Stress-dispersed porous plastic modified composite particles and molding method

Abstract

This invention discloses a stress-dispersing porous plastic modified composite particle and its molding method. By weight, the raw materials include 100 parts of matrix resin, 10-25 parts of stress-dispersing modified masterbatch, 3-10 parts of compatibilizer, 0.5-2.5 parts of composite pore-forming agent, 0.1-0.5 parts of antioxidant, and 0.2-0.8 parts of lubricant. The matrix resin is copolymer polypropylene with a melt index of 15-35 g / 10min at 230℃ and a load of 2.16 kg. The polypropylene composite material with the addition of the particles of this invention exhibits a tensile strength decrease of no more than 5%, and a room-temperature notched impact strength more than 2.5 times that of pure polypropylene. When the particles are subjected to stress, the internal micron-sized closed pores first undergo elastic compression to buffer the stress, and then the stress is transferred to halloysite nanotubes. The host-guest inclusion complex within the nanotubes undergoes reversible unpacking and energy dissipation within the confined space. Maleic anhydride-grafted polypropylene enhances the interfacial bonding, ensuring effective stress transfer. Gradient water cooling and side-feeding processes ensure uniform closed-cell structure, preventing collapse during processing.

Description

Technical Field

[0001] This invention relates to porous plastic modified composite particles, and more particularly to a stress-dispersing porous plastic modified composite particle and its molding method. Background Technology

[0002] Polypropylene (PP) possesses advantages such as low density, chemical resistance, and ease of processing and molding, making it widely used in automotive parts, home appliances, athletic footwear, and packaging materials. However, its low low-temperature impact strength limits its applications. Existing toughening modification methods primarily involve elastomer toughening, rigid particle toughening, or porous fillers.

[0003] Elastomer toughening involves introducing rubber phases such as EPDM rubber and polyolefin elastomers into a polypropylene matrix, utilizing the cavitation of rubber particles to dissipate energy. This method offers good toughening effects, but its drawback is a significant reduction in the tensile strength and flexural modulus of the material, which is highly detrimental to rigidity. Rigid particle toughening uses inorganic fillers such as calcium carbonate and talc, which offers advantages such as low cost and minimal impact on rigidity, but its toughening effect is limited. Following the emergence of these two methods, porous filler toughening technology has been developed, which utilizes the deformation of the filler's internal pore structure under stress to absorb energy, theoretically improving toughness while maintaining rigidity. However, in existing porous filler solutions, the filler skeleton and matrix are generally physically encapsulated or simply blended, resulting in weak interfacial bonding. After repeated stress, the skeleton and matrix easily separate, and the stress dispersion effect decays rapidly over time.

[0004] In the field of polypropylene toughening modification, existing technologies do not yet offer a better solution for how to effectively improve toughness while maintaining material rigidity, or how to ensure that fillers maintain a stable stress dispersion effect after repeated stress. Summary of the Invention

[0005] To address the shortcomings of the aforementioned technologies, this invention provides a stress-dispersing porous plastic modified composite particle and its molding method.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a stress-dispersing porous plastic modified composite particle, which, by weight, comprises: 100 parts of matrix resin, 10-25 parts of stress-dispersing modified masterbatch, 3-10 parts of compatibilizer, 0.5-2.5 parts of composite pore-forming agent, 0.1-0.5 parts of antioxidant, and 0.2-0.8 parts of lubricant; The base resin is copolymer polypropylene, with a melt index of 15-35 g / 10min at 230℃ and 2.16kg load; The stress dispersion modified masterbatch was prepared by vacuum infusion and cross-linking reaction of halloysite nanotubes, carboxymethyl-β-cyclodextrin, ferrocene carboxylic acid, polypropylene glycol diglycidyl ether and triethylenetetramine. The inner lumen of the halloysite nanotubes contains a host-guest inclusion complex formed by carboxymethyl-β-cyclodextrin and ferrocene carboxylic acid.

[0007] Furthermore, the preparation method of the stress dispersion modified masterbatch includes: S1: Dry halloysite nanotubes under vacuum at 110-130℃ for 2-4 hours, place them in a vacuum reactor, evacuate to -0.09 to -0.1MPa, and maintain the pressure for 20-40 minutes; S2: Prepare an aqueous solution containing carboxymethyl-β-cyclodextrin and ferrocene carboxylic acid, with a carboxymethyl-β-cyclodextrin concentration of 0.08-0.15 mol / L and a molar ratio of ferrocene carboxylic acid to carboxymethyl-β-cyclodextrin of 1:0.8-1.2. Stir at 40-60℃ for 1-2 hours to form a host-guest inclusion complex solution. S3: Maintaining a vacuum state, inject the inclusion complex solution from step S2 into the reactor to impregnate halloysite nanotubes. After restoring normal pressure, ultrasonically disperse for 15-30 minutes, let stand for 6-12 hours, filter, and vacuum dry the solid at 60-80℃ to obtain halloysite nanotubes filled with host-guest inclusion complexes. S4: Mix halloysite nanotubes obtained in step S3 with polypropylene glycol diglycidyl ether and triethylenetetramine at a mass ratio of 1:0.4-0.8:0.1-0.2, knead at 35-45℃ for 15-25 minutes, then cure at 60-70℃ for 2-3 hours, pulverize and sieve to obtain stress dispersion modified masterbatch.

[0008] Furthermore, the halloysite nanotubes in step S1 have a tube length of 0.5-2.5 μm, an outer diameter of 40-80 nm, an inner diameter of 15-40 nm, and a specific surface area of ​​45-75 m² / g.

[0009] Furthermore, the compatibilizer is maleic anhydride-grafted polypropylene with a grafting rate of 0.5-1.5%; the composite porogen is prepared by compounding azodicarbonamide and ammonium bicarbonate at a mass ratio of 1:0.3-0.8.

[0010] Furthermore, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:0.8-1.2; the lubricant is calcium stearate or ethylene bis-stearamide.

[0011] Furthermore, the composite particles have a particle size of 1.5-5.0 mm, an internal closed-cell structure, a porosity of 20-45%, and an apparent density of 0.50-0.78 g / cm³.

[0012] A method for molding stress-dispersing porous plastic modified composite particles includes the following steps:

[0013] Step A1: Prepare stress dispersion modified masterbatch; Step A2: Mix the matrix resin, stress dispersion modified masterbatch, compatibilizer, composite pore-forming agent, antioxidant, and lubricant in a high-speed mixer according to the formula. The mixing temperature is 35-50℃, the speed is 600-900 r / min, and the time is 8-15min. Step A3: Feed the mixture obtained in the above steps into a twin-screw extruder for melt extrusion. The temperatures of each section of the extruder are as follows: Zone 1 145-155℃, Zone 2 165-175℃, Zone 3 185-195℃, Zone 4 192-202℃, Zone 5 185-192℃, Zone 6 170-180℃, and the die head 175-185℃. The screw speed is 220-300 r / min. Step A4: The extruded strips are subjected to gradient water cooling, air drying, and pelletizing. They are then dried at 70-90℃ for 2-4 hours and sieved to obtain stress-dispersed porous plastic modified composite particles.

[0014] Furthermore, in step A3, the fourth zone barrel of the twin-screw extruder is equipped with a side feed port, through which the composite pore-forming agent is added.

[0015] Furthermore, the gradient water cooling in step A4 is set in three stages: the first stage water temperature is 45-55℃, the second stage water temperature is 25-35℃, and the third stage water temperature is 8-15℃, with a dwell time of 2-4 seconds in each stage.

[0016] A stress-dispersing porous plastic modified composite particle and its molding method are disclosed. In this method, after the porous plastic modified composite particle is added to a polypropylene matrix, the tensile strength decrease is controlled within 5%, while the room temperature notched impact strength can reach more than 2.5 times that of pure polypropylene.

[0017] The stress dispersion function mainly relies on structural design: carboxymethyl-β-cyclodextrin and ferrocene form a host-guest inclusion complex within the halloysite nanotube cavity. When the material is subjected to external force, ferrocene molecules slide out of the cyclodextrin cavity, a process that consumes energy. After the external force is removed, the ferrocene molecules slide back into the cavity under thermal motion, and the inclusion complex returns to its original state, demonstrating the ability to repeatedly consume energy. The confined space of the halloysite nanotube restricts the movement of the inclusion complex molecules, and the energy consumption of a single unpacking and unpacking is higher than that in the free solution state. In addition, the high aspect ratio structure of the nanotube itself can effectively transfer stress, dispersing the external load to multiple inclusion complex molecules within the cavity.

[0018] The micron-sized closed pores formed inside the particles by the composite porogen undergo elastic compression under stress, absorbing some energy. The stress that is not completely absorbed by the micron-sized pores continues to be transmitted to the stress-dispersion modified masterbatch, triggering molecular-scale unpacking and energy dissipation. The molecular energy dissipation mechanisms in the micron-sized pores and nanotube cavities respond sequentially during the stress process, forming a two-level stress dispersion system.

[0019] Maleic anhydride-grafted polypropylene, acting as a compatibilizer, accumulates at the interface between the polypropylene matrix and the stress-dispersion modified masterbatch. Through chemical bonding and chain segment entanglement, it enhances the interfacial bonding strength, ensuring that stress can be effectively transferred from the matrix to the interior of the particles. The epoxy-amine crosslinking network binds the filled halloysite nanotubes into the masterbatch, preventing the nanotubes from agglomerating during processing and protecting the filler inside the tube from extrusion and shear damage.

[0020] The three-stage gradient water cooling process makes the cooling rate of the particle surface and interior more consistent, reducing cell shrinkage and internal stress concentration. The resulting closed-cell structure is less prone to collapse during subsequent injection molding. The side-feeding method adds some composite pore-forming agent, which shortens the residence time of the foaming agent in the high-temperature zone and makes the cell distribution more uniform. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to specific embodiments.

[0022] This embodiment relates to stress-dispersed porous plastic modified composite particles and their molding method. The stress-dispersed porous plastic modified composite particles, by weight, consist of: 100 parts matrix resin, 10-25 parts stress-dispersing modified masterbatch, 3-10 parts compatibilizer, 0.5-2.5 parts composite pore-forming agent, 0.1-0.5 parts antioxidant, and 0.2-0.8 parts lubricant. The matrix resin is copolymer polypropylene with a melt index of 15-35 g / 10min at 230℃ and a load of 2.16 kg. The stress-dispersing modified masterbatch is prepared by vacuum infusion and crosslinking reaction of halloysite nanotubes, carboxymethyl-β-cyclodextrin, ferrocene, polypropylene glycol diglycidyl ether, and triethylenetetramine. The inner lumen of the halloysite nanotubes contains a host-guest inclusion complex formed by carboxymethyl-β-cyclodextrin and ferrocene.

[0023] Regarding the preparation of stress dispersion modified masterbatch, multiple preparation examples were actually tested.

[0024] Example 1: Preparation of Stress Dispersion Modified Masterbatch

[0025] S1, Vacuum pretreatment of halloysite nanotubes

[0026] Take 200g of halloysite nanotubes with a length of 0.5-1.5μm, an outer diameter of 45-65 nm, an inner diameter of 12-25 nm, a specific surface area of ​​52-68 m² / g, and a purity ≥95%. Before use, dry the nanotubes in a vacuum drying oven at 120℃ for 4 hours. Then, spread the dried halloysite nanotubes flat on a tray and place them in a vacuum drying oven. Dry them at 120℃ and -0.095 MPa for 3.5 hours. Afterward, transfer them to a vacuum reactor, seal the reactor, and evacuate to -0.098 MPa. Hold the pressure for 30 minutes to allow the gas inside the tubes to be fully expelled.

[0027] S2. Preparation of host-guest inclusion complex solution

[0028] Weigh 28.6 g of carboxymethyl-β-cyclodextrin (degree of substitution 4.5-5.5, purity ≥98%) and dissolve it in 200 mL of deionized water to obtain a colorless and transparent solution with a concentration of approximately 0.12 mol / L. Weigh 5.5 g of ferrocene carboxylic acid (purity ≥98%) and add it to the solution in portions with stirring in a 50 °C water bath. The molar ratio of ferrocene carboxylic acid to carboxymethyl-β-cyclodextrin is 1:1. Continue stirring for 1.5 hours. When the solution changes from light yellow to deep orange, it indicates that the host-guest inclusion complex has been formed.

[0029] S3, Vacuum Injection Filling

[0030] Maintain a vacuum of -0.098 MPa in the reactor, and inject the solution obtained in step S2 into the halloysite nanotubes; close the feed valve and maintain the vacuum for 5 minutes, then restore atmospheric pressure and continue impregnation for 30 minutes; transfer the mixture into a beaker, ultrasonically disperse it at 300W and 40kHz for 25 minutes, and let it stand at room temperature for 12 hours; then centrifuge at 8000rpm for 15 minutes, discard the supernatant, and wash the precipitate twice with deionized water; dry the solid under vacuum at 70℃ and -0.095 MPa for 8 hours to obtain halloysite nanotubes filled with host-guest inclusion complexes.

[0031] S4, epoxy-amine crosslinking granulation

[0032] Take 200g of the product obtained in step S3 and mix it with 120g of polypropylene glycol diglycidyl ether (epoxy value 0.30-0.35 mol / 100g) and 30g of triethylenetetramine (purity ≥95%). Add the mixture to a kneader and knead at 40℃ for 20 minutes. Spread the material on a tray to a thickness of about 1cm and cure at 65℃ for 2.5 hours. After the cured product is crushed, pass it through a 100-mesh sieve to obtain stress dispersion modified masterbatch, denoted as M1.

[0033] Example 2: Preparation of stress dispersion modified masterbatch

[0034] S1: Same as preparation example one.

[0035] S2: 35.8 g of carboxymethyl-β-cyclodextrin was dissolved in 200 mL of deionized water to obtain a 0.15 mol / L solution; 8.3 g of ferrocene carboxylic acid was used, with a molar ratio of 1.2:1. The rest was the same as in Preparation Example 1.

[0036] S3: Same as preparation example 1.

[0037] S4: Take 200g of the product obtained in step S3, mix it with 160g of polypropylene glycol diglycidyl ether and 40g of triethylenetetramine, and then proceed as in preparation example 1 to obtain stress dispersion modified masterbatch M2.

[0038] Example 3: Preparation of stress dispersion modified masterbatch

[0039] S1: Halloysite nanotubes with a length of 1.2-2.0 μm were selected, and the pretreatment was the same as in Preparation Example 1.

[0040] S2: Same as preparation example one.

[0041] S3: Same as preparation example 1.

[0042] S4: Take 200g of the product obtained in step S3, mix it with 80g of polypropylene glycol diglycidyl ether and 20g of triethylenetetramine, and then proceed as in preparation example 1 to obtain stress dispersion modified masterbatch M3.

[0043] Based on the above description, the preparation of stress-dispersing porous plastic modified composite particles includes several embodiments, as detailed below: Example 1

[0044] Copolymer polypropylene (melt index 18 g / 10min, 230℃ / 2.16kg), 100 parts, actual feed amount 3.0kg; Stress dispersion modified masterbatch M1, 16 parts, actual feed amount 0.48kg; Maleic anhydride grafted polypropylene (grafting rate 0.8-1.0%), 5 parts, actual feed amount 0.15kg; Composite porogen, 1.5 parts, actual feed amount 45g; Antioxidant (1010 and 168 mixed at a 1:1 mass ratio), 0.25 parts, actual feed amount 7.5g; Calcium stearate, 0.4 parts, actual feed amount 12g.

[0045] The composite porogen is prepared by compounding azodicarbonamide (decomposition temperature 205-215℃, gas generation 220 mL / g) and ammonium bicarbonate (decomposition temperature 36-60℃) at a mass ratio of 1:0.5.

[0046] All raw materials, except for the side feeder, including 35g of composite pore-forming agent, are put into a high-speed mixer and mixed at 800r / min and 40℃ for 12 minutes.

[0047] The mixture is added to the main feed port of the twin-screw extruder. Extruder temperatures: Zone 1 150℃, Zone 2 170℃, Zone 3 190℃, Zone 4 197℃, Zone 5 188℃, Zone 6 175℃, Die head 180℃. Screw speed 260 r / min; 10g of the remaining composite pore-forming agent is added to the barrel-side feed port in Zone 4.

[0048] The extruded strips are water-cooled in three stages: the first stage at 50℃, the second stage at 30℃, and the third stage at 12℃, with each stage lasting about 3 seconds. They are then air-dried, pelletized, dried at 80℃ for 3.5 hours, and sieved to obtain particles with a diameter of 2-4 mm. The porosity was measured to be 32%, and the apparent density was 0.61 g / cm³.

[0049] Example 2

[0050] Unlike Example 1, the specific formulation of this example is adjusted as follows: 20 parts of stress dispersion modified masterbatch M2 (0.60 kg), 6.7 parts of maleic anhydride grafted polypropylene (0.20 kg), and 2.0 parts of composite porogen (60 g).

[0051] Extrusion temperatures: Zone 1 152℃, Zone 2 172℃, Zone 3 192℃, Zone 4 200℃, Zone 5 190℃, Zone 6 178℃, Die head 183℃; Screw speed 280 r / min, 14g of composite pore-forming agent added for side feeding; the rest is the same as in Example 1; the porosity measured in this example is 41%, and the apparent density is 0.53 g / cm³.

[0052] Example 3

[0053] Unlike Examples 1 and 2, the specific formulation of this example is adjusted as follows: 12 parts of stress dispersion modified masterbatch M3 (0.36 kg), 4 parts of maleic anhydride grafted polypropylene (0.12 kg), and 1.0 part of composite porogen (30 g).

[0054] Extrusion temperatures: Zone 1 148℃, Zone 2 168℃, Zone 3 188℃, Zone 4 194℃, Zone 5 185℃, Zone 6 172℃, Die head 178℃; Screw speed 240 r / min, 5g of composite pore-forming agent added for side feeding; In this example, the porosity was measured to be 23%, and the apparent density was 0.74 g / cm³.

[0055] Comparative Example 1

[0056] Comparative Example 1 did not prepare stress dispersion modified masterbatch, but used conventional direct physical blending. The raw materials included: copolymer polypropylene, 3.0 kg; halloysite nanotube powder, 276 g; carboxymethyl-β-cyclodextrin, 39 g; ferrocene carboxylic acid, 7.5 g; maleic anhydride grafted polypropylene, 0.15 kg; composite porogen, 45 g; antioxidant, 7.5 g; calcium stearate, 12 g.

[0057] All raw materials were mixed in a high-speed mixer, and the extrusion process was the same as in Example 1.

[0058] Comparative Example 2

[0059] Pure copolymer polypropylene, without any added modifying components.

[0060] Based on all the above preparations, performance tests were conducted; the granules or raw materials obtained in Examples 1-3 and Comparative Examples 1-2 were mixed with copolymer polypropylene at an addition rate of 20 wt% and injection molded; the injection temperature was 175-195℃ and the pressure was 75 MPa.

[0061] Testing standards:

[0062] Tensile strength and elongation at break: GB / T 1040.2-2006, 50 mm / min, 23℃; Notched impact strength: GB / T 1043.1-2008, simply supported beam, V-notch, 4J, 23℃; Apparent density: GB / T 1033.1-2008, impregnation method.

[0063] Table 1 Performance Test Results

[0064] The performance test results show that the impact strength of Example 1 is 263% higher than that of pure PP material, while the tensile strength is only 1.9% lower; the impact strength of Comparative Example 1 is only 100% higher, while the tensile strength is 11.3% lower. The comparison shows that vacuum-injecting the host-guest inclusion complex into the halloysite nanotube cavity and introducing it in the form of cross-linked masterbatch is an effective additive that produces excellent stress dispersion effect.

[0065] The porous plastic modified composite particles in the technical solution of this invention, after being added to a polypropylene matrix, reduce the tensile strength by less than 5%, while the room temperature notched impact strength can reach more than 2.5 times that of pure polypropylene.

[0066] The stress dispersion function mainly relies on structural design: carboxymethyl-β-cyclodextrin and ferrocene form a host-guest inclusion complex within the halloysite nanotube cavity. When the material is subjected to external force, ferrocene molecules slide out of the cyclodextrin cavity, a process that consumes energy. After the external force is removed, the ferrocene molecules slide back into the cavity under thermal motion, and the inclusion complex returns to its original state, demonstrating the ability to repeatedly consume energy. The confined space of the halloysite nanotube restricts the movement of the inclusion complex molecules, and the energy consumption of a single unpacking and unpacking is higher than that in the free solution state. In addition, the high aspect ratio structure of the nanotube itself can effectively transfer stress, dispersing the external load to multiple inclusion complex molecules within the cavity.

[0067] The micron-sized closed pores formed inside the particles by the composite porogen undergo elastic compression under stress, absorbing some energy. The stress that is not completely absorbed by the micron-sized pores continues to be transmitted to the stress-dispersion modified masterbatch, triggering molecular-scale unpacking and energy dissipation. The molecular energy dissipation mechanisms in the micron-sized pores and nanotube cavities respond sequentially during the stress process, forming a two-level stress dispersion system.

[0068] Maleic anhydride-grafted polypropylene, acting as a compatibilizer, accumulates at the interface between the polypropylene matrix and the stress-dispersion modified masterbatch. Through chemical bonding and chain segment entanglement, it enhances the interfacial bonding strength, ensuring that stress can be effectively transferred from the matrix to the interior of the particles. The epoxy-amine crosslinking network binds the filled halloysite nanotubes into the masterbatch, preventing the nanotubes from agglomerating during processing and protecting the filler inside the tube from extrusion and shear damage.

[0069] The three-stage gradient water cooling process makes the cooling rate of the particle surface and interior more consistent, reducing cell shrinkage and internal stress concentration. The resulting closed-cell structure is less prone to collapse during subsequent injection molding. The side-feeding method adds some composite pore-forming agent, which shortens the residence time of the foaming agent in the high-temperature zone and makes the cell distribution more uniform.

[0070] The above embodiments are not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solutions of the present invention are also within the protection scope of the present invention.

Claims

1. A stress-dispersing porous plastic modified composite particle, characterized in that, By weight, the raw materials include: 100 parts of matrix resin, 10-25 parts of stress dispersion modified masterbatch, 3-10 parts of compatibilizer, 0.5-2.5 parts of composite pore-forming agent, 0.1-0.5 parts of antioxidant, and 0.2-0.8 parts of lubricant; The matrix resin is copolymer polypropylene, with a melt index of 15-35 g / 10min at 230℃ and 2.16kg load; The stress dispersion modified masterbatch is prepared by vacuum infusion and cross-linking reaction of halloysite nanotubes, carboxymethyl-β-cyclodextrin, ferrocene carboxylic acid, polypropylene glycol diglycidyl ether and triethylenetetramine. The halloysite nanotube contains a host-guest inclusion complex formed by carboxymethyl-β-cyclodextrin and ferrocene carboxylic acid in its inner lumen.

2. The stress-dispersing porous plastic modified composite particles according to claim 1, characterized in that, The method for preparing the stress dispersion modified masterbatch includes: S1: Dry halloysite nanotubes under vacuum at 110-130℃ for 2-4 hours, place them in a vacuum reactor, evacuate to -0.09 to -0.1MPa, and maintain the pressure for 20-40 minutes; S2: Prepare an aqueous solution containing carboxymethyl-β-cyclodextrin and ferrocene carboxylic acid, with a carboxymethyl-β-cyclodextrin concentration of 0.08-0.15 mol / L and a molar ratio of ferrocene carboxylic acid to carboxymethyl-β-cyclodextrin of 1:0.8-1.

2. Stir at 40-60℃ for 1-2 hours to form a host-guest inclusion complex solution. S3: Maintaining a vacuum state, inject the inclusion complex solution from step S2 into the reactor to impregnate halloysite nanotubes. After restoring normal pressure, ultrasonically disperse for 15-30 minutes, let stand for 6-12 hours, filter, and vacuum dry the solid at 60-80℃ to obtain halloysite nanotubes filled with host-guest inclusion complexes. S4: Mix halloysite nanotubes obtained in step S3 with polypropylene glycol diglycidyl ether and triethylenetetramine at a mass ratio of 1:0.4-0.8:0.1-0.2, knead at 35-45℃ for 15-25 minutes, then cure at 60-70℃ for 2-3 hours, pulverize and sieve to obtain stress dispersion modified masterbatch.

3. The stress-dispersing porous plastic modified composite particles according to claim 2, characterized in that: The halloysite nanotubes in step S1 have a tube length of 0.5-2.5 μm, an outer diameter of 40-80 nm, an inner diameter of 15-40 nm, and a specific surface area of ​​45-75 m² / g.

4. The stress-dispersing porous plastic modified composite particles according to claim 1, characterized in that: The compatibilizer is maleic anhydride-grafted polypropylene with a grafting rate of 0.5-1.5%; the composite porogen is prepared by compounding azodicarbonamide and ammonium bicarbonate at a mass ratio of 1:0.3-0.

8.

5. The stress-dispersing porous plastic modified composite particles according to claim 1, characterized in that: The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:0.8-1.2; the lubricant is calcium stearate or ethylene bis-stearamide.

6. The stress-dispersing porous plastic modified composite particles according to claim 1, characterized in that: The composite particles have a particle size of 1.5-5.0 mm, an internal closed-cell structure, a porosity of 20-45%, and an apparent density of 0.50-0.78 g / cm³.

7. A method for molding stress-dispersing porous plastic modified composite particles according to any one of claims 1-6, characterized in that, Includes the following steps: Step A1: Prepare stress dispersion modified masterbatch; Step A2: Mix the matrix resin, stress dispersion modified masterbatch, compatibilizer, composite pore-forming agent, antioxidant, and lubricant in a high-speed mixer according to the formula. The mixing temperature is 35-50℃, the speed is 600-900 r / min, and the time is 8-15min. Step A3: Feed the mixture obtained in the above steps into a twin-screw extruder for melt extrusion. The temperatures of each section of the extruder are as follows: Zone 1 145-155℃, Zone 2 165-175℃, Zone 3 185-195℃, Zone 4 192-202℃, Zone 5 185-192℃, Zone 6 170-180℃, and the die head 175-185℃. The screw speed is 220-300 r / min. Step A4: The extruded strips are subjected to gradient water cooling, air drying, and pelletizing. They are then dried at 70-90℃ for 2-4 hours and sieved to obtain the stress-dispersed porous plastic modified composite particles.

8. The molding method according to claim 7, characterized in that: The fourth zone barrel of the twin-screw extruder in step A3 is equipped with a side feed port, through which the composite pore-forming agent is added.

9. The molding method according to claim 7, characterized in that: The gradient water cooling in step A4 is set in three stages: the first stage has a water temperature of 45-55℃, the second stage has a water temperature of 25-35℃, and the third stage has a water temperature of 8-15℃, with a dwell time of 2-4 seconds in each stage.

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