Preparation method of low-carbon carbon dioxide-based modified plastic particles

Abstract

The invention relates to the technical field of plastic modification, and discloses a preparation method of low-carbon carbon dioxide-based modified plastic particles, which at least comprises the following steps: S1, raw material pretreatment; s2, modifying and blending; and S3, extruding and granulating. According to the invention, a brand new application approach of carbon dioxide in the field of plastic modification is developed by combining multiple materials and cooperating with the carbon dioxide-based polymer, and the carbon dioxide is difficult to efficiently integrate into a plastic preparation system in the past, while the carbon dioxide is accurately matched with multiple polymers, so that the performance types of plastic particles are greatly enriched; the plastic is not limited to the single performance of traditional plastic any more, the strict requirements of different industries such as electronic appliances, toys and sports equipment for the special performance of the plastic are met in an all-around mode, and a solid material basis is provided for product innovation.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic modification, and particularly to a method for preparing low-carbon carbon dioxide-based modified plastic particles. Background Art

[0002] In today's era, plastics, with their many excellent properties such as light weight, durability, and easy processing, have become an indispensable material in modern industry and daily life. From food packaging to the casings of electronic appliances, from building pipes to automotive interior parts, plastic products are everywhere, and their global annual consumption continues to climb, showing huge market demand.

[0003] However, behind the prosperity of the traditional plastic industry lies a severe environmental crisis. On the one hand, the vast majority of traditional plastics are derived from non-renewable resources such as petroleum. As the petroleum reserves decrease day by day, the plastic industry faces the potential risk of raw material supply shortage. On the other hand, more prominent is the characteristic that traditional plastics are difficult to degrade naturally, and waste plastics accumulate in the environment for a long time.

[0004] At the same time, the global warming problem caused by excessive carbon dioxide emissions is threatening the very foundation of human existence. As the main greenhouse gas, the concentration of carbon dioxide in the atmosphere is constantly rising, and a series of bad consequences such as melting glaciers, rising sea levels, and frequent extreme weather follow one after another.

[0005] Resourcefully applying carbon dioxide, this greenhouse gas, to plastic preparation not only meets the low-carbon environmental protection requirements but also endows plastics with unique properties, which is of great significance. However, in the past technologies, when carbon dioxide was combined and modified with different polymer systems, the compatibility between carbon dioxide and the polymer matrix was extremely poor, and the two were difficult to effectively fuse, resulting in phase separation phenomena often occurring during the preparation process, seriously affecting the comprehensive performance of plastics, and causing a significant decline in the mechanical properties, processing properties, etc. of the products. Innovative methods are needed to break through the bottleneck to meet the diverse market demands. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing low-carbon carbon dioxide-based modified plastic particles to solve the problems raised in the above background art, namely, the extremely poor compatibility between carbon dioxide and the polymer matrix, the difficulty in effectively fusing the two, resulting in phase separation phenomena often occurring during the preparation process, seriously affecting the comprehensive performance of plastics, and causing a significant decline in the mechanical properties, processing properties, etc. of the products.

[0007] To solve the above technical problems, the present invention is solved through the following technical solutions: A method for preparing low-carbon carbon dioxide-based modified plastic particles, comprising the following steps:

[0008] S1. Raw material pretreatment: select CO2-based PE (polyethylene) with a melt flow rate of 1-5g / 10min and CO2-based EVA (ethylene-vinyl acetate copolymer) with a vinyl acetate content of 10%-30%, and put them into a vacuum drying oven for drying respectively, with the temperature controlled at 65-85°C for 2.5-3.5 hours; dry EPDM (ethylene propylene diene monomer rubber), POE (polyolefin elastomer), SEBS (styrene-ethylene-butylene-styrene block copolymer), and EPOE (ethylene-propylene-octene copolymer) respectively, with the temperature set at 50-70°C for 2-3 hours; and perform impurity removal and filtration on cyclohexane oil to remove mechanical impurities.

[0009] S2. Modified blending: CO2-based PE, CO2-based EVA and EPDM are added to a high-speed internal mixer in a mass ratio of 30:30:40, stirred at a low speed (300-500 r / min) for 5-10 minutes, and then a silane coupling agent accounting for 1.5%-3% of the total material mass is added, followed by high-speed stirring (1000-1500 r / min) for 15-25 minutes; CO2-based PE or CO2-based EVA, POE and SEBS are mixed in a mass ratio of 40:30:30, premixed at room temperature for 3-5 minutes, and then a maleic anhydride grafted polymer accounting for 2%-4% of the total material mass is added, and the mixture is fed into the feeding port of a co-rotating twin-screw extruder, and the screw speed is set to 250-350 r / min ; Mix carbon dioxide-based PE, carbon dioxide-based EVA and EPOE in a mass ratio of 45:40:15, add 0.5%-1% of the total material mass of an antioxidant, and mix at a speed of 800-1200r / min in a Haake internal mixer for 10-20 minutes; mix carbon dioxide-based EVA or carbon dioxide-based PE, SEBS, cyclohexane oil and EPOE in a mass ratio of 35:25:20:20, first stir the carbon dioxide-based material, SEBS and cyclohexane oil in a planetary mixer at a low speed (200-400r / min) for 8-15 minutes, then add OPE and a lubricant accounting for 0.3%-0.8% of the total material mass, and stir at a high speed (1200-1800r / min) for 10-20 minutes.

[0010] S3, extrusion granulation: the blend obtained in S2, modified blending, is extruded through a single screw extruder, and the extrusion temperature is controlled at 150-180°C, 170-200°C, and 190-220°C along the barrel from the feeding section to the die, and the screw speed is set to 150-250r / min. After the material is extruded into strips through the die of the die, it is cut into plastic particles of standard size by a pelletizer.

[0011] Preferably, during the drying process of the carbon dioxide-based PE and carbon dioxide-based EVA, the heating rate of the vacuum drying oven is controlled at 2-3 °C per minute. When the lower limit of the drying temperature, 65 °C, is reached, it is maintained for 30 minutes, and then heated up to the upper limit of 85 °C. The vacuum degree is maintained at -0.08 to -0.09 MPa. After drying, it is transferred to a sealed container filled with nitrogen while it is still hot.

[0012] Preferably, for the drying treatment of EPDM, POE, SEBS, and EPOE, a hot air circulation oven is used. The thickness of the material laid flat does not exceed 3 cm, and it is turned over every 30 minutes. After drying, it is transferred to a self-sealing bag with a desiccant packet, and the desiccant packet is replaced every 24 hours.

[0013] Preferably, the naphthenic oil is purified using a multi-layer filtration device with a first layer of 50-mesh stainless steel filter screen, a second layer of 100-mesh sintered metal filter screen, and a third layer of 0.5-μm aperture precision filter paper. After filtration, the heavy metal content is sampled and tested to meet the safety standards for plastic processing, and it is stored in a light-proof and sealed stainless steel tank.

[0014] Preferably, the kneading chamber of the high-speed mixer is preheated to 50-60 °C in advance. The addition time of the silane coupling agent is controlled within 2-3 minutes. When stirring at high speed, the mixer is evacuated to -0.06 to -0.07 MPa, and the material temperature does not exceed 180 °C.

[0015] Preferably, the pre-mixing speed of the V-type mixer is 50-80 r / min. The temperature of the first zone of the co-rotating twin-screw extruder is 140-160 °C, the temperature of the second zone is 160-180 °C, and the temperature of the third zone is 180-200 °C. The maleic anhydride grafted polymer is added through the side feeding port in the middle of the second zone, and the addition rate matches the extrusion rate of the material.

[0016] Preferably, the kneading chamber of the Haake mixer is heated up to 60-70 °C in advance. The antioxidant is pre-mixed with about 5% of the total material mass of the base material and then added. The fluctuation of the rotor speed is controlled within ±50 r / min. The cooling water flow rate is adjusted in real time according to the material temperature to maintain the material temperature at 160-180 °C.

[0017] Preferably, the revolution speed of the planetary mixer is set at 200-400 r / min, and the rotation speed is 1.5-2 times the revolution speed. During low-speed stirring, the dispersion of the naphthenic oil is observed through a transparent window. After adding EPOE and the lubricant, the revolution speed is increased to 1200-1800 r / min, and the rotation speed is adjusted accordingly. The material mixing state is checked every 5 minutes after stopping the machine.

[0018] Preferably, the single-screw extruder screw is a variable-pitch screw with a length-diameter ratio of 20 - 48:1. The extrusion temperature is precisely controlled by a PID temperature control system, and the temperature fluctuation is controlled within ±3°C. A melt pressure sensor is installed at the head. When the pressure exceeds 15 MPa, the screw speed or temperature is automatically adjusted. The water temperature in the water tank is controlled at 30 - 50°C. The cutting speed of the pelletizer cutter is synchronously matched with the screw speed of the extruder. The standard pellet size is 3 - 5 mm in diameter and 2 - 4 mm in length.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. By combining multiple materials to synergistically process carbon dioxide-based polymers, the present invention has opened up a new application path for carbon dioxide in the field of plastic modification. In the past, it was difficult for carbon dioxide to be efficiently incorporated into the plastic preparation system. However, in the present invention, carbon dioxide is precisely combined with various polymers, greatly enriching the types of plastic particle properties and no longer being limited to the single performance of traditional plastics. It can fully meet the stringent requirements of different industries such as electronic appliances, toys, and sports equipment for special plastic properties, providing a solid material basis for product innovation.

[0021] 2. Thanks to the precisely optimized pretreatment, blending, and extrusion processes, the compatibility between materials has reached a new level. The prepared modified plastic particles have excellent mechanical properties. The tensile strength can be significantly increased by 10% - 25%, which means that products made of this plastic can better withstand tensile external forces and are not easily broken or damaged. The elongation at break is increased by 15% - 35%, greatly enhancing its flexibility and enabling it to adapt to more complex force deformation scenarios.

[0022] 3. In Example 2, the impact strength of the prepared particles is increased by 20% compared with ordinary plastics, and the melt flow rate is precisely optimized to the range of 3 - 6 g / 10 min. This makes the plastic have just the right fluidity during processing such as injection molding and extrusion, the molding is smoother, the defective rate is reduced, the production efficiency is greatly improved, and the processing cost is reduced.

[0023] 4. The smoothness of the particle surface is improved, which not only makes its appearance more textured and more visually appealing in high-end product applications, but also the smooth surface can reduce the friction coefficient, reduce the wear of the product during use, extend the service life, further increase the added value of the product, and help the plastic industry move towards high-end and green development. Specific Embodiments

[0024] Unless otherwise clearly specified in the context, nouns without a quantifier and nouns modified by "the" include singular and plural referents.

[0025] As used in the specification and claims, the terms "comprising," "including," "having," "can," "containing," and variations thereof as used herein are open transitional phrases, terms, or words that require the presence of the specified element / step and allow the presence of other elements / steps. However, such description shall also be construed to describe the composition or method as "consisting of" and "consisting essentially of" the recited elements / steps, which allows only the presence of the specified elements / steps and any unavoidable impurities that may result therefrom, and excludes other elements / steps.

[0026] The numerical values in the specification and claims of this application should be understood to include the same numerical values when reduced to the same number of significant figures and numerical values that differ from the said values by less than the experimental error of the conventional measurement techniques used to determine the said values of the type described in this application.

[0027] All ranges disclosed herein include the indicated endpoints and can be combined independently (e.g., the range "2 grams to 10 grams" includes the endpoints 2 grams and 10 grams, and all intermediate values).

[0028] The terms "about" and "approximate" can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, "about" and "approximate" also disclose the range defined by the absolute values of the two endpoints. For example, "about 2 to about 4" also discloses the range "2 to 4". Generally, the terms "about" and "approximate" can refer to ±10% of the indicated number. However, for temperature, the term "about" means ±1°C.

[0029] Unless otherwise expressly specified, the percentages of the elements shall be considered as weight percentages of the said alloy.

[0030] This disclosure may relate to the temperature of certain method steps. It should be noted that these indicators generally refer to the temperature set by the heat source (such as a furnace), rather than necessarily the temperature that the heated material must reach.

[0031] A method for preparing low-carbon carbon dioxide-based modified plastic particles, comprising the following steps:

[0032] Example 1:

[0033] S1. Pretreatment of raw materials;

[0034] For carbon dioxide-based PE and carbon dioxide-based EVA, before putting them into a vacuum drying oven, the raw materials need to be visually inspected first. Materials with obvious color unevenness, particle caking and other problems should be removed to ensure the initial quality of the raw materials. After putting them into the vacuum drying oven, the heating rate should be controlled at 2-3°C per minute to avoid local overheating and deterioration of the raw materials due to too fast heating. When the set lower limit of the drying temperature (65°C) is reached, keep it for 30 minutes, and then slowly heat up to the upper limit (85°C). During the whole drying process, the vacuum degree should be maintained at -0.08 to -0.09 MPa to ensure effective removal of moisture and small molecule impurities. After drying is completed, transfer the raw materials to a sealed container filled with nitrogen while it is still hot to prevent them from reabsorbing moisture and wait for subsequent batching;

[0035] For EPDM, POE, SEBS and EPOE, the equipment used for drying treatment is a hot air circulation oven. Before putting the materials in, turn on the oven and run it empty for 10-15 minutes to preheat and stabilize the internal air flow temperature. The materials are laid flat on a stainless steel wire mesh tray with a thickness not exceeding 3 cm to ensure that the hot air can penetrate evenly. During drying, turn the materials over every 30 minutes to make the drying effect consistent. After drying is completed, quickly transfer the materials to a self-sealing bag with a desiccant pack and store them temporarily in a dry and cool place. The desiccant pack should be replaced every 24 hours to ensure a dry environment inside the bag;

[0036] For naphthenic oil, a multi-layer filtration device is used for impurity removal. The first layer is a 50-mesh stainless steel filter screen to remove large particle impurities; the second layer is a 100-mesh sintered metal filter screen to intercept slightly smaller particles; the third layer is a precision filter paper with a pore size of 0.5 μm to further filter fine impurities. The filtered naphthenic oil needs to be sampled and tested, and the heavy metal content is determined by atomic absorption spectrometry to ensure that it meets the safety standards for plastic processing. After passing the test, it is stored in a light-proof and sealed stainless steel tank.

[0037] S2. Modified Blending: Carefully add the carbon dioxide-based PE, carbon dioxide-based EVA, and EPDM weighed according to the mass ratio of 30:30:40 into the mixing chamber of a high-speed internal mixer. The mixing chamber needs to be preheated to 50 - 60 °C in advance to reduce the heat shock caused by the temperature difference between the material and the equipment. First, stir at a low speed of 300 - 500 r / min for 5 - 10 minutes. During this stage, the upper cover of the internal mixer is half-opened to facilitate observing the initial state of material mixing and ensure that there is no dead corner for material accumulation. When the materials are initially mixed evenly to form loose aggregates, stop the machine. Slowly add the silane coupling agent (the addition amount is 1.5% - 3% of the total material mass) through the feeding port at the top of the internal mixer, and control the addition time within 2 - 3 minutes to prevent a large amount of coupling agent from entering at one time, which may cause too high local concentration and affect the effect. Subsequently, close the upper cover of the internal mixer, evacuate to -0.06 to -0.07 MPa, and stir at a high speed of 1000 - 1500 r / min for 15 - 25 minutes. During the process, the temperature of the material is monitored in real time through the temperature control system of the internal mixer to ensure that it does not exceed 180 °C to avoid material degradation, and finally, a uniform blend is formed.

[0038] S3. Extrusion Pelletizing: Transfer the obtained blend to the hopper of a single-screw extruder. An electromagnetic vibrating feeder is set below the hopper to control the feeding rate and enable the material to enter the extruder stably and continuously. The screw of the extruder adopts a gradually variable screw with a length-diameter ratio of 20 - 25:1 to enhance the plasticization and conveying effect of the material. The extrusion temperature is controlled at 150 - 180 °C, 170 - 200 °C, and 190 - 220 °C in sequence along the barrel from the feeding section to the die head. The temperature of each zone is precisely regulated through the PID temperature control system, and the temperature fluctuation is controlled within ±3 °C. The screw speed is set at 150 - 250 r / min. At the same time, a melt pressure sensor is installed at the die head to monitor the melt pressure in real time. When the pressure exceeds the set threshold (such as 15 MPa), the screw speed or temperature is automatically adjusted to prevent material blockage. After the material is extruded into a strip through the die head of the extruder, it enters the water tank for cooling. The water temperature in the water tank is controlled at 30 - 50 °C. The cooled strip is cut into plastic pellets of standard size (such as diameter 3 - 5 mm and length 2 - 4 mm) by a pelletizer. The cutting speed of the cutting knife of the pelletizer is synchronously matched with the screw speed of the extruder to ensure uniform and regular pelletizing.

[0039] Specific steps: Before putting carbon dioxide-based PE and carbon dioxide-based EVA into the vacuum drying oven, it is necessary to first conduct an appearance inspection on the raw materials, remove the materials with obvious color unevenness, particle agglomeration and other problems to ensure the initial quality of the raw materials. After putting them into the vacuum drying oven, the heating rate is controlled at 2-3°C per minute to avoid local overheating and deterioration of the raw materials due to too fast heating. When the set lower limit of the drying temperature (65°C) is reached, maintain it for 30 minutes, and then slowly heat up to the upper limit (85°C). During the whole drying process, the vacuum degree is maintained at -0.08 to -0.09 MPa to ensure the effective removal of moisture and small molecule impurities. After drying is completed, transfer the raw materials to a sealed container filled with nitrogen while it is still hot to prevent it from absorbing moisture again and wait for subsequent batching. The equipment used for drying treatment is a hot air circulation oven. Before putting EPDM, POE, SEBS and EPOE, first turn on the oven and run it empty for 10-15 minutes to preheat and stabilize the internal air flow temperature. The materials are laid flat on a stainless steel wire mesh tray with a thickness not exceeding 3 cm to ensure that the hot air can penetrate evenly. During drying, turn the materials over every 30 minutes to make the drying effect consistent. After drying is completed, quickly transfer the materials to a self-sealing bag with a desiccant packet and store them temporarily in a dry and cool place. The desiccant packet is replaced every 24 hours to ensure the dryness of the environment inside the bag. Use a multi-layer filtration device to remove impurities from the naphthenic oil. The first layer is a 50-mesh stainless steel filter screen to remove large particle impurities; the second layer is a 100-mesh sintered metal filter screen to intercept slightly smaller particles; the third layer is a precision filter paper with a pore size of 0.5 μm to further filter fine impurities. The filtered naphthenic oil needs to be sampled and tested, and the heavy metal content is determined by atomic absorption spectrometry to ensure that it meets the plastic processing safety standards. After passing the test, it is stored in a light-proof and sealed stainless steel tank. Carefully add the weighed carbon dioxide-based PE, carbon dioxide-based EVA and EPDM in a mass ratio of 30:30:40 to the mixing chamber of the high-speed internal mixer. The mixing chamber needs to be preheated to 50-60°C in advance to reduce the heat shock caused by the temperature difference between the materials and the equipment. First, stir at a low speed of 300-500 r / min for 5-10 minutes. At this stage, the upper cover of the internal mixer is half open to facilitate observing the initial state of the material mixing and ensure that there is no dead angle of material accumulation. When the materials are initially mixed evenly and form loose aggregates, stop the machine, and slowly add the silane coupling agent (the addition amount is 1.5%-3% of the total material mass) through the feeding port at the top of the internal mixer. The addition time is controlled within 2-3 minutes to prevent the coupling agent from entering in a large amount at one time and causing too high local concentration and affecting the effect. Then close the upper cover of the internal mixer and evacuate to -0.06 to -0.07 MPa, stir at a high speed of 1000 - 1500 r / min for 15 - 25 minutes. During the process, the temperature of the material is monitored in real time through the temperature control system of the internal mixer to ensure that it does not exceed 180 °C, avoiding material degradation. Finally, a uniform blend is formed. Transfer the obtained blend to the hopper of a single-screw extruder. An electromagnetic vibrating feeder is set below the hopper to control the feeding rate, enabling the material to enter the extruder stably and continuously. The screw of the extruder adopts a variable-pitch screw with a length-diameter ratio of 20 - 48:1 to enhance the plasticization and conveying effect of the material. The extrusion temperature is controlled at 150 - 180 °C, 170 - 200 °C, and 190 - 220 °C in sequence along the barrel from the feeding section to the die head. The temperature of each zone is precisely regulated through the PID temperature control system, and the temperature fluctuation is controlled within ±3 °C. The screw speed is set at 150 - 250 r / min. At the same time, a melt pressure sensor is installed at the die head to monitor the melt pressure in real time. When the pressure exceeds the set threshold (such as 15 MPa), the screw speed or temperature is automatically adjusted to prevent blockage. After the material is extruded into strips through the die head of the machine head, it enters the water tank for cooling. The water temperature in the water tank is controlled at 30 - 50 °C. The cooled strips are cut into plastic particles of standard size (such as diameter 3 - 5 mm and length 2 - 4 mm) by a pelletizer. The cutting speed of the cutting knife of the pelletizer is synchronously matched with the screw speed of the extruder to ensure uniform and regular pelletizing.

[0040] Example 2:

[0041] S1. Raw material pretreatment: The same as in Example 1.

[0042] S2. Modified blending: First, pour carbon dioxide-based PE (or carbon dioxide-based EVA), POE, and SEBS weighed according to a mass ratio of 40:30:30 at room temperature into a V-type mixer. The V-type mixer runs at a speed of 50 - 80 r / min for 3 - 5 minutes for premixing. After premixing, transfer the material to a hopper with a vacuum feeding device and precisely feed it into the feeding port of a co-rotating twin-screw extruder through vacuum feeding. A loss-in-weight scale is set above the feeding port to monitor the feeding rate of the material in real time to ensure stable and precise feeding. The screw speed is set at 250 - 350 r / min. The temperature settings for each section of the extruder are: zone 1 at 140 - 160 °C, zone 2 at 160 - 180 °C, and zone 3 at 180 - 200 °C. During the extrusion process of the material, dynamic blending is achieved under the action of screw shear and heat conduction. At the same time, a maleic anhydride-grafted polymer (the addition amount is 2% - 4% of the total material mass) is added through a side feeding port in the middle of zone 2, and the addition rate is matched with the extrusion rate of the material to ensure uniform dispersion of the compatibilizer and optimize the particle properties.

[0043] S3. Extrusion and pelletizing: The same as in Example 1.

[0044] Specific steps: Before putting carbon dioxide-based PE and carbon dioxide-based EVA into the vacuum drying oven, the appearance of the raw materials needs to be inspected first, and the materials with obvious color unevenness, particle caking and other problems should be removed to ensure the initial quality of the raw materials. After putting them into the vacuum drying oven, the heating rate should be controlled at 2-3°C per minute to avoid local overheating and deterioration of the raw materials due to too fast heating. When the set lower limit of the drying temperature (65°C) is reached, keep it for 30 minutes, and then slowly heat up to the upper limit (85°C). During the whole drying process, the vacuum degree should be maintained at -0.08 to -0.09 MPa to ensure the effective removal of moisture and small molecule impurities. After drying, transfer the raw materials to a sealed container filled with nitrogen while it is still hot to prevent it from reabsorbing moisture and wait for subsequent batching. The equipment used for drying treatment is a hot air circulation oven. Before putting EPDM, POE, SEBS and EPOE, start the oven to run empty for 10-15 minutes to preheat and stabilize the internal air flow temperature. The materials are laid flat on a stainless steel wire mesh plate with a thickness not exceeding 3 cm to ensure that the hot air can penetrate evenly. During drying, turn the materials over every 30 minutes to make the drying effect uniform. After drying, quickly transfer the materials to a self-sealing bag with a desiccant packet and store them temporarily in a dry and cool place. The desiccant packet should be replaced every 24 hours to ensure the dryness of the environment inside the bag. Use a multi-layer filtration device to remove impurities from the naphthenic oil. The first layer is a 50-mesh stainless steel filter screen to remove large particle impurities; the second layer is a 100-mesh sintered metal filter screen to intercept slightly smaller particles; the third layer is 0.Precision filter paper with a pore size of 5 μm is used to further filter out fine impurities. The filtered naphthenic oil needs to be sampled and tested, and the heavy metal content is determined by atomic absorption spectrometry to ensure that it meets the safety standards for plastic processing. After passing the test, it is stored in a light-proof and sealed stainless steel tank. First, at room temperature, carbon dioxide-based PE (or carbon dioxide-based EVA), POE, and SEBS weighed according to a mass ratio of 40:30:30 are poured into a V-type mixer. The V-type mixer runs at a speed of 50 - 80 r / min for 3 - 5 minutes for premixing. After the premixing is completed, the material is transferred to a hopper with a vacuum feeding device and precisely fed into the feeding port of a co-rotating twin-screw extruder through vacuum feeding. A loss-in-weight scale is set above the feeding port to monitor the feeding rate of the material in real time to ensure stable and precise feeding. The screw speed is set at 250 - 350 r / min. The temperature settings for each section of the extruder are as follows: zone 1 is 140 - 160 °C, zone 2 is 160 - 180 °C, and zone 3 is 180 - 200 °C. During the extrusion process, the material undergoes dynamic blending under the action of screw shear and heat conduction. At the same time, a maleic anhydride grafted polymer (the addition amount is 2% - 4% of the total material mass) is added through a side feeding port in the middle of zone 2, and the addition rate matches the extrusion rate of the material to ensure uniform dispersion of the compatibilizer and optimize the particle properties. The obtained blend is transferred to the hopper of a single-screw extruder, and an electromagnetic vibrating feeder is set below the hopper to control the feeding rate and make the material enter the extruder stably and continuously. The screw of the extruder is a tapered screw with a length-diameter ratio of 20 - 48:1 to enhance the plasticization and conveying effect of the material. The extrusion temperature is controlled at 150 - 180 °C, 170 - 200 °C, and 190 - 220 °C in sequence from the feeding section to the die head along the barrel. The temperature of each zone is precisely regulated by a PID temperature control system, and the temperature fluctuation is controlled within ±3 °C. The screw speed is set at 150 - 250 r / min. At the same time, a melt pressure sensor is installed at the die head to monitor the melt pressure in real time. When the pressure exceeds the set threshold (such as 15 MPa), the screw speed or temperature is automatically adjusted to prevent blockage. After the material is extruded into strips through the die head of the machine head, it enters a water bath for cooling. The water temperature of the water bath is controlled at 30 - 50 °C. The cooled strips are cut into plastic particles of standard size (such as diameter 3 - 5 mm and length 2 - 4 mm) by a pelletizer. The cutting speed of the cutting knife of the pelletizer is synchronized with the screw speed of the extruder to ensure uniform and regular pelletizing.

[0045] Example 3:

[0046] S1. Raw material pretreatment: The same as in Example 1.

[0047] S2. Modified Blending: Weigh carbon dioxide-based PE, carbon dioxide-based EVA, and EPOE accurately according to the mass ratio of 45:40:15, and put them into the mixing chamber of a Haake mixer. The mixing chamber is preheated to 60 - 70 °C in advance. Then add antioxidants (0.5% - 1% of the total material mass). The antioxidants need to be pre-mixed evenly with a small amount of base material (about 5% of the total material mass) and then added as a whole to prevent the agglomeration of antioxidants. Mix at a speed of 800 - 1200 r / min for 10 - 20 minutes. During the mixing process, the rotational speed fluctuation of the rotor of the Haake mixer is controlled within ±50 r / min to ensure uniform mixing intensity. At the same time, the cooling water flow rate of the mixer is adjusted in real time according to the material temperature to keep the material temperature at 160 - 180 °C, obtaining a blend with excellent performance.

[0048] S3. Extrusion Granulation: The same as in Example 1.

[0049] Specific steps: Before putting the carbon dioxide-based PE and carbon dioxide-based EVA into the vacuum drying oven, it is necessary to first conduct an appearance inspection on the raw materials, remove the materials with obvious problems such as uneven color and particle agglomeration, and ensure the initial quality of the raw materials. After putting them into the vacuum drying oven, the heating rate is controlled at 2-3 °C per minute to avoid local overheating and deterioration of the raw materials due to too fast heating. When the set lower limit of the drying temperature (65 °C) is reached, keep it for 30 minutes, and then slowly heat up to the upper limit (85 °C). During the whole drying process, the vacuum degree is maintained at -0.08 to -0.09 MPa to ensure effective removal of moisture and small molecule impurities. After drying is completed, transfer the raw materials to a sealed container filled with nitrogen while it is still hot to prevent it from reabsorbing moisture and wait for subsequent batching. The equipment used for drying treatment is a hot air circulation oven. Before putting in EPDM, POE, SEBS, and EPOE, start the oven to run empty for 10-15 minutes to preheat and stabilize the internal air flow temperature. The materials are laid flat on a stainless steel wire mesh tray with a thickness not exceeding 3 cm to ensure that the hot air can penetrate evenly. During drying, turn the materials over every 30 minutes to make the drying effect consistent. After drying is completed, quickly transfer the materials to a self-sealing bag with a desiccant pack and store them temporarily in a dry and cool place. Replace the desiccant pack every 24 hours to ensure the dryness of the environment inside the bag. Use a multi-layer filtration device to remove impurities from the naphthenic oil. The first layer is a 50-mesh stainless steel filter screen to remove large particle impurities; the second layer is a 100-mesh sintered metal filter screen to intercept slightly smaller particles; the third layer is a precision filter paper with a pore size of 0.5 μm to further filter fine impurities. The filtered naphthenic oil needs to be sampled and tested, and the heavy metal content is determined by atomic absorption spectrometry to ensure that it meets the plastic processing safety standards. After passing the test, store it in a light-proof and sealed stainless steel tank. Weigh the carbon dioxide-based PE, carbon dioxide-based EVA, and EPOE accurately according to the mass ratio of 45:40:15 and put them into the mixing chamber of the Haake mixer. The mixing chamber is preheated to 60-70 °C in advance, and an antioxidant (0.(5%-1%), the antioxidant needs to be pre-mixed evenly with a small amount of base material (about 5% of the total material mass) and then added as a whole to prevent the antioxidant from agglomerating. Mix at a speed of 800-1200 r / min for 10-20 minutes. During the mixing process, the rotor speed fluctuation of the Haake mixer is controlled within ±50 r / min to ensure uniform mixing intensity. At the same time, the cooling water flow rate of the mixer is adjusted in real time according to the material temperature to maintain the material temperature at 160-180 °C, obtaining a blend with excellent performance. Transfer the obtained blend to the hopper of a single-screw extruder. An electromagnetic vibrating feeder is set below the hopper to control the feeding rate and make the material enter the extruder stably and continuously. The extruder screw adopts a variable-pitch screw with a length-diameter ratio of 20-25:1 to enhance the plasticization and conveying effect of the material. The extrusion temperature is controlled at 150-180 °C, 170-200 °C, and 190-220 °C in sequence from the feeding section to the die head along the barrel. The temperature of each zone is accurately controlled by a PID temperature control system, and the temperature fluctuation is controlled within ±3 °C. The screw speed is set at 150-250 r / min. At the same time, a melt pressure sensor is installed at the die head to monitor the melt pressure in real time. When the pressure exceeds the set threshold (such as 15 MPa), the screw speed or temperature is automatically adjusted to prevent blockage. After the material is extruded into strips through the die head of the machine head, it enters the water tank for cooling. The water temperature of the water tank is controlled at 30-50 °C. The cooled strips are cut into plastic particles of standard size (such as diameter 3-5 mm, length 2-4 mm) by a granulator. The cutting speed of the cutting knife of the granulator is synchronously matched with the screw speed of the extruder to ensure uniform and regular granulation.

[0050] Example 4:

[0051] S1. Raw material pretreatment: The same as in Example 1.

[0052] S2. Modified blending: Weigh carbon dioxide-based EVA (or carbon dioxide-based PE), SEBS, naphthenic oil, and EPOE according to the mass ratio of 35:25:20:20. First, add the carbon dioxide-based material, SEBS, and naphthenic oil to a planetary mixer. The revolution speed of the planetary mixer is set at 200-400 r / min, and the rotation speed is 1.5-2 times the revolution speed. Stir at a low speed for 8-15 minutes. During the stirring process, observe the dispersion of the naphthenic oil through the transparent window of the mixer to ensure that it evenly wraps around the surface of the polymer particles. Then stop the machine and add EPOE and an appropriate amount of lubricant (0.3%-0.8% of the total material mass) through the top feeding port. Start the mixer again, increase the revolution speed to 1200-1800 r / min, and adjust the rotation speed accordingly. Stir at a high speed for 10-20 minutes to prepare a blend with a unique feel and performance. During this period, stop the machine every 5 minutes to check the mixing state of the material to ensure the mixing quality.

[0053] S3. Extrusion granulation: The same as in Example 1

[0054] Specific steps: Before putting the carbon dioxide-based PE and carbon dioxide-based EVA into the vacuum drying oven, it is necessary to first conduct an appearance inspection on the raw materials, remove the materials with obvious color unevenness, particle caking and other problems, and ensure the initial quality of the raw materials. After putting them into the vacuum drying oven, the heating rate is controlled at 2-3°C per minute to avoid local overheating and deterioration of the raw materials due to too fast heating. When the set lower limit of the drying temperature (65°C) is reached, maintain it for 30 minutes, and then slowly heat up to the upper limit (85°C). During the whole drying process, the vacuum degree is maintained at -0.08 to -0.09 MPa to ensure effective removal of moisture and small molecule impurities. After drying is completed, transfer the raw materials to a sealed container filled with nitrogen while it is still hot to prevent it from reabsorbing moisture and wait for subsequent batching. The equipment used for drying treatment is a hot air circulation oven. Before putting EPDM, POE, SEBS and EPOE, start the oven to run empty for 10-15 minutes to preheat and stabilize the internal air flow temperature. The materials are laid flat on a stainless steel wire mesh tray with a thickness not exceeding 3 cm to ensure that the hot air can penetrate evenly. During drying, turn the materials over every 30 minutes to make the drying effect uniform. After drying is completed, quickly transfer the materials to a self-sealing bag with a desiccant pack and store them temporarily in a dry and cool place. Replace the desiccant pack every 24 hours to ensure a dry environment inside the bag. Use a multi-layer filtration device to remove impurities from the naphthenic oil. The first layer is a 50-mesh stainless steel filter screen to remove large particle impurities; the second layer is a 100-mesh sintered metal filter screen to intercept slightly smaller particles; the third layer is a precision filter paper with a pore diameter of 0.5 μm to further filter fine impurities. The filtered naphthenic oil needs to be sampled and tested, and the heavy metal content is determined by atomic absorption spectrometry to ensure that it meets the plastic processing safety standards. After passing the test, store it in a light-proof and sealed stainless steel tank. Weigh carbon dioxide-based EVA (or carbon dioxide-based PE), SEBS, naphthenic oil and EPOE according to the mass ratio of 35:25:20:20. First, add the carbon dioxide-based material, SEBS and naphthenic oil to a planetary mixer. The revolution speed of the planetary mixer is set at 200-400 r / min, and the rotation speed is 1.5-2 times the revolution speed. Stir at a low speed for 8-15 minutes. During the stirring process, observe the dispersion of the naphthenic oil through the transparent window of the mixer to ensure that it evenly wraps the polymer particles.After shutdown, add EPOE and an appropriate amount of lubricant (0.3%-0.8% of the total material mass) through the top feeding port. Restart the mixer, increase the revolution speed to 1200-1800 r / min, adjust the rotation speed accordingly, and stir at high speed for 10-20 minutes to prepare a blend with unique feel and performance. During this period, stop the machine every 5 minutes to check the mixing state of the material to ensure the mixing quality. Transfer the obtained blend to the hopper of a single-screw extruder. An electromagnetic vibrating feeder is set below the hopper to control the feeding rate so that the material enters the extruder stably and continuously. The screw of the extruder is a variable-pitch screw with a length-diameter ratio of 20-48:1 to enhance the plasticization and conveying effect of the material. The extrusion temperature is controlled at 150-180°C, 170-200°C, and 190-220°C in sequence along the barrel from the feeding section to the head. The temperature of each zone is precisely regulated by a PID temperature control system, and the temperature fluctuation is controlled within ±3°C. The screw speed is set at 150-250 r / min. At the same time, a melt pressure sensor is installed at the head to monitor the melt pressure in real time. When the pressure exceeds the set threshold (such as 15 MPa), the screw speed or temperature is automatically adjusted to prevent material blockage. After the material is extruded into strips through the die of the head, it enters the water tank for cooling. The water temperature in the water tank is controlled at 30-50°C. The cooled strips are cut into plastic particles of standard size (such as diameter 3-5 mm and length 2-4 mm) by a pelletizer. The cutting speed of the cutting knife of the pelletizer is synchronously matched with the screw speed of the extruder to ensure uniform and regular pelletizing.

[0055] Verification of Example 1:

[0056] After testing the prepared plastic particles, the tensile strength is increased by 18% compared with traditional PE-based plastics, the elongation at break is increased by 22%, and the Shore hardness is reduced by 5 units, showing good improvement in flexibility and being suitable for the manufacture of toy parts with high flexibility requirements.

[0057] Verification of Example 2:

[0058] After forming into particles, the impact strength is increased by 20% compared with ordinary plastics, the melt flow rate is optimized within the range of 3-6 g / 10 min, and the processing performance is excellent. It is successfully applied to the injection molding of electronic and electrical appliance casings to meet the requirements of appearance and structural strength.

[0059] Verification of Example 3:

[0060] The tear strength of the particle product is increased by 15%, and the weather resistance is enhanced. It performs excellently in applications such as outdoor sports equipment like yoga mats and skipping rope handles. After half a year of outdoor exposure test, the performance attenuation is extremely small.

[0061] Verification of Example 4:

[0062] The prepared plastic particles have a soft and delicate feel, with a 20% reduction in flexural modulus. They can be used in high-end artificial leather, flexible packaging and other fields, and have received good market feedback, enhancing the added value of the products.

[0063] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing low-carbon carbon dioxide-based modified plastic particles, characterized in that: The following steps are involved: S1. Raw material pretreatment: select CO2-based PE (polyethylene) with a melt flow rate of 1-5g / 10min and CO2-based EVA (ethylene-vinyl acetate copolymer) with a vinyl acetate content of 10%-30%, and put them into a vacuum drying oven for drying respectively, with the temperature controlled at 65-85°C for 2.5-3.5 hours; dry EPDM (ethylene propylene diene monomer rubber), POE (polyolefin elastomer), SEBS (styrene-ethylene-butylene-styrene block copolymer), and EPOE (ethylene-propylene-octene copolymer) respectively, with the temperature set at 50-70°C for 2-3 hours; and perform impurity removal and filtration on cyclohexane oil to remove mechanical impurities. S2. Modified blending: CO2-based PE, CO2-based EVA and EPDM are added to a high-speed internal mixer in a mass ratio of 30:30:40, stirred at a low speed (300-500 r / min) for 5-10 minutes, and then a silane coupling agent accounting for 1.5%-3% of the total material mass is added, followed by high-speed stirring (1000-1500 r / min) for 15-25 minutes; CO2-based PE or CO2-based EVA, POE and SEBS are mixed in a mass ratio of 40:30:30, premixed at room temperature for 3-5 minutes, and then a maleic anhydride grafted polymer accounting for 2%-4% of the total material mass is added, and the mixture is fed into the feeding port of a co-rotating twin-screw extruder, and the screw speed is set to 250-350 r / min ; Mix carbon dioxide-based PE, carbon dioxide-based EVA and EPOE in a mass ratio of 45:40:15, add 0.5%-1% of the total material mass of an antioxidant, and mix at a speed of 800-1200r / min in a Haake internal mixer for 10-20 minutes; mix carbon dioxide-based EVA or carbon dioxide-based PE, SEBS, cyclohexane oil and EPOE in a mass ratio of 35:25:20:20, first stir the carbon dioxide-based material, SEBS and cyclohexane oil in a planetary mixer at a low speed (200-400r / min) for 8-15 minutes, then add EPOE and a lubricant accounting for 0.3%-0.8% of the total material mass, and stir at a high speed (1200-1800r / min) for 10-20 minutes. S3, extrusion granulation: the blend obtained in S2, modified blending, is extruded through a single screw extruder, and the extrusion temperature is controlled at 150-180°C, 170-200°C, and 190-220°C along the barrel from the feeding section to the die, and the screw speed is set to 150-250r / min. After the material is extruded into strips through the die of the die, it is cut into plastic particles of standard size by a pelletizer.

2. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: During the drying process of the carbon dioxide-based PE and carbon dioxide-based EVA, the heating rate of the vacuum drying oven is controlled at 2-3°C per minute, and when the drying temperature reaches the lower limit of 65°C, it is maintained for 30 minutes, and then the temperature is raised to the upper limit of 85°C, and the vacuum degree is maintained at -0.08 to -0.09MPa. After drying, the mixture is transferred to a sealed container filled with nitrogen while still hot.

3. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The EPDM, POE, SEBS and EPOE are dried in a hot air circulation oven. The material is laid flat with a thickness of no more than 3 cm and is turned over every 30 minutes. After drying, the material is transferred to a ziplock bag with a desiccant bag. The desiccant bag is replaced every 24 hours.

4. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The cycloparaffinic oil is purified by a multi-layer filtration device including a first layer of 50-mesh stainless steel filter, a second layer of 100-mesh sintered metal filter, and a third layer of 0.5 μm pore size precision filter paper. After filtration, sampling is performed to detect the heavy metal content, which complies with the plastic processing safety standard, and the oil is stored in a light-proof, sealed stainless steel tank.

5. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The high-speed internal mixer is preheated to 50-60°C in advance, the silane coupling agent is added for 2-3 minutes, the internal mixer is vacuumed to -0.06 to -0.07MPa during high-speed stirring, and the material temperature does not exceed 180°C.

6. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The premixing speed of the V-type mixer is 50-80r / min, the temperature of the first zone of the co-rotating twin-screw extruder is 140-160°C, the temperature of the second zone is 160-180°C, and the temperature of the third zone is 180-200°C. The maleic anhydride grafted polymer is added to the side feed port in the middle section of the second zone, and the addition rate matches the material extrusion rate.

7. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The Hake mixer chamber is heated to 60-70°C in advance, the antioxidant is mixed with about 5% of the total material mass before being added, the rotor speed fluctuation is controlled within ±50r / min, and the cooling water flow rate is adjusted in real time according to the material temperature to maintain the material temperature at 160-180°C.

8. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The revolution speed of the planetary mixer is set to 200-400r / min, and the rotation speed is 1.5-2 times of the revolution speed. During low-speed stirring, the dispersion of cyclohexane oil is observed through a transparent window. After the addition of EPOE and lubricant, the revolution speed is increased to 1200-1800r / min, and the rotation speed is adjusted accordingly. The machine is stopped every 5 minutes to check the mixing status of the materials.

9. The method for preparing low-carbon carbon dioxide-based modified plastic particles according to claim 1, characterized in that: The single-screw extruder screw adopts a gradual-change screw with a length-to-diameter ratio of 20-48:

1. The extrusion temperature is precisely controlled by a PID temperature control system, and the temperature fluctuation is controlled within ±3°C. A melt pressure sensor is installed at the die head. When the pressure exceeds 15MPa, the screw speed or temperature is automatically adjusted. The water temperature of the water tank is controlled at 30-50°C. The speed of the pelletizer cutter is synchronously matched with the speed of the extruder screw. The standard size of the pelletizer is 3-5mm in diameter and 2-4mm in length.