 mPa·s, and the solid content is 70%.

[0033] In step three, the reactive extrusion bulk polymerization uses a modified twin-screw extruder. The modification of the twin-screw extruder includes: The screw structure was changed to a combined screw, including a conveying section, a compression section, and a reaction section. The thread depth of the reaction section is 7mm, and the length-to-diameter ratio is 50:1. A temperature control system was added to the barrel, with a temperature control accuracy of ±1℃. The extruder outlet is connected to a vacuum devolatilization device with a vacuum degree of 0.03MPa, which is used to remove monomers and volatiles. During the reactive extrusion process, the residence time of the material in the extruder is 3 minutes, and the extrusion pressure is 7MPa.

[0034] Step four, the addition and mixing of auxiliary agents, specifically includes: The antistatic agent is at least one of quaternary ammonium salts, fatty acid esters, or carbon black, and its addition amount is 8 parts by weight. The dispersant is at least one of polyethylene wax, stearic acid, or silicone oil, and its addition amount is 2 parts by weight. The lubricant is at least one of stearamide, oleamide, or paraffin wax, and its addition amount is 1.5 parts by weight. The mixing process is carried out in a high-speed mixer with a mixer speed of 350 r / min, a mixing time of 20 minutes, and a mixing temperature controlled at 65℃.

[0035] Step five, cutting and granulation, employs a high-pressure underwater cutting and forming process, specifically including: The mixture is extruded through a twin-screw extruder with an extrusion die diameter of 2 mm and an extrusion temperature of 200℃. After extrusion, the material immediately enters the underwater cutting chamber, where the water temperature is controlled at 20℃, the underwater pressure is 10 MPa, the cutting blade speed is 1000 r / min, and the particle size obtained by cutting is 2 mm. The particle shape is spherical or cylindrical, and the particle size variation coefficient is less than 5%.

[0036] Step six, drying and sieving, includes: The drying process uses a fluidized bed dryer or a vacuum drying oven, drying at 90℃ for 1.5 hours to control the moisture content of the particles. The sieving process uses a vibrating screen with a mesh size of 15 to obtain particles with uniform particle size. The sieved particles are then mixed in batches.

[0037] Step seven involves a foaming process using supercritical carbon dioxide foaming technology, specifically including: The foaming process is carried out in a supercritical carbon dioxide foaming device, which includes a high-pressure vessel with a jacketed circulation system, a carbon dioxide pressurization and injection system with an accuracy of ±0.1 MPa, platinum resistance temperature and pressure sensors directly connected to the inside of the vessel, and an electric pressure relief valve controlled by an industrial computer. Using this device, the following steps are specifically performed: First, supercritical or high-purity carbon dioxide gas is introduced. The pressure inside the reactor is adjusted to 15 MPa through a pressurization and injection system, and the temperature is adjusted to 120°C through a jacketed circulation system. Then, the pressure and temperature are maintained for 2 hours. During this process, the industrial computer controls the micro-pressure compensation operation of the pressurization system based on the signal feedback from the pressure sensor, keeping the pressure fluctuation range within ±0.5 MPa, so that the carbon dioxide reaches the supercritical state. Finally, the industrial computer controls the electric pressure relief valve to quickly depressurize at a linear pressure relief rate of 1 MPa / s. After the pressure relief is completed, the cooling program of the jacketed circulation system is started, cooling to room temperature at a rate of 15°C / min to obtain the foamed material.

[0038] In the foaming process, the cell structure is controlled by the synergistic effect of the depressurization rate and the cooling rate: the depressurization rate is controlled at 1 MPa / s, and the cooling rate is controlled at 5℃ / min. Under these synergistic conditions, a uniform multi-level cell structure with closed cells as the main structure is formed inside the foamed material. The main cell diameter is 100 micrometers, and secondary cells with a diameter of 3 micrometers are distributed in the main cell wall, accounting for 20% of the total number.

[0039] The foaming material contains the following components in parts by weight: The foamed polystyrene / rubber block copolymer contains 100 parts of expandable polystyrene / rubber block copolymer, 8 parts of antistatic agent, 2 parts of dispersant, and 1.5 parts of lubricant. The expandable polystyrene / rubber block copolymer contains 30 parts of rubber nanoparticles and 70 parts of polystyrene. The foamed material has a closed-cell structure formed by supercritical carbon dioxide foaming, and the cell distribution is uniform.

[0040] Example 3: A high-toughness expandable polystyrene blend foam material and its preparation method, the method comprising the following steps: Step 1: Preparation of rubber nanoparticles. Rubber raw materials are subjected to nano-grinding to obtain rubber nanoparticles with a particle size of 100 nanometers. Step 2: Prepolymerization. By weight, 100 parts of styrene monomer, 40 parts of rubber nanoparticles, 2 parts of initiator and 3 parts of stabilizer are mixed and prepolymerized in a reactor at a reaction temperature of 120°C for 3 hours to obtain the prepolymer. Step 3: Reactive extrusion bulk polymerization. The prepolymer is added to a twin-screw extruder and reactive extrusion is carried out at a screw speed of 300 r / min and a barrel temperature of 200℃ to remove unreacted monomers and volatiles, thereby obtaining expandable polystyrene / rubber block copolymer. Step 4: Additives and mixing. Add antistatic agent, dispersant and lubricant to expandable polystyrene / rubber block copolymer and mix. Mix in a mixer at 80℃ and 500r / min for 30 minutes to obtain a homogeneous mixture. Step 5: Cutting and granulation. High-pressure underwater cutting process is used to extrude the mixture through a mold and cut it underwater into particles with a diameter of 3mm. The cutting water pressure is 15MPa and the cutting speed is 30cm / s. Step 6: Drying and sieving. The particles are dried at 100°C until the moisture content is below 2.5%, and then sieved to obtain expandable polystyrene blend particles with uniform particle size. Step 7: Foaming treatment. The expandable polystyrene blend particles are placed in a supercritical carbon dioxide foaming device, carbon dioxide gas is introduced, the pressure is adjusted to 20 MPa, the temperature is adjusted to 150℃, and the pressure and temperature are maintained for 3 hours to make the carbon dioxide reach the supercritical state. Then, the pressure is rapidly released at a depressurization rate of 2 MPa / s, and the material is cooled to room temperature to set, thus obtaining a high-toughness expandable polystyrene blend foam material.

[0041] The preparation of rubber nanoparticles in step one includes the following steps: At least one of natural rubber or synthetic rubber is selected, including styrene-butadiene rubber, butadiene rubber, or ethylene propylene rubber. The rubber raw material is crushed into particles with a particle size of 5 mm, and then placed in a nano-grinding mill. A grinding aid is added, which is either polyvinylpyrrolidone or a silane coupling agent. The mass ratio of the grinding aid to the rubber is 0.05:1. The grinding is carried out at a speed of 3000 r / min for 60 minutes to obtain rubber nanoparticles with a particle size of 100 nanometers. The temperature is controlled at 40℃ during the grinding process.

[0042] The pre-polymerization in step two includes the following specific parameters: The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, or potassium persulfate, and the stabilizer is at least one of calcium stearate, zinc stearate, or organotin stabilizer. The prepolymerization reaction is carried out under inert gas protection, with nitrogen or argon as the inert gas and a gas flow rate of 50 sccm. The viscosity of the prepolymer obtained after prepolymerization is 2000 mPa·s, and the solid content is 80%.

[0043] In step three, the reactive extrusion bulk polymerization uses a modified twin-screw extruder. The modification of the twin-screw extruder includes: The screw structure was changed to a combined screw, including a conveying section, a compression section, and a reaction section. The thread depth of the reaction section is 10mm, and the length-to-diameter ratio is 60:1. A temperature control system was added to the barrel, with a temperature control accuracy of ±1℃. The extruder outlet is connected to a vacuum devolatilization device with a vacuum degree of 0.05MPa, which is used to remove monomers and volatiles. During the reactive extrusion process, the material residence time in the extruder is 5 minutes, and the extrusion pressure is 10MPa.

[0044] Step four, the addition and mixing of auxiliary agents, specifically includes: The antistatic agent is at least one of quaternary ammonium salts, fatty acid esters, or carbon black, and its addition amount is 10 parts by weight. The dispersant is at least one of polyethylene wax, stearic acid, or silicone oil, and its addition amount is 3 parts by weight. The lubricant is at least one of stearamide, oleamide, or paraffin wax, and its addition amount is 2 parts by weight. The mixing process is carried out in a high-speed mixer with a mixer speed of 500 r / min, a mixing time of 30 minutes, and a mixing temperature controlled at 80℃.

[0045] Step five, cutting and granulation, employs a high-pressure underwater cutting and forming process, specifically including: The mixture is extruded through a twin-screw extruder with an extrusion die diameter of 3 mm and an extrusion temperature of 220°C. After extrusion, the material immediately enters the underwater cutting chamber, where the water temperature is controlled at 30°C, the underwater pressure is 15 MPa, the cutting blade speed is 1500 r / min, and the particle size obtained by cutting is 3 mm. The particle shape is spherical or cylindrical, and the particle size variation coefficient is less than 5%.

[0046] Step six, drying and sieving, includes: The drying process uses a fluidized bed dryer or a vacuum drying oven to dry at 100℃ for 2 hours to control the moisture content of the particles. The sieving process uses a vibrating screen with a mesh size of 20 to obtain particles with uniform particle size. The sieved particles are then mixed in batches.

[0047] Step seven involves a foaming process using supercritical carbon dioxide foaming technology, specifically including: The foaming process is carried out in a supercritical carbon dioxide foaming device, which includes a high-pressure vessel with a jacketed circulation system, a carbon dioxide pressurization and injection system with an accuracy of ±0.1 MPa, platinum resistance temperature and pressure sensors directly connected to the inside of the vessel, and an electric pressure relief valve controlled by an industrial computer. Using this device, the following steps are specifically performed: First, supercritical or high-purity carbon dioxide gas is introduced. The pressure inside the reactor is adjusted to 20 MPa through a pressurization and injection system, and the temperature is adjusted to 150°C through a jacketed circulation system. Then, the pressure and temperature are maintained for 3 hours. During this process, the industrial computer controls the micro-pressure compensation operation of the pressurization system based on the signal feedback from the pressure sensor, keeping the pressure fluctuation range within ±0.5 MPa, so that the carbon dioxide reaches the supercritical state. Finally, the industrial computer controls the electric pressure relief valve to quickly depressurize at a linear pressure relief rate of 2 MPa / s. After the pressure relief is completed, the cooling program of the jacketed circulation system is started, cooling to room temperature at a rate of 20°C / min to obtain the foamed material.

[0048] In the foaming process, the cell structure is controlled by the synergistic effect of the depressurization rate and the cooling rate: the depressurization rate is controlled at 2MPa / s, and the cooling rate is controlled at 20℃ / min. Under these synergistic conditions, a uniform multi-level cell structure with closed cells as the main cell is formed inside the foamed material. The main cell diameter is 200 micrometers, and secondary cells with a diameter of 5 micrometers are distributed in the main cell wall, accounting for 30% of the total number.

[0049] The foaming material contains the following components in parts by weight: The foamed polystyrene / rubber block copolymer contains 100 parts of expandable polystyrene / rubber block copolymer, 10 parts of antistatic agent, 3 parts of dispersant, and 2 parts of lubricant. The expandable polystyrene / rubber block copolymer contains 40 parts of rubber nanoparticles and 60 parts of polystyrene. The foamed material has a closed-cell structure formed by supercritical carbon dioxide foaming, and the cell distribution is uniform.

[0050] Comparative Example 1: The difference between this comparative example and Example 1 is that no rubber nanoparticles were added during the preparation process of this comparative example.

[0051] Comparative Example 2 differs from Example 1 in that: this comparative example did not undergo supercritical carbon dioxide foaming treatment after reactive extrusion.

[0052] Comparative Example 3 differs from Example 1 in that no antistatic agent was added in the additive addition and mixing steps of this comparative example.

[0053] Comparative Example 4 differs from Example 1 in that the synergy between the depressurization rate and the cooling rate was not controlled in the foaming process of this comparative example.

[0054] The high-toughness expandable polystyrene blend foam materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests. The test items and test methods are as follows: Impact resistance test: A pendulum impact tester is used to apply an impact load to a V-notch specimen of specified size at room temperature of 23±2℃, measure the energy absorbed when the specimen breaks, and calculate the impact strength. Compression performance testing was conducted using a universal testing machine. In an environment with a relative humidity of 50%±5% and a temperature of 23±2℃, a compressive load was applied to the foamed material sample, the compressive stress of the sample under a specific deformation was recorded, and the compressive strength was calculated. Dimensional stability testing involves placing the sample in a specific temperature and humidity environment for a specified time, then using precision measuring instruments to measure the dimensional changes of the sample in the length, width, and thickness directions, and calculating the rate of dimensional change. Cell structure testing involves observing the cross-sectional morphology of the foamed material using a scanning electron microscope, statistically analyzing the cell diameter distribution using image analysis software, calculating the average cell diameter and cell density, and evaluating the uniformity of the cell structure.

[0055] The high-toughness expandable polystyrene blend foam materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests. The test items and test methods are as follows: Comparison and analysis of the data in the table show that the high-toughness expandable polystyrene blend foam materials prepared using the processes in Examples 1-3 exhibit superior performance compared to the foam materials prepared using the processes in Comparative Examples 1-4. This indicates that by processing the rubber raw material into nanoscale particles using nano-grinding technology and then using reactive extrusion bulk polymerization to form a block copolymer structure with the polystyrene monomer, the rubber phase achieves uniform dispersion and chemical bonding at the molecular level within the polystyrene matrix. Serving as stress absorption points, this enhances the co-toughness, impact resistance, and mechanical property consistency, avoiding phase separation and stress concentration, and ensuring uniform deformation capacity and energy dissipation mechanism under stress. Supercritical carbon dioxide foaming technology, by controlling the temperature, pressure, and rate of change during the foaming process, allows carbon dioxide to reach a supercritical state in the polymer matrix, achieving uniform nucleation and controllable growth, forming a closed-cell structure with a dense and uniform multi-level cell morphology. This cell structure not only endows the material with excellent buffering and thermal insulation properties but also ensures high resilience, low density, and good dimensional stability, avoiding performance defects caused by coalescence and collapse. By optimizing the material formulation and adding antistatic agents, dispersants, and lubricants, and achieving uniform mixing and stable bonding with the polymer matrix during processing, the surface of the blended material obtains a durable and reliable antistatic effect, preventing the risks of use caused by static electricity accumulation. At the same time, the introduction of rubber nanoparticles and the synergistic effect of the cell structure enhance the water resistance and environmental stress resistance of the material, enabling it to maintain stable performance in humid and variable environments.

[0056] By comparing and analyzing the relevant data in the table, it can be seen that the high-toughness expandable polystyrene blend foam material prepared by the molding process of this invention has excellent comprehensive performance.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] 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 method for preparing a high-toughness expandable polystyrene blend foam material, characterized in that: The method includes the following steps: Step 1: Preparation of rubber nanoparticles. Rubber raw materials are subjected to nano-grinding to obtain rubber nanoparticles with a particle size of 50-100 nanometers. Step 2: Prepolymerization. By weight, 100 parts of styrene monomer, 20-40 parts of the rubber nanoparticles, 0.5-2 parts of initiator and 1-3 parts of stabilizer are mixed and prepolymerized in a reactor at a reaction temperature of 80-120℃ for 1-3 hours to obtain the prepolymer. Step 3: Reactive extrusion bulk polymerization. The prepolymer is added to a twin-screw extruder and reactive extrusion is carried out at a screw speed of 100-300 r / min and a barrel temperature of 150-200℃ to remove unreacted monomers and volatiles, thereby obtaining expandable polystyrene / rubber block copolymer. Step 4: Additives and mixing. Antistatic agent, dispersant and lubricant are added to the expandable polystyrene / rubber block copolymer and mixed. The mixture is mixed in a mixer at a temperature of 50-80℃ and a speed of 200-500r / min for 10-30 minutes to obtain a homogeneous mixture. Step 5: Cutting and granulation. The mixture is extruded through a mold and cut underwater into particles with a diameter of 1-3 mm. The cutting water pressure is 5-15 MPa and the cutting speed is 10-30 cm / s. Step 6: Drying and sieving. The particles are dried at 80-100℃ until the moisture content is less than 2.5%, and then sieved to obtain expandable polystyrene blend particles with uniform particle size. Step 7: Foaming treatment. The expandable polystyrene blend particles are placed in a supercritical carbon dioxide foaming device, carbon dioxide gas is introduced, the pressure is adjusted to 10-20 MPa, the temperature is adjusted to 100-150℃, and the pressure and temperature are maintained for 1-3 hours to make the carbon dioxide reach the supercritical state. Then, the pressure is rapidly released at a depressurization rate of 0.5-2 MPa / s, and the material is cooled to room temperature to set, thus obtaining a high-toughness expandable polystyrene blend foam material.

2. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: The preparation of rubber nanoparticles in step one includes the following steps: At least one of natural rubber or synthetic rubber is selected, wherein the synthetic rubber includes styrene-butadiene rubber, cis-butadiene rubber, or ethylene-propylene rubber. The rubber raw material is crushed into particles with a particle size of 1-5 mm, and then placed in a nano-grinding mill. A grinding aid is added, wherein the grinding aid is one of polyvinylpyrrolidone or silane coupling agent. The mass ratio of the grinding aid to the rubber is 0.01-0.05:

1. The grinding is carried out at a mill speed of 1000-3000 r / min for 30-60 minutes to obtain rubber nanoparticles with a particle size of 50-100 nanometers. The temperature is controlled at 20-40℃ during the grinding process.

3. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: The pre-polymerization in step two includes the following specific parameters: The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, or potassium persulfate, and the stabilizer is at least one of calcium stearate, zinc stearate, or organotin stabilizer. The prepolymerization reaction is carried out under inert gas protection, with nitrogen or argon as the inert gas and a gas flow rate of 10-50 sccm. The viscosity of the prepolymer obtained after prepolymerization is 500-2000 mPa·s, and the solid content is 60-80%.

4. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: In step three, the reactive extrusion bulk polymerization employs a modified twin-screw extruder. The modification of the twin-screw extruder includes: The screw structure has been changed to a combined screw, including a conveying section, a compression section, and a reaction section. The thread depth of the reaction section is 5-10mm, and the length-to-diameter ratio is 40:1-60:

1. A temperature control system is added to the barrel, with a temperature control accuracy of ±1℃. The extruder outlet is connected to a vacuum devolatilization device with a vacuum degree of 0.01-0.05MPa, which is used to remove monomers and volatiles. During the reactive extrusion process, the residence time of the material in the extruder is 2-5 minutes, and the extrusion pressure is 5-10MPa.

5. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: The addition and mixing of auxiliary agents in step four specifically includes: The antistatic agent is at least one of quaternary ammonium salts, fatty acid esters, or carbon black, and its addition amount is 5-10 parts by weight. The dispersant is at least one of polyethylene wax, stearic acid, or silicone oil, and its addition amount is 1-3 parts by weight. The lubricant is at least one of stearamide, oleamide, or paraffin wax, and its addition amount is 1-2 parts by weight. The mixing process is carried out in a high-speed mixer with a mixer speed of 200-500 r / min, a mixing time of 10-30 minutes, and a mixing temperature controlled at 50-80℃.

6. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: Step five, the cutting and granulation process, employs a high-pressure underwater cutting molding technology, specifically including: The mixture is extruded through a twin-screw extruder with an extrusion die diameter of 1-3 mm and an extrusion temperature of 180-220°C. After extrusion, the material immediately enters an underwater cutting chamber with a water temperature controlled at 10-30°C, an underwater pressure of 5-15 MPa, and a cutting blade speed of 500-1500 r / min. The resulting particles have a diameter of 1-3 mm and are spherical or cylindrical in shape, with a particle size variation coefficient of less than 5%.

7. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: The drying and sieving in step six include: The drying process uses a fluidized bed dryer or a vacuum drying oven to dry at 80-100℃ for 1-2 hours to control the moisture content of the particles. The sieving process uses a vibrating screen with a mesh size of 10-20 to obtain particles with uniform particle size. The sieved particles are then mixed in batches.

8. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 1, characterized in that: The foaming process in step seven employs supercritical carbon dioxide foaming technology, specifically including: The foaming process is carried out in a supercritical carbon dioxide foaming device, which includes a high-pressure vessel with a jacketed circulation system, a carbon dioxide pressurization and injection system with an accuracy of ±0.1 MPa, a platinum resistance temperature sensor and a pressure sensor directly connected to the inside of the vessel, and an electric pressure relief valve controlled by an industrial computer. Using this device, the following steps are specifically performed: First, supercritical or high-purity carbon dioxide gas is introduced. The pressure inside the reactor is adjusted to 10-20 MPa through the pressurization and injection system, and the temperature is adjusted to 100-150℃ through the jacket circulation system. Then, the pressure and temperature are maintained for 1-3 hours. During this process, the industrial computer controls the micro-pressure compensation operation of the pressurization system based on the signal feedback from the pressure sensor to maintain the pressure fluctuation range within ±0.5 MPa, so that the carbon dioxide reaches the supercritical state. Finally, the industrial computer controls the electric pressure relief valve to quickly depressurize at a linear pressure relief rate of 0.5-2 MPa / s. After the pressure relief is completed, the cooling program of the jacket circulation system is started, and the material is cooled to room temperature at a rate of 10-20℃ / min to obtain the foamed material.

9. The method for preparing a high-toughness expandable polystyrene blend foam material according to claim 8, characterized in that: In the foaming process, the cell structure is controlled by the synergistic effect of the pressure relief rate and the cooling rate: the pressure relief rate is controlled within the range of 0.5-2 MPa / s, while the cooling rate is controlled within the range of 10-20℃ / min. Under this synergistic condition, a uniform multi-level cell structure with closed pores is formed inside the foamed material. The diameter of the main cell is 50-200 micrometers, and secondary cells with a diameter of 1-5 micrometers are distributed in the main cell wall, accounting for 10%-30% of the total number.

10. A high-toughness expandable polystyrene blend foam material, prepared by the preparation method of the high-toughness expandable polystyrene blend foam material according to any one of claims 1-9, characterized in that: The foaming material comprises the following components in parts by weight: The foaming material contains 100 parts of expandable polystyrene / rubber block copolymer, 5-10 parts of antistatic agent, 1-3 parts of dispersant, and 1-2 parts of lubricant. The expandable polystyrene / rubber block copolymer contains 20-40 parts of rubber nanoparticles and 60-80 parts of polystyrene. The foaming material has a closed-cell structure formed by supercritical carbon dioxide foaming, and the cells are evenly distributed.

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